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Aims Across tropical regions, large forest areas have been converted to different agricultural land uses. These uses impose ecological disturbances affecting forest regeneration potential after field abandonment. Finding ways to identify those agricultural land uses limiting forest regeneration is a critical issue for conserving biodiversity in human-modified landscapes. Here, we developed a fast and inexpensive index, useful for quantifying ecological disturbance regimes associated with agricultural land uses, and tested its power to predict forest regeneration potential. Location Municipality of Marqués de Comillas, southeast Mexico. Methods Interviews were conducted with local farmers to quantify disturbance components (size, duration and severity) associated with agricultural land uses. The scaled values of these disturbance components were added in a simple ecological disturbance index ( EDI). In each one of nine recently abandoned fields representing a wide range of EDI values, two 10-m2 plots, one close to and one far from nearby forest remnants, were established. On each plot, all woody plants of 10-100 m in height were counted, identified and measured in four 1-m2 subplots, at the time of field abandonment and 2 yr later. In addition, at each plot, 18 site condition (microclimate and soil) attributes were quantified at the time of abandonment. Plant density, biomass, species richness and species diversity were used as regeneration variables, and EDI and site condition attributes as independent ones. Results Two years after abandonment, most regeneration variables declined exponentially with EDI. Biomass was not explained by EDI but changed positively with light availability. EDI was strongly correlated to vapour pressure deficit, which also predicted regeneration potential (except biomass). Conclusions EDI is a cheap and easy tool for quantifying the ecological disturbance produced by a wide range of agricultural land uses. The index predicted several regeneration variables as well as or better than direct measurements of the site condition at the time of abandonment. EDI can be used to identify biodiversity-friendly agricultural land uses in human-modified landscapes. [ABSTRACT FROM AUTHOR]

Anthropogenic disturbances frequently exceed resilience of riparian forests. In small-scale restoration projects revegetation is a common technique, but its success depends on the plant species used and some environmental filters. We investigated whether grass competition and soil compaction together with seasonal drought and flooding limit the establishment of seven tree species experimentally planted in abandoned riparian pastures in Southern Mexico. We tested the effects of grass clearing and soil tilling and analyzed seasonal variation of vertical distance to water level, and changes in tree performance, microclimate, and vegetation biomass after planting. Seedling survival was low (19 ± 3 %), ranging between 3 ( Brosimum alicastrum, Moraceae) and 38 % ( Pachira aquatica, Bombacaceae). Survival was negatively correlated to vertical distance to water level, highlighting the importance of the short but severe dry season that may occur in the humid tropics, which reduced survival by >60 %. Flooding events also produced high seedling mortality (80 % after the two first events). Clearing but not tilling enhanced seedling survival. Clearing also significantly increased seedling growth of some species, suggesting competition release. Tilling did not have any consistent effect on growth, but it appears to counteract the positive effects of clearing. Both pre-existing and planted trees ameliorated microclimate to produce better conditions for establishment of new trees following natural regeneration. We conclude that clearing can enhance seedling establishment in riparian abandoned tropical pastures, but other revegetation treatments intended to reduce soil drying and uprooting by flooding during early establishment should be evaluated to improve the cost-benefit of restoring riparian forest. [ABSTRACT FROM AUTHOR]

Although forest succession has traditionally been approached as a deterministic process, successional trajectories of vegetation change vary widely, even among nearby stands with similar environmental conditions and disturbance histories. Here, we provide the first attempt, to our knowledge, to quantify predictability and uncertainty during succession based on the most extensive long-term datasets ever assembled for Neotropical forests. We develop a novel approach that integrates deterministic and stochastic components into different candidate models describing the dynamical interactions among three widely used and interrelated forest attributes-stem density, basal area, and species density. Within each of the seven study sites, successional trajectories were highly idiosyncratic, even when controlling for prior land use, environment, and initial conditions in these attributes. Plot factors were far more important than stand age in explaining successional trajectories. For each site, the best-fit model was able to capture the complete set of time series in certain attributes only when both the deterministic and stochastic components were set to similar magnitudes. Surprisingly, predictability of stem density, basal area, and species density did not show consistent trends across attributes, study sites, or land use history, and was independent of plot size and time series length. The model developed here represents the best approach, to date, for characterizing autogenic successional dynamics and demonstrates the low predictability of successional trajectories. These high levels of uncertainty suggest that the impacts of allogenic factors on rates of change during tropical forest succession are far more pervasive than previously thought, challenging the way ecologists view and investigate forest regeneration. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Over half of the world's forests are disturbed, and the rate at which ecosystem processes recover after disturbance is important for the services these forests can provide. We analyze the drivers' underlying changes in rates of key ecosystem processes (biomass productivity, litter productivity, actual litter decomposition, and potential litter decomposition) during secondary succession after shifting cultivation in wet tropical forest of Mexico. We test the importance of three alternative drivers of ecosystem processes: vegetation biomass (vegetation quantity hypothesis), community-weighted trait mean (mass ratio hypothesis), and functional diversity (niche complementarity hypothesis) using structural equation modeling. This allows us to infer the relative importance of different mechanisms underlying ecosystem process recovery. Ecosystem process rates changed during succession, and the strongest driver was aboveground biomass for each of the processes. Productivity of aboveground stem biomass and leaf litter as well as actual litter decomposition increased with initial standing vegetation biomass, whereas potential litter decomposition decreased with standing biomass. Additionally, biomass productivity was positively affected by community-weighted mean of specific leaf area, and potential decomposition was positively affected by functional divergence, and negatively by community-weighted mean of leaf dry matter content. Our empirical results show that functional diversity and community-weighted means are of secondary importance for explaining changes in ecosystem process rates during tropical forest succession. Instead, simply, the amount of vegetation in a site is the major driver of changes, perhaps because there is a steep biomass buildup during succession that overrides more subtle effects of community functional properties on ecosystem processes. We recommend future studies in the field of biodiversity and ecosystem functioning to separate the effects of vegetation quality (community-weighted mean trait values and functional diversity) from those of vegetation quantity (biomass) on ecosystem processes and services. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Primates are important seed dispersers, especially of large-seeded tree species, but the impact that these animals have on seedling recruitment is unclear. Evidence suggests that forest regeneration might be disrupted in forest fragments in which primates were extirpated. We tested this hypothesis by assessing seedling recruitment in 3 forest fragments occupied (OF) by primates, 3 fragments unoccupied (UF) by primates, and 3 areas within a continuous forest (CF) in the Lacandona rainforest, Mexico. Species and stem densities of tree, palm and liana seedlings were recorded over 16 months. Individuals were classified according to dispersal mode: large-seeded animal-dispersed (LS), small- and medium-seeded animal-dispersed (SS), and abiotically-dispersed species (AD). We assessed the influence of primate presence, adult tree assemblage, and fragment spatial metrics (size, age, distance to nearest fragment, and distance to continuous forest) on seedling assemblages. We recorded 6879 seedlings belonging to 90 species, and 59 genera in 405 1-m2 plots. Both seedlings and adults showed similar differences in species and stem densities of LS, SS and AD species among forest types, suggesting that seedling assemblages were strongly influenced by the adult assemblages. The recruitment of each LS species varied among study sites, but evidence supporting higher recruitment enhancement of these species in continuous forest and occupied fragments was weak. Distance to continuous forest was the unique fragment spatial metric related (negatively) to the recruitment of LS species. Thus, primate extirpation does not appear to disrupt seedling assemblages in the Lancandona rainforest. Nevertheless, we cannot reject the hypothesis that certain LS species such as Spondias radlkoferi may be affected by the extirpation of primates. Am. J. Primatol. 77:468-478, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Harvesting of highly valuable non-timber forest products ( NTFPs) has been considered a win-win strategy where local people profit while conserving forest biodiversity ecosystem services. Nevertheless the sustainability of NTFP harvesting has been debated as the nature of NTFPs harvesting regimes scale of commercialization are highly heterogeneous, few studies have evaluated the cumulative ecological economic effects of such regimes. Here we assessed the medium-term (10 years) sustainability of NTFP harvesting using Chamaedorea palm leaves a major NTFP from Mesoamerica that is highly valued in the international floral industry as a case study., We used an experimental ecological study and an economic assessment to analyse the sustainability of leaf harvesting in C. ernesti-augustii. A 4-year leaf removal experiment was conducted to assess effects of increasing levels of defoliation (0%, 25%, 50%, 75%, 100% leaf removal, biannually) on palm survivorship, leaf production and leaf quality. Results of this experiment were combined with estimations of harvest economic value to make projections of the availability of leaves and profit per unit area. Finally, we determined harvesting regimes that maximize profit while maintaining medium-term viability of exploited populations., Palms tolerated up to 50% chronic defoliation, but higher defoliation levels reduced survivorship, leaf production and leaf quality. In the long term, this 50% defoliation level maximized harvest volume and profit without significantly affecting palm survival and leaf quality. Our results show that harvesters face the dilemma of either maximizing short-term income leading to rapid exhaustion of stocks, or maintaining exploited populations but maximizing income in the long term., Synthesis and applications. Our study shows that intermediate harvesting levels (≤50% leaf removal) are needed to achieve long-term sustainability of Chamaedorea palm leaves. Results of this study have an immediate application for the amendment of the official Mexican law, which enables higher harvesting intensities of Chamaedorea leaves, and for the design of sustainable management strategies. Applications of such strategies should consider community-based management, fair markets, regulating norms, as well as a thorough communication among stakeholders. [ABSTRACT FROM AUTHOR]

Copyright of Economic Botany is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant species produce far more seedlings than those surviving to adulthood. It would seem reasonable to take advantage of that excess production, by relocating seedlings to desired restoration sites. There is, however, little information available on this issue. In the present study, we collected naturally regenerated seedlings of two native species, Calophyllum brasiliense ("barí") and Vochysia guatemalensis ("corpo"), in old‐growth forest patches, and transplanted them for the enrichment of a secondary tropical forest in Veracruz, Mexico. For transplanted C. brasiliense seedlings, overall survival was 32% after 20 months, and for V. guatemalensis seedlings it was 66% after 26 months. The mean height (±standard error) of all C. brasiliense and V. guatemalensis seedlings that survived until the end of the study, was 33 ± 2 cm (from initially 12.9 ± 0.2 cm) and 52 ± 5 cm (from 4.6 ± 0.1 cm), respectively. We applied a cost–benefit model to assess the trade‐off between initial‐investment costs and the resulting survival of transplanting naturally regenerated seedlings in the current study, in comparison with direct seeding (with and without the protection of seeds and emerged seedlings) reported in a previous study for the same area and species. For C. brasiliense, the success of transplanting naturally regenerated seedlings was always inferior to direct seeding without protection, whereas for V. guatemalensis it was always superior. Comparing the transplantation of naturally regenerated seedlings with direct seeding with protection, the best propagation strategy depended on the (monetary) value that a treelet is expected to be worth after 2 years. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Question How to evaluate and integrate relevant ecological, social and technical criteria to select species to be introduced in restoration projects of highly diverse ecosystems such as tropical riparian forests. Location Riparian forest, Marqués de Comillas municipality, southeast Mexico (16°54′N, 92°05′W). Methods We proposed a 'species selection index' ( SSI) using five independent criteria related to ecological, social and technical information. SSI targeted species that (1) are important in the reference forest; (2) are less likely to establish following disturbance; (3) are not specific to a particular habitat; (4) are socially accepted; and (5) their propagation requires a reasonable time and financial investment. SSI may range between zero and 50, with higher values meaning higher potential for restoration purposes. Results Out of a local pool of 97 species, we identified 30 target tree species that together represented >60% of total importance value index in the reference riparian forests. SSI averaged 28.3 ± 1.0 over the studied species, suggesting that species with high values are not frequent. For 20 species, reintroduction by means of active forest restoration was deemed necessary. Species that established through natural regeneration, following secondary regrowth, had lower social value among local farmers. Nearly half of the identified species showed technical constraints for easy propagation and seeding. Conclusions The proposed procedure is useful for selecting species to initiate forest restoration projects and of other woody ecosystems that harbour high biodiversity, and is suitable for several stakeholders interested in restoration. [ABSTRACT FROM AUTHOR]

Deterministic theories predict that local communities assemble from a regional species pool based on niche differences, thus by plant functional adaptations. We tested whether functional traits can also explain patterns in species dominance among the suite of co-occurring species., We predicted that along a gradient of secondary succession, the main driver of species dominance changes from environmental filtering in the relatively harsh (dry and hot) early successional conditions, towards increased competitive interactions and limiting similarity in later successional conditions (when light is limited)., We used the Kurtosis ( K) (a measure of peakedness) of the functional trait distribution of secondary forest communities in high-diversity tropical rain forest in Chiapas, Mexico. The forests ranged 1-25 years in age, and we used eight functional leaf traits related to a plants' carbon, water and heat balance. We calculated the functional trait distribution based on species dominance, where trait values were weighted by species' relative basal area, as well as based on species presence, all species counting once. ' K-ratio' was subsequently computed by dividing kurtosis based on species dominance by kurtosis based on species presence. If the K-ratio is high, the dominant species are functionally similar and we interpreted this as environmentally driven functional convergence allowing species to become dominant. If the K-ratio is small, dominant species are a functionally dissimilar subset of the species present and we interpreted this as competitively driven functional divergence allowing species to become dominant., We found that in early succession, dominant species represent a functionally narrow subset of species with similar traits, and in late succession, dominant species increasingly represent a wide subset of the species present. This trend was found for traits that reflect photosynthetic performance and light capture, and indicates increased competition for light with succession. No trend was found for traits that indicate defence against herbivory, suggesting no successional changes in herbivore pressure., Synthesis. This is one of the first studies showing that drivers of species dominance change along a gradient of secondary succession. During the early successional time window we evaluated, the importance of environmental filtering as a driving force fades away rapidly, and the importance of niche partitioning for species dominance starts to emerge. [ABSTRACT FROM AUTHOR]