Summary 1.A key issue in plant/herbivore interaction research is to understand which plant traits drive differences in herbivore damage. Variation in chemical, physical or phenological traits of plants may all modulate the degree of herbivore damage among species and individuals, yet the relative importance of these factors is still subject to debate, particularly in species-rich systems such as tropical rain forests. 2. To address this issue, we quantified leaf herbivore damage in 28 common tree species of the Yasunı forest dynamic plot (YFDP) in the Ecuadorian Amazon over 11 months. Census data from the YFDP allowed us to quantify several aspects of tree ecology potentially affecting herbivory including leaf turnover and spatial distribution patterns. We measured six chemical, eight physical and four ecological traits of the focal species. Using a combination of multivariate analyses and phylogenetic generalized linear regression model (PGLS), we assessed trade-offs between physical and chemical traits and the relative effect of all these traits on leaf herbivore damage. 3. Herbivore damage was highly variable among species and individuals, with leaves on average displaying damage over 13.4% (2.5-29.5%) of their area. We found no significant trade-off between physical and chemical defences for the 28 studied tree species. Overall, leaf size, shearing resistance, cellulose, ash content and leaf size 9 ash were the best predictors of herbivore damage. Surprisingly, condensed tannins and latex did not significantly correlate with herbivore damage. In addition, we found no relationships between herbivory and local tree density. However, we did find a weak effect of tree clustering and strong effect of tree leaf turnover rates on herbivore damage. 4. Synthesis. In the western Amazon, leaves are defended against herbivores through a combination of physical (toughness), chemical (toughness-related elements), and phenological (rapid leaf replacement) characteristics that do not appear to be subject to obvious trade-offs. Conventional strategies, such as condensed tannins or latex, do not seem to be strongly involved as a defence against herbivores in this community.
SummaryIt 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 Yasun ı 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 leaflitter 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 intraspecific 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.
Aedes (Stegomyia) albopictus (Skuse), (Diptera: Culicidae), the Asian tiger mosquito, is one of the most widespread invasive vector-borne disease insect in tropical and temperate zones. This species has invaded the Americas over the past 3 decades and has spread to six countries. We report Ae. albopictus in Guayaquil city, the first time it has been identified in Ecuador. Outdoor BG-Sentinel traps without lures collected a total of 21 Ae. albopictus.
Global biodiversity loss is creating a more urgent need to understand the role organisms play in ecosystem functioning and mechanisms of control. Decomposition of dead organic matter is a key ecological process that ensures soil formation, nutrient availability, and carbon sequestration. To gain understanding of how biodiversity and ecosystems function together to control leaf‐litter decomposition processes in a tropical rain forest (Yasuní National Park, Ecuador), we predicted the consequences of the decomposition process using a protocol in which we systematically disassemble the structural functionality of the soil macrofauna communities. We (1) describe the structure and function of the edaphic communities in detail and (2) explore the functional consequences of structural changes in these communities using a non‐random exclusion experiment to simulate body size‐related extinctions. To do this, we manipulated access of five size classes of soil invertebrates to eight types of plant leaf‐litter resources. After measuring and identifying about 4400 soil individuals belonging to 541 morphospecies, 12 functional groups, and following the fate of about 2000 tree leaves in a 50‐ha plot, we showed that (1) soil invertebrate communities were composed of a few common and many rare morphospecies that included mostly leaf‐litter transformer groups, with the most morphospecies and the greatest abundance coming from Hymenoptera, Collembola, and Coleoptera; (2) our survey captured 63–74% of the total soil biodiversity of the study area (meaning there may be up to 860 morphospecies); (3) litter transformers covered the widest range of body volume, and all groups were evenly distributed at small and large spatial scales (i.e., we found no patterns of spatial aggregation); (4) changes in food web structure significantly altered biomass loss for only three of the eight leaf‐litter treatments, suggesting the decomposition process was highly resistant to drastic changes such as size‐biased biodiversity loss independent of resource quality. We conclude organic matter decomposition may depend on all non‐additive effects that arise from multi‐species interactions, including facilitation, interspecific interference competition, and top‐down control that predators exert over detritivores at all body size ranges.
Regrowing secondary forests dominate tropical regions today, and a mechanistic understanding of their recovery dynamics provides important insights for conservation. In particular, land‐use legacy effects on the fauna have rarely been investigated. One of the most ecologically dominant and functionally important animal groups in tropical forests are the ants. Here, we investigated the recovery of ant communities in a forest–agricultural habitat mosaic in the Ecuadorian Chocó region. We used a replicated chronosequence of previously used cacao plantations and pastures with 1–34 years of regeneration time to study the recovery dynamics of species communities and functional diversity across the two land‐use legacies. We compared two independent components of responses on these community properties: resistance, which is measured as the proportion of an initial property that remains following the disturbance; and resilience, which is the rate of recovery relative to its loss. We found that compositional and trait structure similarity to old‐growth forest communities increased with regeneration age, whereas ant species richness remained always at a high level along the chronosequence. Land‐use legacies influenced species composition, with former cacao plantations showing higher resemblance to old‐growth forests than former pastures along the chronosequence. While resistance was low for species composition and high for species richness and traits, all community properties had similarly high resilience. In essence, our results show that ant communities of the Chocó recovery rapidly, with former cacao reaching predicted old‐growth forest community levels after 21 years and pastures after 29 years. Recovery in this community was faster than reported from other ecosystems and was likely facilitated by the low‐intensity farming in agricultural sites and their proximity to old‐growth forest remnants. Our study indicates the great recovery potential for this otherwise highly threatened biodiversity hotspot.
One of the largest species in its genus, Odontomachus davidsoni Hoenle, Lattke & Donoso, sp. nov. is described from workers and queens collected at lowland forests in the Chocó-Darién bioregion in coastal Ecuador. The workers are characterized by their uniform red coloration, their large size (16–18 mm body length), and their frontal head striation that reaches the occipital margin. DNA barcodes (COI) and high resolution 2D images of the type material are provided, as well as an updated key for the Neotropical species of Odontomachus. In addition, a three-dimensional digital model of the worker holotype and a paratype queen scanned with DISC3D based on photogrammetry is presented, for the first time in a species description. Findings of large and conspicuous new species are uncommon around the world and suggest that these Ecuadorian rainforests may conceal many more natural treasures that deserve conservation.
Microhabitat differentiation of species communities such as vertical stratification in tropical forests contributes to species coexistence and thus biodiversity. However, little is known about how the extent of stratification changes during forest recovery and influences community reassembly. Environmental filtering determines community reassembly in time (succession) and in space (stratification), hence functional and phylogenetic composition of species communities are highly dynamic. It is poorly understood if and how these two concurrent filters—forest recovery and stratification—interact. In a tropical forest chronosequence in Ecuador spanning 34 years of natural recovery, we investigated the recovery trajectory of ant communities in three overlapping strata (ground, leaf litter, lower tree trunk) by quantifying 13 traits, as well as the functional and phylogenetic diversity of the ants. We expected that functional and phylogenetic diversity would increase with recovery time and that each ant community within each stratum would show a distinct functional reassembly. We predicted that traits related to ant diet would show divergent trajectories reflecting an increase in niche differentiation with recovery time. On the other hand, traits related to the abiotic environment were predicted to show convergent trajectories due to a more similar microclimate across strata with increasing recovery age. Most of the functional traits and the phylogenetic diversity of the ants were clearly stratified, confirming previous findings. However, neither functional nor phylogenetic diversity increased with recovery time. Community‐weighted trait means had complex relationships to recovery time and the majority were shaped by a statistical interaction between recovery time and stratum, confirming our expectations. However, most trait trajectories converged among strata with increasing recovery time regardless of whether they were related to ant diet or environmental conditions. We confirm the hypothesized interaction among environmental filters during the functional reassembly in tropical forests. Communities in individual strata respond differently to recovery, and possible filter mechanisms likely arise from both abiotic (e.g. microclimate) and biotic (e.g. diet) conditions. Since vertical stratification is prevalent across animal and plant taxa, our results highlight the importance of stratum‐specific analysis in dynamic ecosystems and may generalize beyond ants.
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