Tropical Forest Diversity Research Articles

Disturbance Impacts of Logging on Ground Herbaceous Plant Species Richness, Diversity, and Composition of Lowland Rainforest of Papua New Guinea

The impact of logging activities on species richness, diversity, and composition of the ground herbaceous layer of the lowland forest of Papua New Guinea was analyzed. Data from the first multipurpose National Forest Inventory were collected in 52 plots from logged and unlogged low altitude forest on plains and fans (P) and forest on uplands (H) in Madang, West New Britain and Central Provinces. The abundance of 10,609 ground herbaceous plants classified in 174 species from 103 genera and 35 families. Based on importance values, Arecaceae was the dominating family in both logged and unlogged P forest type, while Urticaceae and Arecaceae were dominating respectively in logged and unlogged H forest type. At species level, Donax canniformis and Elatostema beccarii are dominating the P type, and Elatostema novoguineensis and Selaginella durvillei the H type. Analysis of species richness, diversity, and composition showed significant differences between the two types with the H type being richer and more diverse than P type. No differences emerged between logged and unlogged of both types, indicating that the current intensity of disturbance does not seem to have a significant impact on the ground herbaceous layer. Since herbaceous species are an important component of the tropical forest diversity, further inventories must be conducted along a wider elevation gradient to make these results more robust and better observe species turn over patterns and beta diversity.

Forest composition and structure after 200 years of succession following the eruption of Mount Tambora (Indonesia)

ABSTRACT We examined the changes in tropical forest diversity, structure and trait composition during primary succession after volcanic disturbance. Whilst many studies have examined early stages of succession, fewer have looked at a precisely dated older location: 200 years old in this instance. To do this, we established a 0.5 ha plot on the lower slopes of Gunung (Mount) Tambora (Sumbawa, Indonesia) in which we enumerated and identified all trees ≥ 10 cm dbh, determined their key traits and calculated forest above-ground biomass. Saplings (1.5–3.0 cm dbh) were enumerated in one quarter of this area. We recorded 214 stems ≥ 10 cm dbh within 21 taxa contributing to an above-ground biomass of 135 Mg ha−1. Most trees had light wood and broad distributions suggestive of early successional traits, but leaves were generally small; most trees were insect pollinated and animal dispersed as expected at later stages of succession. Saplings were variable in their density and showed some floristic similarity with adult trees, but differences indicated the future trajectory of succession. Our floristic and structural data from the poorly studied drier forests of eastern Indonesia show that this 200-year-old forest is still undergoing succession at a slow rate.

Topography in tropical forests enhances growth and survival differences within and among species via water availability and biotic interactions

Abstract Topography is associated with variation in soil water, biogeochemical properties and climate, which drive diversity by filtering species and promoting niche differences. However, the potential for topography to promote fitness differences and diversity among tree species and populations remains poorly tested in tropical rainforests, especially at small spatial scales in everwet climates. We reciprocally transplanted tree seedlings between ridge and riparian sites and manipulated neighbour abundance and water availability to assess growth and survival differences both among species and between populations within species in response to changes in biotic interactions and soil water gradients associated with topographic heterogeneity. Seedling growth rates were higher on the ridge, but probability of survival was lower on the ridge than the riparian site. Topography also altered growth and survival responses to water availability such that seedlings in the inundated soils in the riparian site had the lowest growth and survival but increased rapidly with moderate soil drying. By contrast, growth and survival on the ridge were generally unresponsive to drying, although severe drought on the ridge reinforced differences among species in growth rates and probability of survival. The patterns of growth and survival within species did not provide evidence of local adaptation between seedlings from lowland and upslope origins. However, within species, topographic seed‐origin determined the response of seedling growth and survival to increasing neighbour abundance, indicative of divergent selective pressures between individuals growing in different topographic environments. Combined, these results suggest that topographic heterogeneity promotes tropical forest diversity both at the species level via environmental filtering due to water availability and at the population level via functional responses to the density of neighbouring vegetation. A free Plain Language Summary can be found within the Supporting Information of this article.

Tree diversity and species composition of tropical dry forests in Vietnam's Central Highlands Region

Abstract Tree species inventories, particularly of poorly known dry forests, are necessary to protect and restore them in degraded landscapes. The present research has been conducted to compare taxonomic diversity and community composition in four dry forests (DF) categories with different standing volume levels: very low (DFV), low (DFP), medium (DFM) and high (DFR). This quantitative assessment of taxonomic diversity, forest structure and species composition were obtained from 103 sample plots (0.1 ha each). The regeneration potential of trees was assessed in 515 subplots (4 m × 4 m) located within the 103 plots. A total of 1,072 trees representing 87 species belonging to 37 families were recorded in 10.3 ha of total sampled area. The ranges of diversity indices observed in the four forest types were: Margalef's (5.44–8.43), Shannon-Wiener (1.80–2.29), Simpson diversity (0.76–0.87) and evenness (0.32–0.35). The regeneration potential of rare and threatened species Dalbergia oliveri, Hopea recopei, Dalbergia bariensis, Sindora siamensis, Parashorea stellata was observed to be poor. Conversely, Cratoxylon formosum, Shorea obtusa, Dipterocarpus tuberculatus, Dipterocarpus obtusifolius, Terminalia alata, Shorea siamensis and Xylia xylocarpa were the most dominant species at the seedling and sapling stage, showing a strong potential for regeneration. Overall, this study provides useful information on tree species diversity and composition for tropical dry forests which can be used as baseline data to develop incoming plans for forest management and conservation in Vietnam's Central Highlands Region.

Individual tree damage dominates mortality risk factors across six tropical forests.

The relative importance of tree mortality risk factors remains unknown, especially in diverse tropical forests where species may vary widely in their responses to particular conditions. We present a new framework for quantifying the importance of mortality risk factors and apply it to compare 19 risks on 31 203 trees (1977 species) in 14 one-year periods in six tropical forests. We defined a condition as a risk factor for a species if it was associated with at least a doubling of mortality rate in univariate analyses. For each risk, we estimated prevalence (frequency), lethality (difference in mortality between trees with and without the risk) and impact ('excess mortality' associated with the risk, relative to stand-level mortality). The most impactful risk factors were light limitation and crown/trunk loss; the most prevalent were light limitation and small size; the most lethal were leaf damage and wounds. Modes of death (standing, broken and uprooted) had limited links with previous conditions and mortality risk factors. We provide the first ranking of importance of tree-level mortality risk factors in tropical forests. Future research should focus on the links between these risks, their climatic drivers and the physiological processes to enable mechanistic predictions of future tree mortality.

A test of the Janzen‐Connell hypothesis in a species‐rich Mediterranean woodland

AbstractThe Janzen‐Connell (JC) hypothesis predicts that conspecific negative density dependence contributes to the maintenance of plant diversity by lowering the recruitment of locally abundant plant species. The JC hypothesis is a widely evoked explanation for the high species diversity in tropical forests, but remains poorly tested in other species‐rich systems such as Mediterranean woodlands. As such, we tested if the JC operates and the role of soil‐borne oomycetes in a species‐rich Mediterranean woodland of Western Australia, where post‐fire recruitment can lead to high seedling densities, using the common Banksia attenuata as a case study. We attempted to decipher the effects of oomycete pathogens and distance from conspecific trees on intraspecific seedling survival and growth. Contrary to the JC hypothesis, we found little evidence of negative density dependence, but our results suggest positive density dependence survival under conspecific trees. Oomycete‐driven mortality in seedlings was also found regardless of the type of tree. Our results suggest that short‐term seedling recruitment patterns in this species‐rich, fire‐prone ecosystem do not follow the JC hypothesis. Future studies should explore whether negative conspecific density and distance dependence could play a greater role in later stages of the post‐fire recovery process.

Trap type affects dung beetle taxonomic and functional diversity in Bornean tropical forests

AbstractBaited pitfall traps (BPTs) and flight intercept traps (FITs) are the most common methods employed for sampling dung beetle communities. These methods vary in their efficacy and are affected by factors such as the bait types used and the dispersal abilities of different dung beetle species. We present the first quantitative comparison of the community composition, taxonomic and functional diversity of dung beetles caught in human dung BPTs and FITs in Bornean tropical forests. Functional diversity metrics were calculated based on the three functional traits of nesting method, body length, and diel activity. We show that BPTs and FITs captured complementary communities with different functional traits, and that BPTs captured more functionally diverse communities. We therefore recommend using a combination of both BPTs and FITs for studies assessing the composition of dung beetles across habitat types. Our results also highlight that it is important to consider how trap type affects the trait composition of communities when relating dung beetle communities and functional traits to ecological functioning. We suggest modifications to FITs based on the design of harp traps to increase their effectiveness in capturing larger‐bodied beetles.

Gardeners of the forest: hornbills govern the spatial distribution of large seeds

Seed dispersal by frugivores is vital to the maintenance of tree diversity in tropical forests. However, determining the influence of different frugivores over the distribution of their food plants is difficult, given the complexity of these interactions in the tropics. Consequently, most studies have been restricted to small scales, examining seed dispersal and establishment associated with nests, roosts or fruiting trees. Here, we evaluate the role of frugivorous hornbills in dispersing seeds at spatial scales of 1 ha. We monitored hornbills and seed rain at a tropical forest site in north‐east India. We quantified the abundance of hornbill food plants and recruits of large‐seeded plants. We estimated removal rates of dispersed, large seeds to determine post‐dispersal seed fate. We found that the distribution of large‐seeded canopy food plants influenced the distribution of the relatively abundant Rhyticeros undulatus. The overall distribution of hornbills resulted in spatially contagious seed rain patterns for the large‐seeded plant species. Patches with canopy food plants had a higher recruit diversity. Our results show positive feedback between distribution of rare but important hornbill food plants, hornbills and distribution of seeds and saplings of large‐seeded plants in the landscape. Widespread loss of hornbills due to hunting and habitat loss in the region have likely disrupted these feedback mechanisms that are critical for tree species regeneration.

Earth history events shaped the evolution of uneven biodiversity across tropical moist forests

Far from a uniform band, the biodiversity found across Earth's tropical moist forests varies widely between the high diversity of the Neotropics and Indomalaya and the relatively lower diversity of the Afrotropics. Explanations for this variation across different regions, the "pantropical diversity disparity" (PDD), remain contentious, due to difficulty teasing apart the effects of contemporary climate and paleoenvironmental history. Here, we assess the ubiquity of the PDD in over 150,000 species of terrestrial plants and vertebrates and investigate the relationship between the present-day climate and patterns of species richness. We then investigate the consequences of paleoenvironmental dynamics on the emergence of biodiversity gradients using a spatially explicit model of diversification coupled with paleoenvironmental and plate tectonic reconstructions. Contemporary climate is insufficient in explaining the PDD; instead, a simple model of diversification and temperature niche evolution coupled with paleoaridity constraints is successful in reproducing the variation in species richness and phylogenetic diversity seen repeatedly among plant and animal taxa, suggesting a prevalent role of paleoenvironmental dynamics in combination with niche conservatism. The model indicates that high biodiversity in Neotropical and Indomalayan moist forests is driven by complex macroevolutionary dynamics associated with mountain uplift. In contrast, lower diversity in Afrotropical forests is associated with lower speciation rates and higher extinction rates driven by sustained aridification over the Cenozoic. Our analyses provide a mechanistic understanding of the emergence of uneven diversity in tropical moist forests across 110 Ma of Earth's history, highlighting the importance of deep-time paleoenvironmental legacies in determining biodiversity patterns.

Frugivore diversity increases evenness in the seed rain on deforested tropical landscapes

The diversity of tropical forests is strongly shaped by mutualistic interactions involving plants and frugivores that disperse their seeds. However, it is little known how decreases in the diversity of frugivores can affect seed dispersal patterns, plant community composition and species' coexistence in tropical forest landscapes. Here, we investigated the effects of bird frugivore diversity on seed dispersal of rare plant species and on the magnitude of equalizing effects on the seed rain in open areas within 12 fragmented landscapes in the Brazilian Atlantic Forest. We monitored the production of bird‐dispersed seeds and bird abundance in forest fragments, and sampled the seed rain and the activity of birds attracted to experimental tree nuclei established in neighboring pastures. The activity of frugivores in tree nuclei was positively correlated with the diversity of birds recorded in nearby forest fragments, and the seed rain diversity increased with frugivore activity. The proportion of seeds dispersed more frequently than expected by chance in tree nuclei increased linearly with the species' richness of birds. The richness and abundance of active frugivores in deforested areas promoted a seed rain with evenness and diversity up to five times greater than the seed pool available in forest fragments due to the proportional increase in the dispersal of rare plant species and a concomitant proportional decrease in the dispersal of dominant fruiting plants. Furthermore, every additional bird species detected in a site was associated with a 10% increase in the equalizing effect on dispersed seeds' relative abundance. Our results show that the aggregated behavior of avian frugivore communities on deforested areas results in higher species richness in the seed rain of plant communities and underscore the urgency to reduce bird species' loss and the simplification of their communities in tropical landscapes.

BIOVERA-Tree: tree diversity, community composition, forest structure and functional traits along gradients of forest-use intensity and elevation in Veracruz, Mexico.

BackgroundHere, we describe BIOVERA-Tree, a database on tree diversity, community composition, forest structure and functional traits collected in 120 forest plots, distributed along an extensive elevational gradient in Veracruz State, Mexico. BIOVERA-Tree includes information on forest structure from three levels of forest-use intensity, namely old-growth, degraded and secondary forest, replicated across eight elevations from sea-level to near the tree line at 3500 m and on size and location of 4549 tree individuals with a diameter at breast height ≥ 5 cm belonging to 216 species, 154 genera and 80 families. We also report measurements of eight functional traits, namely wood density for 143 species, maximum height for 216 species and leaf traits including: specific leaf area, lamina density, leaf thickness, chlorophyll content and leaf area for 148 species and leaf dry matter content for 145 species.New informationBIOVERA-Tree is a new database comprising data collected in a rigorous sampling design along forest-use intensity and elevational gradients, contributing to our understanding of how interactive effects of forest-use intensity and elevation affect tree diversity, community composition and functional traits in tropical forests.

Abundance and diversity of edaphic mites (Arachnida, Acari) under different forest management systems in Indonesia

Abstract. Ihsan M, Puspitarini RD, Afandhi A, Fernando I. 2021. Abundance and diversity of edaphic mites (Arachnida, Acari) under different forest management systems in Indonesia. Biodiversitas 22: 3685-3692. Edaphic mites play crucial roles in maintaining ecosystem services that are essential to human needs. However, the conversion of natural habitats followed by agricultural intensification may adversely affect edaphic mites. The objective of this study was to investigate the influence of different management systems on edaphic mite abundance, richness, and diversity in tropical rain forests in Indonesia. There were five forest management systems, which were as follows: secondary forest, production forest (pine monoculture), and three agroforestry systems (pine + coffee, mahogany + coffee, and mahogany + new cocoyam). We established a transect containing five research plots for each forest management system. Litter and soil from each plot were collected from December to March 2021. Temperature, relative humidity, and pH of litter and soil, as well as litter thickness, were measured. We found that edaphic mite abundance, richness, and diversity in the secondary forest were similar to managed forests. However, the aforementioned variables were significantly higher in “pine” systems than in “mahogany” systems. Our analysis evidenced positive correlations between litter thickness and edaphic mite abundance, richness, and diversity. Our findings may assist in selecting the appropriate forest management systems to rationalize the conversion of secondary forests to production forests and agroforestry.

Carbon Stocks, Species Diversity and Their Spatial Relationships in the Yucatán Peninsula, Mexico

Integrating information about the spatial distribution of carbon stocks and species diversity in tropical forests over large areas is fundamental for climate change mitigation and biodiversity conservation. In this study, spatial models showing the distribution of carbon stocks and the number of species were produced in order to identify areas that maximize carbon storage and biodiversity in the tropical forests of the Yucatan Peninsula, Mexico. We mapped carbon density and species richness of trees using L-band radar backscatter data as well as radar texture metrics, climatic and field data with the random forest regression algorithm. We reduced sources of errors in plot data of the national forest inventory by using correction factors to account for carbon stocks of small trees (<7.5 cm DBH) and for the temporal difference between field data collection and imagery acquisition. We created bivariate maps to assess the spatial relationship between carbon stocks and diversity. Model validation of the regional maps obtained herein using an independent data set of plots resulted in a coefficient of determination (R2) of 0.28 and 0.31 and a relative mean square error of 38.5% and 33.0% for aboveground biomass and species richness, respectively, at pixel level. Estimates of carbon density were influenced mostly by radar backscatter and climatic data, while those of species richness were influenced mostly by radar texture and climatic variables. Correlation between carbon density and species richness was positive in 79.3% of the peninsula, while bivariate maps showed that 39.6% of the area in the peninsula had high carbon stocks and species richness. Our results highlight the importance of combining carbon and diversity maps to identify areas that are critical—both for maintaining carbon stocks and for conserving biodiversity.

Negative effects of long-term phosphorus additions on understory plants in a primary tropical forest

Human activities have disturbed global phosphorus (P) cycling by introducing substantial amounts of P to natural ecosystems. Although natural P gradients and fertilization studies have found that plant community traits are closely related to P availability, it remains unclear how increased P supply affects plant growth and diversity in P-deficient tropical forests. We used a decadal P-addition experiment (2007–2017) to study the effects of increased P input on plant growth and diversity in understory layer in tropical forests. We monitored the dynamics of seedling growth, survival rate, and diversity of understory plants throughout the fertilization period under control and P addition at 15 g P m−2 yr−1. To identify the drivers of responses, P concentration, photosynthesis rate and nonstructural carbon were analyzed. Results showed that long-term P addition significantly increased P concentrations both in soil pools and plant tissues. However, P addition did not increase the light-saturated photosynthesis rate or growth rate of the understory plants. Furthermore, P addition significantly decreased the survival rate of seedlings and reduced the species richness and density of understory plants. The negative effects of P addition may be attributed to an increased carbon cost due to the tissue maintenance of plants with higher P concentrations. These findings indicate that increased P supply alone is not necessary to benefit the growth of plants in ecosystems with low P availability, and P inputs can inhibit understory plants and may alter community composition. Therefore, we appeal to a need for caution when inputting P to tropical forests ecosystems.

Monitoring restored tropical forest diversity and structure through UAV-borne hyperspectral and lidar fusion

Remote sensors, onboard orbital platforms, aircraft, or unmanned aerial vehicles (UAVs) have emerged as a promising technology to enhance our understanding of changes in ecosystem composition, structure, and function of forests, offering multi-scale monitoring of forest restoration. UAV systems can generate high-resolution images that provide accurate information on forest ecosystems to aid decision-making in restoration projects. However, UAV technological advances have outpaced practical application; thus, we explored combining UAV-borne lidar and hyperspectral data to evaluate the diversity and structure of restoration plantings. We developed novel analytical approaches to assess twelve 13-year-old restoration plots experimentally established with 20, 60 or 120 native tree species in the Brazilian Atlantic Forest. We assessed (1) the congruence and complementarity of lidar and hyperspectral-derived variables, (2) their ability to distinguish tree richness levels and (3) their ability to predict aboveground biomass (AGB). We analyzed three structural attributes derived from lidar data—canopy height, leaf area index (LAI), and understory LAI—and eighteen variables derived from hyperspectral data—15 vegetation indices (VIs), two components of the minimum noise fraction (related to spectral composition) and the spectral angle (related to spectral variability). We found that VIs were positively correlated with LAI for low LAI values, but stabilized for LAI greater than 2 m2/m2. LAI and structural VIs increased with increasing species richness, and hyperspectral variability was significantly related to species richness. While lidar-derived canopy height better predicted AGB than hyperspectral-derived VIs, it was the fusion of UAV-borne hyperspectral and lidar data that allowed effective co-monitoring of both forest structural attributes and tree diversity in restoration plantings. Furthermore, considering lidar and hyperspectral data together more broadly supported the expectations of biodiversity theory, showing that diversity enhanced biomass capture and canopy functional attributes in restoration. The use of UAV-borne remote sensors can play an essential role during the UN Decade of Ecosystem Restoration, which requires detailed forest monitoring on an unprecedented scale.

Functional diversity and redundancy of tropical forests shift with elevation and forest‐use intensity

Abstract Change and intensification of forest use alter tropical ecosystems, influencing biodiversity and, subsequently, ecosystem functioning. The implications of eroding biodiversity may go beyond decreases in species diversity, resulting in changes of functional diversity, that is, the diversity of ecological strategies present in the community, and functional redundancy, that is, how redundant these strategies are to biodiversity loss. However, how environmental conditions and anthropogenic influences shape functional diversity and redundancy in tropical forests remains poorly understood. Here, we examine how tropical forests respond to forest‐use intensity along an extensive elevational gradient in Mexico from the tropical lowlands to high‐elevational mountain forests (0–3,500 m), in terms of functional diversity and functional redundancy, and how these biodiversity facets are related to forest structure. In our study, elevation was crossed with three levels of forest‐use intensity: old‐growth, degraded and secondary forests. At eight elevational sites, five replicate plots were inventoried for each level of forest‐use intensity (total n = 120 plots). Functional diversity and redundancy were calculated using leaf and wood traits of 144 tree species for Hill numbers zero, one and two. Interactive effects between elevation and forest‐use intensity significantly affected biodiversity facets. However, interactive effects resulted from forest‐use intensity influencing biodiversity facets at only a few elevations, and not from a consistent, negative impact of forest‐use intensity. Forest structure, specifically stem density and the Gini coefficient, explained variation across biodiversity facets when these facets gave equal weight to common and rare species. Synthesis and applications. High functional diversity and functional redundancy from lowland to mid‐elevation tropical forests suggest that these ecosystems can be resilient to future disturbances. Our results indicate that the ability of high‐elevation forests may be particularly susceptible to climate change and increasing forest‐use intensity. For these high‐elevation forests, we recommend that forest managers implement enrichment plantings with native species that can tolerate future environmental conditions. Finally, our study shows that efforts to conserve structurally heterogeneous forests and actively managing forests to increase structural heterogeneity will enhance the resilience of tropical forests while conserving their biodiversity.

Discovery-defense strategy as a mechanism of social foraging of ants in tropical rainforest canopies

AbstractMany hypotheses have been proposed to explain the coexistence of ants sharing similar food resources, including ecological trade-offs, however, these hypotheses have mostly been tested in ground-dwelling ant communities. For instance, the discovery-dominance trade-off hypothesis states that species with overlapping food resources differ in their ability to find and dominate resources. However, ant species may use different strategies to share food resources, including discovery-defense, in which the first species to arrive at a food resource maintains control of it. Here, we evaluated whether the discovery-dominance trade-off hypothesis, or the discovery-defense strategy could be a mechanism that promotes coexistence of ant species in the canopy of highly diverse tropical forest canopies. We evaluated the succession of ant species on 72 baits exposed on 24 trees during 13 observation periods (15–195 min) in the canopy of a tropical rain forest in Mexico. In general, we observed little variation in ant species composition (i.e., low β-diversity values) during the 195 min of bait exposure. Moreover, we found that ant species with the greatest ability to discover new food resources were those that dominated them. These findings empirically show that the discovery-defense strategy can be a social foraging strategy in rain forest canopy ants and reject the discovery-dominance trade-off. In short, our results highlight the importance of the discovery of a food resource in the canopy of a tropical rain forest, allowing it to be dominated.

Hydraulically-vulnerable trees survive on deep-water access during droughts in a tropical forest.

Summary Deep‐water access is arguably the most effective, but under‐studied, mechanism that plants employ to survive during drought. Vulnerability to embolism and hydraulic safety margins can predict mortality risk at given levels of dehydration, but deep‐water access may delay plant dehydration. Here, we tested the role of deep‐water access in enabling survival within a diverse tropical forest community in Panama using a novel data‐model approach.We inversely estimated the effective rooting depth (ERD, as the average depth of water extraction), for 29 canopy species by linking diameter growth dynamics (1990–2015) to vapor pressure deficit, water potentials in the whole‐soil column, and leaf hydraulic vulnerability curves. We validated ERD estimates against existing isotopic data of potential water‐access depths.Across species, deeper ERD was associated with higher maximum stem hydraulic conductivity, greater vulnerability to xylem embolism, narrower safety margins, and lower mortality rates during extreme droughts over 35 years (1981–2015) among evergreen species. Species exposure to water stress declined with deeper ERD indicating that trees compensate for water stress‐related mortality risk through deep‐water access.The role of deep‐water access in mitigating mortality of hydraulically‐vulnerable trees has important implications for our predictive understanding of forest dynamics under current and future climates.

Soil‐associated drivers of plant traits and functional composition in Atlantic Forest coastal tree communities

AbstractThe severe deforestation of Brazil’s Atlantic Forest and the increasing effects of climate change underscore the need to understand how tree species respond to climate and edaphic factors. To identify the most important environmental drivers of coastal Atlantic Forest diversity and functional composition, we studied 42 plots of coastal Atlantic Forest (restinga), which has a high diversity of plant communities and spans strong environmental gradients. We examined how forest physiognomy and functional composition respond to changes in the environment, hydraulic, and soil properties. We tested different hypotheses relating the roles of nutrients and soil water availability in driving shifts in tropical forest diversity and functioning. We collected wood samples and leaves from ˜85% of the plant species identified in the forest inventory and estimated the community‐weighted tree height, aboveground biomass, basal area of individual plants, specific leaf area, wood density, and the total tree biomass per community by the sum of all trees’ aboveground biomass per plot. We measured water table depth and 24 physicochemical soil parameters. Hypotheses relating to these factors were formalized via both generalized additive models and piecewise structural equation models and null models of community assembly. Increasing drought, as reflected by increasing water table depth, coarse sand, and soil concentration of aluminum (>6 cmol/kg), was found to be a primary driver of shifts in all measured functional traits. Water table depth was found to be the main environmental driver of restinga species diversity, but shifts in species richness were largely decoupled from functional richness and functional dispersion. Our results suggest that decreases in soil water availability are a central driver of local phenotype–environment matching and that increasing water limitation increases the role of environmental filtering on multiple traits. Our results show that drought leads to a strong convergence (standardized effect size < −1.95) in forest function and leads to shifts to smaller statured forest in particular. These findings reveal important differences in the drivers of forest structure and functioning, suggesting that changes in local spatial variation in soil and moisture variables will be a central issue in restinga management and conservation.

Success in conserving the bird diversity in tropical forests through private protected areas in Western Ecuador

Private protected areas have recently attained more importance at a worldwide level as regards nature conservation. Particularly, the specific region of Western Ecuador receives hardly any protection from the State, and private reserves could, therefore, be a suitable tool to ensure the preservation of its forests and their associated wildlife biodiversity. In this work, we compare the bird species richness between private reserves and public protected areas (managed by the State) located in this region. We also show a checklist of bird species found in the Buenaventura Reserve, a private reserve located in south-western Ecuador. Our comparison shows that smaller private reserves may harbour a similar number of bird species than larger protected areas managed by the state, and they have a higher number of bird species per area. In particular, a total of 233 different bird species were registered in Buenaventura, which were distributed in 16 orders and 42 families. Three species were classified as endangered at an international level: El Oro Parakeet (Pyrrhura orcesi), El Oro Tapaculo (Scytalopus robbinsi), and the Grey-backed Hawk (Pseudastur occidentalis), and another three at a national level: the Long-wattled Umbrellabird (Cephalopterus penduliger), the Slaty-winged Foliage-gleaner (Philydor fuscipenne), and the White-vented Plumeleteer (Chalybura buffonii). Therefore, private reserves can be appreciated as a suitable conservation tool for bird conservation, and they should not be undervalued because of their smaller size. Buenaventura Reserve is a good example of how private reserves are extremely important in fragmented landscapes, as is the case with tropical forests in Western Ecuador.