characteristics of surface soil creep on a forest slope in japan abstract soil creep was monitored for 6 years using the strain probe method and compared to soil moisture conditions in order to reveal details of the soil creep mechanism on a forest slope in a weathered granite area of central japan the results revealed a relationship between soil creep and soil moisture changes bending strain of the topsoil was induced downslope by soil drying and was reversed by soil wetting however an amount of bending strain remained which accumulated annually to form net soil creep on the upper slope when rainfall exceeded a certain threshold miniature sliding sometimes occurred caused by soil destruction in areas where shear deformation became concentrated on the middle slope topsoil deformation was more complex in order to monitor the soil creep phenomenon related to the concentration of shear deformation in a narrow zone improvement of the strain probe method is needed

the effectiveness of dendrogeomorphic methods for reconstruction of past spatio temporal landslide behaviour abstract dendrogeomorphic methods are in fact frequently used for spatio temporal landslide behaviour reconstruction however their real accuracies have not yet been deeply evaluated the purpose of this study is to evaluate the effectiveness and accuracy of tree ring based methods by comparing them with field monitoring data on landslide behaviours a total of 876 increment cores have been extracted from 219 p sylvestris individuals to reconstruct the past spatio temporal activity of the ubietova landslide 1977 the landslide re activation events recorded within the tree ring series of each tree have been spatially interpolated those data have been compared with the long term field monitoring based on the measured changes in the stabilized geodetic point positions in general the tree ring based spatio temporal landslide evolution revealed a higher landslide activity than the monitoring based one particularly in the lower part of the landslide however higher activity was recorded from the monitoring in the northern part of the upper half of the landslide while approximately 30 of the studied landslide area revealed highly similar normalized values based on both approaches the best fit between the results 80 was in areas with mean cumulative surface displacements of approximately 200 mm monitoring based results and mean event recurrence time of 14 5 years tree ring based results the potential sources of uncertainties that should be considered in future dendrogeomorphic research are the irregular spatial positions and spatial density of trees the physiology of the tree species the inertia of tree growth responses within tree ring sequences and the type of studied landslide

ice storms tree throw and hillslope sediment transport in northern hardwood forests in december 2008 694 trees uprooted within a 108 ha 1 08 km2 watershed in central massachusetts due to a severe ice storm resulting in the displacement of 1300 m3 of root material unconsolidated sediment and fractured bedrock overall we find that uprooting and tree throw is often grouped in clusters and cascades conifers displace more material than deciduous trees areas with abundant mature hemlock and steep slopes are more susceptible to tree throw with clusters as dense as 125 per hectare and failure is predominantly downhill suggesting that ice storms promote efficient downslope hillslope sediment transport in northern hardwood forests combining the recurrence interval of severe storms in new england 20 75 years with the forest response presented here we calculate a sediment transport rate of 2 5 10 5 m3 m 1 a 1 averaged over the entire watershed forest susceptibility to tree throw differed based on location in the watershed some areas experienced up to 30 higher than average sediment transport rates while others experienced no tree throw two severe storms following the 2008 ice storm hurricane in 2011 snow storm in october 2012 did not result in significant tree throw within the study area highlighting that the coupling of storm severity and forest susceptibility controls the amount of tree throw during a given forest disturbance in addition to recent tree throw from the 2008 ice storm widespread pit and mound microtopography in the study area indicates that tree throw is a recurrent process in this landscape two factors emerge that will influence future ice storms related hillslope sediment transport in the steep forested hillslopes of new england regional climate gradients and changing climate determine the size intensity and recurrence of ice storms forest management practices and health control the tree age and type copyright 2015 john wiley sons ltd

tree root mounds and their role in transporting soil on forested landscapes the growth and decay of tree roots can stir and transport soil this is one process that contributes to the mass movement of soil on hillslope to explore the efficiency of this process we document the mounding of soil beside ponderosa and lodgepole pine trees in the forests that dominate the mid elevations of colorado s boulder creek watershed mounds are best expressed around ponderosa pines reaching vertical displacements above the far field slopes of order 10 20 cm fading into the slope by roughly 100 cm distance from the trunks with common diameters of 30 cm positive mounding occurs on all sides of trees on slopes indicating that the mounding is not attributable to deflection of a creeping flow of soil around the tree but rather to the insertion of root volume on all sides in the subsurface mounding is commonly asymmetric even on cross slope profiles significant variation in the mound sizes results in no clear relationship between tree diameter and root volume displaced these observations motivated the development of a discrete element model of tree root growth using the liggghts model in which grains we specified to be root cells were allowed to enlarge within the simulated granular matrix mounding could be reproduced with the majority of the vertical displacement of the surface being attributable to reduction of the bulk density due to dilation of the granular matrix during root enlargement finally we develop a previous analysis of the role of roots in transporting soil during growth and decay cycles we find that even in shallow soils the root cycle can drive significant soil transport down forested montane slopes copyright 2013 john wiley sons ltd

impacts of old comparatively stable treethrow microtopography on soils and forest dynamics in the northern hardwoods of michigan usa abstract uprooting represents a key disturbance process in forests forming pit mound microtopography which can then dramatically impact pedogenesis and the forest ecology at our study sites in northern michigan where well drained sandy spodosols dominate pit mound microtopography tends to persist for millennia because of its persistence the influence of this type of microtopography is greater here than in most forests in that respect our sites represent an end member along a continuum of forest soil disturbance by uprooting we studied post uprooting pedogenesis at 14 dated pit mound pairs mapped and characterized the pit mound topography over 2 8 ha the soils below within 317 soil profiles and the trees above to better understand the complex interactions among this type of disturbance regime and forest dynamics we used a pair correlation function and chi square test approach to study the relationships between treethrow features and the living trees at one of these sites soil variability as affected by microtopography was studied using geostatistics pit mound microtopography here covers 17 of the surface and are generally randomly distributed across the forest floor mounds are more prominent features of the forest floor than are pits pits infill with sediment and litter obscuring them whereas mounds persist for millennia in the sandy sediment because runoff is limited and litter forms a protective armor treethrow features had volumes of roughly 214 225 m3 ha and on average each uprooting event translocated 0 6 m3 of soil about 0 8 m laterally and 0 1 0 2 m vertically areas of the pit mound features did not differ between slope aspects supporting an idea that on the gentle slopes of the study sites uprooting does little to affect the movement of sediment downslope the exceptional longevity of the treethrow features is probably a factor in the statistical randomness with which treethrow features are distributed on the forest floor as footprints of many uprooting events are interlaced across the forest floor as reported elsewhere soil development was accelerated in pits leading to increasingly greater differences in soil development between pits and mounds over time and illustrating the concept of locally divergent pedogenesis in older pits the abnormally thick soil profiles extent so far below the depth of rooting that they are unlikely to be disturbed by future uprooting events on the coarser spatial scale of the forest stand uprooting decreased the ranges and increased the sills of spatial autocorrelation for o e and bhs horizon thicknesses the effect of treethrow dynamics on soil characteristics was greatest and statistically most significant for e horizon thicknesses where the range was decreased from 13 m to 10 m whereas the maximal level of semivariance sill increased by 42 all tree species preferred treethrow mounds to pits or undisturbed microsite for regeneration especially acer saccharum

spatial and temporal analysis of mass movement using dendrochronology tree growth and inclination on sloping land is affected by mass movement suitable analysis of tree growth and tree form can therefore provide considerable information on mass movement activity this paper reports a new automated method for studying the temporal and spatial aspects of mass movement activity ringwidth data from only a few cores per tree are required the method uses filtering techniques and statistical time series analysis preliminary results for two landslides in the barcelonnette area of the french alps show a relative stability of movement activity over the last hundred years no trend and short periodicity six to seven year periods of mass movement activity the advantages of the method over other mostly visual methods are its clearness flexibility repeatability and rapidity however further testing is needed to examine its reliability

conditions for feedbacks between geomorphic and vegetation dynamics on lateral moraine slopes a biogeomorphic feedback window little ice age lateral moraines represent one of the most important sediment storages and dynamic areas in glacier forelands following glacier retreat simultaneous paraglacial adjustment and vegetation succession affect the moraine slopes geomorphic processes e g debris flows interrill erosion gullying solifluction disturb and limit vegetation development while increasing vegetation cover decreases geomorphic activity thus feedbacks between geomorphic and vegetation dynamics strongly control moraine slope development however the conditions under which these biogeomorphic feedbacks can occur are insufficiently understood and major knowledge gaps remain this study determines feedback conditions through the analysis of geomorphic and vegetation data from permanent plots in the turtmann glacier foreland switzerland results from multivariate statistical analysis i confirm that dryas octopetala l is an alpine ecosystem engineer species which influences geomorphic processes on lateral moraines and thereby controls ecosystem structure and function and ii demonstrate that biogeomorphic feedbacks can occur once geomorphic activity sufficiently decreases for d octopetala to establish and cross a cover threshold in the subsequent ecosystem engineering process the dominant geomorphic processes change from flow and slide to bound solifluction increasing slope stabilization induces a decline in biogeomorphic feedbacks and the suppression of d octopetala by shrubs we conceptualize this relationship between process magnitude frequency and species resilience and resistance to disturbances in a biogeomorphic feedback window concept our approach enhances the understanding of feedbacks between geomorphic and alpine vegetation dynamics on lateral moraine slopes and highlights the importance of integrating geomorphic and ecological approaches for biogeomorphic research copyright 2015 john wiley sons ltd

quantification of soil production and downslope creep rates from cosmogenic 10be accumulations on a hillslope profile average soil transport rates over a period of 3500 yr on a convex soil mantled hillslope have been quantified using a mass balance model that incorporates the soil concentration of the cosmogenic isotope 10 be the 10 be model results support the assumption used in most geomorphic models that the soil creep rate is proportional to surface gradient the predicted diffusion coefficient is 360 55 cm 3 yr 1 cm 1 contour length and the average rate of soil production is 0 026 0 007 cm yr within the uncertainty of this technique the data do not reject g k gilbert9s hypothesis that some hillslopes may exist in a condition of dynamic equilibrium with a uniform soil production rate however the model does not require an assumption of dynamic equilibrium and may be an approach that uniquely allows the quantification of a local soil production rate law

tracing hillslope sediment production and transport with in situ and meteoric 10be 1 we use in situ produced and meteoric 10be analyzed in soils from 28 pits on four hillcrest parallel transects along a 14 hillslope in the great smoky mountains north carolina as tracers of soil production and transport we rely upon amalgamation both to investigate and smooth spatial variability in 10be concentrations lidar indicates that the hillslope is topographically complex and that soil is moved downslope diffusively until it encounters the ephemeral channel network and is rapidly exported in situ produced 10be measured in depth profiles indicates that over millennial timescales soils are mixed above the soil saprolite boundary in contrast meteoric 10be concentrations increase with depth and are correlated to concurrent increases of dithionite extractable al and ph observations explained by similar al and be mobility in the soil the concentrations of both meteoric and in situ produced 10be increase downslope proportional to the maximum soil particle path length the data suggest virtual downslope soil velocities of 1 1 1 7 cm yr 1 in a well mixed active transport layer 60 cm thick the thickness of this transport layer is constant downslope and depends on the rooting depth and consequent root wad thickness of downed trees on the slope both of which reflect depth to the soil saprolite boundary both meteoric and in situ produced 10be suggest that soil production is balanced by surface denudation at rates between 10 and 13 m myr 1 soil residence times on the slope range from 21 to 33 kyr based on the meteoric 10be inventories major element geochemical analysis suggests little if any elemental loss during soil transport downslope

short term soil mixing quantified with fallout radionuclides soil mixing plays a significant role in contaminant transport carbon sequestration and landscape evolution yet the rates and driving mechanisms are poorly constrained here we use depth profiles and advection diffusion modeling of fallout nuclides to quantify differences in short term 7 be and weapons derived isotopes and quantify mixing with a steady state model of vertical 210 pb transport on a forested landscape in the bega valley in southeastern australia and on grasslands in marin county california where bioturbation is documented as the dominant sediment transport mechanism we calculate diffusion like mixing coefficients of 1 2 cm 2 yr 1 in montane forest soils of northern new england we observe little field evidence of short term mixing and find that the traditional advection diffusion model fails to describe 210 pb profiles because nuclide profiles here can be described with a simple model of litterfall organic matter decay and radioactive decay we argue that diffusion like processes are barely active on short time scales and that the advection diffusion model overestimates diffusion like transport while animal bioturbation and soil freezing cycles have little effect on the fate of elements in new england physical soil mixing drives transport at bega valley and marin county we suggest that the absence of soil stirring that we quantify in new england forests may explain the slow physical erosion here 0 2 cm k y relative to the actively bioturbated soils of bega valley and marin county 5 10 cm k y

the soil production function a brief history and its rediscovery abstract in 1877 g k gilbert reasoned that the rate at which bedrock is converted to soil reaches a maximum under an optimal soil depth that facilitates contact between bedrock and water such that freeze thaw and chemical weathering are maximised in doing so he outlined the functional dependence of soil production bedrock weathering on local soil depth however the concept of a soil production function does not appear to have been utilised until well into the following century when carson and kirkby carson m a kirkby m j 1972 hillslope form and process cambridge university press cambridge 475 pp expressed it as a notional relationship they also noted that at depths less than optimum instability exists that will either drive soil depth to the optimal weathering depth or to zero depth more recent work has also described a declining exponential soil production function in which the highest rate is at zero soil depth despite dealing with a fundamental issue in soil science viz soil formation the soil production concept has been applied mostly to landscape evolution studies the situation is ripe for its use in soil science and developments in techniques such as cosmogenic nuclides will assist this

converse pathways of soil evolution caused by tree uprooting a synthesis from three regions with varying soil formation processes abstract post disturbance pedogenetic pathways were characterized in three landscapes representing different degrees of weathering and leaching tree uprooting has been the main form of disturbance in all three landscapes we hypothesized that the pedogenetic effect of trees due to uprooting is mainly governed by the regional degree of pedogenesis which in turn affects soil and landscape evolution the three regions were characterized by a chronosequence of treethrow pit mound pairs from fresh to almost leveled forms two sequences originated from the czech republic one on haplic cambisols and one on entic podzols the third and the oldest chronosequence in michigan usa was on albic podzols dating back to 4080 bce we analyzed 38 chemical and physical soil properties for 700 samples from 42 pit mound pairs in these regions ordination and regression techniques allowed us to evaluate the effect of sample depth microsite pit mound and undisturbed control position and age of the soils formed after uprooting depth was the most significant variable in all regions p

evolution of a young parasitic cone towards a mature central vent izalco and santa ana volcanoes in el salvador central america abstract izalco volcano is a young parasitic cone located 4 km south and seaward from the central crater of santa ana volcano a mature composite cone at equal sio 2 contents izalco s lavas have lower large ion lithophile element lile contents than santa ana s lavas but the compositions of izalco s lavas have converged toward those of santa ana with time possibly by open system fractionation short term fluctuations in the sio 2 content of lavas at izalco are closely related to the level of preceding activity the higher the level of preceding activity the lower the sio 2 content a stratigraphic section of lavas from the santa ana crater appears to be an inverted magma chamber with a zoned silicic top and a uniform basaltic base these observations suggest that graded silicic zones are regularly developed at the top of the basaltic magma bodies feeding this volcanic center nearly contemporaneous eruptions of distinctly different magma types 1770 1965 at izalco 1904 at santa ana and 1722 at san marcellino suggests the presence of three different magma bodies beneath the santa ana complex a lile poor mafic magma body beneath izalco a lile rich mafic magma body beneath santa ana and a rhyolitic magma beneath the coatepeque caldera located on the northeast flank of santa ana

the complex nature of creep movements on steeply sloping ground in southern rwanda long term soil creep motion is often represented as a type of laminar flow with velocity vectors parallel to the slope and constant in time records on a hillslope in southern rwanda reveal that creep movements there compare more with turbulent flow characterized by a a1 humic horizon superlayer creeping over a subsoil affected by more irregular creep deformation

lateglacial and holocene vegetation belts in the pirin mountains southwestern bulgaria pollen stratigraphy of a core 270 cm long from lake dalgoto at 2310 m in the northern pirin mountains southern bulgaria was treated by optimal partitioning and compared to a broken stick model to reveal statistically significant pollen zones the vegetational reconstructions presented here are based on pollen percentages and pollen influx on comparisons of modern and fossil pollen spectra and on macrofossil dates from other sites in the mountains during the younger dryas 11000 10200 14c yr bp an open xerophytic herb vegetation with artemisia and chenopodiaceae was widely developed around the lake deciduous trees growing at lower elevations contributed to the pollen rain deposited at the higher elevation sampling sites specifically from 10200 to 8500 yr bp quercus ulmus tilia and betula expanded rapidly at low and intermediate elevations and between 8500 and 6500 yr bp they extended to higher elevations close to the upper forest limit which was formed by betula pendula at about 1900 m coniferous species were limited in the region at this time after 6500 yr bp the expansion of conifers pinus peuce p sylvestris p mugo abies alba at high elevations forced the deciduous trees downward between 6500 and 3000 yr bp the forest limit at 2200 m was formed by p peuce and a alba had its maximum vertical range up to 1900 m later the abundance and vertical range of p peuce and a alba were reduced after 3000 yr bp picea expanded

the effects of bioturbation on soil processes and sediment transport abstract plants and animals exploit the soil for food and shelter and in the process affect it in many different ways for example uprooted trees may break up bedrock transport soil downslope increase the heterogeneity of soil respiration rates and inhibit soil horizonation in this contribution we review previously published papers that provide insights into the process of bioturbation we focus particularly on studies that allow us to place bioturbation within a quantitative framework that links the form of hillslopes with the processes of sediment transport and soil production using geometrical relationships and data from others work we derive simple sediment flux equations for tree throw and root growth and decay

gelifluction viscous flow or plastic creep this paper reports results from two scaled centrifuge modelling experiments designed to simulate thaw related gelifluction a planar 12 prototype slope was modelled in each experiment using the same natural fine sandy silt soil however two different scales were used in experiment 1 the model scale was 1 10 tested in the centrifuge at 10 gravities g and in experiment 2 the scale was 1 30 tested at 30 g centrifuge scaling laws indicate that the time scaling factor for thaw consolidation between model and prototype is n2 where n is the number of gravities under which the model was tested however the equivalent time scaling for viscous flow is 1 1 if gelifluction is a viscosity controlled flow process scaling conflicts will therefore arise during centrifuge modelling of thawing slopes and rates of displacement will not scale accurately to the prototype if however no such scaling conflicts are observed we may conclude that gelifluction is not controlled by viscosity but rather by elasto plastic soil deformation in which frictional shear strength depends on effective stress itself a function of the thaw consolidation process models were saturated consolidated and frozen from the surface downwards on the laboratory floor the frozen models were then placed in the geotechnical centrifuge and thawed from the surface down each model was subjected to four freeze thaw cycles soil temperatures and pore water pressures were monitored and frost heave thaw settlement and downslope displacements measured pore water pressures displacement rates and displacement profiles reflecting accumulated shear strain were all similar at the two model scales and volumetric soil transport per freeze thaw cycle when scaled to prototype were virtually identical displacement rates and profiles were also similar to those observed in earlier full scale laboratory floor experiments it is concluded therefore that the modelled gelifluction was not a time dependent viscosity controlled flow phenomenon but rather elasto plastic in nature a first approximation flow law is proposed based on the cam clay constitutive model for soils

preface multiscale feedbacks in ecogeomorphology 1 introductiongeomorphic systems are known to exhibit nonlinear responses tophysical biological feedbacks thornes 1985 baas 2002 reinhardtet al 2010 these responses make understanding and or predictingsystem response to change highly challenging with growingconcerns over ecosystem health a pressing need exists for researchthat tries to elucidate these feedbacks jerolmack 2008 darby 2010 national research council 2010 a session was convened at the fall2008 meeting of the american geophysical union agu to providean outlet for some of this truly interdisciplinary and original research which is central to understanding geomorphic and ecologicaldynamics the session attracted over 39 contributions which weredivided into two well attended oral sessions and a very busy postersession this special issue presents new research from the agu session which highlights clear physical biological feedbacks the aim is tobring together contrasting perspectives on biological and geomorphicfeedbacks in a diversity of physiographic settings ranging fromwetlands and estuaries through rivers to uplands these papershighlight biological and physical feedbacks which involve themodulation or ampli cation of geomorphic processes these paperswill be of interest to a core geomorphology audience and should alsodraw attention from the elds of ecohydraulics hydroecology ecohydrology ecomorphology biogeochemistry and biogeography and biogeomorphology as well as the more traditional elds ofhydrology ecology and biology in this preface to the special issue we a review past contributionsto the emerging eld of ecogeomorphology and related disciplines b provide some context for how this topical special issue came tofruition and c summarize the contributions to this special issue 2 what is ecogeomorphology examples of studies explicitly integrating ecology and geomor phology date back to at least the late 1800s e g cowles 1899 withmore examples appearing in the 1950s e g olson 1958 and 1960s e g hack and goodlet 1960 terms such as ecogeomorphology andbiogeomorphologyonlybecamepopularinthe1990s osterkampandhupp 2010 the 1990 british geomorphology research groupannual meeting thornes 1990 and the 1995 binghamton sympo sium on biogeomorphology hupp et al 1995b were two of the rstsymposiums to emphasize the theme of biogeomorphology ecogeo morphology and biogeomorphology are generally considered syno nyms hupp et al 1995a but they do sprout from slightly differentresearch interests both are part of a larger family of terms thatresearchers have used somewhat inconsistently to describe researchat the interface between some combination of hydrology geomor phologyand orecology biology fig 1 unlikesomeoftheothereco geo hydro combinations in fig 1 the eco or bio root is an adjectivemodifying the noun geomorphology based on the types of researchpublished under these two banners the biogeomorphology commu nity has generally focused more on how chemical and physicalweathering are ampli ed and modulated with biological feedbacks ecogeomorphology is commonly used to describe studies that focusmore on the ampli cation and modulation of erosion and depositionprocesses both are fundamentally concerned with the bidirectionalin uences of biota and landscapes on each other biogeomorphologyis concerned with both the in uence of landforms on plants animalsand micro organisms distribution and development as well as thein uence of those plants animals and micro organisms on earthsurfaceprocessesandthelandformsshapedbythoseprocesses viles 1988 naylor et al 2002 p 4 loosely de ne biogeomorphology asinvolving the cooperation between ecology and geomorphology tostudy two way linkages between ecological and geomorphologicalprocesses murray et al 2008 argue that biomorphodynamics is amore restrictive term than biogeomorphology or ecogeomorphology and that it highlights landscape dynamics in which an explicit twoway coupling i e feedback occurs between biotic and physicalprocesses therelatedzoogeomorphology e g butler 1995 termhasreceived less play but it is worth mentioning that research under thisbanner focuses on examples of animals in uencing geomorphicprocesses and landforms e g beaver salmon burrowing animals etc the term biogeomorphology has been more widely used sinceviles 1988 rst attempted to provide a comprehensive overview ofwhat was at that time an emerging discipline a review of web of

effects of treethrow microtopography on the characteristics and genesis of spodosols michigan usa summary this study examined the pedogenic effects of pit and mound microtopography formed by tree uprooting in a spodosol haplorthods landscape most soils in treethrow pits were entic haplorthods or spodic upidsamments whereas mound soils usually classified as typic udipsamments suggesting that degree of profile development is undisturbed pit mound given that pit and mound soils are substantially younger than pedons on undisturbed sites rates of pedogenesis are thought to be pit undisturbed mound strong pedogenesis in pits was explained by 1 greater water contents in the upper sola which may facilitate weathering processes 2 thicker o horizons which may lead to increased production of organic acids and 3 greater insulation by thick litter and snow cover which reduces the incidence of soil freezing in winter mound soils may develop impermeable layers of concrete soil frost that impede infiltration of snowmelt waters whereas pit soils remain unfrozen or acquire only a porous granular frost layer thus saturated flow of snowmelt within pits is relatively unrestricted resulting in maximal leaching and profile differentiation

geomorphic controls of soil spatial complexity in a primeval mountain forest in the czech republic abstract soil diversity and complexity is influenced by a variety of factors and much recent research has been focused on interpreting or modeling complexity based on soil topography relationships and effects of biogeomorphic processes we aimed to i describe local soil diversity in one of the oldest forest reserves in europe ii employ existing graph theory concepts in pedocomplexity calculation and extend them by a novel approach based on hypothesis testing and an index measuring graph sequentiality the extent to which soils have gradual vs abrupt variations in underlying soil factors and iii reveal the main sources of pedocomplexity with a particular focus on geomorphic controls a total of 954 soil profiles were described and classified to soil taxonomic units stu within a 46 ha area we analyzed soil diversity using the shannon index and soil complexity using a novel graph theory approach pairwise tests of observed adjacencies spectral radius and a newly proposed sequentiality index were used to describe and quantify the complexity of the spatial pattern of stus this was then decomposed into the contributions of three soil factor sequences sfs i degree of weathering and leaching processes ii hydromorphology and iii proportion of rock fragments six reference soil groups and 37 second level soil units were found a significant portion of pedocomplexity occurred at distances shorter than the 22 m spacing of neighbouring soil profiles the spectral radius an index of complexity of the pattern of soil spatial adjacency was 14 73 to which the individual sfs accounted for values of 2 0 8 0 and 3 5 respectively significant sequentiality was found for degree of weathering and hydromorphology exceptional overall pedocomplexity was particularly caused by enormous spatial variability of soil wetness representing a crucial soil factor sequence in the primeval forest moreover the soil wetness gradient was partly spatially correlated with the gradient of soil weathering and leaching suggesting synergistic influences of topography climate hydro geology and biomechanical and biochemical effects of individual trees the pattern of stony soils random in most respects resulted probably from local geology and quaternary biogeomorphological processes thus while geomorphology is the primary control over a very locally complex soil pattern microtopography and local disturbances mostly related to the effects of individual trees are also critical considerable local pedodiversity seems to be an important component of the dynamics of old growth mixed temperate mountain forests with implications for decreasing pedodiversity in managed forests and deforested areas

change in the frequency of extreme events as the indicator of climatic change in the holocene in fluvial systems abstract the transformation of natural systems of climatic origin in the holocene may be realised by a change in the type of extreme events or by a change in their frequency or by both the rapid warming at the younger dryas preboreal transition exemplifies a parallel drop in frequency and a change in the type of events several wetter phases of the holocene are characterised by rises in frequency of various types of extreme rainfalls the fragmentary records of events in the fluvial and slope systems coincide with smoothed variations in stable ecosystems and shifts of ecotonal zones such as tree line and lake levels

the role of trees in the geomorphic system of forested hillslopes a review abstract forested hillslopes form a special geoecosystem an environment of geomorphic processes that depend strongly on forest ecology including the growth and decay of trees changes in structure disturbances and other fluctuations hence the following various functions of trees are reviewed here their role in both biomechanical and biochemical weathering as well as their importance for the hillslope geomorphic subsystem and for transport of soil material via tree uprooting and root growth special attention is paid to tree uprooting a process considered the most efficient and most frequent biogeomorphological indicator of bio physical activity within forest in complex terrain trees have varied implications for soil formation in different environments boreal to tropical forests and altitudes in this paper an attempt has been made to emphasize how trees not only modulate geomorphic processes but also how they act as a direct or indirect agent of microrelief formation the most striking example of which being widespread and long lasting pit and mound microtopography based on the analyzed literature it seems that some problems attributed to forest ecology can have a fundamental effect on forested hillslope dynamics a relationship which points to the need for its integration and interpretation within the field of geomorphology the biology of individual trees has a key influence on the development of e g rock faces weathering front migration and changes in the soil biomantle within upper and lower forest belts additionally forms and sediments depend largely on the horizontal and vertical extent volume and structure of root systems as well as on active processes taking place in the root zone and rhizosphere furthermore although trees to a large extent stabilize slope surfaces their presence can also have a dual effect on slope stability due to tree uprooting a process which in some circumstances can trigger mass movements e g debris avalanches so far several attempts at quantifying the influence of trees on slopes have been made via the use of mathematical equations enabling researchers to calculate 1 the root plate volume of uprooted trees 2 the amount of soil displacement due to tree root growth and 3 rates of erosion sedimentation and soil creep in light of the reviewed literature the most urgent issue appears to be the need for a thorough study of the interactions and feedbacks occurring between trees and geomorphic systems e g soil mixing and biotransport by trees in different climate zones altitudes and time frames especially in terms of the development of forest ecosystems during the holocene

vegetation as a major conductor of geomorphic changes on the earth surface toward evolutionary geomorphology earth surface processes and landforms may have coadjusted with plant morphology biomechanics and life history we suggest that the colonization of land by plants at the early silurian and their propagation inside continents represent critical phases of the coupling between geomorphic and biological processes on the earth at a global scale the consideration of this coupling involving geomorphic biological feedback mechanisms at the scales of ecological succession and organisms evolution may promote the emergence of an evolutionary geomorphology copyright 2009 john wiley sons ltd

roots rock and regolith biomechanical and biochemical weathering by trees and its impact on hillslopes a critical literature review the role of trees and forests as a critical component of the biosphere and critical zone and of the earth system more generally is widely appreciated less known and acknowledged are the geomorphological functions of tree roots although their importance has been widely referred to in soil studies paleopedology and paleobotany tree roots and their impact on weathering processes and soil production were incorporated in the devonian plant hypothesis and tree root casts served as a key evidence of recognition of past soils in geology sedimentology and paleopedology however knowledge of biomechanical and biochemical weathering induced by vascular plant roots mainly trees has been rarely utilized in geomorphic studies biogeomorphic and pedologic studies in recent decades have highlighted the importance of tree uprooting in which roots play a primary role in soil development regolith disturbance and bedrock mining other important functions of roots were also recognized e g soil displacement by growing roots infilling of stump holes and root cavities root groove development direct and indirect effects taking place in the rhizosphere and mycorrhizosphere mainly biochemical weathering of minerals support by microbial communities and symbiotic fungi and changes in porosity permeability and hydrology of soils in the root zone however further studies are urgently needed because many aspects of biochemical and biomechanical weathering are not well understood this is especially true with respect to taxa specific impacts variations in root architectures edaphic settings ecological relationships and geographic ranges result in substantially different biogeomorphic impacts of different tree species additionally the same species in different environmental settings may have different effects

regolith properties under trees and the biomechanical effects caused by tree root systems as recognized by electrical resistivity tomography ert abstract following previous findings regarding the influence of vascular plants mainly trees on weathering soil production and hillslope stability in this study we attempted to test a hypothesis regarding significant impacts of tree root systems on soil and regolith properties different types of impacts from tree root system direct and indirect are commonly gathered under the key term of biomechanical effects to add to the discussion of the biomechanical effects of trees we used a non invasive geophysical method electrical resistivity tomography ert to investigate the profiles of four different configurations at three study sites within the polish section of the outer western carpathians at each site one long profile up to 189 m of a large section of a hillslope and three short profiles up to 19 5 m that is microsites occupied by trees or their remnants were made short profiles included the tree root zone of a healthy large tree the tree stump of a decaying tree and the pit and mound topography formed after a tree uprooting the resistivity of regolith and bedrock presented on the long profiles and in comparison with the short profiles through the microsites it can be seen how tree roots impact soil and regolith properties and add to the complexity of the whole soil regolith profile trees change soil and regolith properties directly through root channels and moisture migration and indirectly through the uprooting of trees and the formation of pit and mound topography within tree stump microsites the impact of tree root systems evaluated by a resistivity model was smaller compared to microsites with living trees or those with pit and mound topography but was still visible even several decades after the trees were windbroken or cut down the ert method is highly useful for quick evaluation of the impact of tree root systems on soils and regolith this method in contrast to traditional soil analyses offers a continuous dataset for the entire microsite and at depths not normally reached by standard soil excavations the non invasive nature of ert studies is especially important for protected areas as it was shown in the present study

breaking ground pedological geological and ecological implications of soil bioturbation abstract soil and its biota are fundamental components of the critical zone earth s living skin that most directly sustains life within that zone geologically rapid soil and saprolite displacement by biota particularly invertebrate meso and macrofauna affects a large proportion of earth s soils this was first recognised by late 19th century observers on both sides of the atlantic ocean who regarded bioturbation as fundamental to soil formation throughout much of the 20th century however the agronomical focus of soil scientists and the dominant paradigm of landscape evolution relegated bioturbation as a result many aspects of bioturbation are still not widely appreciated only in the last few decades has a re evaluation commenced in a range of disciplines primary effects of bioturbation which we quantify herein include soil production from saprolite the formation of surface mounds soil burial and downslope transport rates of bioturbation can be as rapid as sustained maximum rates of tectonic uplift in concert with surface geomorphic processes bioturbation alters fundamental properties of soil including particle size distribution porosity the content of carbon and other nutrients and creep flux rate the precise influence of biotic mixing is regulated by its depth function earth s incredibly diverse soil biota also perform a number of functions at a range of spatial and temporal scales that extend beyond soil to landscape evolution ecosystem engineering niche construction and carbon cycling understanding these linkages which have operated since the evolution of trees in the devonian period is of growing importance as we seek a fuller picture of earth s history to predict and manage its future

surface processes and interactions with forest vegetation on a steep mudstone slope stolowe mountains sw poland abstract in this study we recognize complex physical biotic abiotic interactions on a steep forested slope in the moderately elevated mountain terrain of the sudetes central europe using geomorphological pedological and dendrochronological methods on the forested hillslopes of mt rogowa kopa the evidence of disturbance in natural systems is widespread in the geomorphic subsystem its most obvious manifestation is the origin and disappearance of pit and mound microtopography resulting from tree uprooting 82 pit and mound associations have been mapped on a test slope providing quantitative data for calculating sediment flux the flux is around 2 10 4 m 3 m 1 year 1 hence less than suggested in the literature but within the same order of magnitude nevertheless in the long term such a transport rate is comparable with the one typical for creep while it affects a greater thickness of hillslope regolith tree bending and abrupt changes in tree ring width are indicators of disturbed tree growth causally linked to soil creep of mudstone derived regolith eccentric growth is best recorded in wet years and in younger trees which have to adapt to the pre existing pit and mound surface topography we offer a conceptual model that links biotic and abiotic factors and discuss implications of the widespread tree uprooting we suggest that veneers of angular clasts and occasional larger boulders are not necessarily residuals of washed pleistocene solifluction mantles but may result from root plate degradation after uprooting recent catastrophic wind events may through tree uprooting lead to structural changes in cover deposits so that they lose their inherited periglacial signatures

anthropogenic sources stimulate resonance of a natural rock bridge the natural modes of vibration of bedrock landforms as well as the sources and effects of stimulated resonance remain poorly understood here we show that seismic energy created by an induced earthquake and an artificial reservoir has spectral content coincident with the natural modes of vibration of a prominent rock bridge we measured the resonant frequencies of rainbow bridge utah using data from two broadband seismometers placed on the span and identified eight distinct vibrational modes between 1 and 6 hz a distant induced earthquake produced local ground motion rich in 1 hz energy stimulating a 20 db increase in measured power at the bridge s fundamental mode moreover we establish that wave action on lake powell an artificial reservoir generates microseismic energy with peak power 1 hz also exciting resonance of rainbow bridge these anthropogenic sources represent relatively new energy input for the bridge with unknown consequences for structural fatigue

dendrogeomorphological analysis of mass movement a technical note on the research method dating of mass movement events by examining the course of eccentricity of the annual rings of trees inclined as a result of these movements can be a problem in the case of multiple inclined trees showing compound trunk curvature and complex reaction wood these problems however can be solved when sampling of ring width cores is based on accurate analysis of the form of the trunk

soil creep problems raised by a 23 year study in australia in october 1965 and february 1966 55 young pits were installed in tropical northern territory nt and temperate new south wales nsw pits were monitored in 1968 1971 and 1974 also for the nt only in 1988 in each region half of the pits are on weathered granite and half on sandstone local relief is 30m or less and slopes are up to 20 annual rainfall is evenly distributed in the nsw sites 800 mm a 1 but is confined to the five to six month wet season in nt 1200 mm a 1 six pits suffered external disturbance and so were not analysed analysis of 160 rods in 49 undisturbed pits shows 1 vectorial movement generally not downslope parallel to the ground surface but dominated by a vertically downward component 2 significant uphill and vertically upward components of movement for many rods 3 a weak correlation between total movement and sine of slope 4 rapid movement during 1965 68 and slow movement thereafter 5 significantly higher creep rates on the nt granites than on all other sites perhaps because mound building termites are especially active there we conclude that our data do not support soil creep models which assume that all movement is downslope and slope parallel repeated long term measurements are essential to distinguish long term creep rates from the short term effects of disturbance copyright 1999 john wiley sons ltd

soil creep process and its role in debris slide generation field measurements on the north side of tsukuba mountain in japan we measured the ground inclination movement moisture content and amount of rainfall on a valley head slope and a side slope along the valley on the northern side of tsukuba mountain and elucidated the process and role of soil creep in debris slide generation soil creep usually occurs during and after rain the amount of creep caused by one rainfall has a positive correlation with the amount of rain and increase in soil moisture for the valley head slope soil creeps down and accumulates at the bottom bottleneck part of the head hollow in which soil is compressed and forms a wavy landform the lower end of the head hollow gradually becomes steeper and unstable side slopes along a valley head slope show differences in topsoil thickness and creep speed between sections near and below a knick line the amount of soil creep per year is larger in a section near a knick point than that below it soil gradually concentrates directly below the knick point and the slope becomes steeper and unstable the total amount of soil movement in 1 year was several millimeters for both the valley head and side slopes this means several liters year of soil squeeze out for every slope section of 1 m in width this value is similar to the general speed of erosion caused by debris slide mainly topsoil failure or shallow landslide in japan furthermore neither surface erosion nor internal erosion has been observed in this site soil creep seems to carry most of the debris to places where debris slides will occur in this site soil creep prepares future debris slides and dominates the cycle of debris slide as well

can low magnitude earthquakes act as a triggering factor for landslide activity examples from the western carpathian mts poland abstract there are numerous examples of the impact of strong earthquakes on landslide activity there is however very little information about the ability of low magnitude earthquakes m

processes responsible for the development of a pit and mound microrelief abstract hummocky ground is a conspicuous feature of some cultivated pastures in the mountain forests of the alps in the german scientific literature this pit and mound microrelief is termed buckelwiese literally hummocky meadow and is commonly interpreted as a fossil late glacial relief of cryogenic origin this paper suggests an alternative hypothesis namely that relief formation was initiated by the uprooting of trees during storms in the rootstock pits karst processes gradually amplified the initial relief this alternative hypothesis is tested in a buckelwiesen area of the northern limestone alps where pit to mound vertical relief amounts to 52 cm and mounds are 250 510 cm long and 170 270 cm wide and the density of pits and mounds is 400 ha 1 field investigations included a ground survey using a tacheometer and the excavation of a trench to check the internal structure of one pit mound couple the trench was subsequently used to estimate solution rates in the subsurface material of pits and mounds based on the results of the field measurements and two radiocarbon dates from the test site the paper concludes that in the study area a treethrow event occurred between 1120 and 1280 ad subsequently the pits created by the uprooted trees were deepened by limestone solution at a rate of 77 2 mm 1000 years the reconstructed formation history of the microrelief of the study area is consistent with a holocene origin with rates of limestone dissolution as measured in the field and with the morphometry of the features themselves

soil creep dynamics soil moisture and temperature conditions on a forested slope in the granitic vosges mountains france soil creep soil water tension and soil temperature were monitored at the schildmatt experimental site over a 7 month period in order to study the dynamics of creep movements measured with a specially designed strain gauge probe the limited displacements and the very low signals which had to be measured were taken into account in estimating the uncertainty in measurements the results obtained emphasize the very discontinuous and highly reversible character of the creep movements and their seasonal nature displacements occurred mainly during two events their size were 10 mm and 2 mm but the overall displacements for the whole intensive study period january july 1985 was only 3 mm the relationships with soil moisture and temperature conditions indicated that ice segregation and saturated conditions are major influences but more needs to be known about the way they act on soil creep

biotic origin for mima mounds supported by numerical modeling article i nfo mima mounds are 1 m high hillocks found on every continent except antarctica despite often numbering in the millions within a single field their origin has been a mystery with proposed explanations ranging from gla cialprocesses to seismic shaking one hypothesisproposes that mounds innorth america are built by burrowing mammals to provide refuge from seasonally saturated soils we test this hypothesis with a numerical model parameterized with measurements of soil transport by gophers from a california mound field that couples animal behavior with geomorphic processes the model successfully simulates the development of the mounds as well as key details such as the creation of vernal pools small intermound basins that provide habitat for en demic species furthermore we demonstrate that the spatial structure of the modeled mound fields is similar to actual mound fields and provides an example of self organized topographic features we conclude that scaled by body mass mima mounds are the largest structures built by nonhuman mammals and may provide a rare example of an evolutionary coupling between landforms and the organisms that create them

breakage or uprooting how tree death type affects hillslope processes in old growth temperate forests abstract tree breakage and uprooting are two possible scenarios of tree death that have differing effects on hillslope processes in this study we aimed to i reveal the long term structure of the biomechanical effects of trees bets in relation to their radial growth and tree death types in four old growth temperate forests in four different elevation settings with an altitudinal gradient of 152 1105 m a s l ii quantify affected areas and soil volumes associated with the studied bets in reserves and iii derive a general model of the role of bets in hillslope processes in central european temperate forests we analyzed the individual dynamics of circa 55 000 trees in an area of 161 ha within four old growth forests over 3 4 decades basal tree censuses established in all sites in the 1970s and repeated tree censuses in the 1990s and 2000s provided detailed information about the radial growth of each tree of dbh 10 cm as well as about types of tree death we focused on the quantification of i surviving still living trees ii new recruits iii standing dead trees iv uprooted trees and v broken trees frequencies of phenomena were related to affected areas and volumes of soil using individual statistical models the elevation contrasts were a significant factor in the structure of bets differences between sites increased from frequencies of events through affected areas to volumes of soil associated with bets an average 2 7 m3 ha 1 year 1 was associated with all bets of the living and dying trees in lowlands while there was an average of 7 8 m3 ha 1 year 1 in the highest mountain site differences were caused mainly by the effects of dying trees bets associated with dead trees were 7 8 times larger in the mountains effects of dying trees and particularly treethrows represented about 70 of all bets at both mountain sites while it was 58 at the highland site and only 32 at the lowland site our results show a more significant role of bets in hillslope processes including slope denudation in the mountains we would expect a significant decrease of the biogeomorphic effect of trees in managed forests but with a greater relative effect in mountains

10be chronometry of bedrock to soil conversion rates abstract we report concentrations of cosmogenic 10 be t 1 2 1 5 10 6 yrs in soil excavated from a soil mantled hillslope in black diamond mines regional park contra costa county california the most striking features of the data are 1 the similarity in the downward decreasing trends of 10 be concentrations in two soil profiles collected 75 m apart 2 the coincidence in each soil profile of the soil bedrock interface as defined by visual inspection of soil pits and the level at which 10 be concentrations attain very low values 4 10 6 atoms g and 3 the extremely low 10 be concentrations in the underlying regolith 0 5 10 6 atoms gram the inventory of 10 be in these soils is low equivalent to about 6000 yrs of 10 be accumulation in a soil initially containing no 10 be on the basis of these measurements and with the aid of simple models of soil 10 be motions on the hillslope we conclude that 10 be loss from the surface is dominated by its removal in soil by creep we calculate local rates of bedrock to soil conversion of between 0 15 and 0 27 km 10 6 yrs comparing these with uplift rates determined for coastal regions of california indicates that soil creep alone is capable of removing soil from the local geomorphic system at a rate equivalent to the rate of uplift of much of the coast

evidence for nonlinear diffusive sediment transport on hillslopes and implications for landscape morphology steep soil mantled hillslopes evolve through the downslope movement of soil driven largely by slope dependent transport processes most landscape evolution models represent hillslope transport by linear diffusion in which rates of sediment transport are proportional to slope such that equilibrium hillslopes should have constant curvature between divides and channels on many soil mantled hillslopes however curvature appears to vary systematically such that slopes are typically convex near the divide and become increasingly planar downslope this suggests that linear diffusion is not an adequate model to describe the entire morphology of soil mantled hillslopes here we show that the interaction between local disturbances such as rainsplash and biogenic activity and frictional and gravitational forces results in a diffusive transport law that depends nonlinearly on hillslope gradient our proposed transport law 1 approximates linear diffusion at low gradients and 2 indicates that sediment flux increases rapidly as gradient approaches a critical value we calibrated and tested this transport law using high resolution topographic data from the oregon coast range these data obtained by airborne laser altimetry allow us to characterize hillslope morphology at 2 m scale at five small basins in our study area hillslope curvature approaches zero with increasing gradient consistent with our proposed nonlinear diffusive transport law hillslope gradients tend to cluster near values for which sediment flux increases rapidly with slope such that large changes in erosion rate will correspond to small changes in gradient therefore average hillslope gradient is unlikely to be a reliable indicator of rates of tectonic forcing or baselevel lowering where hillslope erosion is dominated by nonlinear diffusion rates of tectonic forcing will be more reliably reflected in hillslope curvature near the divide rather than average hillslope gradient

comparison of earthquake strains over 102 and 104 year timescales insights into variability in the seismic cycle in the central apennines italy in order to study the existence of possible deficits or surpluses of geodetic and earthquake strain in the lazio abruzzo region of the central apennines compared to 15 3 kyrs multi seismic cycle strain rates horizontal strain rates are calculated in 5 km x 5 km and 20 km x 20 km grid squares using slip vectors from striated faults and offsets of late pleistocene holocene landforms and sediments strain rates calculated over 15 3 kyrs within 5 km x 5 km grid squares vary from zero up to 2 34 0 54 x 10 7 yr 1 and resolve variations in strain orientations and magnitudes along the strike of individual faults surface strain rates over a time period of 15 3 kyrs from 5 km x 5 km grid squares integrated over an area of 80 km x 160 km shows the horizontal strain rate of the central apennines is 1 18 0 04 0 12 x10 8 yr 1 and 1 83 4 43 3 80 x 10 10 yr 1 parallel and perpendicular to the regional principal strain direction 043 degrees 223 degrees 1 degrees associated with extension rates of ms 6 0 magnitude historical earthquakes have been reported to be as low as zero this demonstrates the importance of comparing the exact same areas and that strain rates vary spatially on the length scale of individual faults and on a timescale between 10 2 yr and 10 4 yr in the central apennines we use these results to produce a fault specific earthquake recurrence interval map and discuss the regional deformation related to plate boundary and sub crustal forces temporal earthquake clustering and the natural variability of the seismic cycle

application of eccentric growth of trees as a tool for landslide analyses the example of picea abies karst in the carpathian and sudeten mountains central europe abstract a method based on dendrochronology was developed to analyse the spatial and temporal variability of landslide activity as an alternative and complement to methods such as field monitoring of landslide relief aerial photography and remote sensing the method involves a feature of wood anatomy tree ring eccentricity which is used in the dating procedure the degree of eccentricity is used as an indicator of the intensity of the mechanical stress affecting a tree stem in a certain year the objective was to develop a mathematical indicator of tree ring eccentricity for dating the recent dynamics of landslides a method presented in the paper is also designed for practical application in detecting initial landslide activity and allowing the determination of triggering factors the index developed is dimensionless and for this reason is independent of the absolute ring variations of the single trees analysed using reference results from stable slopes as thresholds in dating an objective method for detecting landslide activity was developed the method was used in the carpathian and sudeten mountains on three landslides with different sizes and geological settings it was found that the values of eccentricity index in trees growing on stable slopes rarely exceed at 100 while in trees growing on landslides they can reach hundreds to thousands per cent a spatial analysis of the eccentricity values conducted for a single landslide has revealed that the method developed allows one to identify areas of landslide activation and to observe the down or upslope propagation of instability a comparison of the results obtained regarding the precipitation record has shown that by using the method that has been developed it is possible to detect past mass movement episodes caused by heavy long term rainfall as well as by single short lasting but torrential downpours

soil transport driven by biological processes over millennial time scales downslope soil transport in the absence of overland flow has been attributed to numerous mechanisms including particle by particle creep and disturbances associated with biological activity process stochasticity and difficulties associated with field measurement have obscured the characterization of relevant long term soil transport rates and mechanisms in a series of incised fluvial terraces along the charwell river south island new zealand we documented vertical profiles of tephra concentration and topographic derivatives along a hillslope transect to quantify soil transport processes along the undissected hilltop we observed a thin primary tephra layer ca 22 6 ka within loess deposits 80 cm below the landscape surface in the downslope direction the depth to the highly concentrated tephra layer decreases coincident with an increase in hillslope convexity which is proportional to landscape lowering rate if soil flux varies linearly with hillslope gradient exhumation of the tephra layer results from landscape lowering due to disturbance driven soil transport approximately 20 m downslope of the interfluve the depth to the tephra layer declines to 40 50 cm peak tephra concentrations decrease by a factor of 4 and tephra is distributed uniformly within the upper 40 cm of soil the transition from a thin highly concentrated tephra layer at depth to less concentrated widely distributed tephra in the upper soil may result from soil mixing and transport by biological disturbances along our transect the depth to this transition is 50 cm coincident with the rooting depth of podocarp and nothofagus trees that populated the region during much of the holocene our observations can be used to calibrate the linear transport model but more important they suggest that over geomorphic time scales stochastic bioturbation may generate a well mixed and mobile soil layer the depth of which is primarily determined by flora characteristics

modelling hillslope evolution linear and nonlinear transport relations many recent models of landscape evolution have used a diffusion relation to simulate hillslope transport in this study a linear diffusion equation for slow quasi continuous mass movement e g creep which is based on a large data compilation is adopted in the hillslope model transport relations for rapid episodic mass movements are based on an extensive data set covering a 40 yr period from the queen charlotte islands british columbia a hyperbolic tangent relation in which transport increases nonlinearly with gradient above some threshold gradient provided the best fit to the data model runs were undertaken for typical hillslope profiles found in small drainage basins in the queen charlotte islands results based on linear diffusivity values defined in the present study are compared to results based on diffusivities used in earlier studies linear diffusivities adopted in several earlier studies generally did not provide adequate approximations of hillslope evolution the nonlinear transport relation was tested and found to provide acceptable simulations of hillslope evolution weathering is introduced into the final set of model runs the incorporation of weathering into the model decreases the rate of hillslope change when theoretical rates of sediment transport exceed sediment supply the incorporation of weathering into the model is essential to ensuring that transport rates at high gradients obtained in the model reasonably replicate conditions observed in real landscapes an outline of landscape progression is proposed based on model results hillslope change initially occurs at a rapid rate following events that result in oversteepened gradients e g tectonic forcing glaciation fluvial undercutting steep gradients are eventually eliminated and hillslope transport is reduced significantly

soil creep and convex upward velocity profiles theoretical and experimental investigation of disturbance driven sediment transport on hillslopes the movement of unconsolidated materials near the earth s surface is often driven by disturbances that occur at a range of spatial and temporal scales the nature of these disturbances ranges from highly variable such as tree turnover to periodic and predictable such as frost heave or creep to explore the effect of probabilistic disturbances on surface processes we formulated a granular creep model with analogy to rate process theory rpt used for chemical reactions according to the theory individual particles must be energized to a height greater than adjacent particles in order for grain dilation and transport to occur the height of neighbouring particles which is akin to activation energy in chemical reactions varies with slope angle such that energy barriers get smaller in the downslope direction as slopes steepen when slopes approach the friction limited angle of repose the height of energy barriers approaches zero and grains ow in the absence of disturbance an exponential function is used to describe the probability distribution of particle excitation height although alternative distributions are possible we tested model predictions of granular dynamics in an experimental sandpile in the sandpile acoustic energy serves as the disturbance agent such that grains dilate and shear in response particle velocities are controlled by the frequency of energy pulses that result in grain displacement using tracer particles we observed a convex upward velocity pro le near the surface of the sandpile consistent with predictions of our rpt based velocity model in addition we depth integrated the velocity model to predict how ux rates vary with inclination of the sandpile and observed non linear ux gradient curves consistent with model predictions by varying the acoustic energy level in the experimental sandpile we documented changes in the rate of grain movement similar changes in modelled velocities were achieved by varying the exponent of the particle excitation probability distribution the general agreement between observed and modelled granular behaviour in our simple laboratory sandpile supports the utility of rpt based methods for modelling transport processes e g soil creep frost heave and till deformation thus enabling us to account for the probabilistic nature of disturbances that liberate sediment in natural landscapes copyright 2004 john wiley sons ltd

increased sediment transport via bioturbation at the last glacial interglacial transition global sedimentation rates increased during the quaternary due to frequent landscape adjustment to climatic oscillations although high rates of sediment transport are commonly associated with glacial conditions in mountainous terrain the infl uence of climate and vegetation on geomorphic response is poorly constrained outside of glaciated settings along a low gradient 30 hillslope valley transect on a moderately dissected loess mantled fl uvial terrace in the charwell basin new zealand we coupled records of colluvial infi lling and vegetation change via phytoliths to show that late pleistocene sediment fl ux was 0 0012 m 3 m 1 a 1 under a shrubland grassland mosaic and holocene sediment fl ux was 0 0022 m 3 m 1 a 1 under forest this near doubling through the last glacial interglacial transition appears to refl ect increased bioturbation and downslope soil transport associated with a forest ecosystem such an increase in sediment transport contrasts with a contemporaneous decrease inferred for adjacent steep landslide prone catchments suggesting that geomorphic response to climate change is heavily modulated by biology topography and geological substrate our fi ndings appear to contradict the commonly cited notion that forest colonization universally stabilizes soils and suppresses erosion instead over long time scales bioturbation associated with forests may increase transport along gentle portions of the landscape not subject to slope instability or erosion by overland fl ow

small scale lobate hillslope features on mars a comparative 3d morphological study with terrestrial solifluction lobes and zebra stripe lobes abstract small scale lobes ssl observed at the surface of mars are thought to be the result of solifluction hence their existence has important implications for our understanding of recent climate history the distribution of thaw liquids and its geomorphic effects as water is believed not to have been recently stable at the martian surface these small scale lobes are limited to sloping terrains and often occur alongside polygonal patterned ground attesting to the presence of ice in the environment in this study we perform a comparative 3d morphometric analysis of the lobes on mars with terrestrial analogues we use data from high resolution imaging science experiment hirise camera in order to create digital terrain models dtms on mars at 1 m pix for the terrestrial analogues we use dtms and orthophotos from five periglacial environments with solifluction lobes and from one site with lobate features found in the atacama desert the lobate features in the atacama desert are found within features called zebra stripes which are apparently unique to the atacama and are now generally accepted to be the result of seismic shaking we show that ssl on mars overlap morphometrically with terrestrial solifluction lobes and are less similar to zebra stripe lobes the majority of martian ssl occur below the angle of repose which demonstrates that a dry fall mechanism cannot be responsible for their formation and that lubrication of the subsurface is required we found that martian ssl only occur on slopes greater than 10 a constraint not observed for terrestrial solifluction lobes nor zebra stripe lobes in atacama we hypothesise that this apparent constraint does not result from the lowered gravity on mars but instead from differing soil properties and or thermal regime between mars and earth which affects the slope at which creep can initiate we cannot rule out a role of co2 sublimation in lobe formation based on our terrestrial measurements

dynamic earth system and ecological controls of rainfall initiated landslides abstract rainfall initiated landslides continue to inflict damages and loss of life throughout the world processes and mechanisms revealed from hydrological geomorphic geotechnical pedological geological hydrochemical and biological investigations have advanced our understanding of these effects on slope stability however the interactions amongst these processes and attributes as they affect the initiation and propagation of landslides are not as well understood too often landslide studies are conducted from only one or at most two of these perspectives moreover while precipitation and hydrology are recognized as dynamic influences the earth system and ecological effects are often assumed to be static we assess the interplay of these processes related to landslides triggered by positive pore water accretion and loss of soil suction each of these conditions arguably requires a different view on the processes that cause slope failure and predictive approaches this review starts from the perspective of dynamic adapting earth and ecological systems and discusses how these attributes relate to landslide initiation mode location and timing specifically the role that large and small scale preferential flow plays in both contributing to and mitigating instability is elucidated including effects of bedrock exfiltration we also examine how and under what conditions these pathways manifest in different soils lithology and landforms the multiple effects of rhizosphere processes on slope stability are discussed including root reinforcement evaporation from canopies and litter layers transpiration and the role of root structure affecting preferential flow paths rainfall initiated landslides involve highly dynamic hydrologic earth surface and ecological processes that persist over a range of spatial and temporal scales however guidance for overcoming these challenges has been elusive a conceptual framework is presented to shed light on these dynamic and interactive processes that should lend insights into why and when certain slopes fail during storms while other seemingly similar slopes do not fail such advances will benefit landslide hazard assessments and disaster responsiveness protocols

soil creep in a mesotidal salt marsh channel bank fast seasonal and water table mediated abstract muddy banks of marsh channels experience soil creep a viscous like slow deformation resulting in a net downslope transport here we present the first field evidence of soil creep in a mesotidal salt marsh using both pole displacement and high precision measurements of soil deformation taken with a vibrating wire extensometer over two years soil extended 2 4 mm m year in the high marsh platform and 20 40 mm m year in the low marsh bank this was equivalent to a soil diffusivity of about 0 2 m2 year which is much higher than the diffusivity on hillslopes and also matches the high value predicted by long term marsh evolution models high precision 0 03 mm soil deformation measurements shed light on the dynamics of the creep process first the low bank compressed and extended by 5 mm m every tidal cycle suggesting that the diurnal changes in water level play a role in the bank movements second net soil extension took place mostly during fall net soil extension preceded the period of ice formation suggesting that freezing and ice rafting are not a leading cause of soil creep net soil extension was likely triggered by an increase in water table during fall which decreased the effective stress and thus destabilized the bank this high water table was caused by a combination of an abiotic factor the increase in atmospheric precipitation and a biotic factor the decrease in evapotranspiration triggered by vegetation senescence this study confirms that creep is a significant process in marsh morphodynamics and that vegetation can reduce mass wasting in marsh channels

bedrock erosion by root fracture and tree throw a coupled biogeomorphic model to explore the humped soil production function and the persistence of hillslope soils 1 in 1877 g k gilbert reasoned that bedrock erosion is maximized under an intermediate soil thickness and declines as soils become thinner or thicker subsequent analyses of this humped functional relationship proposed that thin soils are unstable and that perturbations in soil thickness would lead to runaway thinning or thickening of the soil to explore this issue we developed a numerical model that simulates the physical weathering of bedrock by root fracture and tree throw the coupled biogeomorphic model combines data on conifer population dynamics rootwad volumes tree throw frequency and soil creep from the pacific northwest usa although not hardwired into the model a humped relationship emerges between bedrock erosion and soil thickness the magnitudes of the predicted bedrock erosion rates and their functional dependency on soil thickness are consistent with independent field measurements from a coniferous landscape in the region imposed perturbations of soil erosion during model runs demonstrate that where bedrock weathering is episodic and localized hillslope soils do not exhibit runaway thinning or thickening the pit and mound topography created by tree throw produces an uneven distribution of soil thicknesses across a hillslope thus although episodes of increased erosion can lead to temporary soil thinning and even the exposure of bedrock patches local areas of thick soils remain these soil patches provide habitat for trees and serve as nucleation points for renewed bedrock erosion and soil production model results also suggest that where tree throw is a dominant weathering process the initial mantling of bedrock is not only a vertical process but also a lateral process soil mounds created by tree throw flatten over time spreading soil over bedrock surfaces

evidence for repeated re activation of old landslides under forest local reactivations of landslides in forests are rarely reported in landslide catalogues the occurrence of hillslope sections with fresh morphological landslide features in forested old deep seated landslides however suggests that landslide reactivations are not restricted to residential areas in this study a dendrogeomorphological analysis of beech stands was used to investigate the periods of reactivation of a deep seated rotational slide in the koppenberg forest flemish ardennes belgium the relation to rainfall and the correspondence to landslide reactivations reported in a nearby built up area were also analysed a dendrometrical study preceding the dendrochronological analysis proved that compared with the nearby reference site trees on the koppenberg forest landslide site were significantly more inclined and showed more knees indicating that the landslide site has not stabilized yet as the sampled trees are younger than the landslide dendrochronology did not allow determination of the year in which the landslide was initiated but analysis of two different tree ring width parameters i e ring eccentricity and growth change calculated for trees sampled on the koppenberg landslide and the reference site proved to be of great help in determining the temporal sequence of landslide reactivation during the past 80 years several periods indicative of local reactivations i e 1943 1945 1949 1952 1967 1970 1972 1977 1979 1981 1988 1997 were found within the investigated landslide but delineation of the spatial extent of the reactivations during these indicative periods was not straightforward these periods generally correspond to years with above average rainfall finally the fact that at least 34 of the years indicative of reactivation of the koppenberg forest landslide correspond to a year in which a landslide reactivation was reported in the flemish ardennes suggests that in built up areas apart from anthropogenic interventions natural triggering factors remain very important copyright 2009 john wiley sons ltd

curved tree trunks indicators of soil creep and other phenomena tree trunks are often curved as a result of external factors including catastrophic events the availability of light and soil creep where trees with curved trunks due to soil creep can be recognized they may provide a useful indication of slope instability trees with trunks which are curved downslope to resemble catenaries probably owe their shape to downslope soil creep sharp curves in tree trunks are usually the result of catastrophic events but snow ice pressure may cause trees to bow with gentle curves also phototropism may cause shade intolerant trees to grow with gently curved trunks such curves are quite distinct from those induced by soil creep

rates of surface processes on slopes slope retreat and denudation results taken from 270 publications on rates are summarized and collated with those from 149 publications reviewed previously young 1969 1974 the data are classified by major climatic zone normal or steep relief and consolidated or unconsolidated rocks representative rates and their ranges are given for soil creep solifluction surface wash solution chemical denudation rock weathering slope retreat cliff free face retreat marine cliff retreat and denudation the last being compared with representative rates of uplift solifluction is of the order of 10 times faster than soil creep but both cause only very slow ground loss solution is an important cause of ground loss for siliceous rocks on which it may be half as rapid as on limestones total denudation brought about mainly by surface wash reaches a maximum in the semi arid and probably also the tropical savanna zones acceleration of natural erosion rates by human activities ranges from 2 3 times with moderately intense land use to about 10 times with intensive land use and considerably higher still where there is recognized accelerated soil erosion where there is active uplift typical rates are of the order of 10 times faster than denudation although in some high steep mountain ranges these may approach equality

solifluction rates processes and landforms a global review abstract field data on the rates of solifluction and associated parameters are compiled from the literature in an attempt to evaluate factors controlling the spatial variability in solifluction processes and landforms with special attention on the climate solifluction relationship the analyzed data originate from 46 sites over a wide range of periglacial environments from antarctic nunataks to tropical high mountains solifluction broadly defined as slow mass wasting resulting from freeze thaw action in fine textured soils involves several components needle ice creep and diurnal frost creep originating from diurnal freeze thaw action annual frost creep gelifluction and plug like flow originating from annual freeze thaw action and retrograde movement caused by soil cohesion the depth and thickness of ice lenses and freeze thaw frequency are the major controls on the spatial variation in solifluction processes near the warm margin of the solifluction affected environment diurnal freeze thaw action induces shallow but relatively rapid movement of a superficial layer 5 10 cm thick on average often creating the thin stone banked lobes typically seen on tropical high mountains in addition to diurnal movement annual frost creep and gelifluction may occur on slopes with soil climates of seasonal frost to warm permafrost dislocating a soil layer shallower than 60 cm at a rate of centimeters per year and eventually producing medium size solifluction lobes in high arctic cold permafrost regions two sided freezing can induce plug like flow of a soil mass 60 cm or thicker the correlation between process and landform suggests that the riser height of lobes is indicative of the maximum depth of movement and prevailing freeze thaw type climate change may result in new different ground freezing conditions thereby influencing the surface velocity and maximum depth of soil movement soil moisture and topography also control solifluction high moisture availability in the seasonal freezing period enhances diurnal freeze thaw action and subsequent seasonal frost heaving the latter contributes to raising the moisture content of the thawed layer and promotes gelifluction during the thawing period the slope angle defines the upper limit of the surface velocity of solifluction a diagram correlating the potential frost creep with the actual surface velocity permits an inter site comparison of the relative magnitude of solifluction components physically based modelling of periglacial slope evolution requires synthetic and more detailed field monitoring and laboratory simulations of solifluction processes

soil creep the driving factors evidence and significance for biogeomorphic and pedogenic domains and systems a critical literature review abstract soil and regolith creep have been analyzed for at least the last 140 years using many methodological configurations and temporal and spatial scales the general concept of creeping soil and its mechanism first proposed by w m davis and g k gilbert at the end of the 19th century evolved since the 1940s towards theoretical models and precise short and long term field measurements this fruitful epoch continued with results enhanced at the turn of the 20th century by the application of new research methods e g radiometry and a redefinition of the term soil creep to encompass the sum of stochastic shallow subsurface and near surface processes causing net downslope movement of soil or regolith simultaneously another possibility of creep detection was noticed in dendrochronology and since the 1970s in the formally defined discipline of dendrogeomorphology indirect evaluations of creep activity were performed based on tree ring analyses of bent trees this method found many followers but was also heavily criticized as imprecise and lacking in evidence of which kind of tree trunk curvature e g pistol butt like deformation s shape curvature could be ascribed to creep movement from the beginning soil creep was associated with the activity of living organisms on hillslopes however this aspect of creep studies has never been fully developed in spite of the solid foundations and directions of potential studies pointed out by charles darwin at the end of the 19th century in this paper we focus on the historical context of soil creep studies and highlight forest ecosystems as probably the most active environment of biogenic creep mainly due to tree uprooting and other biomechanical effects of living and dead trees root channel infilling tree root mounding etc that are a factors in biotransport in the final sections the position of biogenic creep in the structure of biogeomorphic systems is discussed in relation to such important conceptual frameworks as the biogeomorphic ecosystem biogeomorphic feedback window and ecosystem engineering we also describe several hypotheses that should be carefully tested in the future and propose several research methods that have the ability to further our knowledge about soil creep radiometry laser scanning and soil micromorphology

reciprocal interactions and adjustments between fluvial landforms and vegetation dynamics in river corridors a review of complementary approaches abstract until recently one way relationships between flow dynamics geomorphology and plant ecology were considered dominantly when studying the functioning of river systems whereby fluvial landforms and hydrogeomorphic processes drive the evolution of riparian plant communities however biological communities may significantly control geomorphic processes and have strong impacts on landform dynamics in order to fully identify the processes linked to river dynamics changes in time and space of fluvial landforms and associated plant communities conceptual multidisciplinary progress is clearly needed to understand the mutual interactions and feedbacks between fluvial landforms and vegetation community dynamics this paper presents a detailed literature review of fluvial geomorphology riparian plant ecology and hydraulic engineering knowledge the historical and recent development of ecological plant succession theory toward the integration of hydrogeomorphic disturbances is discussed as well as the integration of vegetation within geomorphology as a significant landform control factor incorporating both hydrogeomorphic controls on riparian vegetation dynamics and mechanical impacts of vegetation structures on flow properties and sediment dynamics recent progress in ecology hydraulic engineering and fluvial geomorphology emphasises interdependence between biological and physical forms and processes based on this literature review a fluvial biogeomorphic succession concept is proposed to link fluvial landform and riparian vegetation community evolution within a bi directional model the succession of fluvial landforms and associated vegetation communities is composed of four main critical phases that represent a shift in the relative dominance of hydrogeomorphic and ecological processes as a response to biostabilisation and passive bioconstruction processes the positive feedbacks associated with this shift lead to the development of characteristic biogeomorphic structures such as vegetated banks islands or floodplains which are moderated by the biogeomorphic functional roles of ecosystem engineers that induce or reinforce the positive feedbacks this fluvial biogeomorphic succession concept relates the natural darwinian selection and ecological succession theories to fluvial geomorphology

gopher bioturbation field evidence for non linear hillslope diffusion it has generally been assumed that diffusive sediment transport on soil mantled hillslopes is linearly dependent on hillslope gradient fieldwork was done near santa barbara california to develop a sediment transport equation for bioturbation by the pocket gopher thomomys bottae and to determine whether it supports linear diffusion the route taken by the sediment is divided into two parts a subsurface path followed by a surface path the first is the transport of soil through the burrow to the burrow opening the second is the discharge of sediment from the burrow opening onto the hillslope surface the total volumetric sediment flux as a function of hillslope gradient is found to be qs cm3 cm 1 a 1 176 dz dx 3 189 dz dx 2 68 dz dx 34 dz dx 0 4 this result does not support the use of linear diffusion for hillslopes where gopher bioturbation is the dominant mode of sediment transport a one dimensional hillslope evolution program was used to evolve hillslope profiles according to non linear and linear diffusion and to compare them to a typical hillslope the non linear case more closely resembles the actual profile with a convex cap at the divide leading into a straight midslope section copyright 2000 john wiley sons ltd

can tree tilting indicate mechanisms of slope movement abstract slope movements are a common natural hazard that is why considerable funds are spent annually to limit their effects or to research their prevention this study evaluates dendrometric approaches as a fast and low cost alternative to classical methods of slope movement mechanism analysis a total of 1688 trees growing on the mazak landslide in the moravskoslezske beskydy mts and 100 reference trees growing out of the landslide area were analysed the mazak landslide is approximately 400 m in length and presents varied morphological features scarps rotated blocks scree slopes shallow landslide areas etc the slope and direction of stem inclination was recorded for each tree the results were categorized into four distinct landforms scarp with outcrops of bedrock scree slope front of partial landslide block plateau of partial landslide block and were then compared with parameters for the reference trees the general model of tree tilting for the landslide area was verified and partially confirmed trees growing on the plateau of rotated blocks are predominantly oriented upslope trees growing on scree slopes of shallow movement and creep are predominantly oriented downslope trees growing on rocky scars do not differ significantly from the reference trees trees growing from fronts of rotated blocks are oriented both upslope and downslope from these results several recommendations regarding dendrometric evidence of slope movement mechanisms are presented i all trees growing on the landslide are to be analysed ii old trees maintain stem tilt intensities and directions for long periods but young trees are more sensitive to ground movements iii tree root depth influences root sensitivity to movements of various depths iv the general shape of a stem can denote specific mechanisms of slope movement and v comparisons with reference trees should always be conducted to exclude potential non geomorphic effects on tree stem tilt

soil moisture and texture controls of selected parameters of needle ice growth needle ice was grown in the laboratory to determine the limits of soil moisture and texture on the growth of needle ice as the percentage of fines in the soil increases the lower limit of soil moisture required for growth decreases and may be defined by a linear boundary the efficiency of conversion of soil water to needle ice in soil samples used peaked at about 16 per cent soil fines contrary to expectations the finer textured soils produced significantly thicker ice crystals quantity of soil lifted by needle ice was related to ice height the ice mass to atmospheric void ratio soil texture and moisture and soil surface roughness however no definite quantitative relationships could be determined a test to determine if needle ice is selective in the grain sizes of particles lifted suggested no selectivity

biological energy in landscape evolution traditional conceptual models of landscape evolution view topography as an outcome of endogenic forces uplift working against exogenic forces of denudation the energy considerations of these concepts have focused on the conversion of the potential energy of landscape relief to kinetic energy the concept of the biosphere as a planetary membrane for capturing and converting solar energy coupled with the critical geomorphic role of biota call for a consideration of biotic contributions to geomorphic work a review of estimates of global rates of kinetic energy of denudation and uplift and net primary production npp indicates that the energy density of npp is on average three to seven orders of magnitude greater than the others if even a tiny fraction of npp is geologically significant then the biological subsidy to the energy of landscape evolution must be considered on a par with that of geophysical and geochemical phenomena a case study in eastern kentucky shows that even if only 0 1 percent of npp is geomorphically significant it still far exceeds the energy inputs from uplift and conversion of potential to kinetic energy by denudation this is unlikely to be unique though the relative importance of biological and geophysical processes must obviously vary with climate tectonic setting and other factors results indicate that particularly where biological activity is significant geomorphic work performed by biota may be greater than that associated with endogenic processes and with the kinetic energy of denudation

domination of hillslope denudation by tree uprooting in an old growth forest abstract razula forest preserve in the carpathian mountains of the czech republic is an unmanaged forest that has not been logged or otherwise anthropically disturbed for at least 83 years preceded by only infrequent selective logging we examined this 25 ha area to determine the dominant geomorphological processes on the hillslope tree uprooting displaces about 2 9 m 3 of soil and regolith per year representing about 1 5 uprooted trees ha 1 yr 1 based on forest inventory records dating back to 1972 and contemporary measurements of displaced soil and pit mound topography resulting from uprooting pits and mounds occupy 14 of the ground surface despite typical slope gradients of 0 05 mm 1 and up to 0 41 little evidence of mass wasting e g slump or flow scars or deposits colluvial deposits was noted in the field except in association with pit mound pairs small avalanche and ravel features are common on the upslope side of uproot pits surface runoff features were rare and poorly connected but do include stemwash erosion associated with stemflow no rills or channels were found above the valley bottom area and only small localized areas of erosion and forest litter debris indicating overland flow where these features occurred they either disappeared a short distance downslope indicating infiltration or indicate flow into tree throw pits surface erosion is also inhibited by surface armoring of coarse rock fragments associated with uprooting as well as by the nearly complete vegetation and litter cover these results show that the combination of direct and indirect impacts of tree uprooting can dominate slope processes in old growth unmanaged forests the greater observed expression of different hillslope processes in adjacent managed forests where tree uprooting dynamics are blocked by management activities suggests that human interventions can change the slope process regime in forest ecosystems

biogeomorphology past present and future abstract since the 1970s there has been a considerable expansion in biogeomorphological research which considers the complex two way relationships between biological ecological and geomorphological systems over a wide range of spatial and temporal scales advances have been made in theoretical methodological thematic and applied aspects of biogeomorphology a review of key publications and symposia over the period illustrates growth in biogeomorphology with particular advances in quantitative understandings of biogeomorphic interactions in interdisciplinary participation and in theoretical framings theoretical advances have been influenced by the desire to answer four fundamental questions how do ecological and geomorphological systems interact is there a geomorphological signature of life how important is biodiversity to landscape evolution and vice versa how have life and landscape co evolved a review of methodological advances in biogeomorphology confirms the continuing importance of field monitoring and the increasingly tight collaboration between experimental and modelling based research thematically particularly strong progress has been made in disentangling the complex bidirectional biogeomorphic interactions in coastal sedimentary environments and fluvial and riparian systems it is increasingly obvious that variation in ecological traits leads to large differences in biogeomorphic impacts of different species in different circumstances this poses challenges for applications of biogeomorphology to environmental management and conservation seven key topics emerge from this review and provide the basis for a biogeomorphological research agenda to usher in the next 50 yr of progress

deterministic chaos and historical geomorphology a review and look forward the study of nonlinear dynamics in geomorphology has been dominated by analytical techniques derived largely from other fields ultimately however confronting nonlinear complexity requires problematizing from within a geomorphological context this paper focuses on deterministic chaos the major classes of techniques for detecting chaos in geomorphic systems are reviewed while the long time series most amenable to traditional methods of chaos detection are only occasionally available to geomorphologists there are methods for detecting chaos in spatial data including qualitative and categorical data many of these are similar to or are adaptations of familiar techniques for partitioning within and between unit variation and for identifying elementary uniform landscape units the manifestations of chaos in landforms and landscapes take the form of divergent vs convergent evolution increasing vs decreasing irregularity disproportionality vs proportionality of response to perturbations or initial variations and the lack of geographical consistency or commonality of response these also serve as criteria for distinguishing between achievement of a new steady state and unstable divergence in interpreting geomorphic changes study of nonlinear dynamics in earth science need not be dominated by theoreticians and modellers as complex nonlinear behaviors can be identified and diagnosed using the types of data observations and methods typically available to geomorphologists even more important is the need to further inform the study of nonlinear dynamics on the basis of field based geomorphology

how fast does soil grow abstract quantifying the rate of soil formation has become important in response to the consideration of soil as a renewable resource the availability of new sophisticated laboratory techniques has opened up the possibility of addressing the demand of quantifying processes of soil landscape evolution in the critical zone here we investigated the rate of soil formation of world soils based on published results of tcn derived terrestrial cosmogenic nuclides 10 be soil production rates spr the compilation of published tcn derived spr for different climatic zones and lithologic conditions showed exponentially decreasing spr with increasing soil thickness for the majority of the discussed studies this implies that the presence of a soil mantle protects the bedrock from further weathering we found that rates of soil production in australia appear to be similar in range when compared with other parts of the world we concluded that we can formulate an average quantitative estimate of global soil production based on tcn soil production rate mm kyr 1 114 11 exp 2 05 soil thickness in mm such a rate is useful for global modelling of soil formation to better understand the role of soils in landscape evolution

dendrogeomorphic chronologies of landslides dating of true slide movements dendrogeomorphic chronologies of landslide movements are frequently used to investigate past landslide activity slide areas are often affected by other slope movements e g creep simultaneously trees growing on landslides record all types of ground movements which potentially creates significant noise in tree ring based chronologies of landslide movements the effect of creep movements on dendrogeomorphic landslide chronologies was evaluated in a block type landslide in the south western foreland of the orlicke hory mts in total 272 trees p abies and f sylvatica were sampled 1088 increment cores on the sub horizontal surfaces of rotated slide blocks which were presumably created only by slide movements and on the steep internal scarps separating landslide blocks which were presumably created and affected by a combination of slide and creep movements ground movements were dated based on growth disturbances identified in an analysis of eccentric tree growth the trees growing on the internal landslide scarps separating the rotated blocks exhibited a significantly higher number and frequency of growth disturbances than those growing on the sub horizontal block surfaces all eight dated block surface movements were also identified on the internal scarps creep based events represented as many as 70 of the dated movement events on the internal scarps varying the it thresholds did not filter out more than 40 of the noise without significantly reducing the number of true dated slide events a significant difference was observed between the ability of p abies and f sylvatica to record ground movements by eccentric growth probably due its shallower roots and weaker anchoring of the tree to landslide blocks p abies appears to be more sensitive to surficial ground movement which potentially increases the proportion of dated creep events noise thus the careful selection of sampled tree species with different physiologies should be considered during dendrogeomorphic field sampling

contribution to understanding the historical evolution of meandering rivers using dendrochronological methods example of the mala panew river in southern poland the mala panew is a meandering river that flows 20 km through a closed forest during times of high discharge the riverbed and floodplain are transformed under the influence of riparian trees the changes provide the opportunity to measure the intensity of erosion and sediment accumulation based on tree ages the dating of coarse woody debris cwd in the riverbed and the dating of eccentric growth of tilting trees and exposed roots the bed and floodplain in reaches of the mala panew river with low banks were greatly altered as a result of long periods of flooding between 1960 and 1975 banks were undercut during these floods and black alders tilted those parts of alder crowns or stems which tilt and sink generate small sand shadows when erosion is intensive alder clumps are undercut from concave banks and become mid channel islands while on the other side of the channel meandering bar levels are created the reaches with higher banks were altered by large floods especially in 1985 and 1997 the concave banks are undercut and sediment with cwd is deposited within the riverbed forming sand shadows behind the cwd copyright 2006 john wiley sons ltd

the illusion of diffusion field evidence for depth dependent sediment transport soil covered upland landscapes are common in much of the habitable world and our understanding of their evolution as a function of different climatic tectonic and geologic regimes is important across a wide range of disciplines erosion laws direct quantitative study of the processes shaping earth s surface and form the basis of landscape evolution modeling but are based on limited field data here we use in situ produced cosmogenic 1 0 be and 2 6 al concentrations from granitic saprolite to quantify an exponential decline in soil production with increasing soil thickness for a new field site in point reyes california results are similar to soil production functions from two different previously studied field sites and are used with extensive measurements of soil thickness to quantify depth integrated sediment transport flux plots of calculated sediment fluxes against the product of soil depth and hillslope gradient provide the first field based evidence that soil transport is a nonlinear depth dependent function data from all sites suggest that the widely used linear diffusion equation is only appropriate for shallow gradient convex up regions while the depth dependent transport law is more broadly applicable quantifying both the mobile soil thickness and landscape morphology is therefore critical to understanding how landscapes evolve