G. Arturo Sánchez-Azofeifa

Bio: G. Arturo Sánchez-Azofeifa is an academic researcher from University of Alberta. The author has contributed to research in topics: Tropical and subtropical dry broadleaf forests & Deforestation. The author has an hindex of 39, co-authored 80 publications receiving 7119 citations. Previous affiliations of G. Arturo Sánchez-Azofeifa include Smithsonian Tropical Research Institute.

Widespread amphibian extinctions from epidemic disease driven by global warming

Abstract: As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with 'very high confidence' (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.

Measuring the effectiveness of protected area networks in reducing deforestation

Abstract: Global efforts to reduce tropical deforestation rely heavily on the establishment of protected areas. Measuring the effectiveness of these areas is difficult because the amount of deforestation that would have occurred in the absence of legal protection cannot be directly observed. Conventional methods of evaluating the effectiveness of protected areas can be biased because protection is not randomly assigned and because protection can induce deforestation spillovers (displacement) to neighboring forests. We demonstrate that estimates of effectiveness can be substantially improved by controlling for biases along dimensions that are observable, measuring spatial spillovers, and testing the sensitivity of estimates to potential hidden biases. We apply matching methods to evaluate the impact on deforestation of Costa Rica's renowned protected-area system between 1960 and 1997. We find that protection reduced deforestation: approximately 10% of the protected forests would have been deforested had they not been protected. Conventional approaches to evaluating conservation impact, which fail to control for observable covariates correlated with both protection and deforestation, substantially overestimate avoided deforestation (by over 65%, based on our estimates). We also find that deforestation spillovers from protected to unprotected forests are negligible. Our conclusions are robust to potential hidden bias, as well as to changes in modeling assumptions. Our results show that, with appropriate empirical methods, conservation scientists and policy makers can better understand the relationships between human and natural systems and can use this to guide their attempts to protect critical ecosystem services.

Countryside biogeography: use of human-dominated habitats by the avifauna of southern costa rica

Abstract: Understanding the multifaceted relationship between biodiversity and land- use intensity is key to conservation policy. To begin to characterize this relationship in a tropical region, we investigated the bird fauna in an agricultural landscape in southern Costa Rica. Landsat Thematic Mapper (TM) data show that about 27% of the land remains forested in the 15 km radius study region encompassing our sites. The rest was cleared about 40 yr ago for relatively small-scale coffee and cattle production, intermixed with other crops. Our goals were to: (1) compare the composition of the avifauna found in forest- fragment and open habitats of the countryside; (2) assess the faunal change that has occurred since deforestation; and (3) provide a baseline for future comparisons. We surveyed the avifauna of eight forest fragments (0.3-25 ha) and 13 open-habitat sites (1.0 ha each) in the agricultural landscape. The pre-deforestation avifauna was ap- proximated by the long-term bird list for the largest forest fragment (Las Cruces, LC; 227 ha) in the study region. We assumed conservatively that a species recorded in LC but not detected elsewhere occurred only in LC. Of the 272 locally extant bird species considered in this study, 149 (55%) occurred in forest habitats only. There was a significant positive correlation between forest fragment size and species richness for these forest birds. Of the remaining 123 species, 60 (22% of the total) occurred both in forest and open habitats. Sixty-three species (23%) occurred in open habitats only; the three nonnative species (1%) are in this group. Based on comparisons with larger forest tracts outside of the study region, it appeared that between 4 and 28 species (1-9% of the possible original totals) have gone locally extinct since deforestation began. The avifauna of open habitats was similar through- out the study region and did not vary with proximity to extensive forest. A substantial proportion of the native bird fauna occurs in a densely (human) populated, agricultural landscape almost a half-century after extensive clearance. There are, however, cautionary messages: (1) the common occurrence of forest birds in human-dominated coun- tryside (including both forest-fragment and open habitats) does not necessarily imply that these species maintain sustainable populations there; (2) about half of the species have little prospect of surviving outside of the forest; and (3) ongoing intensification of land use may greatly reduce avian diversity in countryside habitats. Nonetheless, countryside habitats may buy time for the conservation of some species; at best, they may even sustain a moderate fraction of the native biota.

Costa Rica's Payment for Environmental Services Program: Intention, Implementation, and Impact

Abstract: We evaluated the intention, implementation, and impact of Costa Rica's program of payments for environmental services (PSA), which was established in the late 1990s. Payments are given to private landowners who own land in forest areas in recognition of the ecosystem services their land provides. To characterize the distribution of PSA in Costa Rica, we combined remote sensing with geographic information system databases and then used econometrics to explore the impacts of payments on deforestation. Payments were distributed broadly across ecological and socioeconomic gradients, but the 1997-2000 deforestation rate was not significantly lower in areas that received payments. Other successful Costa Rican conservation policies, including those prior to the PSA program, may explain the current reduction in deforestation rates. The PSA program is a major advance in the global institutionalization of ecosystem investments because few, if any, other countries have such a conservation history and because much can be learned from Costa Rica's experiences.

Research priorities for neotropical dry forests

Abstract: El conocimiento actual de las dimensiones humanas y biof´isicas de los cambios en los bosque secos tropicales y sus efectos acumulativos esta en las etapas iniciales del descubrimiento acad´emico En este articulo, introducimos una serie de art´iculos cient´ificos asociados a este n´umero especial sobre bosques secos en los Neotropicos Estos art´iculos provienen de una distribuci´on muy variada de sitios en las Am´ericas y van desde las aplicaciones de sensores multi- e hiperspectrales, hasta el estudio del efecto que los huracanes causan en la regeneraci´on de los bosques secos Presentamos a la comunidad cient´ifica los resultados de un taller dirigido a la discusi´on de aquellas prioridades de investigaci´on en bosques secos La discusi´on se enfoca a lo largo de los v´inculos que se necesitan entre percepci´on remota, ecolog´ia y ciencias sociales La incorporaci´on las ciencias sociales dentro de la investigaci´on ecol´ogica podr´ia contribuir dram´aticamente al entendimiento de los bosque secos tropicales, as´i como tienen len a posibilidad de ayudar en el desarrollo de v´inculos importantes entre ciencia y pol´itica dirigida al manejo de los recursos presentes en este importante ecosistema

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

Ecological and Evolutionary Responses to Recent Climate Change

Abstract: Ecological changes in the phenology and distribution of plants and animals are occurring in all well-studied marine, freshwater, and terrestrial groups These observed changes are heavily biased in the directions predicted from global warming and have been linked to local or regional climate change through correlations between climate and biological variation, field and laboratory experiments, and physiological research Range-restricted species, particularly polar and mountaintop species, show severe range contractions and have been the first groups in which entire species have gone extinct due to recent climate change Tropical coral reefs and amphibians have been most negatively affected Predator-prey and plant-insect interactions have been disrupted when interacting species have responded differently to warming Evolutionary adaptations to warmer conditions have occurred in the interiors of species’ ranges, and resource use and dispersal have evolved rapidly at expanding range margins Observed genetic shifts modulate local effects of climate change, but there is little evidence that they will mitigate negative effects at the species level

Rapid Range Shifts of Species Associated with High Levels of Climate Warming

Abstract: The distributions of many terrestrial organisms are currently shifting in latitude or elevation in response to changing climate Using a meta-analysis, we estimated that the distributions of species have recently shifted to higher elevations at a median rate of 110 meters per decade, and to higher latitudes at a median rate of 169 kilometers per decade These rates are approximately two and three times faster than previously reported The distances moved by species are greatest in studies showing the highest levels of warming, with average latitudinal shifts being generally sufficient to track temperature changes However, individual species vary greatly in their rates of change, suggesting that the range shift of each species depends on multiple internal species traits and external drivers of change Rapid average shifts derive from a wide diversity of responses by individual species

Impacts of climate warming on terrestrial ectotherms across latitude.

Abstract: The impact of anthropogenic climate change on terrestrial organisms is often predicted to increase with latitude, in parallel with the rate of warming. Yet the biological impact of rising temperatures also depends on the physiological sensitivity of organisms to temperature change. We integrate empirical fitness curves describing the thermal tolerance of terrestrial insects from around the world with the projected geographic distribution of climate change for the next century to estimate the direct impact of warming on insect fitness across latitude. The results show that warming in the tropics, although relatively small in magnitude, is likely to have the most deleterious consequences because tropical insects are relatively sensitive to temperature change and are currently living very close to their optimal temperature. In contrast, species at higher latitudes have broader thermal tolerance and are living in climates that are currently cooler than their physiological optima, so that warming may even enhance their fitness. Available thermal tolerance data for several vertebrate taxa exhibit similar patterns, suggesting that these results are general for terrestrial ectotherms. Our analyses imply that, in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest.