Disentangling relationships between habitat conditions, disturbance history, plant diversity, and American black cherry (Prunus serotina Ehrh.) invasion in a European temperate forest

Whether non-native plant invasions are causes, consequences, or independent of the low species diversity in recipient ecosystems remains a debated question. We tried to test these three hypotheses in the special case of the American black cherry ( Prunus serotina Ehrh.), a gap-dependent tree species, which is invading European temperate forests. We compared plant communities, soil properties, and disturbance history between P. serotina -invaded and uninvaded paired-stands in a managed mixed forest. Relationships between invasion, disturbances, plant communities, and environmental conditions were investigated using redundancy analyses with variation partitioning. Several soil characteristics differed between paired stands, but were rather components of stand invasibility than invasion effects, except for topsoil available phosphorus. The disturbance history was similar among paired stands except for the amount of storm-induced tree falls, which correlated with the invader's density. Wild boar-disturbed soil areas were more important beneath P. serotina canopies, suggesting a positive feedback on its own establishment. Overall, species assemblages in invaded and uninvaded stands were similar; their ecological inconsistency suggested a management-sustained non-equilibrium. Habitat conditions and disturbances explained most of the variation in both plant diversity and P. serotina density, the last two factors exhibiting a weak direct association. We conclude that in managed forest ecosystems where plant communities are mainly driven by non-interactive factors and immigration processes, non-native plant species can naturalize without being directly influenced by measured features of the plant community in the receiving environment on the short term.     

Importance of the understory stratum to entomofaunal diversity in a temperate deciduous forest

The vertical stratification of lepidopteran and coleopteran communities in a cool-temperate deciduous forest in Japan was examined to evaluate the hypothesis of an expected uniform distribution of mobile flying insects between the canopy and understory of temperate forests. Lepidopteran and coleopteran insects were trapped using light traps at three sites in each of the canopy and understory for three consecutive nights each month from April to October 2001. For Lepidoptera, species richness, abundance, and family richness were significantly higher in the understory than in the canopy. For Coleoptera, only abundance was larger in the canopy relative to the understory; species and family richness did not differ between the strata. The beta diversity of the lepidopteran community was larger between the strata than among sites, but the coleopteran community showed an inverse pattern. These results imply the presence of vertical stratification within the lepidopteran community, but not within the coleopteran community, in the temperate forest. The understory contributes more than the canopy to lepidopteran diversity in the temperate forest, although this stratification may be relatively weak because, in contrast to the situation in tropical forests, the canopy and understory assemblages share many species.     

Herbivores modify selection on plant functional traits in a temperate rainforest understory

There is limited evidence regarding the adaptive value of plant functional traits in contrasting light environments. It has been suggested that changes in these traits in response to light availability can increase herbivore susceptibility. We tested the adaptive value of plant functional traits linked with carbon gain in contrasting light environments and also evaluated whether herbivores can modify selection on these traits in each light environment. In a temperate rainforest, we examined phenotypic selection on functional traits in seedlings of the pioneer tree Aristotelia chilensis growing in sun (canopy gap) and shade (forest understory) and subjected to either natural herbivory or herbivore exclusion. We found differential selection on functional traits depending on light environment. In sun, there was positive directional selection on photosynthetic rate and relative growth rate (RGR), indicating that selection favors competitive ability in a high-resource environment. Seedlings with high specific leaf area (SLA) and intermediate RGR were selected in shade, suggesting that light capture and conservative resource use are favored in the understory. Herbivores reduced the strength of positive directional selection acting on SLA in shade. We provide the first demonstration that natural herbivory rates can change the strength of selection on plant ecophysiological traits, that is, attributes whose main function is resource uptake. Research addressing the evolution of shade tolerance should incorporate the selective role of herbivores.     

Habitat niche specialization in an understory species in a warm temperate forest

Relationships between microhabitat variables; understory light conditions in summer and winter, altitude, slope inclination and topographic categories (valley, ridge, and slope) and the distribution of Aucuba japonica Thunb. (Cornaceae), a common understory shrub species in Japan were examined using non-contagious 66, 20 × 20 m² quadrats. The Morishita’s I _δ suggested that A. japonica distributions were strongly heterogeneous among the quadrats. Therefore positive spatial autocorrelation of A. japonica at a within-quadrat level (≤20 m) was obvious. Moran’s I statistics showed a significant positive spatial autocorrelation in A. japonica abundance within the distance shorter than 60 m. But the partial Mantel tests suggested that the mass effect from neighboring quadrats would little explain A. japonica abundance in a quadrat. The partial Mantel tests also clearly showed that A. japonica distributions were strongly structured by topography and understory light conditions. Using Monte Carlo randomization tests, we found that A. japonica was aggregately distributed in quadrats in valley which were covered by deciduous canopies. Better understory light conditions in winter together with valley edaphic conditions may increase the abundance of A. japonica there. It is concluded that habitat niche specialization is important in structuring distribution of A. japonica in this forest community.     

Underestimated spider diversity in a temperate beech forest

We used canopy fogging to study the high (20–26 m), intermediate (13–19 m) and low (5–6 m) strata in three European beech patches (Fagus sylvatica) in nine months (2005–2007) and estimate species richness and diversity of arboreal spiders. Eight species (10%) were previously unseen in European beech trees, and one of these is likely a new species. Moreover, two species are on the Bavarian red list. Our results revealed that the high stratum of the old-growth trees provided unique resources and possessed the greatest diversity and evenness, whereas intermediate and low strata had high similarity in respect to diversity, dominance, species, and family composition. Since the majority of beech forests consists of mature and young trees in Central Europe, and old-growth forests are rarely preserved, we recommend young beech be used in a sampling protocol for rapid biodiversity assessment. However, adding samples from the two higher strata to the lowest stratum (55 species), almost doubled the estimated species richness (102 species). This suggests that the lower stratum alone does not represent a true image of the total canopy fauna inventory in this, and likely other, beech stands. To complete this comprehensive inventory in European beeches, the Chao1 predicted that additional sampling would be needed in the highest stratum, where there is a high probability to find previously undetected species in a next survey. Our study clearly shows that neglecting the crowns of the largest, tallest trees risks underestimating the overall spider diversity in Central European forests.     

Impact of invasion of Acer platanoides on canopy structure and understory seedling growth in a hardwood forest in North America

Invasion by exotic plant species is known to affect native communities and ecosystems, but the mechanisms of the impacts are much less understood. In a field study, we examined the effects of a tree invader, Acer platanoides (Norway maple, NM), on canopy structure and seedling growth in the understory of a North American deciduous forest. The experimental site contains a monospecific patch of A. platanoides and a mixed patch of A. platanoides with its native congener, A. rubrum (red maple, RM). In the study, we examined canopy characteristics of three types of trees in the forests, i.e., RM trees in the mixed forest, NM trees in the mixed forest, and NM trees in its monospecific patch. Height growth and biomass production of RM and NM seedlings under intact canopies and newly created gaps of the three types of trees were followed for two growing seasons. We found that removal of half of the canopy from focal trees increased canopy openness and light transmission to the forest floor, but to a greater extent under NM trees than under RM trees. Seedlings of these two Acer species varied greatly in biomass production under canopies of the same type of trees and in their responses to canopy opening. For example, seedlings of the exotic NM grown under the native RM trees in the mixed forests increased biomass production by 102.4% compared to NM seedlings grown under conspecific trees. The native RM seedlings grown under NM trees, however, reduced biomass production by 23.5% compared to those grown under conspecific trees. It was also observed that RM was much more responsive in biomass production to canopy opening than NM. For instance, total seedling biomass increased by 632.2% in RM, but by only 134.6% in NM in response to the newly created gaps. In addition, we found that NM seedlings allocated a greater portion of biomass below-ground as canopy openness increased, whereas the same trend was not observed in RM seedlings. Our results thus demonstrated that invasion of NM significantly altered canopy structure and community dynamics in the hardwood forest. Because the exotic NM seedlings are able to grow well under the native RM trees, but not vice versa, NM will likely expand its distribution in the forests and make it an ever increasingly serious tree invader in its non-native habitats, including North America.     

Genetic diversity and distribution patterns of Ecuadorian capuli (Prunus serotina)

Prunus serotina subsp. capuli (Cav.) is an arboreal species with promising economic prospects in the timber, health-food and neutraceutical markets. Despite its cultural and commercial significance, limited information exists with regards to the degree of genetic variation and ecological history of P. serotina in Ecuador. The main objective of this study was to evaluate the degree of genetic diversity and population structure of Ecuadorian P. serotina, as a preliminary step towards understanding the distribution history of this species in Ecuador and establishing germplasm conservation programs. P. serotina samples (217, representing 8 provinces from the Ecuadorian highlands) were characterized using 8 heterologous SSR markers derived from related Prunus species. Expected heterozygosity across samples (H_e = 0.71) reveals a moderate level of genetic diversity for Ecuadorian P. serotina. Nevertheless, simple allele-count analysis indicates that Ecuadorian capuli has a narrower degree of allelic richness relative to collections from the species’ center of origin in North America. Furthermore, pairwise F statistics (0.0069 ≤ Fst ≤ 0.0319) and Nei genetic distance estimates (0.02 ≤ Ds ≤ 0.09) indicate minimal population differentiation within Ecuadorian capuli. However, Bayesian population structure analysis suggests a subtle genetic contrast between germplasm from the Northern and Southern highlands. Certainly, it is of interest to analyze whether this underlying genetic differentiation between the Northern- and Southern-Highland groups is also manifested in morphological, agronomic or other phenotypic characters that could indicate adaptive differences to divergent agro-ecosystems.     

Seasonal dynamics of arboreal spider diversity in a temperate forest

Measuring and estimating biodiversity patterns is a fundamental task of the scientist working to support conservation and inform management decisions. Most biodiversity studies in temperate regions were often carried out over a very short period of time (e.g., a single season) and it is often-at least tacitly-assumed that these short-term findings are representative of long-term general patterns. However, should the studied biodiversity pattern in fact contain significant temporal dynamics, perhaps leading to contradictory conclusions. Here, we studied the seasonal diversity dynamics of arboreal spider communities dwelling in 216 European beeches (Fagus sylvatica L.) to assess the spider community composition in the following seasons: two cold seasons (I: November 2005-January 2006; II: February-April) and two warm seasons (III: May-July; IV: August-October). We show that the usually measured diversity of the warm season community (IV: 58 estimated species) alone did not deliver a reliable image of the overall diversity present in these trees, and therefore, we recommend it should not be used for sampling protocols aimed at providing a full picture of a forest's biodiversity in the temperate zones. In particular, when the additional samplings of other seasons (I, II, III) were included, the estimated species richness nearly doubled (108). Community I possessed the lowest diversity and evenness due to the harsh winter conditions: this community was comprised of one dominant species together with several species low in abundance. Similarity was lowest (38.6%) between seasonal communities I and III, indicating a significant species turnover due to recolonization, so that community III had the highest diversity. Finally, using nonparametric estimators, we found that further sampling in late winter (February-April) is most needed to complete our inventory. Our study clearly demonstrates that seasonal dynamics of communities should be taken into account when studying biodiversity patterns of spiders, and probably forest arthropods in general.     

Simulating the dispersal of hemlock woolly adelgid in the temperate forest understory

The hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), has spread rapidly across the eastern USA since its introduction from Japan 60 years ago, causing widespread mortality of both eastern hemlock [Tsuga canadensis (L.) Carrière] and Carolina hemlock [Tsuga caroliniana Engelm. (Pinaceae)]. Although HWA spread patterns have been repeatedly analyzed at regional scales, comparatively little is known about its dispersal potential within and between hemlock stands. As the small size and clonal nature of HWA make it nearly impossible to identify the source populations of dispersing individuals, we simulated intra‐stand HWA movement in the field by monitoring the movement of clumps of fluorescent powder that are slightly larger than HWA, but much easier to detect in the forest understory. Using three hemlock trees with three colors of fluorescent powder as source populations, we detected dispersal events at the farthest distances within our trapping array (400 m). However, more than 90% of dispersal events were <25 m. Dispersal patterns were similar from all three source trees and the distribution of dispersal distances in all cases could be described by lognormal probability density functions with mean dispersal distance of 12–14 m, suggesting that dispersal was relatively independent of location of source trees. In general, we documented tens of thousands of passive dispersal events in the forest understory despite the presence of a dense forest canopy. Thus, even under relatively light‐wind conditions, particles of similar dimensions to HWA are capable of intra‐stand movement, suggesting that a large population of HWA could rapidly infest other trees within several hundred meter radius, or beyond.     

Predicting patterns of invasion by black cherry (Prunus serotina Ehrh.) in Flanders (Belgium) and its impact on the forest understorey community

The design of cost-efficient control strategies for invasive species that are too widespread and abundant for complete eradication, at least in the short term, will benefit from a rigorous analysis of invasion patterns and associated effects on native biodiversity. In this paper, the case of the invasive North American tree Prunus serotina in Flanders (Belgium) is presented. Our main objectives were to determine the susceptibility of forest stands to invasion by P. serotina and the subsequent effects of invasion on the understorey community. We used the large database of the first Flemish Forest Inventory. Multiple logistic regressions indicated that P. serotina occurred more frequently in privately owned, younger forest on coarse-textured, dry soils (podzols), and the combination of these factors allowed us to correctly predict presence/absence of P. serotina in 70% of the validation plots. However, locational variables proved to be important as well, indicating that the invasion process is still ongoing. Prediction of P. serotina densities by means of multiple linear regressions was less successful. Effects on the understorey richness were analysed by comparing the number of species and the mean Ellenberg values between pairs of plots, only differing by the presence of P. serotina in the shrub layer. A reduction of the understorey richness following invasion was only pronounced on the more moist soils, while compositional changes mainly occurred on drier soils. It is concluded that priority for control should be given to landscapes with a low fraction of invaded stands and to forest stands located on more moist soils. However, using its potential to threaten native biodiversity as an argument for control should be done with care as further research is needed whether the observed negative effects are due to a species (i.e. native vs. non-native) or a density effect (high vs. low).     

暖温带森林生态系统林下灌木生物量相对生长模型

灌木层作为暖温带森林生态系统的重要组成部分,其生物量估算的精确性及便捷性,成为森林生态系统能量流动、物质循环研究的重要环节。目前可用于暖温带森林生态系统灌木层生物量估算的相对生长模型较少。以河北雾灵山国家级自然保护区暖温带森林生态系统为研究对象,建立了该区域15种常见灌木的相对生长模型。研究发现:15种灌木全株和单一器官的最优相对生长方程均以D2H为自变量,分别以幂函数W=a(D2H)b或二项式函数W=a+b D2H+c(D2H)2为最优化回归方程。统计分析结果显示:判断系数R2值介于0.7331—0.9992之间,显著性检验各参数P0.01,满足回归模型的适用性要求。对研究区域常见灌木全株生物量(WTU)的普适性研究发现:以D2H为自变量的二项式函数回归模型WTU=0.0362+297.03D2H-127.1(D2H)2,R2=0.9434,P0.01,普遍适用于除去六道木(Zabelia biflora)和照山白(Rhododendron micranthum)之外的13种灌木植物的生物量估算。此模型对以上2种植物不适用的原因有待进一步研究。     

Effects of arbuscular mycorrhiza on community composition and seedling recruitment in temperate forest understory

Arbuscular mycorrhizal (AM) fungal communities can influence the species composition of plant communities. This influence may result from effects of AM on seedling recruitment, although the existing evidence is limited to experimental systems. We addressed the impact of AM fungi on the plant community composition and seedling recruitment of two species – Oxalis acetosella and Prunella vulgaris – in a temperate forest understory. We established a field experiment over two years in which soil fertility (using fertilizer to enhance and sucrose to decrease fertility) and the activity of AM fungi (using fungicide) was manipulated in a factorial design. Species richness, diversity and community composition of understory plants were not influenced by soil fertility or AM fungal activity treatments. However, plant community composition was marginally significantly affected by the interaction of these treatments as the effect of AM fungal activity became evident under enhanced soil fertility. Suppression of AM fungal activity combined with decreased soil fertility increased the number of shoots of herbaceous plants. Unchanged activity of AM fungi enhanced the growth of O. acetosella seedlings under decreased soil fertility, but did not influence the growth of P. vulgaris seedlings. We conclude that the role of AM fungi in structuring plant communities depends on soil fertility. AM fungi can have a strong influence on seedling recruitment, especially for those plants that are characteristic of the habitat.     

Interactions between two co-dominant, invasive plants in the understory of a temperate deciduous forest

Negative interactions between non-indigenous and native species has been an important research topic of invasion biology. However, interactions between two or more invasive species may be as important in understanding biological invasions, but they have rarely been studied. In this paper, we describe three field experiments that investigated interactions between two non-indigenous plant species invasive in the eastern United States, Lonicera japonica (a perennial vine) and Microstegium vimineum (an annual grass). A press removal experiment conducted within a deciduous forest understory community indicated that M. vimineum was a superior competitor to L. japonica. We tested the hypothesis that the competitive success of M. vimineum was because it overgrew, and reduced light available to, L. japonica, by conducting a separate light gradient experiment within the same community. Shade cloth that simulated the M. vimineum canopy reduced the performance of L. japonica. In a third complementary experiment, we added experimental support hosts to test the hypothesis that the competitive ability of L. japonica is limited by support hosts, onto which L. japonica climbs to access light. We found that the abundance of climbing branches increased with the number of support hosts. Results of this experiment indicate that these two invasive species compete asymmetrically for resources, particularly light.     

Plant functional trait response to environmental drivers across European temperate forest understorey communities

• Functional traits respond to environmental drivers, hence evaluating trait‐environment relationships across spatial environmental gradients can help to understand how multiple drivers influence plant communities. Global‐change drivers such as changes in atmospheric nitrogen deposition occur worldwide, but affect community trait distributions at the local scale, where resources (e.g. light availability) and conditions (e.g. soil pH) also influence plant communities.
• We investigate how multiple environmental drivers affect community trait responses related to resource acquisition (plant height, specific leaf area (SLA), woodiness, and mycorrhizal status) and regeneration (seed mass, lateral spread) of European temperate deciduous forest understoreys. We sampled understorey communities and derived trait responses across spatial gradients of global‐change drivers (temperature, precipitation, nitrogen deposition, and past land use), while integrating in‐situ plot measurements on resources and conditions (soil type, Olsen phosphorus (P), Ellenberg soil moisture, light, litter mass, and litter quality).
• Among the global‐change drivers, mean annual temperature strongly influenced traits related to resource acquisition. Higher temperatures were associated with taller understoreys producing leaves with lower SLA, and a higher proportional cover of woody and obligate mycorrhizal (OM) species. Communities in plots with higher Ellenberg soil moisture content had smaller seeds and lower proportional cover of woody and OM species. Finally, plots with thicker litter layers hosted taller understoreys with larger seeds and a higher proportional cover of OM species.
• Our findings suggest potential community shifts in temperate forest understoreys with global warming, and highlight the importance of local resources and conditions as well as global‐change drivers for community trait variation.

     

Photographic assessment of temperate forest understory phenology in relation to springtime meteorological drivers

Phenology shows sensitive responses to seasonal changes in atmospheric conditions. Forest understory phenology, in particular, is a crucial component of the forest ecosystem that interacts with meteorological factors, and ecosystem functions such as carbon exchange and nutrient cycling. Quantifying understory phenology is challenging due to the multiplicity of species and heterogeneous spatial distribution. The use of digital photography for assessing forest understory phenology was systematically tested in this study within a temperate forest during spring 2007. Five phenology metrics (phenometrics) were extracted from digital photos using three band algebra and two greenness percentage (image binarization) methods. Phenometrics were compared with a comprehensive suite of concurrent meteorological variables. Results show that greenness percentage cover approaches were relatively robust in capturing forest understory green-up. Derived spring phenology of understory plants responded to accumulated air temperature as anticipated, and with day-to-day changes strongly affected by estimated moisture availability. This study suggests that visible-light photographic assessment is useful for efficient forest understory phenology monitoring and allows more comprehensive data collection in support of ecosystem/land surface models.     

Nitrogen uptake and preference in a forest understory following invasion by an exotic grass

Plant–soil interactions have been proposed as a causative mechanism explaining how invasive plant species impact ecosystem processes. We evaluate whether an invasive plant influences plant and soil-microbe acquisition of nitrogen to elucidate the mechanistic pathways by which invaders might alter N availability. Using a ¹⁵N tracer, we quantify differences in nitrogen uptake and allocation in communities with and without Microstegium vimineum, a shade-tolerant, C₄ grass that is rapidly invading the understories of eastern US deciduous forests. We further investigate if plants or the microbial biomass exhibit preferences for certain nitrogen forms (glycine, nitrate, and ammonium) to gain insight into nitrogen partitioning in invaded communities. Understory native plants and M. vimineum took up similar amounts of added nitrogen but allocated it differently, with native plants allocating primarily to roots and M. vimineum allocating most nitrogen to shoots. Plant nitrogen uptake was higher in invaded communities due primarily to the increase in understory biomass when M. vimineum was present, but for the microbial biomass, nitrogen uptake did not vary with invasion status. This translated to a significant reduction (P < 0.001) in the ratio of microbial biomass to plant biomass nitrogen uptake, which suggests that, although the demand for nitrogen has intensified, microbes continue to be effective nitrogen competitors. The microbial biomass exhibited a strong preference for ammonium over glycine and nitrate, regardless of invasion status. By comparison, native plants showed no nitrogen preferences and M. vimineum preferred inorganic nitrogen species. We interpret our findings as evidence that invasion by M. vimineum leads to changes in the partitioning of nitrogen above and belowground in forest understories, and to decreases in the microbial biomass, but it does not affect the outcome of plant–microbe–nitrogen interactions, possibly due to functional shifts in the microbial community as a result of invasion.     

Bird species diversity in forest understory: Analysis of mist-net samples

Summary Mist-netted samples of forest understory birds in neotropical (Costa Rica) and temperate (Illinois) forests (during spring migration) supported certain earlier observations: the neotropical understory sample contained more species, more rare species, and more species that use resources not sufficiently available in temperate forest.During spring migration in Illinois, the number of bird species in a mist-netted sample of the community approaches (albeit temporarily) that of neotropical forests and is sometimes even equivalent. But the constitution of these samples seems to be quite different in different regions. Costa Rican samples showed greater within-habitat variability and individual recapture distances were shorter, implying a greater local patchiness of bird distributions than in Illinois in spring.     

Functional and phylogenetic diversity determine woody productivity in a temperate forest

Understanding the relationships between biodiversity and ecosystem productivity has become a central issue in ecology and conservation biology studies, particularly when these relationships are connected with global climate change and species extinction. However, which facets of biodiversity (i.e. taxonomic, functional, and phylogenetic diversity) account most for variations in productivity are still not understood very well. This is especially true with regard to temperate forest ecosystems. In this study, we used a dataset from a stem‐mapped permanent forest plot in northeastern China exploring the relationships between biodiversity and productivity at different spatial scales (20 × 20 m; 40 × 40 m; and 60 × 60 m). The influence of specific environmental conditions (topographic conditions) and stand maturity (expressed by initial stand volume and biomass) were taken into account using the multivariate approach known as structural equation models. The variable “Biodiversity” includes taxonomic (Shannon), functional (FDis), and phylogenetic diversity (PD). Biodiversity–productivity relationships varied with the spatial scales. At the scale of 20 × 20 m, PD and FDis significantly affected forest biomass productivity, while Shannon had only indirect effects. At the 40 × 40 m and 60 × 60 m scales, biodiversity and productivity were weakly correlated. The initial stand volume and biomass were the most important drivers of forest productivity. The local environmental conditions significantly influenced the stand volume, biomass, biodiversity, and productivity. The results highlight the scale dependency of the relationships between forest biodiversity and productivity. The positive role of biodiversity in facilitating forest productivity was confirmed at the smaller scales. Our findings emphasize the fundamental role of environmental conditions in determining forest ecosystem performances. The results of this study provide a better understanding of the underlying ecological processes that influence specific forest biodiversity and productivity relationships.     

Multi-scale analysis on species diversity within a 40-ha old-growth temperate forest

In order to better explore the maintenance mechanisms of biodiversity,data collected from a 40-ha undisturbed Pinus forest were applied to the Individual SpecieseArea Relationship model (ISAR) to determine distribution patterns for species richness.The ecological processes influencing species abundance distribution patterns were assessed by applying the same data set to five models:a LogNormal Model (LNM),a Broken Stick Model (BSM),a Zipf Model (ZM),a Niche Preemption Model (NPM),and a Neutral Model (NM).Each of the five models was used at six different sampling scales (10 m×10 m,20 m×20 m,40 m×40 m,60 m×60 m,80 m×80 m,and 100 m×100 m).Model outputs showed that:(1) Accumulators and neutral species strongly influenced species diversity,but the relative importance of the two types of species varied across spatial scales.(2) Distribution patterns of species abundance were best explained by the NPM at small scales (10 me20 m),whereas the NM was the best fit model at large spatial scales.(3) Species richness and abundance distribution patterns appeared to be driven by similar ecological processes.At small scales,the niche theory could be applied to describe species richness and abundance,while at larger scales the neutral theory was more applicable.