bluuebunny/crossref_metadata_2025_split huggingface dataset:
What limits the spread of fire‐dependent vegetation? Evidence from geographic variation of serotiny in a New Zealand shrub
Authors: Bond William J. , Dickinson Katharine J. M. , Mark Alan F. 
Published: February 2004

ABSTRACTAim  To determine the geographical variation in serotiny in a common New Zealand shrub as a contemporary indicator of past fire regimes. The distribution of serotiny could then be used to explore factors limiting the spread of fire‐dependent vegetation.Location  South Island, New Zealand.Methods  Serotiny was assessed as the proportion of closed capsules on a shoot of standard stem diameter for 5–35 plants in 45 widely scattered populations of Leptospermum scoparium. Site characteristics, including locality, altitude, rainfall, habitat type and minimum burnable area were recorded at sampling sites.Results  Serotiny was distributed bimodally within and among populations with capsules either mostly closed or mostly open. There was considerable geographical variation in capsule behaviour, most of which we attribute to variation in fire history. In wetlands and other sites unsuitable for forest growth, populations were all serotinous above a minimum area of 30 km2 and nonserotinous below this threshold. In grassy habitats in the drier eastern areas, most populations were serotinous. The nonserotinous exceptions occurred in areas thought to have been cleared of forests by Polynesian settlers before the arrival of Europeans or in areas with numerous barriers to fire in the form of large rivers, floodplains, glaciers and barren mountain tops.Conclusions  We suggest that serotiny in L. scoparium is a reflection of a long history of fire in the South Island. As such, it provides a contemporary signature of a past fire regime. Landscape barriers to the spread of fire were major obstacles limiting the spread of serotiny and associated fire‐dependent vegetation. Rivers, lakes, glaciers, and sparsely vegetated floodplains prevented the spread of fire in high rainfall regions more than the lack of dry weather. People, by igniting fires in small open areas seldom struck by lightning, could radically increase the importance of fire on islands.
Variation in litterfall‐climate relationships between coniferous and broadleaf forests in Eurasia
Authors: Liu Chunjiang , Westman Carl J. , Berg Björn , Kutsch Werner , Wang Gary Z. , Man Rongzhou , Ilvesniemi Hannu 
Published: February 2004

ABSTRACTAim  The objectives of this study were to determine the relationships between climatic factors and litterfall in coniferous and broadleaf forests in Eurasia and to explore the difference in litterfall between coniferous and broadleaf forests as related to climate at a continental scale.Location  We have used data from across Eurasia.Methods  The relationships between litterfall and climatic factors were examined using linear regression analysis of a compilation of published data from coniferous and broadleaf forests in Eurasia.Results  The relationships between litterfall and climatic factors show that in the temperate, subtropical, and tropical areas, broadleaf forests had higher litterfall than coniferous ones, whilst the opposite was found for boreal forests. Combining all climatic zones, a multiple regression analysis using annual mean temperature (T) and annual precipitation (P) as independent variables gave an adjusted R2 () of 0.272 for total litterfall in coniferous forests (n = 199, P < 0.001), 0.498 for broadleaf litterfall (n = 240, P < 0.001), and 0.535 for combined coniferous and broadleaf litterfall (n = 439, P < 0.001). The linear models for broadleaf stands have significantly higher coefficients for T and P than those for coniferous ones but the intercepts were similar. Thus, litterfall in broadleaf forests increased faster with T and P than that in coniferous forests. Further, a transformation of temperature and precipitation to relative units showed that a relative‐unit change in T had a larger impact than P on total litterfall in broadleaf forests. The results indicate that at a continental scale, climatic controls over litterfall differ between coniferous and broadleaf forests.Conclusions  A relative unit change in annual mean temperature has a greater effect on litterfall compared to the same change in annual precipitation across the Eurasian forests. Further, the higher response to T for broadleaf forests indicates a difference in climate control between coniferous and broadleaf forests at a continental scale, and consequently different litterfall responses to climate change.
An evaluation of the Lost World and Vertical Displacement hypotheses in the Chimantá Massif, Venezuelan Guayana
Authors: Rull Valentí 
Published: February 2004

ABSTRACTAim To document the occurrence of vertical displacements of vegetation in the high plateaus of the Venezuelan Guayana (tepuis) over the last c. 6000 years, and to discuss their significance for the origin of their flora, especially the endemism patterns observed in their flat summits. Two hypotheses have been proposed for the origin of the summit flora. One (the Lost World hypothesis) proposes a long history of evolution in isolation from the surrounding plains, while the other (the Vertical Displacement hypothesis) suggests that vertical movements of vegetation during the Pleistocene glacial‐interglacial cycles would have resulted in floristic mixing within the lowlands, and genetic interchange among plateau summits.Location This work has been conducted on the flat summit of the Churí‐tepui, in the Chimantá massif, at 5°15′ Lat. N and 62°01′ Long. W, around 2250 m altitude.Methods Pollen analysis and radiocarbon dating of two peat outcrops, using modern analogue technique and numerical methods for palaeoecological interpretation were used.Results The replacement of a high‐altitude plant community (a paramoid Chimantaea shrubland) by a lower elevation (< 2300 m) Stegolepis meadow, occurred about 2500 years before present (yr bp). This vegetation change is inferred to have resulted from a regional climatic shift to higher temperature and moisture. A subsequent decrease in temperature and moisture led to the establishment of present conditions after about 1450 yr bp.Main conclusions The highland vegetation of the tepuis responded to climate shifts with vertical displacements, supporting the hypothesis of vertical mixing. However, a physiographical analysis shows that around half of the tepuis would never have been connected by lowlands. Therefore, both hypotheses are needed to explain the origins of the summit flora in the tepuis.
Changes in rain forest butterfly diversity following major ENSO‐induced fires in Borneo
Authors: Cleary Daniel F. R. , Genner Martin J. 
Published: February 2004

ABSTRACTAims  Throughout South‐East Asia, droughts associated with ENSO (El Niño Southern Oscillation) events have resulted in large‐scale fires affecting millions of hectares of rain forest. However, the long‐term impacts of these fires on the rain forest faunas are only poorly understood. Our aim was to study the recovery of rain forest butterfly assemblages following the 1997–98 ENSO event, which resulted in the largest‐scale fires in the recorded history of the region.Location  A 420‐km2 area in the Balikpapan‐Samarinda region of East Kalimantan, Indonesian Borneo.Methods  Four landscapes were assessed after the 1997–98 ENSO event, including one landscape that was assessed prior to the event. Comparisons of species richness, species composition and guild abundance were made among landscapes and years. The relative importance of environment, geographical distance between sampling sites, and time between sampling years was quantified during the succession phase using a variance partitioning technique.Results  The fires dramatically altered the butterfly community and resulted in a major decline in observed species richness within the landscape surveyed prior to the ENSO event. Following fires in 1998, butterfly assemblages in all landscapes were dominated by large‐winged generalist species. During 1999 and 2000, assemblages became increasingly dominated by smaller specialist species. Species endemic to Borneo that were present before fires were absent in 2000, despite intensive sampling over enhanced spatial and environmental scales. Community similarity was significantly dependent upon local environmental variables, geographical distance between sampling sites, and time between sampling years. Together, these explained over 52% of the observed variation in samples.Conclusions  The importance of geographical distance between sampling sites indicates that recovery was dependent upon colonization from proximate habitats. Despite an apparent trend of return to pre‐ENSO community structure, low species richness throughout the survey area indicates that full recovery had not taken place by 2000.
The implications of Tertiary and Quaternary sea level rise events for avian distribution patterns in the lowlands of northern South America
Authors: Nores Manuel 
Published: February 2004

ABSTRACTAim  To assess the correspondence between current avian distributions in the lowlands of northern South America with respect to the hypothesized importance of sea level rise and other events over the past 15 million years on speciation.Location  Tropical lowlands of north‐western South America.Methods  To establish which bird taxa may have originated in each area of endemism, I examined the ranges of all bird species occurring in the Pacific and the Caribbean lowlands. To determine land and sea distribution during a sea level rise of 100 m in north‐western South America and eastern Central America, I traced the 100 m contour line from the Geoatlas of Georama and the Global 30‐Arc‐Second Elevation Data (GTOPO30) produced by the US Geological Survey.Results  During a sea level rise of ∼100 m, marine incursions would have occurred from the Caribbean Sea and the Pacific Ocean. Several areas of tropical forest and dry/arid vegetation would have been isolated, currently known as the Darién, Chocó, Nechí, Catatumbo, Tumbesian and Guajiran areas of animal and plant endemism.Main conclusions  A large part of the high diversity of forest and nonforest birds and other animals and plants in the Pacific rain forest and the Caribbean woodland likely arose as the result of sea level rises, dispersal and other geological and climatic events.
Scale and trends in species richness: considerations for monitoring biological diversity for political purposes
Authors: Weber Darius , Hintermann Urs , Zangger Adrian 
Published: February 2004

ABSTRACTSwitzerland's governmental ‘Biodiversity Monitoring’ program is designed to produce factual information on the dynamics of biodiversity within the country for governmental agencies, politicians, and the general public. Monitoring a complex issue like biodiversity in order to give relevant and accurate messages to the general public and politicians within a politically relevant timescale and at moderate cost means focusing on few elements. Because relevant human impacts on biodiversity operate differently at different spatial scales, we need at least three different indicators to observe changes over time in local (‘within‐habitat’), landscape (‘habitat‐mosaic’), and macro‐scale (‘regional’) diversity. To keep things as simple as possible, we use species richness as an indicator for all three levels of diversity, just defining three different spatial scales (10 m2, 1 km2, regions, respectively). Each indicator is based on a number of taxonomic groups which have been selected mainly on the basis of costs and the availability of appropriate methods.
Terrestrial bird community patterns on the coralline islands of the Dahlak Archipelago, Red Sea, Eritrea
Authors: Azeria Ermias T. 
Published: February 2004

ABSTRACTAim  This study aims to explain the patterns of species richness and nestedness of a terrestrial bird community in a poorly studied region.Location  Twenty‐six islands in the Dahlak Archipelago, Southern Red Sea, Eritrea.Methods  The islands and five mainland areas were censused in summer 1999 and winter 2001. To study the importance of island size, isolation from the mainland and inter‐island distance, I used constrained null models for the nestedness temperature calculator and a cluster analysis.Results  Species richness depended on island area and isolation from the mainland. Nestedness was detected, even when passive sampling was accounted for. The nested rank of islands was correlated with area and species richness, but not with isolation. Idiosyncrasies appeared among species‐poor and species‐rich islands, and among common and rare species. Cluster analysis showed differences among species‐rich islands, close similarity among species‐poor and idiosyncratic islands, and that the compositional similarity among islands decreased with increasing inter‐island distance. Thus, faunas of species‐poor, smaller islands were more likely to be subsets of faunas of species‐rich, larger islands if the distance between the islands was short.Main conclusions  Species richness and nestedness were related to island area, and nestedness also to inter‐island distances but not to isolation from the mainland. Thus, nestedness and species richness are not affected in the same way by area and distance. Moreover, idiosyncrasies may have been the outcome of species distributions among islands being influenced also by non‐nested distributions of habitats, inter–specific interactions, and differences in species distributions across the mainland. Idiosyncrasies in nested patterns may be as important as the nested pattern itself for conservation – and conservation strategies based on nestedness and strong area effects (e.g. protection of only larger islands) may fail to preserve idiosyncratic species/habitats.
Body size structure in north‐western Mediterranean Plio‐Pleistocene mammalian faunas
Authors: Rodríguez Jesús , Alberdi María T. , Azanza Beatriz , Prado José L. 
Published: February 2004

ABSTRACTAim  We investigated the patterns of body‐size changes of the north‐western Mediterranean Plio‐Pleistocene large mammal faunas (excluding rodents, bats, lagomorphs and insectivores) in order to identify the tempo and mode of the major shifts in body size distribution, and to put them in the context of Plio‐Pleistocene environmental changes and the development of the Mediterranean climate.Location  We analysed fossil faunas of Spain, France and Italy. A set of recent regional faunas from several macroclimatic regions was selected to serve as elements for comparison of the size distribution of past faunas, consisting of: Spain, France and Italy together, Florida, California, Central Chile, Indochina, India, Korea‐Manchuria, Malawi, The Cape, North Africa, Turkey and Australia.Methods  Mammal species were grouped into five body size categories for carnivores and four categories for noncarnivore species. The number of species in each size category was computed and the resulting matrix of body weight classes × regions and time intervals was used as an input matrix in a Correspondence Analysis.Results  Recent and fossil faunas strongly differ in body size structure. The distribution of recent faunas within the CA seems to reflect both ecological and historic factors, intertwined in a complex fashion. No clear relationship has been observed between body size structure and environmental factors. During the late Pliocene to early Pleistocene there were only minor changes in the pattern of size distribution, although plant communities were in a transition process from subtropical forests to Mediterranean woodlands and steppes. The major change in body size structure of the north‐western Mediterranean fauna occurred at the Galerian, around 1 Ma ago. This marked the beginning of the modern fauna, and a general trend towards a larger body size, reduction in the number of medium sized herbivores, and an increase of large herbivores and megaherbivores.Main conclusions  The Plio‐Pleistocene faunas lack modern analogues. The body size structure of mammalian regional faunas appears to be strongly dependent on historical factors. The only major shift in body size distribution occurred during the Plio‐Pleistocene, in the late Villafranchian‐Galerian transition, coincident with the onset of the Pleistocene high intensity glacial cycles.
LIDAR Data Filtering and DTM Interpolation Within GRASS
Authors: Brovelli Maria A , Cannata Massimiliano , Longoni Ulisse M 
Published: February 2004

AbstractLIDAR (Light Detection and Ranging) is one of the most recent technologies in surveying and mapping. LIDAR is based on the combination of three different data collection tools: a laser scanner mounted on an aircraft, a Global Positioning System (GPS) used in phase differential kinematic modality to provide the sensor position and an Inertial Navigation System (INS) to provide the orientation. The laser sends towards the ground an infrared signal, which is reflected back to the sensor. The time employed by the signal, given the aircraft position and attitude, allows computation of the earth point elevation. In standard conditions, taking into account the flight (speed 200–250 km/hour, altitude 500–2,000 m) and sensor characteristics (scan angle ± 10–20 degrees, emission rate 2,000–50,000 pulses per second), earth elevations are collected within a density of one point every 0.5–3 m. The technology allows us therefore to obtain very accurate (5–20 cm) and high resolution Digital Surface Models (DSM). For many applications, the Digital Terrain Model (DTM) is needed: we have to automatically detect and discard from the previous DSM all the features (buildings, trees, etc.) present on the terrain. This paper describes a procedure that has been implemented within GRASS to construct DTMs from LIDAR source data.
A New GIS‐based Solar Radiation Model and Its Application to Photovoltaic Assessments
Authors: Šúri Marcel , Hofierka Jaroslav 
Published: February 2004

AbstractThe solar radiation model r.sun is a flexible and efficient tool for the estimation of solar radiation for clear‐sky and overcast atmospheric conditions. In contrast to other models, r.sun considers all relevant input parameters as spatially distributed entities to enable computations for large areas with complex terrain. Conceptually the model is based on equations published in the European Solar Radiation Atlas (ESRA). The r.sun model was applied to estimate the solar potential for photovoltaic systems in Central and Eastern Europe. The overcast radiation was computed from clear‐sky values and a clear‐sky index. The raster map of the clear‐sky index was computed using a multivariate interpolation method to account for terrain effects, with interpolation parameters optimized using a cross‐validation technique. The incorporation of terrain data improved the radiation estimates in terms of the model's predictive error and the spatial pattern of the model outputs. Comparing the results of r.sun with the ESRA database demonstrates that integration of the solar radiation model and the spatial interpolation tools in a GIS can be especially helpful for data at higher resolutions and in regions with a lack of ground measurements.
Development and Application of 2D and 3D GRASS Modules for Simulation of Thermally Driven Slope Winds
Authors: Ciolli Marco , De Franceschi Massimiliano , Rea Roberto , Vitti Alfonso , Zardi Dino , Zatelli Paolo 
Published: February 2004

AbstractThe ability to manage and process fully three‐dimensional information has only recently been made available for a few Geographical Information Systems (GIS). An example of integrated and complementary use of 2D and 3D GRASS modules for the evaluation and representation of thermally induced slope winds over complex terrain is presented. The analytic solution provided by Prandtl (1942) to evaluate wind velocity and (potential) temperature anomaly induced by either diurnal heating or nocturnal cooling on a constant angle slope is adopted to evaluate wind and temperature profiles at any point over both idealised and real complex terrain. As these quantities depend on the slope angle of the ground and on the distance from the slope surface suitable procedures are introduced to determine the coordinate n of a point in the 3D volume measured along the direction locally normal to the terrain surface. A new GRASS module has been developed to evaluate this quantity and to generate a 3D raster file where each cell is assigned the value of the cell on the surface belonging to the normal vector. The application of the algorithm implemented in GRASS to an ideal valley and to a real valley close to the city of Trento in the Alps provides results in accordance with data reported in the literature. An extension of Prandtl's (1942) model to take into account humidity and evaporation processes on the soil is also proposed and implemented.
Construction and Visualization of a Three Dimensional Geologic Model Using GRASS GIS
Authors: Masumoto Shinji , Raghavan Venkatesh , Yonezawa Go , Nemoto Tatsuya , Shiono Kiyoji 
Published: February 2004

AbstractThe present work aims at introducing a basic theory, implementing methodology and algorithms for 3‐D modeling, and visualizing a geologic model using the Open Source Free GIS GRASS environment. A 3‐D geologic model is constructed from the boundary surfaces of geologic units and the logical model of geologic structure. The algorithms for construction and visualization of the proposed model are based on the geologic function g. The geologic function g assigns a unique geologic unit to every point in the objective 3‐D space. The boundary surface that divides the objective space into two subspaces is estimated using data from field survey. The logical model showing the hierarchical relationship between these boundary surfaces and geologic units can be automatically generated based on the stratigraphic sequence and knowledge of geologic structures. Based on these algorithms, a 3‐D geologic model can be constructed virtually in the GRASS GIS. Applying this model, various geologic surfaces and section models can be visualized in the GRASS GIS environment. “Nviz” was used for dynamic visualization of geologic cross‐sections and generation of animated image sequences. Further, the described algorithms and methods are applied and an online 3‐D geologic modeling system is developed.
Mobile Wireless GRASS GIS for Handheld Computers Running GNU/Linux
Authors: Stankovic Jan , Neteler Markus , Flor Roberto 
Published: February 2004

AbstractRecent developments of the communication technologies in the last years opened a new dimension to Geographical Information Systems and Geoinformation Techno‐logies. This new dimension is mobility. It is simplifying data gathering, processing and presentation independent from the area of application. A new branch, Mobile Geoinformation Technologies, is based on wireless communication systems, mobile personal computers, positioning systems and GIS. There are some proprietary GIS software solutions for mobile or handheld devices available on the market, but they are more focused on data logging tasks than providing full powered GIS support or data processing functions. In this paper, we propose a mobile implementation of the free and easily expandable GRASS GIS software in combination with the GNU/Linux operating system run on handheld devices. This approach supports real time in the field computations, data processing and cooperation of several active mobile clients using wireless networking.