bluuebunny/crossref_metadata_2025_split huggingface dataset:
Species frequency dynamics in an old‐field succession: Effects of disturbance, fertilization and scale
Authors: Gibson David J. , Middleton Beth A. , Foster Kari , Honu Yohanes A.K. , Hoyer Erik W. , Mathis Marilyn 
Published: February 2009

AbstractQuestion:Can patterns of species frequency in an old‐field be explained within the context of a metapopulation model? Are the patterns observed related to time, spatial scale, disturbance, and nutrient availability?Location:Upland and lowland old‐fields in Illinois, USA.Method:Species richness was recorded annually for seven years following plowing of an upland and lowland old‐field subject to crossed fertilizer and disturbance treatments (mowing and rototilling). Species occupancy distributions were assessed with respect to the numbers of core and satellite species.Results:In both fields, species richness became higher in disturbed plots than in undisturbed plots over time, and decreased in fertilized plots irrespective of time. A bimodal pattern of species richness consistent with the Core‐satellite species (CSS) hypothesis occurred in the initial seed bank and through the course of early succession. The identity of native and exotic core species (those present in > 90% of blocks) changed with time. Some core species from the seed bank became core species in the vegetation, albeit after several years. At the scale of individual plots, a bimodal fit consistent with the CSS hypothesis applied only in year 1 and rarely thereafter.Conclusions:The CSS hypothesis provides a metapopulation perspective for understanding patterns of species richness but requires the assessment of spatial and temporal scaling effects. Regional processes (e.g. propagule availability) at the largest scale have the greatest impact influencing community structure during early secondary succession. Local processes (e.g., disturbance and soil nutrients) are more important at smaller scales and place constraints on species establishment and community structure of both native and exotic species. Under the highest intensity of disturbance, exotic species may be able to use resources unavailable to, or unused by, native species.
Resource use efficiency as a function of species richness and stand composition in upper montane conifer forests of the Sierra Nevada
Authors: DeClerck Fabrice A.J. , Barbour Michael G. , Sawyer John O. 
Published: February 2009

AbstractQuestions:1. Does resource use efficiency increase with increased species richness in conifer forests? 2. Do patterns found in resource use support niche differentiation/complementarity between species, or is any increase indicative of a selection effect?Location:All data were collected from upper montane (2200–2600 m a.s.l) conifer forests of the Desolation Wilderness in the central California Sierra Nevada, USA.Methods:We established 281 plots of varying levels of conifer richness throughout the wilderness area. Within each plot we used hemispherical photos to measure canopy closure and LAI, total soil carbon and nitrogen from the A‐horizon, and stand basal area. We used linear regression and ANOVA to analyse the relationship between stand species richness and resource availability.Results:We found no correlation of either soil nitrogen or carbon with stand biomass. Nor did soil nitrogen and carbon levels change with species richness. Canopy closure increased with species richness but also varied significantly between pure stands of different species. PurePinus monticolastands had the lowest canopy closure,Tsuga mertensianastands the highest. Composition explained more canopy cover variation than did species richness. We found evidence supporting both the sampling effect and niche differentiation models at different stages of stand development.Conclusions:During initial stages of stand development, the interaction between the shade‐intolerantPinusspecies and shade‐tolerantAbies magnificaandT. mertensianafollowed the niche differentiation model, but switched to the sampling effect model during the competitive‐exclusion stage. In contrast, interaction betweenA. magnificaandT. mertensianafollowed the niche differentiation model.
Plant species as predictors of soil pH: Replacing expert judgement with measurements
Authors: Wamelink G.W. Wieger , Goedhart Paul W. , Van Dobben Han F. , Berendse Frank 
Published: February 2009

AbstractQuestion:The use of expert‐based indicator values to estimate abiotic conditions from vegetation is widespread. However, recent research has shown that expert judgement may contain considerable bias and thereby introduces a large amount of uncertainty. Could expert based indicator values be replaced by indicator values based on field measurements?Location:Europe.Methods:We developed a method to estimate species response based on measured physical data, and a method to predict abiotic conditions from the vegetation composition using these responses. This method was tested for soil pH.Results:We were able to estimate the pH response of 556 species of the Dutch flora. Ca. 20% of the responses were, at least, bimodal and many responses had a very wide range. The simplest method (‘raw mean’) yielded the best prediction of pH; the indicator value of a species is the mean of the soil pH values of the sites where it was observed. A list of all raw‐mean estimates per species is given. The predicted pH of a new site is the mean of the indicator values of the present species. The estimated species responses were validated on independent Dutch and European data sets. Older successional stages seem to be predicted better than younger stages.Conclusions:Our method performed better than the popular Ellenberg indicator system for the Dutch data set, while being just as easy to use, because it only needs a single value per species. We foresee that, when more data become available, our method has the potential to replace the Ellenberg system.
Effects of resource availability and heterogeneity on the slope of the species‐area curve along a floodplain‐upland gradient
Authors: Désilets P. , Houle G. 
Published: February 2009

AbstractQuestion:What are the relative effects of resource availability and heterogeneity on the slope of the species‐area curve along a floodplain‐upland gradient?Location:Réserve Léon‐Provancher, Québec, Canada.Methods:The mean and coefficient of variation of several environmental variables (soil organic matter, N and pH; irradiance; elevation) were estimated in 70 plots along a floodplain‐upland gradient. The slope of the species‐area curve was calculated from subplots nested within each plot. Path analysis was used to determine the effects of the environmental variables on the slope of the species‐area curve.Results:Spatial variation in flooding intensity created a complex gradient along which resource availability, but not resource heterogeneity, varied. Together, the environmental variables explained 73% of the variance in the slope of the species‐area curve. Elevation, soil variables (but not light) and heterogeneity in soil fertility (but not in light) were all significantly associated with the slope of the species‐area curve. Resource availability explained three times as much of the variance as resource heterogeneity.Conclusion:The expected positive relationships between resource availability, resource heterogeneity and diversity were obscured by effects of flooding stress and species dominance. Flooding intensity varies inversely with elevation and restricts the pool of species that can occupy the more fertile/heterogeneous section of the gradient, i.e. near the river. The few species combining flooding stress tolerance and competitive ability use the abundant resources near the river to grow quickly and utilize space, thereby enhancing the negative effect of the flooding stress on diversity.
Multivariate exploratory analysis of ordinal data in ecology: Pitfalls, problems and solutions
Authors: Podani János 
Published: February 2009

AbstractQuestions:Are ordinal data appropriately treated by multivariate methods in numerical ecology? If not, what are the most common mistakes? Which dissimilarity coefficients, ordination and classification methods are best suited to ordinal data? Should we worry about such problems at all?Methods:A new classification model family, OrdClAn (OrdinalClusterAnalysis), is suggested for hierarchical and non‐hierarchical classifications from ordinal ecological data, e.g. the abundance/dominance scores that are commonly recorded in relevés. During the clustering process, the objects are grouped so as to minimize a measure calculated from the ranks of within‐cluster and between‐cluster distances or dissimilarities.Results and Conclusions:Evaluation of the various steps of exploratory data analysis of ordinal ecological data shows that consistency of methodology throughout the study is of primary importance. In an optimal situation, each methodological step is order invariant. This property ensures that the results are independent of changes not affecting ordinal relationships, and guarantees that no illusory precision is introduced into the analysis. However, the multivariate procedures that are most commonly applied in numerical ecology do not satisfy these requirements and are therefore not recommended. For example, it is inappropriate to analyse Braun‐Blanquet abudance/dominance data by methods assuming that Euclidean distance is meaningful. The solution of all problems is that the dissimilarity coefficient should be compatible with ordinal variables and the subsequent ordination or clustering method should consider only the rank order of dissimilarities. A range of artificial data sets exemplifying different subtypes of ordinal variables, e.g. indicator values or species scores from relevés, illustrate the advocated approach. Detailed analyses of an actual phytosociological data set demonstrate the classification by OrdClAn of relevés and species and the subsequent tabular rearrangement, in a numerical study remaining within the ordinal domain from the first step to the last.
Promotion of species co‐existence in old‐growth coniferous forest through interplay of life‐history strategy and tree competition
Authors: Nishimura Naoyuki , Hara Toshihiko , Kawatani Midori , Hoshino Daisuke , Yamamoto Shin‐Ichi 
Published: February 2009

AbstractQuestion:Does the interplay of life‐history strategy and tree competition promote tree species co‐existence? Using a growth dynamics model, we investigated mechanisms of co‐existence among major tree species in a sub‐alpine old‐growth coniferous forest.Location:Sub‐alpine old‐growth coniferous forest at 1850–1920 m a.s.l. in the Ontake Forest Reserve of central Japan.Methods:We investigated the growth and mortality rates of trees ≥ 5.0 cm stem DBH and recruitment processes in a 2‐ha study plot, and developed a model for individual growth that incorporated both intra and interspecific competition and analysed the direction and degree of competitive effect.Results:Four species, Picea jezoensis var. hondoensis, Tsuga diversifolia, Abies mariesii and Abies veitchii co‐occurred as dominant species in the canopy layer. P. jezoensis var. hondoensis and T. diversifolia had low stem densities and bell shaped DBH distributions. In contrast, A. mariesii and A. veitchii had high stem densities and inverse J‐shaped DBH distributions. The growth of the species with inverse J‐shaped DBH distributions (Abies spp.) was governed by the abundances of the species with bell shaped DBH distributions (Picea and Tsuga). However, Picea and Tsuga were inferior to Abies spp. in terms of recruitment rate (the number of juveniles that grow up to 5.0 cm DBH per year). Therefore, it was suggested that there was a trade‐off between recruitment pattern and interspecific competition for species co‐existence.Conclusions:Picea and Tsuga, with inferior recruitment, coexisted with Abies spp., with superior recruitment, by suppressing the growth of potential successors of Abies spp. The interplay of life‐history strategies (recruitment and longevity) and interspecific competition therefore plays an important role in promoting species co‐existence in this sub‐alpine old‐growth coniferous forest.
Disturbance dynamics of old‐growth Picea rubens forests of northern Maine
Authors: Fraver Shawn , White Alan S. 
Published: February 2009

AbstractQuestion:How have the spatial and temporal aspects of past disturbance shaped the current structure and composition of old‐growth Picea rubens forests?Location:Northern Maine, USA.Methods:We established three 50 m × 50 m plots in old‐growth Picea rubens forests and mapped the location of trees and saplings. We extracted increment cores from canopy trees, and recorded growth releases indicating past disturbance. By linking spatial data (tree positions) and temporal data (dated growth releases), we reconstructed the location and size of former canopy gaps back to 1920, and determined a more general disturbance chronology extending as far back as 1740.Results:We found no evidence of stand‐replacing disturbances. The disturbance dynamic includes pulses of moderate‐severity disturbances caused by wind storms and host‐specific disturbance agents (spruce budworm, spruce bark beetle) interposed upon a background of scattered smaller canopy gaps. Consequently, rates of disturbance fluctuated considerably over time. Reconstructed canopy gaps were temporally and spatially scattered; during disturbance peaks, they were both larger and more numerous.Conclusions:Despite peaks in disturbance, several of which created relatively large gaps, this system has experienced no significant change in species composition. Instead, the shade‐tolerant Picea rubens has maintained canopy dominance. The patch dynamics described here consist of dramatic structural, not compositional, changes to the forest. The persistence of Picea rubens is attributed to a combination of traits: (1) abundance of advance regeneration; (2) ability to endure suppression and respond favourably to release; and (3) longevity relative to ecologically similar species.
Tree seedling performance in microhabitats along an elevational gradient on Mount Koma, Japan
Authors: Akasaka Munemitsu , Tsuyuzaki Shiro 
Published: February 2009

AbstractQuestions:How do biological invasion patterns of Larix kaempferi seedlings change with different microhabitats along an elevational gradient on a volcano? How are seedling attributes such as establishment, competitive ability and morphological plasticity, advantageous to the invasion of stressful disturbed areas?Location:Mount Koma, Hokkaido, Japan.Methods:Seed sowing experiments and natural seedling censuses were conducted with L. kaempferi and the dominant native tree Betula ermanii. Seed germination, seedling survival and allocation were investigated on three microhabitats (bare ground, Salix reinii patch and Larix understorey) in three elevational zones for three years.Results:Seed germination was higher in Larix understorey than in bare ground and Salix patches, but did not differ between elevations. Survival rates were not different between elevations and microhabitats. Larix had a higher survival rate than Betula. Larix showed the highest natural seedling density in Salix patches, independent of elevational differences, while Betula density was nearly zero. Larix seedlings changed allocations between microhabitats, while the ratio of leaf to total biomass was constant. In bare ground Larix was more stunted and branched and increased its allocation to the roots. This form is adaptive to windy, nutrient‐poor environments. Larix seedlings were taller and more slender in Salix patches, indicating that the priority was light acquisition in shaded habitats. Little change in Betula allocation was detected.Conclusion:Invasive species establish themselves more efficiently than native species in every microhabitat investigated, especially at higher elevations, by having higher survival and growth rates derived from superior seedling performance. Plant communities on and above the tree line are modified by the biological invasion.
Fine‐scale post‐fire dynamics in southern Brazilian subtropical grassland
Authors: Overbeck Gerhard Ernst , Müller Sandra Cristina , Pillar Valério DePatta , Pfadenhauer Jörg 
Published: February 2009

AbstractQuestion:How does fire influence species richness and diversity in subtropical grassland in southern Brazil?Location:Recurrently burned grassland in Porto Alegre, Brazil (30°03′S, 51°07’W; max. altitude 311 m a.s.l.) and abandoned grassland near São Francisco de Paula, Brazil (29°47′S, 50°22’W; ca. 900 m a.s.l.).Methods:In the burned grassland, between‐year changes in community composition and single‐plot diversity, species number and vegetation structure were analysed in two consecutive years for plots with different time since last fire. Responses to fire of individual species were analysed. At the abandoned site, diversity, species number and vegetation structure were examined.Results:Species number and small‐scale species turnover were highest ca. one year after the burn, and decreased as caespitose grasses increased in cover with time since fire until reaching a stable, but less diverse state three to four years after a fire. The abandoned grassland showed higher dominance of caespitose grasses and lower richness and diversity.Conclusions:Fire clearly leads to a short‐term increase in species richness and diversity at the plot scale, as competitive interactions are being reduced and recruitment possibilities are high in early post‐fire vegetation development. Overall community composition does not change after a fire. While small herbs seem to be slightly favoured in the early post‐fire environment, no clear group of fire following species (absent in vegetation unburned for longer) was observed. The results indicate that the community is adapted to the current fire regime and is being maintained under the influence of fire.
Hurricane disturbance accelerates invasion by the alien tree Pittosporum undulatum in Jamaican montane rain forests
Authors: Bellingham Peter J. , Tanner Edmund V.J. , Healey John R. 
Published: February 2009

AbstractQuestions:Do past disturbance, soil nutrients, or species diversity predict the invasion success of the alien tree Pittosporum undulatum in an island montane rain forest? What are the consequences of its invasion for forest composition and species diversity?Location:Blue Mountains, Jamaica.Methods:Censuses of trees ≥ 3 cm DBH in permanent plots in four sites within ca. 7 ha; 1974–2004 (intensive sites) and in 16 plots within 250 ha; 1990–2004 (extensive plots).Results:Pittosporum was unrecorded in the intensive sites before a severe hurricane in 1988: by 2004 all four sites were invaded. Pittosporum had invaded 25% of the extensive plots in 1990 and 69% in 2004, where its basal area increased from 0.5 ± 0.4 (SEM) m2.ha‐1 in 1990 to 2.8 ± 1.3 m2.ha‐1 in 2004. It had zero stem mortality and diameter growth rate exceeded that of native species fourfold. Pittosporum's basal area in the extensive plots in 2004 was positively related to the stand basal area damaged in the 1988 hurricane and negatively related to soil N concentrations. Pittosporum invasion was unrelated to stand‐level tree species diversity in the extensive plots but as its basal area increased over time the basal area of native species and stand‐level diversity declined.Conclusions:There are no obvious functional attributes of Pittosporum unrepresented in the native tree flora although it has high photosynthetic efficiency compared with native trees. More widespread invasion of these forests by Pittosporum seems inevitable since hurricanes, which accelerated the invasion, affect these forests frequently.
Competition and herbivory influence growth and survival of shrubs on old fields: Implications for restoration of renosterveld shrubland
Authors: Midoko‐Iponga Donald , Krug Cornelia B. , Milton Suzanne J. 
Published: February 2009

AbstractQuestion:How does competition by grasses, grazing by indigenous large herbivores, and their interaction affect the establishment, growth and survival of transplanted native woody and herbaceous seedlings on an abandoned agricultural field?Location:West Coast Renosterveld, Cape Floral Region, South Africa.Methods:Indigenous shrub seedlings were planted in different treatments, where either grass competition or herbivory or both were manipulated. Survival, growth and canopy cover of the seedlings were measured on a monthly basis over 14 months, and compared between treatments.Results:Experimental transplanting of indigenous shrubs into an old field showed that most of the plants investigated competed for resources with grasses on the field, and competition negatively affected the seedlings throughout the experiment. Mortality was higher, and growth was reduced for seedlings exposed to grass competition. Herbivory alone had no significant impact on the target species with the exception of Olea europaea ssp. africana. There was no significant interaction between competition and herbivory.Conclusion:Reduction of herbaceous competition significantly accelerates shrubland recovery on abandoned agricultural fields in renosterveld.
Spatial distribution of regeneration patches in an old‐growth Pinus Jeffrey‐mixed conifer forest in northwestern Mexico
Authors: Stephens S.L. , Fry D.L. 
Published: February 2009

AbstractQuestion:What are the shape, abundance, size, and structural characteristics of sapling patches in an old‐growth Pinus jeffreyi‐mixed conifer forest with a relatively intact disturbance regime?Location:Sierra San Pedro Martir, Baja California, Mexico.Methods:Regeneration was quantified by sampling sapling patches on seven 1200 m permanently marked line transects. For all patches intersected, tree size, species, age, and patch canopy cover were recorded. Patch structural characteristics were statistically compared to data from unbiased forest inventory plots. The minimum regeneration patch was defined as three saplings in a 49‐m2 area.Results:We sampled 54 sapling regeneration patches. Patch size varied from 6.6 to 674.8 m2. A small portion of the forest was in patches (patch fraction = 3.8%, patch abundance = 8.5 per ha). The majority of the patches were small; 64.8% were less than the mean patch area of 100.1 m2. Patches were shaped as a rhombus. For all forest characteristics, mean values inside patches were significantly different than those from the unbiased forest inventory plots.Conclusions:These forests have a fine‐grained pattern of regeneration patches. Our largest patch size of 674.8 m2 is the smallest reported in Pinus jeffreyi, P. ponderosa, and mixed conifer forests; other studies have probably had more difficulty delineating regeneration patches because of forest ingrowth from fire exclusion. Frequent fire, irregular seed crops, and seed dispersal by small mammals and birds could create this regeneration patch regime. High variation in nutrient availability after fire could also contribute to increased stand patchiness.