Local lithological drivers of post-fire vegetation recovery and implications for fire-prone regions

Local ecosystem resilience to fire disturbance can be influenced by multiple factors, from topography and climate, to fire history and pre-fire structure of biotic communities. Here we investigated the factors affecting post-fire recovery of scrub vegetation in areas under Mediterranean climate affected by frequent fires. We hypothesized that, under comparable climatic and topographic conditions, geological factors (with bedrock type as a proxy) would be at least as important as fire history in explaining patterns of post-fire recovery. We surveyed scrub vegetation in a mountain study area in Portugal, using a stratified random sampling scheme, with fire frequency, time since last fire, and bedrock type (granite vs. schist) as stratifying layers. Based on vegetation and plant community data from 40 plots, we analyzed total species richness and composition, and the relative abundance of functional groups defined on the basis of general (non fire-specific) life-history traits. We found that, at a local scale, lithology can override fire history in determining post-fire recovery. Vegetation plots on granite exhibited a considerable development of tall scrubs and higher values of total species richness. They also hosted higher numbers of animal-dispersed woody species, of trees and tall scrubs, of woody deciduous species, and of forest, edge and tall scrub species. Differences in the post-fire development of scrub vegetation and in the functional profile of plant communities highlight the need to consider local geological diversity when establishing priorities for post-fire active restoration under scenarios of limited resources.     

Biodiversity in South African fynbos and Mediterranean heathland

Abstract. The theory of convergence predicts that, given similar selective regimes, both present and past, unrelated ecological communities will show similar attributes. Mild Pleistocene climate, highly infertile soils, and similar fire regimes explain the remarkable convergence between mediterranean‐type vegetation from South Africa (fynbos) and Australia (kwongan). Heathlands in the Aljibe Mountains, at the western end of the Mediterranean basin, constitute a single vegetation type within the Mediterranean region. We studied the association between endemism and plant life form in a flora from environmentally similar areas of the South African Cape region (fynbos) and the Aljibe Mountains by contingency table analysis. We included two non‐acid, neighbouring areas to the latter region in the analysis as contrasts. We also compared the patterns of variation in three components of biodiversity (species richness, endemism level and taxonomic singularity) of fynbos and Aljibe heathland woody plant communities along similar soil fertility gradients by means of two‐way ANOVAs. At the regional (flora) level, our results show two common features in the biological aspects of endemism between the two regions: (1) edaphic endemism and (2) association of endemism with the shrub growth form. At the community level, we detected strong similarities in the patterns of variation of endemism and taxonomic singularity of woody communities from both regions along an ecological gradient related to soil fertility. We interpret these similarities, both at the regional and community levels, as suggestive of convergence between fynbos and Aljibe heathland.     

Phylogenetic structure of Brazilian savannas under different fire regimes

Questions: Fire is a strong filter in fire‐prone communities and is expected to assemble closely related species when functional traits are conserved in plant lineages. Do frequent fires assemble savannas with closely related species (phylogenetic clustering)? If so, what are the clades pruned by fire in the phylogenetic trees? Are species of semi‐deciduous seasonal forests, where fires are not frequent, less related than expected by chance (phylogenetic over‐dispersion)? Are life forms conserved in the phylogeny of the species? Location: Central and SE Brazilian savannas (Emas National Park, 18°18′S, 52°54′W; Brasília, 15°56′–15°57′S, 47°53′–47°56′W and Corumbataí‐Itirapina, 22°13′–22°15′S, 47°37′–47°39′W); and close semi‐deciduous seasonal forests (in Pirenópolis, 15°45′S, 49°04′W; Brasília, 15°33′S, 47°51′W; and São Carlos, 21°55′S, 47°48′W). Methods: We recorded woody species in savannas under different fire regimes and in semi‐deciduous seasonal forests. We obtained data from the literature and from field sampling. We compared mean phylogenetic distance of species of savanna and of nearby semi‐deciduous seasonal forest sites. We obtained significance by randomizing the species among the tips of phylogenetic trees. We also assessed whether life forms were evolutionary conserved across phylogeny of the studied plants (phylogenetic signal) with tests based on the variance of phylogenetic independent contrasts. Results: Some sites of savanna under high fire frequency were characterized by phylogenetic over‐dispersion of woody species whereas, in contrast, some sites of semi‐deciduous seasonal forest were characterized by phylogenetic clustering. We found phylogenetic signals in the traits across the phylogeny of the 801 species investigated. Conclusion: Fire may have different roles in assembling plant species in Brazilian savannas than in other fire‐prone communities. We postulate that the absence of phylogenetic clustering in the cerrado is mainly due to the persistence of long‐lived resprouting species from different plant lineages.     

The influence of fire on phylogenetic and functional structure of woody savannas: Moving from species to individuals

Fire is a key determinant of tropical savanna structure and functioning. High fire frequencies are expected to assemble closely related species with a restricted range of functional trait values. Here we determined the effect of fire on phylogenetic and functional diversity of woody species and individuals in savanna communities under different fire frequencies. We found phylogenetic signals for one third of the functional traits studied. High numbers of fires simultaneously led to phylogenetic overdispersion and functional clustering when communities were represented by mean trait values with all traits that putatively should be affected or respond to fire. This finding is important, because it shows that the relationship between ecological processes and the phylogenetic structure of communities is not straightforward. Thus, we cannot always assume that close relatives are more similar in their ecological features. However, when considering a different set of traits representing different plant strategies (fire resistance/avoidance, physiological traits and regeneration traits), the results were not always congruent. When asking how communities are assembled in terms of individuals (not species) the outcome was different from the species-based approach, suggesting that the realised trait values – rather than mean species trait values – have an important role in driving community assembly. Thus, intraspecific trait variability should be taken into account if we want fully to improve our mechanistic understanding of assembly rules in plant communities.     

Multi-scale phylogenetic structure in coastal dune plant communities across the globe

Aims Studies integrating phylogenetic history and large-scale community assembly are few, and many questions remain unanswered. Here, we use a global coastal dune plant data set to uncover the important factors in community assembly across scales from the local filtering processes to the global long-term diversification and dispersal dynamics. Coastal dune plant communities occur worldwide under a wide range of climatic and geologic conditions as well as in all biogeographic regions. However, global patterns in the phylogenetic composition of coastal dune plant communities have not previously been studied.Methods The data set comprised vegetation data from 18463 plots in New Zealand, South Africa, South America, North America and Europe. The phylogenetic tree comprised 2241 plant species from 149 families. We calculated phylogenetic clustering (Net Relatedness Index, NRI, and Nearest Taxon Index, NTI) of regional dune floras to estimate the amount of in situ diversification relative to the global dune species pool and evaluated the relative importance of land and climate barriers for these diversification patterns by geographic analyses of phylogenetic similarity. We then tested whether dune plant communities exhibit similar patterns of phylogenetic structure within regions. Finally, we calculated NRI for local communities relative to the regional species pool and tested for an association with functional traits (plant height and seed mass) thought to vary along sea–inland gradients.Important findings Regional species pools were phylogenetically clustered relative to the global pool, indicating regional diversification. NTI showed stronger clustering than NRI pointing to the importance of especially recent diversifications within regions. The species pools grouped phylogenetically into two clusters on either side of the tropics suggesting greater dispersal rates within hemispheres than between hemispheres. Local NRI plot values confirmed that most communities were also phylogenetically clustered within regions. NRI values decreased with increasing plant height and seed mass, indicating greater phylogenetic clustering in communities with short maximum height and good dispersers prone to wind and tidal disturbance as well as salt spray, consistent with environmental filtering along sea–inland gradients. Height and seed mass both showed significant phylogenetic signal, and NRI tended to correlate negatively with both at the plot level. Low NRI plots tended to represent coastal scrub and forest, whereas high NRI plots tended to represent herb-dominated vegetation. We conclude that regional diversification processes play a role in dune plant community assembly, with convergence in local phylogenetic community structure and local variation in community structure probably reflecting consistent coastal-inland gradients. Our study contributes to a better understanding of the globally distributed dynamic coastal ecosystems and the structuring factors working on dune plant communities across spatial scales and regions.     

Phylogenetic diversity of macromycetes and woody plants along an elevational gradient in Eastern Mexico

Phylogenetic information provides insight into the ecological and evolutionary processes that organize species assemblages. We compared patterns of phylogenetic diversity among macromycete and woody plant communities along a steep elevational gradient in eastern Mexico to better understand the evolutionary processes that structure their communities. Macrofungi and trees were counted and identified in eight sites from 100 to 3500 m asl, and sequence data retrieved from GenBank for the same or closely related species were used to reconstruct their phylogenies. Patterns of species richness and phylogenetic diversity were similar for both macrofungi and trees, but macromycete richness and diversity peaked at mid‐elevations, whereas woody plant richness and diversity did not show significant trends with elevation. Phylogenetic similarity among sites was low for both groups and decreased as elevational distance between sites increased. Macromycete communities displayed phylogenetic overdispersion at low elevations and phylogenetic clustering at high elevations; the latter is consistent with environmental filtering at high elevation sites. Woody plants generally exhibited phylogenetic clustering, consistent with the potential importance of environmental filtering throughout the elevational gradient.     

The role of regional and local scale predictors for plant species richness in Mediterranean forests

Abstract

Both local and regional predictors play a role in determining plant community structure and composition. Climate, soil features as well as different local history and management affect forest understorey and tree species composition, but to date their specific role is relatively unknown. Few studies have addressed the importance of these predictors, especially in the Mediterranean area, where environmental conditions and human impacts have generated heterogeneous forest communities. In this study, the relationships between environmental variables and species richness of different groups of vascular plants (vascular species, woody species and open habitat species) and bryophytes were investigated in Tuscan forests. A total of 37 environmental variables were used by generalised linear model fitting in order to find parsimonious sub-sets of environmental factors (predictors) that are able to explain species diversity patterns at the local scale. Moreover, the role of regional and local variable groups on species richness of the considered plant groups was estimated by using the variance partitioning approach. We found that local variables, such as forest management and structure, explained more variance than regional variables for total species richness, open habitat species richness and bryophyte species richness. On the other hand, regional variables (such as elevation) played a central role for woody species richness.     

Phylogenetic and phenotypic structure among Banksia communities in south‐western Australia

Aim Phylogenetic and phenotypic patterns among coexisting banksias (Banksia, Proteaceae) in the infertile, fire‐prone landscapes of south‐western Australia were examined for evidence of community structuring. It was expected that closely related species would be spatially clustered (underdispersed) as a consequence of widespread recent speciation, strong edaphic fidelity and low dispersability. We also expected that edaphic filtering would result in phenotypic clustering of traits related to habitat specialization and that competitive exclusion among closely related species with similar regeneration biology and growth form would result in phenotypic overdispersion of these latter traits. Location Southwest Australian Floristic Region (SWAFR). Methods Based on published data for coexistence (richness and frequency) of Banksia species at 40 sites in the three floristic provinces, phylogenetic, soil type and morphological mean pairwise distance and mean nearest taxon distance were calculated for each site and compared with null communities. Patterns of co‐occurrence were examined at the local and subregional (provincial) scales. Results Of the 40 sites assessed, 21–30 displayed phylogenetic clustering of Banksia species (5–11 significantly) such that, overall, co‐occurring taxa were more closely related than expected by chance. Banksias in the Transitional Rainfall and Southeast Coastal Provinces were more likely to display phylogenetic clustering than in the High Rainfall Province. A significant trend for phylogenetic clustering associated with edaphic specialization (27–30 sites) was observed, as well as a significant trend for phenotypic overdispersion associated with growth form (25–28 sites). Results for regeneration biology depended on the metric used. Main conclusions We demonstrate spatial clustering of closely related banksias at the local and provincial scales, consistent with their restricted distribution (recent widespread speciation, patchy habitat availability and limited dispersability) in this geologically old and stable region. The clustering of closely related species may also be a consequence of habitat filtering linked to edaphic fidelity in the SWAFR flora, while overdispersion in growth form suggests that functional divergence favours coexistence in Banksia communities.     

Phylogenetic diversity and community assembly in a naturally fragmented system

We sought to assess effects of fragmentation and quantify the contribution of ecological processes to community assembly by measuring species richness, phylogenetic, and phenotypic diversity of species found in local and regional plant communities. Specifically, our fragmented system is Craters of the Moon National Monument and Preserve, Idaho, USA. CRMO is characterized by vegetated islands, kipukas, that are isolated in a matrix of lava. We used floristic surveys of vascular plants in 19 kipukas to create a local species list to compare traditional dispersion metrics, mean pairwise distance, and mean nearest taxon distance (MPD and MNTD), to a regional species list with phenotypic and phylogenetic data. We combined phylogenetic and functional trait data in a novel machine‐learning model selection approach, Community Assembly Model Inference (CAMI), to infer probability associated with different models of community assembly given the data. Finally, we used linear regression to explore whether the geography of kipukas explained estimated support for community assembly models. Using traditional metrics of MPD and MNTD neutral processes received the most support when comparing kipuka species to regional species. Individually no kipukas showed significant support for overdispersion. Rather, five kipukas showed significant support for phylogenetic clustering using MPD and two kipukas using MNTD. Using CAMI, we inferred neutral and filtering models structured the kipuka plant community for our trait of interest. Finally, we found as species richness in kipukas increases, model support for competition decreases and lower elevation kipukas show more support for habitat filtering models. While traditional phylogenetic community approaches suggest neutral assembly dynamics, recently developed approaches utilizing machine learning and model choice revealed joint influences of assembly processes to form the kipuka plant communities. Understanding ecological processes at play in naturally fragmented systems will aid in guiding our understanding of how fragmentation impacts future changes in landscapes.     

Phylogeny, traits, environment, and space in cerrado plant communities at Emas National Park (Brazil)

Soil, drought, and fire are abiotic factors that may act as environmental filters in the cerrado, the Brazilian savanna. We used a framework to analyze environmental filtering in geographic and phylogenetic context, sampling woody species in one of the largest cerrado reserves. In 100 quadrats, we measured 10 functional traits on each woody individual. We also measured several soil variables, altitude and slope as a rough surrogate of water availability, interval between fires, and time since last fire. Almost all environmental variables were spatially auto-correlated. We found an overall trait clustering, but not an overall phylogenetic clustering. Nevertheless, we found a phylogenetic signal for some traits. Linking phylogeny, traits, environment, and space, we were able to detect a major dichotomy between two geomorphological units. The flat tableland was positively related with altitude, fire frequency, and nutrient-richer soil. Environmental filtering caused by water availability and fire lead to trait clustering, with smaller shrubs and trees that presented thicker barks, denser woods, sclerophyllous leaves, highlighted by the prevalance of Myrtaceae. The other geomorphological unit, hilly terrain, was positively related with slope, low fire frequency, and nutrient-poorer soil. Environmental filtering was caused especially by nutrient-poor soil that lead to trait clustering, assembling taller trees, with thinner barks, lighter woods, and compound, large, tender, nutrient-richer leaves, distributed across many lineages, including Fabaceae. Hence, the high environmental variability in space with different environmental filters assembled different combination of plant traits and lineages, increasing the overall diversity in cerrado.     

Woody exotic plant invasions and fire: reciprocal impacts and consequences for native ecosystems

Fire regimes influence and are influenced by the structure and composition of plant communities. This complex reciprocal relationship has implications for the success of plant invasions and the subsequent impact of invasive species on native biota. Although much attention has been given to the role of invasive grasses in transforming fire regimes and native plant communities, little is known about the relationship between woody invasive species and fire regime. Despite this, prescribed burning is frequently used for managing invasive woody species. In this study we review relationships between woody exotic plant invasions and fire in invaded ecosystems worldwide. Woody invaders may increase or decrease aspects of the fire regime, including fire frequency, intensity and extent. This is in contrast to grass invaders which almost uniformly increase fire frequency. Woody plant invasion can lead to escape from a grass-fire cycle, but the resulting reduction in fire frequency can sometimes lead to a cycle of rare but more intense fires. Prescribed fires may be a useful management tool for controlling woody exotic invaders in some systems, but they are rarely sufficient to eliminate an invasive species, and a dearth of controlled experiments hampers evaluation of their benefits. Nevertheless, because some woody invaders have fuel properties that differ substantially from native species, understanding and managing the impacts of woody invaders on fire regimes and on prescribed burns should become an important component of resource and biodiversity management.     

Local versus regional intraspecific variability in regeneration traits

Intraspecific trait variability has a fundamental contribution to the overall trait variability. However, little is known concerning the relative role of local (e.g. disturbances and species interaction) and regional (biogeographical) processes in generating this intraspecific trait variability. While biogeographical processes enhance plant trait variability between distant populations, in fire-prone ecosystems, recurrent fires may have a preponderant role in generating variability at a local scale. We hypothesize that plants respond to the local spatio-temporal heterogeneity generated by fire by having a relatively large local variability in regeneration traits in such a way that overrides the variability at a broader biogeographical scale. We test this hypothesis by assessing the intraspecific variability in fire-related regeneration traits of two species (Cistus salviifolius and Lavandula stoechas) growing in fire-prone ecosystems of the Mediterranean Basin. For each species, we selected six populations in two distant regions, three in the east (Anatolian Peninsula) and three in the west (Iberian Peninsula). For each species and population, we analysed the following regeneration traits: seed size, seed dormancy and stimulated germination by fire-related cues (heat and smoke). To evaluate the distribution of the variability in these traits, we decomposed the variability of trait values at each level, between regions (regional) and between population within region (local), using linear mixed-effect models. Despite the biogeographical and climatic differences between regions, for the two species, intraspecific variability in regeneration traits was higher at a local (within regions) than at a regional scale (between regions). Our results suggest that, in Mediterranean ecosystems, fire is an important source of intraspecific variability in regeneration traits. This supports the prominent role of fire as an ecological and evolutionary process, producing trait variability and shaping biodiversity in fire-prone ecosystems.     

Soil fungal community changes in response to long-term fire cessation and N fertilization in tallgrass prairie

In grasslands, fire management and fertilization are established drivers of plant community change, but associated soil fungal responses are less well defined. We predicted that soil fungal communities would change seasonally, that decades of fire cessation and nitrogen (N) fertilization would alter fungal distributions, and that plant and fungal community change would be correlated. Surface soils were sampled monthly for 1 y from a 30-y fire by fertilization experiment to evaluate fungal community dynamics and assess correlation with plant community heterogeneity. ITS gene community composition was seasonally stable, excepting increased arbuscular mycorrhizal fungal summer abundance in the burned, fertilized treatment. Long-term treatments affected soil fungal and plant communities, with correlated heterogeneity patterns. Despite woody encroachment in the fire cessation treatment, soil fungal communities did not resemble those of forests. This study provides evidence supporting the strength of feedbacks between fungal and plant community change in response to long-term grassland fire and N management changes.     

长江中游干流鱼类群落构建机制分析

研究选取长江中游5个采样点(宜昌、枝江、荆州、汉南、湖口)为代表,采用系统发育群落结构方法分析了不同空间尺度下长江中游鱼类群落的构建机制。结果表明:(1)空间聚类分析显示,在65%的相似性水平上,所有样点可以划分为3个Group:GroupⅠ(宜昌)、GroupⅡ(枝江+荆州)和GroupⅢ(汉南+湖口);在55%的相似性水平上,所有样点可以划分为2个Group:Group A(宜昌)和Group B(枝江+荆州+汉南+湖口),且聚类分析结果与采样点的空间分布相符合。(2)在不同空间尺度下,鱼类群落构建机制存在差异:从地区采样点尺度来看,荆州江段鱼类群落表现为竞争作用主导群落构建,其余采样点鱼类群落均为环境过滤作用;从区域尺度来看,宜昌江段鱼类群落表现为环境过滤作用的建群机制,其余4个采样点在扩大空间尺度后,即分为Group A和Group B的情况下,其鱼类群落构建机制转变为物种间竞争作用。因此,长江中游干流鱼类群落构建机制表现了地区环境和空间尺度的共同作用。由于水流湍急,宜昌始终表现为环境过滤作用。其他江段在采样点尺度多数表现了环境过滤作用,但是在宏观的空间尺度上,却由于空间异质性...     

A plant functional approach to the prediction of changes in Australian rangeland vegetation under grazing and fire

Abstract. Grazing by domestic livestock and changed fire regimes by humans have caused major changes in the productivity and composition of rangelands in Australia and other continents. Of particular concern are the commonly observed loss of perennial forage species and the increasing abundance of woody plants. Grazing and fire‐induced changes are difficult to predict from current process knowledge and are often too costly or time‐consuming to investigate experimentally. We describe the development and use of ARENA, a new simulation model. A plant functional approach is used in which the relative growth rate, competitive ability and life cycle of the plant types are mainly defined by the plant's morphology and allocation pattern, plus its water‐use efficiency and nitrogen concentration. The soil and plant types can be parameterized to a large extent with information from the literature, facilitating application in a broad range of dryland environments. The model has been tested for two soils and pasture communities in the seasonally dry tropics of the Victoria River District, N Australia. Predictions of pasture production and perennial grass fraction under undisturbed conditions agreed with observations in field exclosures. Predictions of maximum tree density also coincided with observations along a rainfall gradient. Simulation experiments were conducted to explore the effect of different stocking levels and fire management regimes on pasture productivity and composition. Responses of pastures on red loam and grey clay soils were generally consistent with regional field experience, but the model did not reproduce the expected changes in the abundance of woody plants.     

Ectomycorrhizal fungal diversity decreases in Mediterranean pine forests adapted to recurrent fires

Fire is a major disturbance linked to the evolutionary history and climate of Mediterranean ecosystems, where the vegetation has evolved fire‐adaptive traits (e.g., serotiny in pines). In Mediterranean forests, mutualistic feedbacks between trees and ectomycorrhizal (ECM) fungi, essential for ecosystem dynamics, might be shaped by recurrent fires. We tested how the structure and function of ECM fungal communities of Pinus pinaster and Pinus halepensis vary among populations subjected to high and low fire recurrence in Mediterranean ecosystems, and analysed the relative contribution of environmental (climate, soil properties) and tree‐mediated (serotiny) factors. For both pines, local and regional ECM fungal diversity were lower in areas of high than low fire recurrence, although certain fungal species were favoured in the former. A general decline of ECM root‐tip enzymatic activity for P. pinaster was associated with high fire recurrence, but not for P. halepensis. Fire recurrence and fire‐related factors such as climate, soil properties or tree phenotype explained these results. In addition to the main influence of climate, the tree fire‐adaptive trait serotiny recovered a great portion of the variation in structure and function of ECM fungal communities associated with fire recurrence. Edaphic conditions (especially pH, tightly linked to bedrock type) were an important driver shaping ECM fungal communities, but mainly at the local scale and probably independently of the fire recurrence. Our results show that ECM fungal community shifts are associated with fire recurrence in fire‐prone dry Mediterranean forests, and reveal complex feedbacks among trees, mutualistic fungi and the surrounding environment in these ecosystems.     

Phylogenetic and phenotypic originality and abundance in a cerrado plant community

The originality of a species is how much that species contributes to the rarity of traits in a community. Here we tested the relation between abundance and both phylogenetic and phenotypic originality. We measured nine traits associated with defence against herbivory, as well as phylogenetic information and abundance for woody plant species in a woodland cerrado in southeastern Brazil. About 90% of the species accounted for about 50% of the phylogenetic and phenotypic originality: most woody species had low originality. Abundance was related to tougher leaves, lower specific leaf area and lower originality based on nutritional quality. Our results suggest that herbivory may reduce the abundance of species with low resistance to herbivory and with different nutritional quality. Nevertheless, abundance was not related to either phylogenetic or phenotypic originality, so extinction of rare species may not endanger overall community function as long as more abundant species are retained. We argue that this is a consequence of the low complementarity of a large number of woody species.     

Stochastic losses of fire‐dependent endemic herbs revealed by a 65‐year chronosequence of dispersal‐limited woody plant encroachment

The factors responsible for maintaining diverse groundcover plant communities of high conservation value in frequently burned wet pine savannas are poorly understood. While most management involves manipulating extrinsic factors important in maintaining species diversity (e.g., fire regimes), most ecological theory (e.g., niche theory and neutral theory) examines how traits exhibited by the species promote species coexistence. Furthermore, although many ecologists focus on processes that maintain local species diversity, conservation biologists have argued that other indices (e.g., phylogenetic diversity) are better for evaluating assemblages in terms of their conservation value. I used a null model that employed beta‐diversity calculations based on Raup–Crick distances to test for deterministic herbaceous species losses associated with a 65‐year chronosequence of woody species encroachment within each of three localities. I quantified conservation value of assemblages by measuring taxonomic distinctness, endemism, and floristic quality of plots with and without woody encroachment. Reductions in herb species richness per plot attributable to woody encroachment were largely stochastic, as indicated by a lack of change in the mean or variance in beta‐diversity caused by woody encroachment in the savannas studied here. Taxonomic distinctness, endemism, and floristic quality (when summed across all species) were all greater in areas that had not experienced woody encroachment. However, when corrected for local species richness, only average endemism and floristic quality of assemblages inclusive of herbs and woody plants were greater in areas that had not experienced woody encroachment, due to the more restricted ranges and habitat requirements of herbs. Results suggest that frequent fires maintain diverse assemblages of fire‐dependent herb species endemic to the region. The stochastic loss of plant species, irrespective of their taxonomic distinctness, to woody encroachment suggests that the relevance of niche partitioning or phylogenetic diversity to the management of biodiversity in wet pine savannas is minimal.     

Stream noise,habitat filtering,and the phenotypic and phylogenetic structure of Neotropical anuran assemblages

The structure of assemblages may be determined by interspecific interactions or environmental factors (e.g. competition and habitat filtering). Since communication between conspecific and heterospecific affects fitness of individuals, habitat characteristics that prevent communication could determine habitat use and co-occurrence of species. However, at present there are few studies, most with birds, testing the relationship between sensory ecology and community ecology. Abiotic noise on streams could impede the detection and decoding of auditory signals by receivers through a process named auditory masking. Therefore, we tested the role of abiotic noise on streams as a habitat characteristic influencing the phenotypic and phylogenetic structure of Neotropical anuran assemblages. We tested this hypothesis using data of male body size, call frequency, calling place (alongside and away from streams), and phylogenetic relationship of 110 and 38 anuran species at regional and local scale, respectively. After we found quantitative evidence suggesting that call frequency and body size are conserved phenotypic traits, we found that assemblages alongside streams exhibit both phenotypic and phylogenetic clustering, while assemblages away from streams exhibit both phenotypic and phylogenetic overdispersion. These results offer quantitative evidence suggesting a role of noise on streams promoting a process of habitat filtering and affecting the structure of anuran assemblages alongside streams both at Neotropical and local scale. This is the first study using modern phylogenetic comparative metrics for covering potential causes of phenotypic and phylogenetic structure of anuran assemblages, and one of the few testing a link between community ecology and the evolutionary biology of acoustic communication to understand the processes mediating species co-occurrence in vertebrates.     

The influence of species pools and local processes on the community structure: a test case with woody plant communities in China's mountains

Understanding how patterns of biodiversity vary among taxonomic levels can provide insights into the mechanisms that regulate the assembly of ecological communities. In this study, we examined the scale and environmental dependence of the relationship between number of species and number of genera/families in woody plant communities to investigate the influences of species pool and local ecological processes on the taxonomic structures of local communities. The data we used are based on a large number of forest plots collected across the eastern part of China and the globe. The results showed that the ratio of the number of genera/families:species and the taxonomic exponents, i.e. the exponents of the genus/family–species relationship, were generally lower than null expectations based on the regional species pool, suggesting that abiotic filtering (e.g. environmental filtering and dispersal limitation) is more important than interspecific competition in shaping local communities. The extent of species pool and the area sampled for local communities both influenced our ability to infer whether local ecological processes were important. In particular, the deviation of the taxonomic ratios and exponents between empirical and null patterns increased as the extent of species pool increased, and the taxonomic exponents declined as area of the local community increased, due partly to the reduced effect of interspecific competition. We conclude that regional species pools and local processes both influenced the taxonomic structure of local woody plant communities, but their effects vary substantially among spatial scales.