Tree diversity is key for promoting the diversity and abundance of forest-associated taxa in Europe

Plant diversity is an important driver of diversity at other trophic levels, suggesting that cascading extinctions could reduce overall biodiversity. Most evidence for positive effects of plant diversity comes from grasslands. Despite the fact that forests are hotspots of biodiversity, the importance of tree diversity, in particular its relative importance compared to other management related factors, in affecting forest-associated taxa is not well known. To address this, we used data from 183 plots, located in different forest types, from Mediterranean to Boreal, and established along a climatic gradient across six European countries (FunDivEUROPE project). We tested the influence of tree diversity, tree functional composition (i.e. functional trait values), forest structure, climate and soil on the diversity and abundance/activity of nine taxa (bats, birds, spiders, microorganisms, earthworms, ungulates, foliar fungal pathogens, defoliating insects and understorey plants) and on their overall diversity and abundance/activity (multidiversity, multiabundance/activity). Tree diversity was a key driver of taxon-level and overall forest-associated biodiversity, along with tree functional composition, forest structure, climate and soil. Both tree species richness and functional diversity (variation in functional trait values) were important. The effects of tree diversity on the abundance/activity of forest-associated taxa were less consistent. Nonetheless, spiders, ungulates and foliar fungal pathogens were all more abundant/active in diverse forests. Tree functional composition and structure were also important drivers of abundance/activity: conifer stands had lower overall multidiversity (although the effect was driven by defoliating insects), while stands with potentially tall trees had lower overall multiabundance/activity. We found more synergies than tradeoffs between diversity and abundance/activity of different taxa, suggesting that forest management can promote high diversity across taxa. Our results clearly show the high value of mixed forest stands for multiple forest-associated taxa and indicate that multiple dimensions of tree diversity (taxonomic and functional) are important.     

Meta-analysis of tree diversity effects on the abundance,diversity and activity of herbivores' enemies

The natural enemies hypothesis predicts that the abundance and diversity of antagonists such as predators and parasitoids of herbivores increases with the diversity of plants, which can lead to more effective top-down control of insect herbivores. However, although the hypothesis has received large support in agricultural systems, fewer studies have been conducted in forest ecosystems and a comprehensive synthesis of previous research is still lacking.We conducted a meta-analysis of 65 publications comparing the diversity, abundance or activity of various groups of natural enemies (including birds, bats, spiders and insect parasitoids) in pure vs. mixed forest stands. We tested the effects of forest biome, natural enemy taxon and type of study (managed vs experimental forest).We found a significant positive effect of forest tree diversity on natural enemy abundance and diversity but not on their activity. The effect of tree diversity on natural enemies was stronger towards lower latitudes but was not contingent on the natural enemy taxon level.Overall, our study contributes toward a better understanding of the “natural enemies hypothesis” in forest systems and provides new insights about the mechanisms involved. Furthermore, we outline potential avenues for strengthening forest resistance to the growing threat of herbivorous insects.     

Disruption of ant-aphid mutualism in canopy enhances the abundance of beetles on the forest floor

Ant-aphid mutualism is known to play a key role in the structure of the arthropod community in the tree canopy, but its possible ecological effects for the forest floor are unknown. We hypothesized that aphids in the canopy can increase the abundance of ants on the forest floor, thus intensifying the impacts of ants on other arthropods on the forest floor. We tested this hypothesis in a deciduous temperate forest in Beijing, China. We excluded the aphid-tending ants Lasius fuliginosus from the canopy using plots of varying sizes, and monitored the change in the abundance of ants and other arthropods on the forest floor in the treated and control plots. We also surveyed the abundance of ants and other arthropods on the forest floor to explore the relationships between ants and other arthropods in the field. Through a three-year experimental study, we found that the exclusion of ants from the canopy significantly decreased the abundance of ants on the forest floor, but increased the abundance of beetles, although the effect was only significant in the large ant-exclusion plot (80*60 m). The field survey showed that the abundance of both beetles and spiders was negatively related to the abundance of ants. These results suggest that aphids located in the tree canopy have indirect negative effects on beetles by enhancing the ant abundance on the forest floor. Considering that most of the beetles in our study are important predators, the ant-aphid mutualism can have further trophic cascading effects on the forest floor food web.     

Influence of Lumbricus terrestris earthworms on the structure of the yeast community of forest litter

The taxonomic structure of yeast communities was studied in forest litter and soil, as well as in substrates transformed by the activity of Lumbricus terrestris earthworms (tree waste from the hole mouths, the gut contents, and coproliths). The activity of L. terrestris has a weak effect on the total yeast abundance but results in substantial changes in their taxonomic composition. The share of ascomycetous yeasts is significantly higher in the substrates associated with the activity of earthworms. The teleomorphic ascomycetes Williopsis saturnus were isolated from the gut contents. The effect of earthworms on the composition of the yeast community in the process of forest litter destruction is more markedly pronounced than seasonal changes.     

The Effect of Local and Landscape-Level Characteristics on the Abundance of Forest Birds in Early-Successional Habitats during the Post-Fledging Season in Western Massachusetts

Many species of mature forest-nesting birds (“forest birds”) undergo a pronounced shift in habitat use during the post-fledging period and move from their forest nesting sites into areas of early-successional vegetation. Mortality is high during this period, thus understanding the resource requirements of post-fledging birds has implications for conservation. Efforts to identify predictors of abundance of forest birds in patches of early-successional habitats have so far been equivocal, yet these previous studies have primarily focused on contiguously forested landscapes and the potential for landscape-scale influences in more fragmented and modified landscapes is largely unknown. Landscape composition can have a strong influence on the abundance and productivity of forest birds during the nesting period, and could therefore affect the number of forest birds in the landscape available to colonize early-successional habitats during the post-fledging period. Therefore, the inclusion of landscape characteristics should increase the explanatory power of models of forest bird abundance in early-successional habitat patches during the post-fledging period. We examined forest bird abundance and body condition in relation to landscape and habitat characteristics of 15 early-successional sites during the post-fledging season in Massachusetts. The abundance of forest birds was influenced by within-patch habitat characteristics, however the explanatory power of these models was significantly increased by the inclusion of landscape fragmentation and the abundance of forest birds in adjacent forest during the nesting period for some species and age groups. Our findings show that including factors beyond the patch scale can explain additional variation in the abundance of forest birds in early-successional habitats during the post-fledging period. We conclude that landscape composition should be considered when siting early-successional habitat to maximize its benefit to forest birds during the post-fledging period, and should also be included in future investigations of post-fledging habitat use by forest birds.     

Comparing aye-aye (Daubentonia madagascariensis) presence and distribution between degraded and non-degraded forest within Ranomafana National Park, Madagascar

The aye-aye is considered the most widely distributed lemur in Madagascar; however, the effect of forest quality on aye-aye abundance is unknown. We compared aye-aye presence across degraded and non-degraded forest at Ranomafana National Park, Madagascar. We used secondary signs (feeding sites, high activity sites) as indirect cues of aye-aye presence and Canarium trees as an indicator of resource availability. All 3 measured variables indicated higher aye-aye abundance within non-degraded forest; however, the differences across forest type were not significant. Both degraded and non-degraded forests showed a positive correlation between feeding sites and high activity sites. We found that Canarium, an important aye-aye food source, was rare and had limited dispersal, particularly across degraded forest. This preliminary study provides baseline data for aye-aye activity and resource utilization across degraded and non-degraded forests.     

Flowers, fruits, and the abundance of the yellow-chevroned parakeet (Brotogeris chiriri) at a gallery forest in the South Pantanal (Brazil).

Parakeets usually forage for massive and ephemeral plant resources at forest canopies. Fruit pulp is widely cited as a major food resource for these birds, which often eat seeds and nectar. In this study, I assessed flower and fruit production at a gallery forest in the Pantanal flood plain (Brazil) in order to evaluate the relationship between food resource production and abundance of a common parakeet, Brotogeris chiriri. Also, I evaluated the relationship between food resource production and foraging activity. Parakeet abundance varied markedly along the year, coinciding with massive episodes of flower and fleshy fruit availability. Inga vera nectar, intensely used during the latter part of dry season, was by far the most exploited food item by parakeets when they were very abundant. The nectar comprised 34% of the parakeets' diet (N = 131 feeding records) at the gallery forest, while fleshy fruits made up the rest. Parakeets principally exploited fruits of Cecropia pachystachya and Ficus luschnathiana, besides palm fruits and Inga vera arils. The consistent relationship between foraging activity and parakeet abundance, as well as the coincidence between fluctuations of these parameters and availability of major food resources, suggests that food availability mostly influenced B. chiriri occurrence in the gallery forest. Furthermore, I found no evidence for gallery forest use for roosting and/or breeding, in spite of the fact that such factors usually influence local parakeet abundance.     

Molecular analysis of fungal communities and laccase genes in decomposing litter reveals differences among forest types but no impact of nitrogen deposition

The fungal community of the forest floor was examined as the cause of previously reported increases in soil organic matter due to experimental N deposition in ecosystems producing predominantly high-lignin litter, and the opposite response in ecosystems producing low-lignin litter. The mechanism proposed to explain this phenomenon was that white-rot basidiomycetes are more important in the degradation of high-lignin litter than of low-lignin litter, and that their activity is suppressed by N deposition. We found that forest floor mass in the low-lignin sugar-maple dominated system decreased in October due to experimental N deposition, whereas forest floor mass of high-lignin oak-dominated ecosystems was unaffected by N deposition. Increased relative abundance of basidiomycetes in high-lignin forest floor was confirmed by denaturing gradient gel electrophoresis (DGGE) and sequencing. Abundance of basidiomycete laccase genes, encoding an enzyme used by white-rot basidiomycetes in the degradation of lignin, was 5-10 times greater in high-lignin forest floor than in low-lignin forest floor. While the differences between the fungal communities in different ecosystems were consistent with the proposed mechanism, no significant effects of N deposition were detected on DGGE profiles, laccase gene abundance, laccase length heterogeneity profiles, or phenol oxidase activity. Our observations indicate that the previously detected accumulation of soil organic matter in the high-lignin system may be driven by effects of N deposition on organisms in the mineral soil, rather than on organisms residing in the forest floor. However, studies of in situ gene expression and temporal and spatial variability within forest floor communities will be necessary to further relate the ecosystem dynamics of organic carbon to microbial communities and atmospheric N deposition.     

Landscape-Scale Implications of the Edge Effect on Soil Fauna Activity in a Temperate Forest

Although studies on edge effects on species richness and abundance are numerous, the responses of ecosystem processes to these effects have received considerably less attention. How ecosystem processes respond to edge effects is particularly important in temperate forests, where small fragments and edge habitats form a considerable proportion of the total forest area. Soil fauna are key contributors to decomposition and soil biogeochemical cycling processes. Using the bait lamina technique, we quantified soil fauna feeding activity, and its dependence on soil moisture and distance to the edge in a broad-leaved forest in Southern England. Feeding activity was 40% lower at the forest edge than in the interior, and the depth of edge influence was approximately 75 m. A watering treatment showed that moisture limitation was the main driver of the reduced feeding activity at the edge. In England, only 33% of the forest area is greater than 75 m from the edge. Therefore, assuming that the results from this single-site study are representative for the landscape, it implies that only one- third of the forest area in England supports activity levels typical for the forest core, and that edge effects reduce the mean feeding activity across the landscape by 17% (with lower and upper 90% confidence intervals of 1.3 and 23%, respectively). Changing climatic conditions, such as summer droughts may exacerbate such effects as edges lose water faster than the forest interior. The results highlight the importance of taking edge effects into account in ecological studies and forest management planning in highly fragmented landscapes.     

Are Basidiomycete Laccase Gene Abundance and Composition Related to Reduced Lignolytic Activity Under Elevated Atmospheric NO<Subscript>3</Subscript><Superscript>−</Superscript> Deposition in a Northern Hardwood Forest?

Anthropogenic release of biologically available N has increased atmospheric N deposition in forest ecosystems, which may slow decomposition by reducing the lignolytic activity of white-rot fungi. We investigated the potential for atmospheric N deposition to reduce the abundance and alter the composition of lignolytic basidiomycetes in a regional network of four northern hardwood forest stands receiving experimental NO₃ ⁻ deposition (30 kg NO₃ ⁻−N ha⁻¹ year⁻¹) for a decade. To estimate the abundance of basidiomycetes with lignolytic potential, we used PCR primers targeting laccase (polyphenol oxidase) and quantitative fluorescence PCR to estimate gene copy number. Natural variation in laccase gene size permitted use of length heterogeneity PCR to profile basidiomycete community composition across two sampling dates in forest floor and mineral soil. Although past work has identified significant and consistent negative effects of NO₃ ⁻ deposition on lignolytic enzyme activity, microbial biomass, soil respiration, and decomposition rate, we found no consistent effect of NO₃ ⁻ deposition on basidiomycete laccase gene abundance or community profile. Rather, laccase abundance under NO₃ ⁻ deposition was lower (−52%), higher (+223%), or unchanged, depending on stand. Only a single stand exhibited a significant change in basidiomycete laccase gene profile. Basidiomycete laccase genes occurring in mineral soil were a subset of the genes observed in the forest floor. Moreover, significant effects on laccase abundance were confined to the forest floor, suggesting that species composition plays some role in determining how lignolytic basidiomycetes are affected by N deposition. Community profiles differed between July and October sampling dates, and basidiomycete communities sampled in October had lower laccase gene abundance in the forest floor, but higher laccase abundance in mineral soil. Although experimental N deposition significantly suppresses lignolytic activity in these forests, this change is not related to the abundance or community composition of basidiomycete fungi with laccase genes. Understanding the expression of laccases and other lignolytic enzymes by basidiomycete fungi and other lignin-decaying organisms appears to hold promise for explaining the consistent decline in lignolytic activity elicited by experimental N deposition. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Nutrient supply and bird predation additively control insect herbivory and tree growth in two contrasting forest habitats

It has been suggested that bottom–up and top–down forces interactively control food web dynamics. While top–down effects would increase with resource availability to plants, bottom–up effects would be stronger under low predator abundance. These predictions, however, have rarely been tested at contrasting sites while keeping the dominant plant species unchanged. Furthermore, few studies have factorially manipulated both types of forces in forest communities. For two years, we evaluated the effects of fertiliser (NPK) addition and bird exclusion on tree growth, leaf traits, insect abundance, and folivory rates in a dry/warm and a wet/cold Nothofagus pumilio forest in Patagonia, Argentina. Overall, we found no interaction between nutrient supply and bird predation, although the strength of bottom–up and top–down forces differed markedly between forest sites. Treatment effects were generally weak in the wet forest, where tree growth rates and insect herbivory were low relative to the dry forest. In the dry forest, fertilisation increased sapling growth, insect abundance and folivory, whereas bird exclusion increased leaf damage and reduced tree growth. In the wet forest, fertilisation enhanced leaf nutrient contents and folivore abundance but not sapling growth, while bird exclusion had little impact on insects or trees. These results imply that factors other than nutrients and birds were important in controlling tree growth and folivore activity in the wet forest. While treatment effect sizes varied widely among feeding guilds, in general, nutrient effects on folivores were stronger than predator effects. We conclude that, within the time‐frame of this study, tree growth and herbivory were additively affected by soil nutrients and predator presence, as bird exclusion effects did not change with elevated folivore activity on fertilised trees. We also show that both top–down and bottom–up cascades were weaker in a forest site characterised by slow‐growing juvenile trees subjected to low folivore pressure.     

Influence of <Emphasis Type="Italic">Lumbricus terrestris</Emphasis> earthworms on the structure of the yeast community of forest litter

The taxonomic structure of yeast communities was studied in forest litter and soil, as well as in substrates transformed by the activity of Lumbricus terrestris earthworms (leaves in heaps, the gut contents, and coproliths). The activity of L. terrestris has a weak effect on the total yeast abundance but results in substantial changes in the community taxonomic composition. The share of ascomycetous yeasts is significantly higher in the substrates associated with the activity of earthworms. The teleomorphic ascomycetes Williopsis saturnus were isolated from the gut contents. The effect of earthworms on the composition of the yeast community in the process of forest litter destruction is more pronounced than seasonal changes.     

Laccase Gene Composition and Relative Abundance in Oak Forest Soil is not Affected by Short-Term Nitrogen Fertilization

Anthropogenic nitrogen (N) deposition affects a wide range of soil processes including phenol oxidase (PO) activity and soil organic matter dynamics. Depression of phenol oxidase activity in response to N saturation is believed to be mediated by the activity of white-rot basidiomycetes, whose production of extracellular oxidative enzymes can be limited by high N availability. We examined the effect of short-term N deposition on basidiomycete laccase gene diversity and relative abundance in temperate oak forest soil in which significant decreases in phenol oxidase and increased SOM have been recorded in response to experimental N deposition. UniFrac was used to compare the composition of laccase genes between three control- and three nitrogen-fertilized (80 kg⁻¹ ha⁻¹ per year) oak forest soils. The relative abundance of laccase genes was determined from qPCR analysis of laccase and basidiomycete ITS gene abundances. Our results indicate that there was no significant shift in the composition of laccase genes between control- and N-fertilized soils, nor was there a significant change in the relative abundance of laccase genes. These data suggest that N deposition effects on mineral soil PO activity do not result from changes in laccase gene diversity of white-rot basidiomycetes but are likely the result of altered microbial abundance or expression in this ecosystem type. Furthermore, laccase gene composition may be tied to factors that structure microbial communities in general, as soil laccase gene communities are more similar to other forest soils than with the corresponding litter.     

The influence of forest stand and site characteristics on the composition of exotic dominated ambrosia beetle communities (Coleoptera: Curculionidae: Scolytinae)

Economic and biological consequences are associated with exotic ambrosia beetles and their fungal associates. Despite this, knowledge of ambrosia beetles and their ecological interactions remain poorly understood, especially in the oak-hickory forest region. We examined how forest stand and site characteristics influenced ambrosia beetle habitat use as evaluated by species richness and abundance of ambrosia beetles, both the native component and individual exotic species. We documented the species composition of the ambrosia beetle community, flight activity, and habitat use over a 2-yr period by placing flight traps in regenerating clearcuts and older oak-hickory forest stands differing in topographic aspect. The ambrosia beetle community consisted of 20 species with exotic ambrosia beetle species dominating the community. Similar percentages of exotic ambrosia beetles occurred among the four forest habitats despite differences in stand age and aspect. Stand characteristics, such as stand age and forest structure, influenced ambrosia beetle richness and the abundances of a few exotic ambrosia beetle species and the native ambrosia beetle component. Topographic aspect had little influence on ambrosia beetle abundance or species richness. Older forests typically have more host material than younger forests and our results may be related to the amount of dead wood present. Different forms of forest management may not alter the percent contribution of exotic ambrosia beetles to the ambrosia beetle community.     

Edge Effects on Species Composition and Exotic Species Abundance in the North Carolina Piedmont

Edges between forest and non-forest habitats often have significant effects on forest microclimate and resource availability, with corresponding effects on species composition and abundance. Exotic species are often increased in abundance near forest edges. This increase in abundance could be either because of the increase in resource availability near edges, or because of increased dispersal into forest edges. We measured species composition and a set of geospatial variables on transects at 66 edges in the North Carolina Piedmont in an attempt to distinguish between these two factors. Mantel tests show that species composition is significantly different in forest edges than in the forest interior, but that this effect only penetrates about 5 m into the forest. Indicator species analysis finds several species that are indicative of edge communities, including trumpet vine (Campsis radicans), two drought-tolerant oak species (Quercus stellata and Q. falcata), a serviceberry (Amelanchier arboreum), and a common exotic species, tree-of-heaven (Ailanthus altissima). Poisson regression techniques showed that in both the seedling and tree strata of the forest, exotic species increased in abundance on flat sites with a high potential seed source. Mapping predicted exotic species abundance onto the landscape. We find that large-scale variation in exotic species abundance is due mostly to variation in potential seed sources, while small-scale variation relates more to edaphic factors. Our results stress that both dispersal and environmental filters are important for determining exotic species abundance, but potentially the filters operate at different spatial scales.     

基于红外相机技术对佛坪国家级自然保护区大熊猫季节性空间分布与活动模式的研究

2015年1月至2017年12月,在陕西佛坪国家级自然保护区海拔1 200～2 500 m的57条大熊猫(Ailuropodamelanoleuca)活动频繁的巡护样线上,布设130台红外相机。累计红外相机有效工作日100 685 d,共拍摄到大熊猫有效独立照片1 831张。将红外相机拍摄的有效照片和相机工作日依据不同竹种类型及保护站归类,对大熊猫季节性空间分布与活动模式进行研究。结果表明:(1)大熊猫春季活动最为频繁,在巴山木竹(Bashania fargesii)林和秦岭箭竹(Fargesia qinlingensis)林中相对多度分别是2.89和3.72;其次是冬季,在巴山木竹林和秦岭箭竹林中的相对多度分别是2.95和2.74。3月份是其活动高峰,巴山木竹林和秦岭箭竹林中的相对多度指数都是最高;11、12和1月份,大熊猫在巴山木竹林中相对多度指数高于秦岭箭竹林;2至10月份,大熊猫在秦岭箭竹林中的相对多度指数都要高于巴山木竹林。(2)大熊猫在佛坪保护区各个保护站均有分布,且存在季节性空间分布差异。三官庙和西河保护站全年的12个月都能够捕获到大熊猫的身影,是大熊猫分布相对多度最高的...     

Danish forest development during the last 3000 years reconstructed from regional pollen data

Most present Danish forest types are a direct result of recent silvicultural practice. We use fossil pollen data converted into estimates of tree abundance to map the development of forest types during the last 3000 radioearbon yr. The forest types were clusters in an artificial neural network based on all available European Holocene pollen data. Diverse deciduous forest types found 3000 yr ago were replaced by less diverse Fagus -dominated types over a period of 2000 yr. The present day map contained many new combinations of tree species, dominated by Picea and Pinus. The association between the increase in non-forest communities and establishment of Fagus suggests that anthropogenic activity has accelerated the loss of species-rich deciduous forest with abundant .Alnus, Corylus, Quercus and Tilia. We conclude that the natural forest composition of Denmark would be deciduous forest today with a significant presence of Fugus sylvatica. Recent forest development has created a break in compositional continuity with the past that is unnatural and has posed problems for forest-dependent biota.     

The role of weather-related habitat use on the impact of the European speckled wood Pararge aegeria on the endemic Pararge xiphia on the island of Madeira

Habitat use and microclimatic constraints on the activity of the endemic Madeiran speckled wood butterfly and European speckled wood were studied in September 1989 and April 1990. The endemic species is the most closely associated with laurel forest and the recently established European speckled wood with pine and eucalyptus forest. The relative abundances of the two species in different sites changes with season, with the endemic species being relatively more common in low level sites in April at the end of the cool season, than in September at the end of the warm summer period. It is suggested that changes of abundance in different locations are related to the thermal biology of the two species. The endemic speckled wood is active at lower air temperature than the European species, and the cool winter period may facilitate occupation of open sunny sites. The activity of the endemic speckled wood is less constrained by cool and dull conditions than is that of the European species, which requires higher temperatures for activity. It is proposed that the activity and behavioural repertoire of the endemic is most suited to climatic conditions in, and structural features of, laurel forest. The European species is most suited for activity in open woodland and agricultural habitats. Interactions between adults of the two species do not indicate direct competition. Changes in the distribution of the two species can be linked to probable changes of habitat on the island of Madeira.     

Disentangling the effects of facilitation on restoration of the Atlantic Forest

Facilitation is an important ecological mechanism with potential applications to forest restoration. We hypothesized that different facilitation treatments, distance from the forest edge and time since initiation of the experiment would affect forest restoration on abandoned pastures. Seed and seedling abundance, species richness and composition were recorded monthly during two years under isolated trees, bird perches and in open pasture. Seed arrival and seedling establishment were measured at 10 m and 300 m from the forest edge. We sampled a total of 131,826 seeds from 115 species and 487 seedlings from 46 species. Isolated trees and bird perches increased re-establishment of forest species; however, species richness was higher under isolated trees. Overall, abundance and richness of seeds and seedlings differed between sampling years, but was unaffected by distance from the forest edge. On the other hand, species composition of seeds and seedlings differed among facilitation treatments, distance from the forest edge and between years. Seedling establishment success rate was larger in large-seeded species than medium- and small-seeded species. Our results suggest that isolated trees enhance forest re-establishment, while bird perches provide a complementary effort to restore tree abundance in abandoned pastures. However, the importance of seed arrival facilitation shifts toward establishment facilitation over time. Arriving species may vary depending on the distance from the forest edge and disperser attractors. Efforts to restore tropical forests on abandoned pastures should take into account a combination of both restoration strategies, effects of time and proximity to forest edge to maximize regeneration.     

Regeneration pattern of primary forest species across forest-field gradients in the subtropical Mountains of Southwestern China

Evergreen broad-leaved forest is now gradually degraded and fragmented, and there is an increase in the amount of habitat edges as a result of long-term human activity. However, the role of edges in the regeneration of primary forest species is poorly understood. After 20 years of the edge creation, we analyzed primary forest species distribution and abundance, and changes in floristic composition, vegetation structure across forest-field gradients in Ailao Mountain, SW China. Our results revealed that there was a higher abundance and richness of primary species, late secondary species and thorny lianas at the distances 0–50 m than at the distances more than 50 m from the edge into the forest exterior. At the distances >50 m, no individuals of dominant canopy trees Lithocarpus xylocarpus, Castanopsis wattii, and L. jingdongensis were found, whereas the abundance of early pioneer shrub species and herbaceous cover was significantly greater. The richness of primary species showed a decrease with increasing distances from the forest edge to the exterior, particularly of medium-seeded primary species showing a drastic decrease. Moreover, no large-seeded primary species occurred at the distances >60 m. This study indicates that the forest edge as a buffer zone may be in favor of primary species regeneration. A dense shrub and herb layer, and seed dispersal may be the major factors limiting the forest regeneration farther from the forest edge. Therefore, to facilitate forest recovery processes, management should give priority to the protection of buffer zones of this forest edge.