Comparing global and local maps of the Caribbean pine forests of Andros, home of the critically endangered Bahama Oriole.

Forest loss is occurring at alarming rates across the globe. The pine rockland forests of Andros, The Bahamas, likely represent some of the largest stands of Bahamian subspecies of Caribbean pine in the world. Given the unique species that inhabit these pine forests, such as the endemic and critically endangered Bahama Oriole, monitoring habitats on Andros is crucial to inform conservation planning. We developed a 2019 land classification map to assess the status of nine terrestrial habitats on Andros. Our Random Forest classification model predicted habitat classes with high overall accuracy. Caribbean pine was the dominant land class making up roughly one-third of the total terrestrial area. Whereas much of the pine forest area was found as small patches, most were close to other patches of pine suggesting isolation of forest patches is low. We compared our known intact forest areas to recent forest loss identified by the Hansen et al. Global Forest Change product and assessed areas of habitat disturbance in high-resolution imagery. Our results suggest that this global map overpredicted forest loss on Andros. The small degree of true forest loss on Andros was driven mostly by anthropogenic activity. A cross-tabulation of the Hansen forest loss with fire data showed that understory fires were frequently associated with falsely classified deforestation. Given the threats of climate change to this open forest type-intensifying fire regimes, strengthening hurricanes, and sea level rise-monitoring changes in open forest extent is a critical task across the Caribbean region and the world.

Potential impacts of COVID-19 on tropical forest recovery.

COVID-19 has impacted humanity and the global environment in myriad ways, and more changes are on the horizon. Here we consider the impact of COVID-19 on our collective ability to restore degraded habitats and facilitate forest recovery in the tropics.

Conceptual Links between Landscape Diversity and Diet Diversity: A Roadmap for Transdisciplinary Research.

Malnutrition linked to poor quality diets affects at least 2 billion people. Forests, as well as agricultural systems linked to trees, are key sources of dietary diversity in rural settings. In the present article, we develop conceptual links between diet diversity and forested landscape mosaics within the rural tropics. First, we summarize the state of knowledge regarding diets obtained from forests, trees, and agroforests. We then hypothesize how disturbed secondary forests, edge habitats, forest access, and landscape diversity can function in bolstering dietary diversity. Taken together, these ideas help us build a framework illuminating four pathways (direct, agroecological, energy, and market pathways) connecting forested landscapes to diet diversity. Finally, we offer recommendations to fill remaining knowledge gaps related to diet and forest cover monitoring. We argue that better evaluation of the role of land cover complexity will help avoid overly simplistic views of food security and, instead, uncover nutritional synergies with forest conservation and restoration.

Positive site selection bias in meta-analyses comparing natural regeneration to active forest restoration.

Several recent meta-analyses have aimed to determine whether natural regeneration is more effective at recovering tropical forests than active restoration (for example, tree planting). We reviewed this literature and found that comparisons between strategies are biased by positive site selection. Studies of natural forest regeneration are generally conducted at sites where a secondary forest was already present, whereas tree planting studies are done in a broad range of site conditions, including non-forested sites that may not have regenerated in the absence of planting. Thus, a level of success in forest regeneration is guaranteed for many studies representing natural regeneration, but not for those representing active restoration. The complexity of optimizing forest restoration is best addressed by paired experimentation at the same site, replicated across landscapes. Studies that have taken this approach reach different conclusions than those arising from meta-analyses; the results of paired experimental comparisons emphasize that natural regeneration is a highly variable process and that active restoration and natural regeneration are complementary strategies.

Environmental and spatial drivers of taxonomic, functional, and phylogenetic characteristics of bat communities in human-modified landscapes.

BACKGROUND: Assembly of species into communities following human disturbance (e.g., deforestation, fragmentation) may be governed by spatial (e.g., dispersal) or environmental (e.g., niche partitioning) mechanisms. Variation partitioning has been used to broadly disentangle spatial and environmental mechanisms, and approaches utilizing functional and phylogenetic characteristics of communities have been implemented to determine the relative importance of particular environmental (or niche-based) mechanisms. Nonetheless, few studies have integrated these quantitative approaches to comprehensively assess the relative importance of particular structuring processes. METHODS: We employed a novel variation partitioning approach to evaluate the relative importance of particular spatial and environmental drivers of taxonomic, functional, and phylogenetic aspects of bat communities in a human-modified landscape in Costa Rica. Specifically, we estimated the amount of variation in species composition (taxonomic structure) and in two aspects of functional and phylogenetic structure (i.e., composition and dispersion) along a forest loss and fragmentation gradient that are uniquely explained by landscape characteristics (i.e., environment) or space to assess the importance of competing mechanisms. RESULTS: The unique effects of space on taxonomic, functional and phylogenetic structure were consistently small. In contrast, landscape characteristics (i.e., environment) played an appreciable role in structuring bat communities. Spatially-structured landscape characteristics explained 84% of the variation in functional or phylogenetic dispersion, and the unique effects of landscape characteristics significantly explained 14% of the variation in species composition. Furthermore, variation in bat community structure was primarily due to differences in dispersion of species within functional or phylogenetic space along the gradient, rather than due to differences in functional or phylogenetic composition. DISCUSSION: Variation among bat communities was related to environmental mechanisms, especially niche-based (i.e., environmental) processes, rather than spatial mechanisms. High variation in functional or phylogenetic dispersion, as opposed to functional or phylogenetic composition, suggests that loss or gain of niche space is driving the progressive loss or gain of species with particular traits from communities along the human-modified gradient. Thus, environmental characteristics associated with landscape structure influence functional or phylogenetic aspects of bat communities by effectively altering the ways in which species partition niche space.

Targeted reforestation could reverse declines in connectivity for understory birds in a tropical habitat corridor.

Re-establishing connectivity between protected areas isolated by habitat clearing is a key conservation goal in the humid tropics. In northeastern Costa Rica, payments for environmental services (PES) and a government ban on deforestation have subsidized forest protection and reforestation in the San Juan-La Selva Biological Corridor (SJLSBC), resulting in a decline in mature forest loss and the expansion of tree plantations. We use field studies and graph models to assess how conservation efforts have altered functional connectivity over the last 25 years for four species of insectivorous understory birds. Field playback studies assessed how reforestation habitat quality affected the willingness of Myrmeciza exsul, Henicorhina leucosticta, Thamnophilus atrinucha, and Glyphorynchus spirurus to travel outside forest habitat for territorial defense. Observed travel distances were greatest in nonnative and native tree plantations with high understory stem density, regardless of overstory composition. In contrast, tree plantations with low stem density had travel responses comparable to open pasture for three of the four bird species. We modeled landscape connectivity for each species using graph models based on varying possible travel distances in tree plantations, gallery forests, and pastures. From 1986 to 2011, connectivity for all species declined in the SJLSBC landscape (5825 km2 ) by 14% to 21% despite only a 4.9% net loss in forest area and the rapid expansion of tree plantations over 2% of the landscape. Plantation placement in the landscape limited their potential facilitation of connectivity because they were located either far from forest cover or within already contiguous forest areas. We mapped current connectivity bottlenecks and identified priority areas for future reforestation. We estimate that reforestation of priority areas could improve connectivity by 2% with only a 1% gain in forest cover, an impressive gain given the small area reforested. Results indicate key locations where spatial targeting of PES within the SJLSBC study region would protect existing forest connectivity and enhance the connectivity benefits of reforestation.

Mechanistic insights into landscape genetic structure of two tropical amphibians using field-derived resistance surfaces.

Conversion of forests to agriculture often fragments distributions of forest species and can disrupt gene flow. We examined effects of prevalent land uses on genetic connectivity of two amphibian species in northeastern Costa Rica. We incorporated data from field surveys and experiments to develop resistance surfaces that represent local mechanisms hypothesized to modify dispersal success of amphibians, such as habitat-specific predation and desiccation risk. Because time lags can exist between forest conversion and genetic responses, we evaluated landscape effects using land-cover data from different time periods. Populations of both species were structured at similar spatial scales but exhibited differing responses to landscape features. Litter frog population differentiation was significantly related to landscape resistances estimated from abundance and experiment data. Model support was highest for experiment-derived surfaces that represented responses to microclimate variation. Litter frog genetic variation was best explained by contemporary landscape configuration, indicating rapid population response to land-use change. Poison frog genetic structure was strongly associated with geographic isolation, which explained up to 45% of genetic variation, and long-standing barriers, such as rivers and mountains. However, there was also partial support for abundance- and microclimate response-derived resistances. Differences in species responses to landscape features may be explained by overriding effects of population size on patterns of differentiation for poison frogs, but not litter frogs. In addition, pastures are likely semi-permeable to poison frog gene flow because the species is known to use pastures when remnant vegetation is present, but litter frogs do not. Ongoing reforestation efforts will probably increase connectivity in the region by increasing tree cover and reducing area of pastures.

Season-specific and guild-specific effects of anthropogenic landscape modification on metacommunity structure of tropical bats.

Fragmentation per se due to human land conversion is a landscape-scale phenomenon. Accordingly, assessment of distributional patterns across a suite of potentially connected communities (i.e. metacommunity structure) is an appropriate approach for understanding the effects of landscape modification and complements the plethora of fragmentation studies that have focused on local community structure. To date, metacommunity structure within human-modified landscapes has been assessed with regard to nestedness along species richness gradients. This is problematic because there is little support that species richness gradients are associated with the factors moulding species distributions. More importantly, many alternative patterns are possible, and different patterns may manifest during different seasons and for different guilds because of variation in resource availability and resource requirements of taxa. We determined the best-fit metacommunity structure of a phyllostomid bat assemblage, frugivore ensemble, and gleaning animalivore ensemble within a human-modified landscape in the Caribbean lowlands of Costa Rica during the dry and wet seasons to elucidate important structuring mechanisms. Furthermore, we identified the landscape characteristics associated with the latent gradient underlying metacommunity structure. We discriminated among multiple metacommunity structures by assessing coherence, range turnover, and boundary clumping of an ordinated site-by-species matrix. We identified the landscape characteristics associated with the latent gradient underlying metacommunity structure via hierarchical partitioning. Metacommunity structure was never nested nor structured along a richness gradient. The phyllostomid assemblage and frugivore ensemble exhibited Gleasonian structure (range turnover along a common gradient) during the dry season and Clementsian structure (range turnover and shared boundaries along a common gradient) during the wet season. Distance between forest patches and forest edge density structured the phyllostomid metacommunity during the dry and wet seasons, respectively. Proportion of pasture and forest patch density structured the frugivore metacommunity during the dry season. Gleaning animalivores exhibited chequerboard structure (mutually exclusive species pairs) during the dry season and random structure during the wet season. Metacommunity structure was likely mediated by differential resource use or interspecific relationships. Furthermore, the interaction between landscape characteristics and seasonal variation in resources resulted in season-specific and guild-specific distributional patterns.