Biotropica最新文献

Evidence for significant declines in insects makes understanding the temporal dynamics of tropical communities a high priority. Here, we address the role of weather in influencing patterns of variation in butterflies across a steep rainfall gradient in western Ecuador. We address three questions: (1) How do climatic factors, driving seasonal patterns in butterfly communities, change across the climatic gradient? (2) Is weather more important in influencing abundance and richness in more seasonal sites than more aseasonal sites? (3) Do wet versus dry-adapted species show similar patterns of seasonality regardless of the ecosystem? We sampled bait-attracted butterflies at three forest sites for three consecutive years, in total, 7046 individuals of 212 species were recorded. Butterfly communities exhibited conspicuous intra- and inter-annual variation in temporal dynamics of abundance and species richness, with overall abundance likely synchronized across study sites and years in seasonal forests but not in the aseasonal forest. The highest numbers of species and individuals occurred during the wet season across all study sites and years, and indeed, rainfall was significantly positively associated with abundance. In addition, the highest abundance of dry and wet forest species occurred in both seasonal sites during 2012, the year with highest rainfall, whereas wet forest species peaked a year later in the aseasonal forest, following the pattern of the entire community at this site. These results show how temporal patterns of butterflies depend on the ecosystem type and rainfall regime and underline the significance of weather, as a driver of population trends in seasonal forests.

Large old native trees are outstanding physical and ecological features in habitat remnants and landscapes in urban areas. Being able to estimate the age of these trees is important to our understanding of the potential impacts of environmental changes and their persistence in urban ecosystems. Here, we report on the ages of several native trees in forest fragments and within the urban landscapes in Singapore, estimated using radiocarbon dating. A Rubroshorea macroptera tree removed due to poor health and safety risk was estimated to be 215–511 years old. A Rubroshorea curtisii tree that had naturally fallen was estimated to be 211–372 years old. Climax forest tree species of Southeast Asia consistently appear to have lifespans of a few hundred years, even in forest fragments and urban landscapes in a city.

Seed dispersal is a critical process in tropical forests. While interspecific variation is relatively well studied, intraspecific variation, as a consequence of differences in body size, foraging behaviors, and ranging patterns, remains understudied. Among vertebrates, primates play a critical role in seed dispersal and exhibit behavioral differences between age and sex categories, making them a suitable study system for intraspecific variation in seed dispersal. Lion-tailed macaques, an endemic frugivorous primate in the Western Ghats Biodiversity Hotspot, provide an excellent model for such studies. Here, we examined the influence of age and sex on (a) diversity of native and non-native fruits consumed; (b) quantity of native and non-native fruits consumed; (c) number of seeds dispersed; (d) movement rates; and (e) seed deposition substrates in lion-tailed macaques. We conducted over 320 h of focal animal sampling in two troops, distributed evenly across adult males, adult females, and subadult males. In both troops, adult males and subadult males consumed a greater diversity of native fruits. While adult females consumed a higher diversity and greater proportion of non-native fruits, subadult males consumed a higher proportion of native fruits. In one troop, subadult males dispersed fewer Ficus seeds than adult females. We found significant differences in relative proportions of non-native species consumed across age-sex categories, though the patterns varied across troops. Our study highlights that the relative differences across age-sex categories may differ across troops, which suggests an idiosyncratic contribution by different age-sex categories across different troops in seed dispersal and consequent recruitment of their food plants.

Falling to the ground is hazardous for arboreal ants. Workers of six ant species dropped onto leaves had the lowest landing success on inclined and wet leaves; epiphyll presence and ant body size had no effect. Consequently, landing on leaves in wet forests apparently is challenging for arboreal ants.

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.