In montane systems, global warming may lead communities to disassemble by forcing organisms to shift their distributions to higher elevations or by causing the extinction of those that are unable to adapt. To predict which species are most at risk from environmental change, physiological responses to multiple factors must be measured in natural conditions at fine spatial and temporal scales. To examine the potential drivers of elevational distributions in tabanid flies, specimens were exhaustively sampled at three altitudes within a tropical montane cloud forest in Western Ecuador. Observed abundances were then correlated with seven environmental variables measured in situ. It was hypothesised that (1) tabanid distributions were significantly associated with particular environmental conditions measured in each altitudinal habitat, and (2) a greater proportion of lowland species were limited to a specific elevation than highland species. Most species occupied well‐defined altitudinal niches corresponding to optimal climatic conditions. Colder weather, higher daily temperature variability, and higher levels of moisture seemed to limit most species from establishing in high elevation sites of this mountainous ecosystem. Despite the high dispersal potential of tabanids within the study area, results suggest that most tabanid flies are limited to the subset of altitudes where their climatic requirements are satisfied.

The conspecific negative density dependence hypothesis states that mortality of young trees (seedlings and saplings) is higher near conspecific adults due to mechanisms such as allelopathy, intraspecific competition, and pest facilitation, explaining why in the tropics, most of plant species tend to be rare and live dispersed. However, there are some tree species that defy this expectation and grow in large clusters of conspecific juveniles and adults. We hypothesize that conspecifics living in clusters show higher and/or more variable defensive profiles than conspecifics with dispersed distributions. We evaluated our hypothesis by assessing the expression of physical leaf traits (thickness, and the resistance to punch, tear and shear) and leaf chemical defenses for six clustered and six non‐clustered tree species in Yasuní National Park, Ecuadorian Amazon. We ask ourselves whether (a) clustered species have leaves with higher physical resistance to damage and more chemical defenses variability than non‐clustered species; (b) saplings of clustered species may show higher physical resistance to damage and higher variation on chemical leaf defenses than their conspecific adults, and (c) saplings of non‐clustered species show lower resistance to physical damage and lower variation in chemical defenses compared to conspecific adults. Overall, our study did not support any of our hypotheses. Remarkably, we found that soluble metabolites were significantly species‐specific.

Quantifying the relative contributions of plant physicochemical traits and environmental conditions to leaf decomposition is essential to increase our understanding of ecosystem processes in forested terrestrial and aquatic habitats. This is particularly crucial in tropical rainforests that display high levels of tree diversity and environmental heterogeneity over relatively small spatial scales. For example, in Amazonia, detritus from hundreds of tree species fuels carbon cycling in watersheds, but much remains to be learned about how species traits interact with environmental conditions to mediate decomposition. We investigated the leaf-litter decomposition of 17 tree species with contrasting traits in soil and stream habitats in Yasuni National Park, Ecuador. We hypothesized that (1) habitat type would be the major determinant of leaf decomposition (faster in stream than soil systems), (2) species would be ranked similarly in terms of leaf decomposition rates, according to decomposability traits (i.e., litter quality), within each habitat, and (3) the variability of leaf decomposition within habitats would be greater for soil than for stream systems. Contrary to our first hypothesis, we found that leaf-litter decomposition rates for any given tree species were similar in stream and soil systems. However, we found that the relative importance of litter traits for decomposition such as concentrations of micronutrients (Mn and Cu, in particular) was consistent across habitats.

Tropical insects are astonishingly diverse and abundant yet receive only marginal scientific attention. In natural tropical settings, insects are involved in regulating and supporting ecosystem services including seed dispersal, pollination, organic matter decomposition, nutrient cycling, herbivory, food webs and waterquality, whichin turn helpfulfill UNSustainable Development Goals (SDGs). Current and future global changes that affect insect diversity and distribution could disrupt key ecosystem services and impose important threats on ecosystems and human well-being. A significant increase in our knowledge of tropical insect roles in ecosystem processes is thus vital to ensure sustainable development on a rapidly changing planet

It is commonly accepted that plant responses to foliar herbivory (e.g. plant defenses) can influence subsequent leaf‐litter decomposability in soil. While several studies have assessed the herbivory–decomposability relationship among different plant species, experimental tests at the intra‐specific level are rare, although critical for a mechanistic understanding of how herbivores affect decomposition and its consequences at the ecosystem scale. Using 17 tree species from the Yasuní National Park, Ecuadorian Amazonia, and applying three different herbivore damage treatments, we experimentally tested whether the plant intra‐specific responses to herbivory, through changes in leaf quality, affect subsequent leaf‐litter decomposition in soil. We found no effects of herbivore damage on the subsequent decomposition of leaf litter within any of the species tested. Our results suggest that leaf traits affecting herbivory are different from those influencing decomposition. Herbivore damage showed much higher intra‐specific than inter‐specific variability, while we observed the opposite for decomposition. Our findings support the idea that interactions between consumers and their resources are controlled by different factors for the green and the brown food‐webs in tropical forests, where herbivory may not necessarily generate any direct positive or negative feedbacks for nutrient cycling.

Studies of altitudinal and latitudinal gradients have identified links between the evolution of insect flight morphology, landscape structure and microclimate. Although lowland tropical rainforests offer steeper shifts in conditions between the canopy and the understorey, this vertical gradient has received far less attention. Butterflies, because of their great phenotypic plasticity, are excellent models to study selection pressures that mould flight morphology. We examined data collected over 5 years on 64 Nymphalidae butterflies in the Ecuadorian Chocó rainforest. We used phylogenetic methods to control for similarity resulting from common ancestry, and explore the relationships between species stratification and flight morphology. We hypothesized that species should show morphological adaptations related to differing micro-environments, associated with canopy and understorey. We found that butterfly species living in each stratum presented significantly different allometric slopes. Furthermore, a preference for the canopy was significantly associated with low wing area to thoracic volume ratios and high wing aspect ratios, but not with the relative distance to the wing centroid, consistent with extended use of fast flapping flight for canopy butterflies and slow gliding for the understorey. Our results suggest that microclimate differences in vertical gradients are a key factor in generating morphological diversity in flying insects.