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1,271 results for “tropical forest”
Varying impacts of logging frequency on tree communities and carbon storage across evergreen and deciduous tropical forests in the Andaman Islands, India
<p>The majority of Earth's tropical forests have been selectively logged; some on repeated occasions. Selective logging is known to affect forest structure, composition and function in various ways, but how such effects vary with logging frequency and across forest types remains unclear. In the Andaman Archipelago in India, we examined adult and pole-sized trees in baseline (unlogged since 1990s), once-logged (logged between 2007 and 2014) and twice-logged (logged in early 1990s and between 2007 and 2014) evergreen and deciduous forests, and tested whether higher logging frequency was associated with lower canopy cover, tree density, tree diversity, aboveground carbon stocks and divergence in species composition, including increased relative abundances of deciduous species in these forests. While once-logged evergreen and deciduous forests were similar to their respective baselines for most attributes assessed, and twice-logged evergreen forests had 22–24% lower adult tree density and diversity, twice-logged deciduous forests had 17–50% lower canopy cover, pole density, adult species diversity and above-ground carbon stocks, and 12% higher deciduous fractions compared to the baselines. Collectively our results reveal lasting impacts of repeated selective logging, even at relative low intensity, on tree communities and carbon storage. These impacts can potentially be mitigated by reducing logging frequency and retaining unlogged patches in logged landscapes, but management must also incorporate heterogeneity in responses and recovery across different forest types. In the Andaman Islands, all forests may require more than 15–25 years between logging events, with deciduous forests potentially requiring more stringent extraction limits compared to evergreen forests.</p>
Variability in tree water uptake determined with stable water isotopes in an African tropical montane forest
<p>Dataset supporting the study <strong>Variability in tree water uptake determined with stable water isotopes in an African tropical montane forest.</strong></p> <p>We investigated relative contributions of different soil depths to tree water uptake of 83 trees and possible species-specific differences in a 50x50 m forest plot at four dates in a tropical montane forest in Kenya using stable water isotopes and the Bayesian mixing model framework MixSIAR.</p> <p>The dataset contains raw isotope data of tree xylem, soil and throughfall water sampled on different dates in a tropical montane forest in Kenya as well as interpolated model input data for the Bayesian mixing model.</p> <p>Further information can be found in the soon to be published article in Ecohydrology.</p> <p> </p>
Data from: Evolutionary constraints on tree size and aboveground biomass in tropical dry forests
<p>1. The extent (or lack) of phylogenetic signal for key ecological traits reveals the role of evolutionary processes on present-day ecosystem function and hints on future ecological trends under climate change scenarios. This approach has been applied to South American tropical moist forests, but not to the highly threatened seasonally dry tropical forests (SDTF), despite acknowledgement of their unique evolutionary history. To fill this knowledge gap, we investigated the legacy of evolutionary processes on vital ecological characteristics among SDTF trees: regional dominance, tree size and soil preference.</p> <p>2. We used tree community data on 313 plots of SDTF (12.52 hectares) and locally collected soil data in central-eastern Brazil. For each assessed trait (three for regional dominance, three for tree size and nine for soil preference), we investigated the legacy of evolution using two different approaches: calculating the extent of phylogenetic signal and comparing the fit of four different models of evolution.</p> <p>3. Aboveground woody biomass and tree size showed strong phylogenetic signal. Most of the SDTF biomass stock was concentrated in a few large-sized and closely related tree genera. Among the soil preference variables, only phosphorus displayed significant, albeit weak, phylogenetic signal.</p> <p>4. Synthesis. Our study is the first to show that evolutionary constraints related to tree size significantly determine regional biomass stocks of SDTF in a few closely related tree lineages. This suggests that even isolated SDTF fragments with low taxonomic and phylogenetic diversity can play an important role in the global carbon cycle, storing disproportionally large amounts of carbon in trees that belong to high-biomass lineages. Whether these lineages also share climate change-induced mortality risk deserves future investigation, as they are largely responsible for the maintenance of regional SDTF biomass stocks.</p>
Closely related tree species support distinct communities of seed-associated fungi in a lowland tropical forest
<p>Previous theoretical work has highlighted the potential for natural enemies to mediate the coexistence of species with similar life-histories via density-dependent effects on survivorship. For plant pathogens to play this role, they must differ in their ability to infect or induce disease in different host plant species. In tropical forests characterized by high diversity, these effects must extend to phylogenetically closely related species pairs. Mortality at the seed and seedling stage strongly influences the abundance and distribution of tropical tree species, but the host preferences and spatial distributions of fungi are rarely determined.</p> <p>We examined how host species identity, relatedness, and seed viability influence the composition of fungal communities associated with seeds of four co-occurring pioneer trees (<em>Cecropia insignis</em>, <em>C. longipes</em>, <em>C. peltata</em>, and <em>Jacaranda copaia</em>). Seeds were buried in mesh bags in five common gardens in the understory of a lowland tropical forest in Panama and retrieved at intervals from 1-30 months. A subset of the seeds in each bag was used to determine germination success. One half of each remaining seed was tested for viability; the other half was used to culture and identify seed-infecting fungi.</p> <p>Seeds were infected by fungi after burial. Although fungal communities differed in viable vs. dead seeds, and across burial locations, community composition primarily varied as a function of plant species identity (30.7% of variation in community composition vs. 4.5% for viability and location together), even for congeneric <em>Cecropia</em> species. Phylogenetic reconstruction showed that relatedness of fungi mostly reflected differences between <em>Jacaranda</em> (Bignoniaceae) and <em>Cecropia</em> (Urticaceae).</p> <p>Although the proportion of germinable seeds decreased gradually over time for all species, intraspecific variation in survival was high at the same location (e.g., ranging from 0-100% for <em>C. peltata</em>) suggesting variable exposure or susceptibility to seed pathogens.</p> <p>Synthesis: Our study provides evidence under field conditions that congeneric tree species with similar life-history differ markedly in seed-associated fungal communities when exposed to the same soilborne fungi. This is a critical first step supporting pathogen mediated coexistence of closely related tree species.</p>
Code and Data Availability of the manuscript: Mapping tree diversity in the tropical forest region of Chocó-Colombia
<p><strong>Code and Data Availability of the manuscript: Mapping tree diversity in the tropical forest region of Chocó-Colombia</strong></p> <p>In revision at Environmental Research letters.</p> <p> </p> <p>J. Camilo Fagua<sup>1</sup>*, Patrick Jantz<sup>1</sup>, Patrick Burns<sup>1</sup>, Richard Massey<sup>1</sup><sub>,</sub> Jeiner Y. Buitrago<sup>2</sup>, Sassan Saatchi<sup>3</sup></p> <p>and Scott J. Goetz<sup>1 </sup></p> <p> </p> <p><sup>1</sup><em> Global Earth Observation & Dynamics of Ecosystems Lab (GEODE), School of Informatics, Computing, and Cyber Systems (SICCS), Northern Arizona University, Flagstaff, Arizona, US<em>.</em></em></p> <p> </p> <p><em><sup>2</sup></em><em> Department of Agronomy, Faculty of Agricultural Sciences, Universidad Nacional de Colombia. Bogota (Colombia).</em></p> <p> </p> <p><em><sup>3</sup></em><em> Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA</em></p> <p> </p> <p>*Corresponding author: J. Camilo Fagua, School of Informatics, Computing, and Cyber Systems (Building #90) 1295 S. Knoles Dr. Flagstaff, AZ 86011. Email: <a href="mailto:Camilo.Fagua@nau.edu">Camilo.Fagua@nau.edu</a></p> <p> </p> <p><strong>1) The files “0_Forest_Structure_maps_in_tif” and “1_Forest_Structure_maps_in_tif” contain seven maps of forest structural metrics for the Chocó region of Colombia in the raster format .tif</strong></p> <p>(a) Canopy height (CH) map: CHOCO_MAP_CH</p> <p>(b) 50th percentile of heights (z_50) map: CHOCO_MAP_z_50</p> <p>(c) Vertical Canopy Heterogeneity (VCH) map: CHOCO_MAP_VCH</p> <p>(d) Standard deviation of normalized heights (z_SD) map: CHOCO_MAP_z_SD</p> <p>(e) Horizontal standard deviation of canopy height (CH_ SD): CHOCO_MAP_CH_SD</p> <p>(f) Horizontal heterogeneity of canopy height (CH_H): CHOCO_MAP_CH_H</p> <p>(g) Rumple Index of canopy height (R_INDEX): CHOCO_MAP_R_INDEX</p> <p> </p> <p><strong>2) The file “2_Diversity_maps_in_tif” contains five maps of forest structural metrics for the Chocó region of Colombia in the raster format .tif</strong></p> <p>(a) Species richness (Richness): MAPS_MEAN_Richness</p> <p>(b) Shannon’s entropy index (ENS-Shannon): MAPS_MEAN_ENS_shannon</p> <p>(c) Simpson’s concentration index (ENS-Simpson): MAPS_MEAN_ENS_Simpson</p> <p>(d) Shannon diversity index (H): MAPS_MEAN_Shannon</p> <p>(e) Simpson diversity index (D): MAPS_MEAN_Simpson</p> <p> </p> <p><strong>3) The file “3_LiDAR_processing” contents data and R codes to estimate forest structural metrics from ALS-LiDAR data (.las) in an Amazon moist forest.</strong></p>
Data from: Contrasting patterns of leaf trait variation among and within species during tropical dry forest succession in Costa Rica
A coordinated response to environmental drivers amongst individual functional traits is central to the plant strategy concept. However, whether the trait co-ordination observed at the global scale occurs at other ecological scales (especially within species) remains an open question. Here, for sapling communities of two tropical dry forest types in Costa Rica, we show large differences amongst traits in the relative contribution of species turnover and intraspecific variation to their directional changes in response to environmental changes along a successional gradient. We studied the response of functional traits associated with the leaf economics spectrum and drought tolerance using intensive sampling to analyse inter- and intra-specific responses to environmental changes and ontogeny. Although the overall functional composition of the sapling communities changed during succession more through species turnover than through intraspecific trait variation, their relative contributions differed greatly amongst traits. For instance, community mean specific leaf area changed mostly due to intraspecific variation. Traits of the leaf economics spectrum showed decoupled responses to environmental drivers and ontogeny. These findings emphasise how divergent ecological mechanisms combine to cause great differences in changes of individual functional traits over environmental gradients and ecological scales.
Bats use live fences to move between tropical dry forest remnants
<p>Linear features can benefit wildlife by assisting animal movement. We captured bats along barbed-wire and live-tree fences connecting Tropical Dry Forest patches in Nicaragua. Bat species richness and captures were higher along live fences but we noted differences in sex ratios, richness, and species composition compared to surrounding natural forests.</p>
Data from: High specialization and limited structural change in plant‐herbivore networks along a successional chronosequence in tropical montane forest
Secondary succession is well‐understood, to the point of being predictable for plant communities, but the successional changes in plant‐herbivore interactions remains poorly explored. This is particularly true for tropical forests, despite the increasing importance of early successional stages in tropical landscapes. Deriving expectations from successional theory, we examine properties of plant‐herbivore interaction networks while accounting for host phylogenetic structure along a succession chronosequence in montane rainforest in Papua New Guinea. We present one of the most comprehensive successional investigations of interaction networks, equating to >40 person years of field sampling, and one of the few focused on montane tropical forests. We use a series of nine 0.2ha forest plots across young secondary, mature secondary and primary montane forest, sampled almost completely for woody plants and larval leaf chewers (Lepidoptera), using forest felling. These networks comprised of 12,357 plant‐herbivore interactions and were analysed using quantitative network metrics, a phylogenetically controlled host‐use index and a qualitative network beta diversity measure. Network structural changes were low and specialisation metrics surprisingly similar throughout succession, despite high network beta diversity. Herbivore abundance was greatest in the earliest stages, and hosts here had more species‐rich herbivore assemblages, presumably reflecting higher palatability due to lower defensive investment. All herbivore communities were highly specialised, using a phylogenetically narrow set of hosts, while host phylogenetic diversity itself decreased throughout the chronosequence. Relatively high phylogenetic diversity, and thus high diversity of plant defenses, in early succession forest may result in herbivores feeding on fewer hosts than expected. Successional theory, derived primarily from temperate systems, is limited in predicting tropical host‐herbivore interactions. All succession stages harbour diverse and unique interaction networks, which together with largely similar network structures and consistent host use patterns, suggests general rules of assembly may apply to these systems.
Data from: Forest fragmentation and loss reduce richness, availability, and specialization in tropical hummingbird communities
Hummingbirds are important pollinators of many native Neotropical plants but their abundance and diversity in landscapes dominated by intensive human uses such as agriculture have rarely been examined, despite such land-uses prevailing in the tropics. We examined how tropical deforestation affects hummingbird community structure in premontane forest patches embedded in a tropical countryside of Coto Brus Canton, Costa Rica. We captured hummingbirds in fourteen landscapes representing a gradient in patch size and forest amount, and tested for the effects of these variables on (1) hummingbird captures at flowers (pollinator availability); (2) species richness; and (3) filtering of functional traits. After accounting for sampling effects, both hummingbird availability and species richness declined by 40% and 50%, respectively, across the gradient in deforestation that we observed (9–66% forest within 1000 m). Focal patch size was the strongest predictor, even after statistically accounting for the amount of forest and matrix composition of landscapes. These reductions in availability and richness were well predicted by functional traits; morphologically specialized species with the capacity to transport long-distance outcrossed pollen and low functional redundancy within the pollinator network showed the greatest sensitivity to landscape change. We hypothesize that declines in hummingbird availability, diversity, and functional traits are important mechanisms driving the observed pollen limitation of ornithophilous flowers in fragmented tropical landscapes. Efforts to conserve large forest patches and enhance matrix permeability are critical for maintaining forest hummingbird communities and pollination services under current and predicted deforestation regimes.
Data from: Seed-dispersal networks in tropical forest fragments: area effects, remnant species, and interaction diversity
<p>Seed dispersal interactions involve key ecological processes in tropical forests that help to maintain ecosystem functioning. Yet this functionality may be threatened by increasing habitat loss, defaunation and fragmentation. However, generalist species, and their interactions, can benefit from the habitat change caused by human disturbance while more specialized interactions mostly disappear. Therefore changes in the structure of the local, within fragment, networks can be expected. Here we investigated how the structure of seed-dispersal networks changes along a gradient of increasing habitat fragmentation. We analysed 16 bird seed-dispersal assemblages from forest fragments of a biodiversity-rich ecosystem. We found significant species-, interaction- and network-area relationships, yet the later was determined by the number of species remaining in each community. The number of frugivorous bird and plant species, their interactions, and the number of links per species decreases as area is lost in the fragmented landscape. In contrast, network nestedness has a negative relationship with fragment area, suggesting an increasing generalization of the network structure in the gradient of fragmentation. Network specialization was not significantly affected by area, indicating that some network properties may be invariant to disturbance. Still, the local extinction of partner species, paralleled by a loss of interactions and specialist-specialist bird-plant seed dispersal associations suggests the functional homogenization of the system as area is lost. Our study provides empirical evidence for network-area relationships driven by the presence/absence of remnant species and the interactions they perform.</p>
Data from: Plant community responses to stand-level nutrient fertilization in a secondary tropical dry forest
The size of the terrestrial carbon (C) sink is mediated by the availability of nutrients that limit plant growth. However, nutrient controls on primary productivity are poorly understood in the geographically extensive yet understudied tropical dry forest biome. To examine how nutrients influence above‐ and belowground biomass production in a secondary, seasonally dry tropical forest, we conducted a replicated, fully factorial nitrogen (N) and phosphorus (P) fertilization experiment at the stand scale in Guanacaste, Costa Rica. The production of leaves, wood, and fine roots was monitored through time; root colonization by mycorrhizal fungi and the abundance of N‐fixing root nodules were also quantified. In this seasonal forest, interannual variation in rainfall had the largest influence on stand‐level productivity, with lower biomass growth under drought. By contrast, aboveground productivity was generally not increased by nutrient addition, although fertilization enhanced growth of individual tree stems in a wet year. However, root growth increased markedly and consistently under P addition, significantly altering patterns of stand‐level biomass allocation to above‐ vs. belowground compartments. Although nutrients did not stimulate total biomass production at the community scale, N‐fixing legumes exhibited a twofold increase in woody growth in response to added P, accompanied by a dramatic increase in the abundance of root nodules. These data suggest that the relationship between nutrient availability and primary production in tropical dry forest is contingent on both water availability and plant functional diversity.
Data from: Early Paleocene tropical forest from the Ojo Alamo Sandstone, San Juan Basin, New Mexico, USA
Earliest Paleocene megafloras from North America are hypothesized to be low diversity and dominated by long-lived cosmopolitan species following the Cretaceous-Paleogene (K/Pg) mass extinction. However, megafloras used to develop this hypothesis are from the Northern Great Plains of North America, and relatively little is known about floras from southern basins. Here, we present a quantitative analysis of an earliest Paleocene megaflora (<350 kyr after K/Pg boundary) from the Ojo Alamo Sandstone in the San Juan Basin (SJB), New Mexico. The megaflora, comprised of 53 morphotypes, was dominated by angiosperms, with accessory taxa composed of pteridophytes, lycophytes, and conifers. Diversity analyses indicate a species rich, highly uneven, and laterally heterogeneous flora. Paleoclimate estimates using multivariate and univariate methods indicate warm temperatures and relatively high precipitation consistent with a modern tropical seasonal forest. When compared to contemporaneous floras from the Denver Basin (DB) of Colorado and the Williston Basin (WB) of North Dakota, the SJB flora had significantly higher species richness but lower evenness. Paleoclimate estimates from the SJB were 7-14 °C warmer than the DB and WB, indicating a shift from a temperate forest in the Northern Great Plains to a tropical forest in the SJB. These results demonstrate the presence of a latitudinal floral diversity and paleoclimatic gradient during the earliest Paleocene in western North America. We hypothesize that the warm, wet conditions in the earliest Paleocene SJB drove rapid rates of speciation following the K/Pg boundary resulting in a diverse and heterogenous flora.
Data from: Do lianas shape ant communities in an early successional tropical forest?
Almost half of lowland tropical forests are at various stages of regeneration following deforestation or fragmentation. Changes in tree communities along successional gradients have predictable bottom-up effects on consumers. Liana (woody vine) assemblages also change with succession, but their effects on animal succession remain unexplored. Here we used a large-scale liana removal experiment across a forest successional chronosequence (7-31 years) to determine the importance of lianas to ant community structure. We conducted 1088 surveys of ants foraging on and living in trees using tree trunk baiting and hand collecting techniques at 34 paired forest plots, half of which had all lianas removed. Ant species composition, β-diversity, and species richness were not affected by liana removal; however, ant species co-occurrence (the coexistence of two or more species in a single tree) was more frequent in control plots, where lianas were present, vs. removal plots. Forest stand age had a larger effect on ant community structure than the presence of lianas. Mean ant species richness in a forest plot increased by ca. 10% with increasing forest age across the 31-year chronosequence. Ant surveys from forest >20 years old included more canopy specialists and fewer ground-nesting ant species vs. those from forests <20 years old. Consequently, lianas had a minimal effect on arboreal ant communities in this early-successional forest, where rapidly changing tree community structure was more important to ant species richness and composition.
Data from: A test of community assembly rules using foliar endophytes from a tropical forest canopy
<p>Community assembly theory assumes that ecological communities are spatially delimited into patches. Within these patches, coexistence results from environmental filtering, competition, and immigration. Truly delineated communities exist in laboratory studies of microbial cultures in Petri dishes, yet empirical tests conducted in continuous environments often use patches defined by convention as opposed to realised boundaries. Here we perform a test of ecological community assembly rules using foliar endophyte communities from a tropical rainforest, where leaves are considered as patches for both fungal and bacterial communities. We determined the diversity of fungal and bacterial endophytes using environmental DNA sequencing of 365 top-canopy leaves, collected from 38 host trees belonging to 22 different species across a 4-hectare research plot. Three leaves were collected from three or more branches within each tree crown. We tested the effect of host tree species and their level of phylogenetic relatedness on community composition as well as the contribution of geographic distance between leaves to endophyte community diversity. Endophyte diversity significantly differed across host tree species, as did community composition. Within certain endophytic orders (Xylariales, Rhizobiales) species assemblages significantly differed across host tree species, but this trend was weaker or non-existent in other orders known to contain pathogens and saprotrophs (Polyporales, Solirubrobacterales). Phylogenetically related host tree species displayed more similar endophyte communities than expected by chance, but geographically close trees did not. Consistent with the finding of host-specificity, nearby leaves tended to host more similar communities than distantly positioned ones. These findings demonstrate that foliar endophytes are structured by dispersal across small spatial scales, but at the scale of the canopy they display patterns of neutral filtering, with only a small part of variation described by host tree differences. Endophyte communities thus act as a model system in evoking the rules predicted by theoretical community ecology.</p>
Data from: Effects of soil type and light on height growth, biomass partitioning, and nitrogen dynamics on 22 species of tropical dry forest tree seedlings: comparisons between legumes and nonlegumes
PREMISE OF THE STUDY: The seedling stage is particularly vulnerable to resource limitation, with potential consequences for community composition. We investigated how light and soil variation affected early growth, biomass partitioning, morphology, and physiology of 22 tree species common in tropical dry forest, including eight legumes. Our hypothesis was that legume seedlings are better at taking advantage of increased resource availability, which contributes to their successful regeneration in tropical dry forests. METHODS: We grew seedlings in a full-factorial design under two light levels in two soil types that differed in nutrient concentrations and soil moisture. We measured height biweekly and, at final harvest, biomass partitioning, internode segments, leaf carbon, nitrogen, δ 13 C, and δ 15 N. KEY RESULTS: Legumes initially grew taller and maintained that height advantage over time under all experimental conditions. Legumes also had the highest final total biomass and water-use efficiency in the high-light and high-resource soil. For nitrogen-fixing legumes, the amount of nitrogen derived from fixation was highest in the richer soil. Although seed mass tended to be larger in legumes, seed size alone did not account for all the differences between legumes and nonlegumes. Both belowground and aboveground resources were limiting to early seedling growth and function. CONCLUSIONS: Legumes may have a different regeneration niche, in that they germinate rapidly and grow taller than other species immediately after germination, maximizing their performance when light and belowground resources are readily available, and potentially permitting them to take advantage of high light, nutrient, and water availability at the beginning of the wet season.
Data from: Evaluating mechanisms of diversification in a Guineo-Congolian tropical forest frog using demographic model selection
The accumulation of biodiversity in tropical forests can occur through multiple allopatric and parapatric models of diversification, including forest refugia, riverine barriers and ecological gradients. Considerable debate surrounds the major diversification process, particularly in the West African Lower Guinea forests, which contain a complex geographic arrangement of topographic features and historical refugia. We used genomic data to investigate alternative mechanisms of diversification in the Gaboon forest frog, Scotobleps gabonicus, by first identifying population structure and then performing demographic model selection and spatially explicit analyses. We found that a majority of population divergences are best explained by allopatric models consistent with the forest refugia hypothesis and involve divergence in isolation with subsequent expansion and gene flow. These population divergences occurred simultaneously and conform to predictions based on climatically stable regions inferred through ecological niche modelling. Although forest refugia played a prominent role in the intraspecific diversification of S. gabonicus, we also find evidence for potential interactions between landscape features and historical refugia, including major rivers and elevational barriers such as the Cameroonian Volcanic Line. We outline the advantages of using genomewide variation in a model-testing framework to distinguish between alternative allopatric hypotheses, and the pitfalls of limited geographic and molecular sampling. Although phylogeographic patterns are often species-specific and related to life-history traits, additional comparative studies incorporating genomic data are necessary for separating shared historical processes from idiosyncratic responses to environmental, climatic and geological influences on diversification.
Data from: Edaphic factors, successional status, and functional traits drive habitat associations of trees in naturally regenerating tropical dry forests
1. Many studies have examined individual environmental drivers of tropical tree species distributions, but edaphic and successional gradients have not been considered simultaneously. Furthermore, determining how functional traits influence species distributions along these gradients may help to elucidate mechanisms behind community assembly. 2. To assess the influence of environmental filtering on tropical dry forest (TDF) tree species distributions we used forest inventory data from sites with large edaphic and successional gradients in NW Costa Rica. Our goals were to determine (1) whether edaphic or successional factors are more important determinants of the abundance of individual tree species in regenerating TDF, (2) how species-level functional traits are related to edaphic and/or successional niche associations of tree species, and (3) correlations between species-level edaphic and successional niche associations. 3. The distributions of 82 focal tree species were strongly driven by both edaphic and successional gradients. Overall, 94% of species responded to soil chemistry, 89% to soil texture, and 94% to stand age gradients. Some functional traits were correlated with the edaphic and successional niche associations of TDF tree species. Species that specialized on soils with high total nutrient concentrations had higher foliar nutrient concentrations (nitrogen and phosphorus) and lower leaf dry matter content (LDMC). Species with wider stand age niches had lower LDMC and wood density. There were no correlations between edaphic and successional niche optima of TDF tree species. 4. Our results indicate that successional and edaphic gradients concurrently drive community assembly in regenerating TDF. Moreover, our work underscores the importance of considering how the functional characteristics of TDF trees dictates species distributions across environmental gradients.
Data from: Disentangling competitive versus climatic drivers of tropical forest mortality
1. Tropical forest mortality is controlled by biotic and abiotic processes, but how these processes interact to determine forest structure is not well understood. Using long-term demography data from permanent forest plots at the Paracou Tropical Forest Research Station in French Guiana, we analyzed the relative influence of competition and climate on tree mortality. We found that self-thinning is evident at the stand level, and is associated with clumped mortality at smaller scales (< 2 m) and regular spacing of living trees at intermediate (2.5-7.5 m) scales. A competition index based on spatial clustering of dead trees was used to build predictive mortality models, which also accounted for climate interactions. 2. The model that most closely fitted observations included both the competition index and climatic variables, with climate-only and competition-only models performing worse than the full model. There was strong evidence for size-specific mortality, with highest mortality for small and very large trees, as well as sensitivity of trees to drought, especially when temperatures were high, and when soils were water saturated. The effect of the competition index was more complex than expected a priori: a higher CI index was associated with lower mortality odds, which we hypothesize is caused by gap-phase dynamics, but there was also evidence for competition-induced mortality at very high index values. 3. The strong signature of competition as a control over mortality at the stand and individual scales confirms that it plays a very important role in determining tropical forest structure. The complexity of the competition-mortality relationship and its interaction with climate indicates that a thorough consideration of the scale of analysis is needed when inferring the role of competition in tropical forests, but demonstrates that climate-only mortality models can be significantly improved by including competition effects, even when ignoring species-specific effects. 4. Synthesis Empirical models such as the one developed here can help constrain and improve process-based vegetation models, serving both as a benchmark and as a means to disentangle mortality processes. Tropical ecosystem dynamic models would benefit greatly from explicitly considering the role of competition in stand development and self-thinning while modeling demography, as well as its interaction with climate.
Data from: Leaf-cutter ants engineer large nitrous oxide hot spots in tropical forests
Though tropical forest ecosystems are among the largest natural sources of the potent greenhouse gas nitrous oxide (N2O), the spatial distribution of emissions across landscapes is often poorly resolved. Leaf-cutter ants (LCA, Atta and Acromyrmex, Myrmicinae) are dominant herbivores throughout Central and South America and influence multiple aspects of forest structure and function. In particular, their foraging creates spatial heterogeneity by concentrating large quantities of organic matter (including nitrogen, N) from the surrounding canopy into their colonies, and ultimately, into colony refuse dumps. Here, we demonstrate that refuse piles created by LCA species Atta colombica in tropical rainforests of Costa Rica provide ideal conditions for extremely high rates of N2O production (high microbial biomass, potential denitrification enzyme activity, N content, and anoxia), and may represent an unappreciated source of heterogeneity in tropical forest N2O emissions. Average instantaneous refuse pile N2O fluxes surpassed background emissions by more than three orders of magnitude (in some cases exceeding 80,000 μg N2O-N m-2 h-1) and generating fluxes comparable to or greater than those produced by engineered systems such as wastewater treatment tanks. Refuse-concentrating Atta species are ubiquitous in tropical forests, pastures and production ecosystems, and increase density strongly in response to disturbance. As such, LCA colonies may represent an unrecognised greenhouse gas point source throughout the Neotropics.
Data from: Demographic costs and benefits of natural regeneration during tropical forest restoration
For tropical forest restoration to result in long‐term biodiversity gains, native trees must establish self‐sustaining populations in degraded sites. While many have asked how seedling recruitment varies between restoration treatments, the long‐term fate of these recruits remains unknown. We address this research gap by tracking natural recruits of 27 species during the first 7 years of a tropical forest restoration experiment that included both planted and naturally regenerating plots. We used an individual‐based model to estimate the probability that a seedling achieves reproductive maturity after several years of growth and survival. We found an advantage for recruits in naturally regenerating plots, with up to 40% increased probability of reproduction in this treatment, relative to planted plots. The demographic advantage of natural regeneration was highest for mid‐successional species, with relatively minor differences between treatments for early‐successional species. Our research demonstrates the consequences of restoration decision making across the life cycle of tropical tree species.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.