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FIGURE 15 in Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand

FIGURE 15. Spatiotemporal variation in Mean Local Turnover (βwL) of species of Empidoidea through 12 months sampling over six 500m elevation zones at Doi Inthanon in 2014. Values of βwL are plotted on a grid of elevation zone (vertical axis) and months (horizontal axis) using the multiquadric gridding algorithm in PAST. Values of βwL (indicated by colour scale bar) vary between 0 (complete identity) and 1.0 (complete non-identity). Data are not available for January and February at <500 m and 500–1000 m.

FIGURES 9–12 in Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand

FIGURES 9–12. Spatiotemporal variation in relative abundance (A* = number of individuals. trap-1. month-1). 9, Empididae; 10, Hybotidae; 11, Dolichopodidae; 12, Empidoidea (Empididae, Hybotidae, Dolichopodidae & Brachystomatidae combined). Values of A* from 12 months sampling over six 500 m elevation zones at Doi Inthanon in 2014 were log2 transformed [as log2(1+A*)] and plotted on a grid of elevation zone (vertical axis) and months (horizontal axis) using the multiquadric gridding algorithm in PAST. Values of A* are indicated by the colour scale bars (note logarithmic scale). Data were not available for January and February at <500 m and 500–1000 m.

FIGURES 5–8 in Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand

FIGURES 5–8. Spatiotemporal variation in observed species richness (Sobs). 5, Empididae; 6, Hybotidae; 7, Dolichopodidae; 8, Estimated species richness (Chao1) of Empidoidea (Empididae, Hybotidae, Dolichopodidae & Brachystomatidae combined). Data from 12 months sampling over six 500 m elevation zones at Doi Inthanon in 2014 are plotted on a grid of elevation zone (vertical axis) and months (horizontal axis) using the multiquadric gridding algorithm in PAST. Values of Sobs and Chao1 are indicated by the colour scale bars. Data were not available for January and February at <500 m and 500–1000 m.

FIGURE 4 in Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand

FIGURE 4. Monthly variation in relative abundance, A* (number of individuals. trap-1. month-1) of Empididae, Hybotidae and Dolichopodidae at all elevations on Doi Inthanon during 2014.

FIGURES 13–14. Spatiotemporal variation. 13 in Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand

FIGURES 13–14. Spatiotemporal variation. 13, Berger-Parker Dominance (DBP); 14, Equitability (J) of Empidoidea (Empididae, Hybotidae, Dolichopodidae & Brachystomatidae combined) through 12 months sampling over six 500 m elevation zones at Doi Inthanon in 2014. Values of DBP and J were calculated in PAST for each month in each elevation zone and smoothed using the adjacent elevation and month algorithm (see Material & methods) before plotting on a grid of elevation zone (vertical axis) and months (horizontal axis) using the multiquadric gridding algorithm in PAST. Values of DBP and J are indicated by the colour scale bars. Data were not available for January and February at <500 m and 500–1000 m.

FIGURE 3 in Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand

FIGURE 3. Monthly variation in species richness (Sobs) of Empididae, Hybotidae, Brachystomatidae and Dolichopodidae at all elevations on Doi Inthanon during 2014.

FIGURE 2 in Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand

FIGURE 2. Variation in relative abundance, A* (number of individuals. trap-1. month-1) of Empididae, Hybotidae and Dolichopodidae across different elevation zones on Doi Inthanon. Note that A* is log10 scale. Error bars indicate standard error.

FIGURE 1 in Composition and organization of highly speciose Empidoidea (Diptera) communities in tropical montane forests of northern Thailand

FIGURE 1. Species richness in each elevation zone as percentage of total richness for each family (%Sobs) at all elevations of Empididae (open squares), Brachystomatidae (closed squares), Dolichopodidae (shaded box) and Hybotidae (plain box) on Doi Inthanon.

Data from: Acceleration and novelty: community restoration speeds recovery and transforms species composition in Andean cloud forest

Community-based tropical forest restoration projects, often promoted as a win-win solution for local communities and the environment, have increased dramatically in number in the past decade. Many such projects are underway in Andean cloud forests, which, given their extremely high biodiversity and history of extensive clearing, are understudied. This study investigates the efficacy of community-based tree-planting projects to accelerate cloud forest recovery, as compared to unassisted natural regeneration. This study takes place in northwest Andean Ecuador, where the majority of the original, highly diverse cloud forests have been cleared, in five communities that initiated tree-planting projects to restore forests in 2003. In 2011, we identified tree species along transects in planted forests (n = 5), naturally regenerating forests (n = 5), and primary forests (n = 5). We also surveyed 120 households about their restoration methods, tree preferences, and forest uses. We found that tree diversity was higher in planted than in unplanted secondary forest, but both were less diverse than primary forests. Ordination analysis showed that all three forests had distinct species compositions, although planted forests shared more species with primary forests than did unplanted forests. Planted forests also contained more animal-dispersed species in both the planted canopy and in the unplanted, regenerating understory than unplanted forests, and contained the highest proportion of species with use value for local people. While restoring forest increased biodiversity and accelerated forest recovery, restored forests may also represent novel ecosystems that are distinct from the region's previous ecosystems and, given their usefulness to people, are likely to be more common in the future.

opencc-zeroDec 2017View details →

Data from: Soil nutrients and dispersal limitation shape compositional variation in secondary tropical forests across multiple scales

1. Soil resource partitioning and dispersal limitation have been shown to shape the tree community structure of mature tropical forests, but are poorly studied in the context of forest succession. We examined the relative contributions of both ecological processes to the variation in the species composition of young tropical secondary forests at different spatial scales, and if the relative importance of these two ecological processes changed during succession. At the species level, we examined if the association between species abundances and soil fertility differed between early and late successional species and/or changed over the course of succession. 2. We used vegetation and soil data from 47 secondary forest sites with two plots each in a tropical agricultural landscape. A distance-based redundancy analysis and variation partition were employed to examine the relative importance of spatial distance (proxy for dispersal limitation) and heterogeneity in soil nutrients (proxy for soil nutrient partitioning) at the landscape scale, and a linear regression to test their effects at the local scale. We examined interspecific variation in species' responses to successional age and soil nutrients with a joint species distribution model. 3. Dispersal limitation and soil niche partitioning drove considerable variation in the composition of plant communities at local and landscape scales. The relative contribution of these two ecological processes changed with scale (local versus landscape), topography (lower slope versus upper slope plots). At the species level, significant abundance-soil fertility associations were mostly positive. Most species became less responsive to soil nutrients over the first few decades of tropical forest succession, probably because light became the main limiting resource in older forests. 4. Synthesis. Our key finding is that spatial heterogeneity in soil resources and spatial distance jointly drive compositional variation within and across early successional forests. Our results highlight that a network of forest fragments enhances the resilience of ecological processes and the potential of secondary forests to restore and preserve biodiversity in human-modified landscapes. To advance our understanding of ecological succession, we need to move beyond single-factor and local-scale studies and examine the effects of multiple variables on succession at multiple spatial scales.

opencc-zeroDec 2017View details →

Data from: Scale-dependent variation in nitrogen cycling and soil fungal communities along gradients of forest composition and age in regenerating tropical dry forests

Rates of ecosystem nitrogen (N) cycling may be mediated by the presence of ectomycorrhizal fungi, which compete directly with free‐living microbes for N. In the regenerating tropical dry forests of Central America, the distribution of ectomycorrhizal trees is affected by succession and soil parent material, both of which may exert independent influence over soil N fluxes. In order to quantify these interacting controls, we used a scale‐explicit sampling strategy to examine soil N cycling at scales ranging from the microsite to ecosystem level. We measured fungal community composition, total and inorganic N pools, gross proteolytic rate, net N mineralization and microbial extracellular enzyme activity at multiple locations within 18 permanent plots that span dramatic gradients of soil N concentration, stand age and forest composition. The ratio of inorganic to organic N cycling was correlated with variation in fungal community structure, consistent with a strong influence of ectomycorrhiza on ecosystem‐scale N cycling. However, on average, > 61% of the variation in soil biogeochemistry occurred within plots, and the effects of forest composition were mediated by this local‐scale heterogeneity in total soil N concentrations. These cross‐scale interactions demonstrate the importance of a spatially explicit approach towards an understanding of controls on element cycling.

Data from: Soil organic matter quantity and quality shape microbial community compositions of subtropical broadleaved forests

As two major forest types in the subtropics, broadleaved evergreen and broadleaved deciduous forests have long interested ecologists. However, little is known about their belowground ecosystems despite their ecological importance in driving biogeochemical cycling. Here, we used Illumina MiSeq sequencing targeting 16S rRNA gene and a microarray named GeoChip targeting functional genes to analyse microbial communities in broadleaved evergreen and deciduous forest soils of Shennongjia Mountain of Central China, a region known as 'The Oriental Botanic Garden' for its extraordinarily rich biodiversity. We observed higher plant diversity and relatively richer nutrients in the broadleaved evergreen forest than the deciduous forest. In odds to our expectation that plant communities shaped soil microbial communities, we found that soil organic matter quantity and quality, but not plant community parameters, were the best predictors of microbial communities. Actinobacteria, a copiotrophic phylum, was more abundant in the broadleaved evergreen forest, while Verrucomicrobia, an oligotrophic phylum, was more abundant in the broadleaved deciduous forest. The density of the correlation network of microbial OTUs was higher in the broadleaved deciduous forest but its modularity was smaller, reflecting lower resistance to environment changes. In addition, keystone OTUs of the broadleaved deciduous forest were mainly oligotrophic. Microbial functional genes associated with recalcitrant carbon degradation were also more abundant in the broadleaved deciduous forests, resulting in low accumulation of organic matters. Collectively, these findings revealed the important role of soil organic matter in shaping microbial taxonomic and functional traits.

opencc-zeroDec 2016View details →

Data from: Root elemental composition in Chinese forests: implications for biogeochemical niche differentiation

1. Trait-based community analysis provides a new approach to integrate functional ecology with community ecology. However, our understanding of the linkages between root chemical traits and community chemical diversity and assembly is still in its infancy. 2. Environmental filtering and niche differentiation are two opposite driving forces of community assembly based on deterministic niche processes. We hypothesize that environmental filtering is a strong driver of root chemical assembly at a large spatial scale, whereas biogeochemical niche differentiation drives root chemical traits divergence among co-occurring species at site scale. 3. We analyzed the concentrations of 15 elements in the fine roots of 281 species across five forest types of China. Discriminant analysis was used to measure the degree of similarity of root chemical traits at the community level and biogeochemical niche differentiation at the species level. 4. Root chemical traits at the community level showed a systematic shift along environmental gradients. The growth rate-related dimension represented by root P and Ca was the most important niche dimension associated with community root chemical assembly, driven by large-scale environmental filters, particularly soils and climate. Biogeochemical niche differentiation of co-occurring species could be a consequence of reducing nutrient competition, especially the competition for nitrogen. 5. Root chemical traits provide a new dimension for assessing the functional niche and may help improve our understanding of the underlying mechanisms of root chemical assembly from the local to the biome scale.

Data from: Massive structural redundancies in species composition patterns of floodplain forest moths

Terrestrial arthropod communities usually consist of very large species numbers. Data from experiments or long time-series would be required to ascertain the functional significance of individual species. Both are largely unavailable for species-rich natural communities. Recognising structural redundancies in species composition allows for an alternative approach to address how strong functional redundancy might be in natural assemblages, if structural and functional redundancies are related to each other. Determining structural redundancies is a regular topic in aquatic ecology, but has rarely been applied to terrestrial communities. We explored the extent of structural redundancy in species-rich terrestrial insect assemblages and whether structural redundancies are contingent to species abundances or functional group affiliations. We used the BVSTEP algorithm to determine structural redundancies in a large data set of moth species (32 181 individuals; 448 species) that had been sampled with light-traps in three different floodplain forests in eastern Austria. We partitioned the moth species into 12 functional types based on larval host-plant affiliations to test if moth species included in reduced subsets represent functional groups in the same proportions as they occur in the entire fauna. We observed far more massive structural redundancies in moth assemblages than previously found in aquatic communities. Subsets containing only 8–15 species (1.8–3.3% of all recorded species) were still highly representative for the overall data. Subsets selected by the BVSTEP procedure performed better than equally small subsets that were defined solely by species abundances or by functional group affiliations. Effective 'surrogate' subsets contained only 6–9 of the 12 functional moth types. High abundance only loosely corresponded with the frequency at which a moth species was included in the subsets. Thus, certain uncommon species contribute importantly to species composition patterns. Our results show unexpectedly extensive structural redundancies in complex floodplain forest moth communities, which may also indicate strong functional redundancies.

opencc-zeroFeb 2020View details →

Extinction-immigration dynamics lag behind environmental filtering in shaping the composition of tropical dry forests within a changing landscape

The impact of rapid habitat loss and fragmentation on biodiversity is a major issue. However, we still lack an integrative understanding of how these changes influence biodiversity dynamics over time. In this study, we investigate the effects of these changes in terms of both niche-based and neutral dynamics. We hypothesize that habitat loss has delayed effects on neutral immigration-extinction dynamics, while edge effects and environmental heterogeneity in habitat patches have rapid effects on niche-based dynamics. We analyzed taxonomic and functional composition of 100 tree communities in a tropical dry forest landscape of New-Caledonia subject to habitat loss and fragmentation. We designed an original, process-based simulation framework, and performed Approximate Bayesian Computation to infer the influence of niche-based and neutral processes. Then, we performed partial regressions to evaluate the relationships between inferred parameter values of communities and landscape metrics (distance to edge, patch area, and habitat amount around communities), derived from either recent or past (65 yrs ago) aerial photographs, while controlling for the effect of soil and topography. We found that landscape structure influences both environmental filtering and immigration. Immigration rate was positively related to past habitat amount surrounding communities. In contrast, environmental filtering was mostly affected by present landscape structure and mainly influenced by edge vicinity and topography. Our results highlight that landscape changes have contrasting spatio-temporal influences on niche-based and neutral assembly dynamics. First, landscape-level habitat loss and community isolation reduce immigration and increase demographic stochasticity, resulting in slow decline of local species diversity and extinction debt. Second, recent edge creation affects environmental filtering, incurring rapid changes in community composition by favoring species with edge-adapted strategies. Our study brings new insights about temporal impacts of landscape changes on biodiversity dynamics. We stress that landscape history critically influences these dynamics and should be taken into account in conservation policies.

opencc-zeroDec 2016View details →

Data from: Bryophyte abundance, diversity and composition after retention harvest in boreal mixedwood forest

1. Variable-retention harvest is widely recognised as an alternative to more intensive methods such as clear-cutting. However, present information is inadequate to judge impact of variable-retention on biodiversity of indigenous forest organisms intolerant of canopy removal, such as forest-inhabiting bryophytes. 2. We examined how bryophyte species cover, richness, diversity and composition change with time in response to a broad range of dispersed retention harvest treatments (2% (clear-cut), 10%, 20%, 50%, 75% retention of original basal area) contrasted with uncut controls (100% retention)) in broadleaf deciduous, mixedwood and conifer-dominated boreal forests in NW Alberta, Canada. Bryophytes were studied in 432 permanent sample plots within 72 compartments before harvest and at three, six and eleven years after harvest. 3. Clear-cut and lower (10% and 20%) retention levels resulted in lower cover and richness of bryophytes than in unharvested control compartments in mixed and conifer-dominated forests, but less so in deciduous-dominated forests, which generally supported low cover and richness. Species composition in each forest type varied along the gradient of harvesting intensity; clear-cuts and lower levels of retention supported similar composition, as did control plots and those representing higher retention levels. Over time the retention harvest treatments became more similar to uncut controls. 4. Synthesis and applications. Increased retention moderated the negative impacts of harvesting on bryophyte assemblages across all forest types, and our results suggest that even 10% retention will facilitate faster post-harvest recovery of bryophytes.02-Aug-2017

opencc-zeroDec 2017View details →

Data from: Can ecosystem functioning be maintained despite climate-driven shifts in species composition? Insights from novel marine forests

1. Climate change is driving a redistribution of species and reconfiguration of ecological communities at a global scale. Persistent warming in many regions has caused species to extend their geographical ranges into new habitats, with thermally-tolerant species often becoming competitively dominant over species with colder affinities. Although these climate-driven changes in species abundance and diversity are well documented, their ecosystem-level implications are poorly understood, and resolving whether reconfigured communities can maintain fundamental ecosystem functions represents a pressing challenge in an increasingly warmer world. 2. Here, we investigated how climate-driven substitutions of foundation species influence processes associated with carbon and nutrient cycling (biomass production, detritus flow, herbivory, decomposition) by comparing two habitat-forming kelp species with contrasting thermal affinities. We examined the wider consequences of the observed (and predicted) emergence of novel marine forests in the NE Atlantic, which are expected to become more dominated by range-expanding, warm-temperate kelps. 3. Warm-temperate kelps both accumulated and released 80% more biomass than the cold-temperate species despite being taxonomically closely-related and morphologically similar. Furthermore, the warm-temperate species accumulated biomass and released detritus year-round, whereas the cold-temperate species did so during short, discrete periods. The warm-temperate kelps supported higher densities of invertebrate grazers and were a preferred food source. Finally, their detritus decomposed 6.5 times faster, despite supporting comparable numbers of detritivores. Overall, our results indicate an important shift in the cycling of organic matter in kelp forests along parts of the NE Atlantic coastline following climate-driven expansion of a warm-affinity kelp, with novel forests supplying large amounts of temporally-continuous—yet highly labile—organic matter. 4. Synthesis. Collectively, our results show that, like species invasions, climate-driven range expansions and consequent shifts in the identity of dominant species can modify a wide range of important ecosystem processes. However, alterations in overall ecosystem functioning may be relatively limited where foundation species share similar ecological and functional traits.

Data from: Re-growing a tropical dry forest: functional plant trait composition and community assembly during succession

A longstanding goal of ecology and conservation biology is to understand the environmental and biological controls of forest succession. However, the patterns and mechanisms that guide successional trajectories, especially within tropical forests, remain unclear. We collected leaf functional trait and abiotic data across a 110-year chronosequence within a tropical dry forest in Costa Rica. Focusing on six key leaf functional traits related to resource acquisition and competition, along with measures of forest stand structure, we propose a mechanistic framework to link species composition, community trait distributions, and forest structure. We quantified the community-weighted trait distributions for specific leaf area, leaf dry matter concentration, leaf phosphorus concentration, leaf carbon to nitrogen ratio, and leaf stable isotopic carbon and nitrogen. We assessed several prominent hypotheses for how these functional measures shift in response to changing environmental variables (soil water content, bulk density and pH) across the chronosequence. Increasingly, older forests differed significantly from younger forests in species composition, above ground biomass and shifted trait distributions. Early stages of succession were uniformly characterized by lower values of community-weighted mean specific leaf area, leaf stable nitrogen isotope, and leaf phosphorus concentration. Leaf dry matter concentration and leaf carbon to nitrogen ratio were lower during earlier stages of succession, and each trait reached an optimum during intermediate stages of succession. The leaf carbon isotope ratio was the only trait to decrease linearly with increasing stand age indicating reduced water use efficiency in older forests. However, in contrast to expectations, community-weighted trait variances did not generally change through succession, and when compared to null expectations were lower than expected. The observed directional shift in community-weighted mean trait values is consistent with the 'productivity filtering' hypothesis where a directional shift in water and light availability shifts physiological strategies from 'slow' to 'fast'. In contrast to expectations arising from niche based ecology, none of the community trait distributions were over-dispersed. Instead, patterns of trait dispersion are consistent with the abiotic filtering and/or competitive hierarchy hypotheses.

Data from: Edge-mediated compositional and functional decay of tree assemblages in Amazonian forest islands after 26 years of isolation

1.Islands formed upstream of mega hydroelectric dams are excellent experimental landscapes to assess the impacts of habitat fragmentation on biodiversity. We examined the effects of plot-, patch- and landscape-scale variables on the patterns of floristic diversity across 34 forest islands that had experienced 26 years of isolation since the creation of the 4,437 km2 Balbina Hydroelectric Reservoir of central Brazilian Amazonia. In addition, three undisturbed continuous forest sites in neighbouring mainland areas were also sampled across a comparable elevational gradient. 2.We identified all live trees ≥10 cm DBH at species level within a total of 87 quarter-hectare forest plots and conducted a comprehensive compilation of functional attributes of each tree species. We then examined species-area relationships (SARs) and the additional effects of patch and landscape scale metrics on patterns of tree assemblage heterogeneity, both in terms of taxonomic and functional diversity. 3.Despite a clearly positive SAR, edge-mediated forest disturbance was the single most important driver of species composition and abundance within islands. Our results suggest that non-random floristic transitions within island plots followed a predictable pattern, with different life-history traits either penalizing or rewarding local persistence of different functional groups. Distance to edges mediated the probability of tree mortality induced by windfalls and episodic surface fires, clearly resulting in faster species turnover and unidirectional changes in guild structure within small islands where light-wooded fast-growing pioneers largely replaced heavy-wooded species of the old-growth flora. 3.Synthesis ─ Following a simultaneous 26-year post-isolation history, we disentangle the effects of habitat loss and insularization on tree assemblages within a large set of Amazonian 'true' forest islands, of variable sizes, sharing a uniform open-water matrix. Area effects are expressed via a response to edge effects, with trees in smaller islands being more vulnerable to edge-related surface fires and windthrows. Additionally, forest edge effects can be a powerful driver of non-random floristic transitions across islands within the Balbina archipelago via a process of rapid pioneer proliferation, drastically affecting both the taxonomic and functional composition of insular tree communities. Finally, our results indicate that detrimental effects of forest fragmentation induced by hydroelectric dams are considerably stronger than those of forest patches embedded within a terrestrial vegetation matrix.