Spatial patterns of adult plants are a consequence of several ecological processes related to seed dispersal and recruitment. Dispersal limitation, mediated by dispersal syndrome, is considered a key factor in the formation of adult plant spatial patterns. Although this initial pattern determined by dispersal has been thoroughly studied, the subsequently modification by the effect of additional ecological factors, such as habitat heterogeneity is less understood. We explored the relative importance of dispersal syndrome and spatial heterogeneity on the realization of spatial patterns of adult trees in an Ecuadorian tropical dry forest. The spatial distribution of 28 species was modeled with four different spatial point processes each: homogeneous Poisson (HPP), inhomogeneous Poisson (IPP), homogeneous Poisson cluster (HPCP), and inhomogeneous Poisson cluster process (IPCP). These models allowed us to discern between effects of random processes, habitat heterogeneity, limited dispersal, and joint effects of habitat heterogeneity and limited dispersal. We employed Akaike's information criterion (AIC) to select the model which best fit the spatial pattern of each species. The best model of each species was used to analyze differences in cluster size and degree of aggregation, between dispersal syndromes. Seventy-five percent of the species showed inhomogeneous patterns. IPCP yielded the best fit for the spatial distribution of 50% of species in the studied forest and was the prevalent model for the three dispersal syndromes. Thus, the effect of spatial heterogeneity was prevalent in the distribution of most species in this dry tropical forest. Only 21% of species had spatial patterns compatible with random mechanisms associated to limited dispersal around parent sources. Clearly, ignoring habitat heterogeneity could bias the analysis of relationships between dispersal syndrome and species patterns.

This study examines the seed dispersal spectrum of the tropical dry forests of Southern Ecuador, in an effort to contribute to the knowledge of the complex dynamics of tropical dry forests. Seed dispersal spectrum was described for a total number of 160 species. Relationships of dispersal syndromes with plant growth form and climatic seasonality were explored. For a subset of 97 species, we determined whether dispersal spectrum changes when species abundance, in addition to species number, is taken into account. The same subset was used to relate dispersal syndromes with the environmental conditions. Zoochorous species dominated in the studied community. When considering the individual abundance of each species, however, anemochory was the prevalent dispersal syndrome. We found a significant difference in the frequency of dispersal syndromes among plant growth forms, with epizoochory only occurring in shrub species. The dispersal spectrum was dependent on climatic seasonality. The largest proportion of anemochorous species fructified during the dry season, while zoochorous diaspores dominated during the rainy season. A fourthcorner analysis indicated that the seed dispersal spectrum of Southern Ecuador dry forests is controlled by environmental conditions such as annual precipitation, annual temperature range or topography. Our results suggest that spatio-temporal changes in the environmental conditions may affect important ecological processes for dispersal. Thus, the predominance of one syndrome or another may depend on the spatial variation of environmental conditions. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp.

Understanding how diversity is maintained in species‐rich communities, such as tropical forests, remains a challenge in ecology. Recent work suggests that the controversy between competing theories could be better resolved by considering the spatial scale at which different processes rule community assembly. Here we use individual species–area relationships (ISAR) to evaluate the spatial organization of tree diversity around individuals of different species in a completely‐mapped tropical dry forest in south Ecuador. We test two hypotheses. First, stressful environmental conditions promote facilitative interactions that will generate spatial signals of accumulation of diversity around individual trees – contrary to what has been reported in humid tropical forests. Second, spatial signals will shift through ontogeny. As, as larger, older trees generate new microsite conditions that affect the recruitment of younger, smaller trees. We compute ISAR functions for adult trees, for young trees and a new crossed‐ISAR function measuring the accumulation of diversity of young trees around the old trees. We compare observed ISARs to the expectations of inhomogeneous Poisson (i.e. null) models controlling for the effects of environmental variation and habitat association on tree distribution. Although the prevalent response among adult trees was not different from null expectations, which means that the organization of diversity in this size class could be explained by environmental heterogeneity alone, most species accumulated more diversity than expected over short spatial scales in the small stem size class. Only two species accumulated significant diversity in the crossed‐ISARs. Our study indicates the role of facilitation in the organization of plant diversity in this dry forest, but that facilitation is limited to some key species acting on early life stages and accumulating diversity around them. Our results demonstrate the benefit of considering different life‐stages and crossed analyses to disentangle the processes affecting community assembly in tropical dry forests.

An understanding of ecosystem dynamics under different scenarios of degradation is required to reverse ecological degradation and identify restoration priorities. Such knowledge can be the result of scientific investigation, but important insight can also reside in observant local land managers. In seasonally dry tropical forests in southern Ecuador, recent decades have seen important advances in the knowledge of the biodiversity values of these forests, but the available data have not yet been integrated and translated into tools that support managers in deciding restoration measures. One powerful framework to organize and communicate information about ecosystem degradation and recovery dynamics is the state-transition model. We generated such a model by combining ecologist and local knowledge obtained through an adaptation of the Stanford/SRI expert elicitation protocol. Through this information, we identified five forest states with specific attributes of vegetation, human pressures, and restoration needs. Ecologists and locals agreed on the restoration actions but partially disagreed on the causes of degradation. Whereas ecologists considered that grazing management, often introduced with or after logging, was the catalyst for a transition to degraded states, locals attributed those transitions to the effects of logging alone. Importantly, however, both ecologists and locals considered that exclusion of livestock grazing was a necessary action to promote ecological recovery. A forward-looking strategy focusing on objectives for ecosystem recovery and ecosystem management for biodiversity and human well-being might be more successful than strategies that emphasize or seek to attribute responsibility for degradation.

Endozoochory is a prominent form of seed dispersal in tropical dry forests. Most extant megafauna that perform such seed dispersal are ungulates, which can also be seed predators. White-tailed deer (Odocoileus virginianus) is one of the last extant megafauna of Neotropical dry forests, but whether it serves as a legitimate seed disperser is poorly understood. We studied seed dispersal patterns and germination after white-tailed deer gut passage in a tropical dry forest in southwest Ecuador. Over 23 mo, we recorded ca 2000 seeds of 11 species in 385 fecal samples. Most seeds belonged to four species of Fabaceae: Chloroleucon mangense, Senna mollissima, Piptadenia flava, and Caesalpinia glabrata. Seeds from eight of the 11 species dispersed by white-tailed deer germinated under controlled conditions. Ingestion did not affect germination of C. mangense and S. mollissima, whereas C. glabrata showed reduced germination. Nevertheless, the removal of fruit pulp resulting from ingestion by white-tailed deer could have a deinhibition effect on germination due to seed release. Thus, white-tailed deer play an important role as legitimate seed dispersers of woody species formerly considered autochorous. Our results suggest that more research is needed to fully understand the ecological and evolutionary effects of the remaining extant megafauna on plant regeneration dynamics in the dry Neotropics.Abstract in Spanish is available with online material.

Chronic disturbance is widely recognized as one of main triggers of diversity loss in seasonally dry tropical forests (SDTFs). However, the pathways through which diffuse disturbance is acting on the forest are little understood. This information is especially demanded in the case of vanishing Neotropical seasonally dry forests such as the Tumbesian ones. We proposed a conceptual model to analyze the factors behind the loss of woody species richness along a forest disturbance gradient, explicitly considering the existence of direct and indirect causal pathways of biodiversity loss. We hypothesized that the chronic disturbance can act on the woody species richness directly, either by selective extraction of resources or by browsing of palatable species for livestock, or indirectly, by modifying characteristics of the forest structure and productivity. To test our model, we sampled forest remnants in a very extensive area submitted to long standing chronic pressure. Our forests cells (200 × 200 m) were characterized both in terms of woody species composition, structure, and human pressure. Our structural equation models (SEMs) showed that chronic disturbance is driving a loss of species richness. This was done mainly by indirect effects through the reduction of large trees density. We assume that changes in tree density modify the environmental conditions, thus increasing the stress and finally filtering some specific species. The analysis of both, direct and indirect, allows us to gain a better understanding of the processes behind plant species loss in this SDTF.

Neotropical dry forests are among the most diverse and threatened ecosystems worldwide. The extent and knowledge of Neotropical dry forests are quite heterogeneous with forests located in the Ecuadorian province especially diverse, threatened and poorly studied. In this work, we review patterns and conservation status of biodiversity, ecosystem processes and human perception of tropical dry forest of the Ecuadorian province. We found that patterns of biodiversity, endemism and conservation status are generally poorly studied. Overall, these forests provide habitat for at least 900 species including trees, birds, mammals, amphibians and reptiles. On average 18% of these species (range 6-25%) are endemic to the region and 25% (3-50%) are recognized as threatened. Little is known about groups such as invertebrates, fish, fungi, or herbaceous plants, and as well as about processes generating and maintaining critical ecosystem functions. Available literature points out the importance of positive ecological interactions such us plant-frugivore and plant-plant facilitation interactions in maintaining the regeneration dynamics of these forests. Faced by the formative state of knowledge about basic biodiversity patterns and ecological functions, the implementation of ecosystem risk assessment under the IUCN criteria for the Red List of Ecosystems may offer constructive means to organize, integrate and advance existing knowledge and conservation priorities for dry forests of the Ecuadorian province. With examples of existing conflicts between people and protected areas, we emphasize the importance of consultation and involvement of local communities in the development of conservation measures including new protected areas. Lastly, we reflect on some encouraging examples where ecosystem goods and services provided by these forests may be used in a sustainable manner, contributing to local communities' income and preserving biodiversity. In this regard, we highlight how the interaction between research and innovation together with local management may lead to sustainable development and, thus, encourage these sectors to work together for the conservation of dry forests of the Ecuadorian province.

Given widespread habitat degradation and loss, reliable indicators are needed that provide a comprehensive assessment of community response to anthropogenic disturbance. The family Phyllostomidae (Order Chiroptera) has frequently been the focus of research evaluating bats’ response to habitat disturbance in seasonally dry tropical forests (SDTFs). However, few studies compare this family to the larger bat assemblage to assess its efficacy as a bioindicator. We compared community and species-specific attributes of understory phyllostomid and all understory bat species: (1) along a gradient of habitat disturbance within a human-modified SDTF landscape; and (2) between forest and riparian habitats within each disturbance level. We captured 290 individuals belonging to 13 species and 4 families. Phyllostomid species exhibited greater sensitivity to disturbance than the understory bat community as a whole based on richness and beta diversity. Both groups were more sensitive to disturbance in forest than riparian habitat, but phyllostomid species were more likely to be lost from highly disturbed forest habitat. The two dominant species declined in abundance with disturbance but variation in body condition was species-specific. These results suggest that Phyllostomidae are more effective indicators of human disturbance in SDTF than the understory bat community as a whole and evaluation of bats’ response to disturbance is best accomplished with a multifaceted approach.