Search

Aim: Successional changes in functional diversity provide insights into community assembly by indicating how species are filtered into local communities based on their traits. Here, we assess successional changes in taxonomic and functional richness, evenness and redundancy along gradients of climate, soil pH and forest cover. Location: Neotropics. Time period: Last 0–100 years. Major taxa studied: Trees. Methods: We used 22 forest chronosequence studies and 676 plots across the Neotropics to analyse successional changes in Hill's taxonomic and functional diversity of trees, and how these successional changes vary with continental-scale gradients in precipitation, soil pH and surrounding forest cover. Results: Taxonomic and functional richness and functional redundancy increased, while taxonomic and functional evenness decreased over time. Functional richness and evenness changed strongly when not accounting for taxonomic richness, but changed more weakly after statistically accounting for taxonomic richness, indicating that changes in functional diversity are largely driven by taxonomic richness. Nevertheless, the successional increases in functional richness when correcting for taxonomic richness may indicate that environmental heterogeneity and limiting similarity increase during succession. The taxonomically-independent successional decreases in functional evenness may indicate that stronger filtering and competition select for dominant species with similar trait values, while many rare species and traits are added to the community. Such filtering and competition may also lead to increased functional redundancy. The changes in taxonomically-independent functional diversity varied with resource availability and were stronger in harsh, resource-poor environments, but weak in benign, productive environments. Hence, in resource-poor environments, environmental filtering and facilitation are important, whereas in productive environments, weaker abiotic filtering a

Succession is defined as a directional change in species populations, the community, and the ecosystem at a site following a disturbance. Succession is a fundamental concept in ecology as it links different disciplines. An improved understanding of succession is urgently needed in the Anthropocene to predict the widespread effects of global change on succession and ecosystem recovery, but a comprehensive successional framework (CSF) is lacking. A CSF is needed to synthesize results, draw generalizations, advance successional theory, and make improved decisions for ecosystem restoration. We first show that succession is an integral part of socio-ecological system dynamics and that it is driven by social and ecological factors operating at different spatial scales, ranging from the patch to the globe. We then present a CSF at the local scale (patch and landscape) at which succession takes place and explain the underlying successional processes and mechanisms operating at that scale. The CSF reflects the increasingly broader perspective on succession and includes recent theoretical advances by not only focusing on species replacement but also on ecosystem development, considering succession as part of a socio-ecological system, and taking the effect of past and current land use, the landscape context, biotic interactions, and feedback loops into account. We discuss how the CSF can be used to integrate and synthesize successional studies, and its implications for ecosystem restoration.

This dataset summarizes forest light strata (canopy, subcanopy or understory), tree height (m), absolute tree height growth rate (m/year), and biomass partitioning to height growth (%) of trees in 14 tropical secondary wet forest stands differing their time since land abandonment in Mexico to assess how he height growth of individual tree differs among forest light strata and successional guilds during succession. Forest light strata were estimated for every tree individual based on their tree height and vertical light profile for each forest stand and census year. Absolute tree height growth rate was calculated as the difference in tree height between two consecutive censuses. Biomass partitioning to height growth was calculated as the percentage of total aboveground biomass growth partitioned to height growth of trees.

Aim: Successional changes in functional diversity provide insights into community assembly by indicating how species are filtered into local communities based on their traits. Here, we assess successional changes in taxonomic and functional richness, evenness and redundancy along gradients of climate, soil pH and forest cover. Location: Neotropics. Time period: Last 0–100 years. Major taxa studied: Trees. Methods: We used 22 forest chronosequence studies and 676 plots across the Neotropics to analyse successional changes in Hill's taxonomic and functional diversity of trees, and how these successional changes vary with continental-scale gradients in precipitation, soil pH and surrounding forest cover. Results: Taxonomic and functional richness and functional redundancy increased, while taxonomic and functional evenness decreased over time. Functional richness and evenness changed strongly when not accounting for taxonomic richness, but changed more weakly after statistically accounting for taxonomic richness, indicating that changes in functional diversity are largely driven by taxonomic richness. Nevertheless, the successional increases in functional richness when correcting for taxonomic richness may indicate that environmental heterogeneity and limiting similarity increase during succession. The taxonomically-independent successional decreases in functional evenness may indicate that stronger filtering and competition select for dominant species with similar trait values, while many rare species and traits are added to the community. Such filtering and competition may also lead to increased functional redundancy. The changes in taxonomically-independent functional diversity varied with resource availability and were stronger in harsh, resource-poor environments, but weak in benign, productive environments. Hence, in resource-poor environments, environmental filtering and facilitation are important, whereas in productive environments, weaker abiotic filtering allo

Questions: Agricultural expansion is one of the dominant drivers of forest and biodiversity loss, and shifting cultivation is the most widely used form of agriculture in many tropical forest regions. Where forests have been cleared, they have the potential to recover once the land is abandoned. However, legacies of land use are often overlooked in successional studies, and a deeper understanding of this legacy effect is needed to define efficient restoration practices using natural or assisted regeneration. Here, we analysed how land-use history affects soil properties and early succession on abandoned agricultural fields in two contrasting Mexican socio-ecological systems. Location: Mexico, Oaxaca and Chiapas. Methods: We sampled soil and monitored vegetation for 2 years after agricultural abandonment, and interviewed landowners about their land-use practices. Results: Land-use practices were clearly influenced by landowners’ social context (residence time, rural or urban origin), and topography and soil type also constrained or facilitated land-use practices. Soil characteristics were strongly affected by three land-use practices: mechanical tillage decreased soil N and K; frequent herbicide and pesticide use increased N and K; and for pasture systems, stocking density increased soil bulk density and decreased pH and N. High-intensity land management practices, specifically use of machinery, had the highest impact on early forest succession. When machinery was not used, the frequency of land-use practices, particularly weeding frequency, is the main factor influencing tree cover and sapling diversity. Conclusions: To facilitate post-agricultural forest recovery, we recommend restoration efforts using natural regeneration in areas with low previous land-use intensity and frequency.

The core principle shared by most theories and models of succession is that, following a major disturbance, plant–environment feedback dynamics drive a directional change in the plant community. The most commonly studied feedback loops are those in which the regrowth of the plant community causes changes to the abiotic (e.g. soil nutrients) or biotic (e.g. dispersers) environment, which differentially affect species availability or performance. This, in turn, leads to shifts in the species composition of the plant community. However, there are many other PE feedback loops that potentially drive succession, each of which can be considered a model of succession. While plant–environment feedback loops in principle generate predictable successional trajectories, succession is generally observed to be highly variable. Factors contributing to this variability are the stochastic processes involved in feedback dynamics, such as individual mortality and seed dispersal, and extrinsic causes of succession, which are not affected by changes in the plant community but do affect species performance or availability. Both can lead to variation in the identity of dominant species within communities. This, in turn, leads to further contingencies if these species differ in their effect on their environment (priority effects). Predictability and variability are thus intrinsically linked features of ecological succession. We present a new conceptual framework of ecological succession that integrates the propositions discussed above. This framework defines seven general causes: landscape context, disturbance and land-use, biotic factors, abiotic factors, species availability, species performance, and the plant community. When involved in a feedback loop, these general causes drive succession and when not, they are extrinsic causes that create variability in successional trajectories and dynamics. The proposed framework provides a guide for linking these general causes into causal pathway

In closed-canopy systems globally, plants exhibit intense competition for light, prioritizing vertical growth to attain elevated positions within the canopy. Light competition is especially intense in tropical rainforests because of their dense shaded stands, and during forest succession because of concomitant changes in vertical light profiles. We evaluated how the height growth of individual tree differs among forest light strata (canopy, sub-canopy and understorey) and successional guilds (early, mid- and late successional species) during secondary succession in a Mexican rainforest. Fourteen secondary forest stands differing in time since agricultural abandonment (1–25 years) were monitored for seven consecutive years. For each stand and census year we estimated relative light intensity (RLI) for each height and categorized trees into forest light strata: understorey (RLI ≦ 33.3%), sub-canopy (33.3% ≦ RLI ≦ 66.6%) and canopy (RLI ≧ 66.6%), and into successional guilds based on the literature. We estimated two measures of height growth: absolute height growth (HGabs, cm year−1) calculated as the difference in tree height between two consecutive censuses, and biomass partitioning to height growth (HGbp, in kg kg−1 × 100) calculated as the percentage of total aboveground biomass growth partitioned to height growth. Earlier in succession, trees for all strata had greater HGabs and HGbp, resulting in rapid vertical forest development. HGabs was fastest for canopy trees, followed by sub-canopy and understorey trees. These differences in HGabs among strata, combined with their inter-specific variation and continuous recruitment of small individuals, lead to a rapid differentiation in tree sizes and increase stand structural heterogeneity. HGbp was greater for understorey and sub-canopy trees than for canopy trees, reflecting ontogenetic changes in the light competition strategy from growth to persistence. With succession, both HGabs and HGbp decreased, most strongly fo

Abandonment of agricultural lands promotes the global expansion of secondary forests, which are critical for preserving biodiversity and ecosystem functions and services. Such roles largely depend, however, on two essential successional attributes, trajectory and recovery rate, which are expected to depend on landscape-scale forest cover in nonlinear ways. Using a multi-scale approach and a large vegetation dataset (843 plots, 3511 tree species) from 22 secondary forest chronosequences distributed across the Neotropics, we show that successional trajectories of woody plant species richness, stem density and basal area are less predictable in landscapes (4 km radius) with intermediate (40–60%) forest cover than in landscapes with high (greater than 60%) forest cover. This supports theory suggesting that high spatial and environmental heterogeneity in intermediately deforested landscapes can increase the variation of key ecological factors for forest recovery (e.g. seed dispersal and seedling recruitment), increasing the uncertainty of successional trajectories. Regarding the recovery rate, only species richness is positively related to forest cover in relatively small (1 km radius) landscapes. These findings highlight the importance of using a spatially explicit landscape approach in restoration initiatives and suggest that these initiatives can be more effective in more forested landscapes, especially if implemented across spatial extents of 1–4 km radius.

Succession is a fundamental concept in ecology because it indicates how species populations, communities, and ecosystems change over time on new substrate or after a disturbance. A mechanistic understanding of succession is needed to predict how ecosystems will respond to land-use change and to design effective ecosystem restoration strategies. Yet, despite a century of conceptual advances a comprehensive successional theory is lacking. Here we provide an overview of 19 successional theories (‘models’) and their key points, group them based on conceptual similarity, explain conceptual development in successional ideas and provide suggestions how to move forward.Four groups of models can be recognised. The first group (patch & plants) focuses on plants at the patch level and consists of three subgroups that originated in the early 20th century. One subgroup focuses on the processes (dispersal, establishment, and performance) that operate sequentially during succession. Another subgroup emphasises individualistic species responses during succession, and how this is driven by species traits. A last subgroup focuses on how vegetation structure and underlying demographic processes change during succession. A second group of models (ecosystems) provides a more holistic view of succession by considering the ecosystem, its biota, interactions, diversity, and ecosystem structure and processes. The third group (landscape) considers a larger spatial scale and includes the effect of the surrounding landscape matrix on succession as the distance to neighbouring vegetation patches determines the potential for seed dispersal, and the quality of the neighbouring patches determines the abundance and composition of seed sources and biotic dispersal vectors. A fourth group (socio-ecological systems) includes the human component by focusing on socio-ecological systems where management practices have long-lasting legacies on successional pathways and where regrowing vegetations deliver