Biotropica最新文献

The rapid expansion of rubber monocultures over the past two decades has degraded extensive areas of tropical rainforest, raising concerns about their restoration. A key factor influencing the recovery of these forests remains their microbially mediated biogeochemical cycling processes. Here, we investigated changes in soil carbon and nutrient concentration, the carbon (C), nitrogen (N), and phosphorus (P)-acquiring soil extracellular enzyme activities and their stoichiometric ratios (reflecting microbial nutrient limitations) following forest restoration in rubber monocultures. Furthermore, we evaluated the effects of restoration strategies (natural regeneration and restoration plantings) and soil abiotic properties on enzyme activities and examined correlations between soil nutrient concentration and enzyme activities stoichiometric ratios. Our findings revealed that the enzyme activities in restored forests differed significantly from those in rubber monocultures, with higher or lower activities depending on the enzyme types and the restoration strategies. As restoration advanced, the enzyme C:N:P became relatively balanced, indicating an alleviation of microbial C- and N-limitation. Both restoration strategies alleviated microbial C-limitation to a similar extent, but restoration plantings showed a higher alleviation of microbial N-limitation than natural regeneration. Soil pH emerged as the main factor influencing enzyme activities. The increase in soil total P concentration significantly decreased microbial C-limitation but increased N-limitation. Furthermore, the increase in soil C:P and N:P ratios significantly alleviated the microbial N-limitation. Our findings highlight that converting monoculture rubber plantations back into tropical forests through natural regeneration and restoration plantings promotes positive changes in soil microbial activity, alleviates microbial nutrient limitations, and fosters a more balanced nutrient acquisition strategy. These results provide critical scientific support for ecological restoration efforts in tropical regions.

Water availability can change substantially at local scales due to topography (i.e., valleys and ridges), filtering out species depending upon their ecological strategies. Under drier conditions on ridges, species are expected to exhibit denser tissues, increased hydraulic safety, and greater water exploration, while simultaneously reducing their functional space, as low water availability acts as an environmental filter. However, it is commonly observed that generalist species are able to perform across a wide range of habitats, and it remains unclear how topographic heterogeneity influences their traits. In this study, we assessed intraspecific trait variation between valleys and ridges for 11 tree generalist species. We focused on ten morphological, physiological, and biomass allocation traits. To account for integrated plant responses, we also measured functional space occupation. We found higher leaf drought tolerance (lower turgor loss point), greater soil exploration (root mass fraction), and less dense tissues (leaf thickness and root tissue density) in drier ridges. Remarkably, π_tlp was the only trait that consistently varied across all species studied, indicating a strong sensitivity of physiological traits to local-scale abiotic changes. Additionally, we found that generalist species exhibited a broader range of functional traits at drier topographic positions, raising new questions about trait optimization in species with these resource use strategies. Overall, the level of intraspecific trait variability enables species to cope with variations in water availability at small spatial scales. We emphasize the importance of considering small-scale abiotic variation and physiological traits to enhance our understanding of the underlying mechanisms of community assembly.

Bromeliads provide key microhabitats for many tropical anurans, offering water reservoirs for reproduction and shelter from predators. We investigated the factors influencing anuran occupancy in bromeliad patches in the Atlantic Forest of northeastern Brazil. Over 13 months, we surveyed 100 bromeliad patches, each consisting of 4–104 individual plants, and recorded eight anuran species, all bromelicolous. Contrary to expectations, morphological traits of bromeliads—including species, size, and spatial arrangement—had no significant effect on anuran richness or abundance. Likewise, canopy cover did not significantly influence anuran richness or abundance, and temperature and humidity were excluded from analysis due to low variation across sampling sites. Despite favorable structural conditions, overall species diversity was low. In contrast, the presence of the predatory theraphosid spider Pachistopelma rufonigrum had a strong negative effect on anuran occupancy, emerging as the most influential factor in our models. This predator–prey interaction may contribute to the apparent absence of bromeligenous frog species in the study area. Our findings highlight the role of biotic interactions—rather than habitat structure—in shaping anuran assemblages in bromeliad microhabitats.

Tropical agricultural landscapes can support biodiversity, including forest spill-over species, shaped by habitat factors operating at multiple scales. Understanding these factors is crucial for conserving biodiversity and maintaining ecosystem services. Using mist-netting data, this study examined how land-cover changes influence understorey birds and identified key factors at stand and landscape levels, along with a site-specific feature, affecting bird assemblages in agroforestry orchards, rubber tree, and oil palm plantations in Peninsular Malaysia. We captured 39 species over 9900 netting hours, with forest-associated species comprising 33% of the total. Agricultural type emerged as a primary driver of bird diversity, with agroforestry orchards supporting greater species richness and abundance. Canopy cover negatively influenced species richness, total abundance, and the occurrence of carnivorous/insectivorous and granivorous/frugivorous birds. Understorey vegetation height positively impacted bird total abundance. Elevation negatively influenced bird abundance and the occurrence of omnivores but positively affected forest-associated species. Distance to forest was negatively correlated with bird abundance and the occurrence of omnivorous birds. Our findings highlight agroforestry orchards as avian refuges and biological corridors that enhance landscape connectivity and ecosystem functioning in agricultural areas. Specifically, in our region, dense canopy cover in monoculture plantations reduced bird richness and abundance, likely due to reduced sunlight suppressing understorey vegetation and limiting resource availability. Conversely, agroforestry orchards with more open canopies and structurally complex vegetation supported a greater diversity of feeding guilds, including certain forest-associated species. These results underscore the importance of managing tropical farmland by maintaining understorey growth, increasing canopy heterogeneity, and reducing isolation from forest remnants.

El Niño events can significantly disrupt ecosystem dynamics by altering species distribution, population size, and food web interactions, often leading to biodiversity losses and imbalances in ecological relationships. Although an understanding of El Niño-associated climate and weather changes is critical, their impact on ecological interactions in the tropics remains understudied. We investigated differences in the predation rate of lepidopteran larvae across El Niño phases within an urban-agricultural landscape in Southcentral Mindanao, the Philippines. Our results demonstrate notable variations throughout the El Niño phases. Predation rates were considerably higher in the pre-El Niño phase (mean ± SD = 18.24% ± 13.48%) than during the peak of the El Niño phase (mean ± SD = 6.41% ± 10.20%) and showed a slight, yet statistically insignificant, rise in the post-El Niño phase (mean = 9.48% ± 17.66%). Although predation by arthropods on herbivorous preys remained predominant during all periods, vertebrate predation was related to the warmer and drier conditions of El Niño associated with the 2023 ENSO. Our study provides initial insights into how El Niño events shape prey–predator relationships and sustain key ecological functions through species interactions, laying a crucial foundation for future research on the ecological impacts of El Niño droughts in tropical agro-urban systems. We highlight the importance of considering climate variability in predator–prey dynamics and recommend future studies on long-term recovery, habitat restoration, and climate-adaptive strategies to strengthen ecosystem resilience.

Tree water use is a critical component of the forest water cycle and is influenced by global climate changes, such as shifts in precipitation patterns. These changes may disproportionately affect forest runoff depending on how sensitive tree water use is to environmental conditions. Therefore, understanding the water-use strategies of different tree species is essential for predicting how forests will respond to environmental change. This study investigated how daily sap flux density (J_s), which represents water flow per unit of sapwood area, varies with environmental factors in common tree species in successional tropical forests in Thailand. Using thermal dissipation probes, we measured J_s in both an old-growth forest (OF) and a young forest (YF). Results indicated that trees in the OF were highly sensitive to rising vapor pressure deficit (VPD) under low soil moisture, indicating a response to atmospheric demand, while trees in the YF could maintain their water use rate regardless of changes in VPD. In addition, species-specific patterns were observed across varying soil moisture conditions at both sites. In OF, Syzygium syzygoides and Cinnamomum subavenium exhibited conservative water use under low soil moisture, which might protect them from negative effects of droughts. In YF, Adinandra integerrima saturated its J_s earlier than other species under low soil moisture, likely to save water, indicating greater drought tolerance compared to others at this site. These findings provide valuable insights into species-specific water-use patterns across different successional stages, helping to predict how tropical forests may respond to environmental changes.