Hugo Romero-Saltos

Extinction rates in the Anthropocene are three orders of magnitude higher than background and disproportionately occur in the tropics, home of half the world's species. Despite global efforts to combat tropical species extinctions, lack of high-quality, objective information on tropical biodiversity has hampered quantitative evaluation of conservation strategies. In particular, the scarcity of population-level monitoring in tropical forests has stymied assessment of biodiversity outcomes, such as the status and trends of animal populations in protected areas. Here, we evaluate occupancy trends for 511 populations of terrestrial mammals and birds, representing 244 species from 15 tropical forest protected areas on three continents. For the first time to our knowledge, we use annual surveys from tropical forests worldwide that employ a standardized camera trapping protocol, and we compute data analytics that correct for imperfect detection. We found that occupancy declined in 22%, increased in 17%, and exhibited no change in 22% of populations during the last 3-8 years, while 39% of populations were detected too infrequently to assess occupancy changes. Despite extensive variability in occupancy trends, these 15 tropical protected areas have not exhibited systematic declines in biodiversity (i.e., occupancy, richness, or evenness) at the community level. Our results differ from reports of widespread biodiversity declines based on aggregated secondary data and expert opinion and suggest less extreme deterioration in tropical forest protected areas. We simultaneously fill an important conservation data gap and demonstrate the value of large-scale monitoring infrastructure and powerful analytics, which can be scaled to incorporate additional sites, ecosystems, and monitoring methods. In an era of catastrophic biodiversity loss, robust indicators produced from standardized monitoring infrastructure are critical to accurately assess population outcomes and identify conservation strategies that can avert biodiversity collapse.

Dry periods caused by El Niño phenomena may last longer in eastern Amazonian forests as a result of global climate change. Among the various responses of the forest to these expected droughts, the functionality of roots and soil water movement are not yet well understood. I used the experimental setup of the Tapajós Throughfall Exclusion Experiment (TTEE) —a large-scale experiment in Pará, Brazil, that simulates an extended drought— to study the effect of rainfall (throughfall) exclusion on the seasonal movement of soil moisture and the seasonal changes in depth of water uptake by three locally abundant species of trees: Coussarea racemosa A.Rich., Sclerolobium chrysophyllum Poepp., and Eschweilera pedicellata (Rich.) S.A.Mori. The TTEE started in January 2000 and consists of two 1-ha plots: treatment and control. The soil of the treatment plot is covered by plastic panels during the wet season. Deuterium-enriched water was sprinkled in both plots around different individuals of eac...

Resumen En el presente documento se despliega información referente a la presencia, estructura y dinámica de los agrosistemas del Distrito Metropolitano de Quito (DMQ) y su evolución en las últimas décadas; algunos de los cambios correspondientes a esta evolución pudieran estar ocurriendo como respuesta tanto al crecimiento demográfico local como a circunstancias asociadas al cambio climático global (CC). Los efectos que el CC pudieran estar generando en este sector socio-económico son ciertamente graduales y se encuentran sujetos a cierto grado de incertidumbre, debido a que la variabilidad climática (a corto plazo) y el mismo cambio climático (a mediano plazo) también lo tienen. Es así como pudieran estar ocurriendo cambios directos (debido a desórdenes de los patrones de precipitación anual, por ejemplo), pero también podrían ocurrir cambios indirectos en el sector agrario asociados con la productividad, solo visibles a lo largo de varios años consecutivos de observación. Desafor...

The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of…

ABSTRACT This chapter examines the pantropical patterns of liana abundance and species diversity and their correlates with climatic characteristics to gain insight into which processes are important for the distribution of tropical lianas. The analyses follow from the standard sampling protocol of liana diversity and abundance used by Alwyn Gentry in the 1980s and 1990s. The chapter examines how climatic conditions are associated with liana density and diversity, by analyzing old-growth continental forests at <1050m in elevation and with mean annual precipitation >850mm yr-1.To broaden the discussion of determinants of liana density and diversity beyond climatic factors, the authors comment on differences between temperate and tropical forests and between continental and island regions. The chapter focuses on sites in the Global Liana Database (GLD) from temperate forests in Australia, subtropical forest in Argentina, and an island in the Caribbean, and also reviews the available literature.

We test the hypotheses proposed by Gentry and Schnitzer that liana density and basal area in tropical forests vary negatively with mean annual precipitation (MAP) and positively with seasonality. Previous studies correlating liana abundance with these climatic variables have produced conflicting results, warranting a new analysis of drivers of liana abundance based on a different dataset. We compiled a pan-tropical dataset containing 28,953 lianas (≥2.5 cm diam.) from studies conducted at 13 Neotropical and 11 Paleotropical dry to wet lowland tropical forests. The ranges in MAP and dry season length (DSL) (number of months with mean rainfall <100 mm) represented by these datasets were 860–7250 mm/yr and 0–7 mo, respectively. Pan-tropically, liana density and basal area decreased significantly with increasing annual rainfall and increased with increasing DSL, supporting the hypotheses of Gentry and Schnitzer. Our results suggest that much of the variation in liana density and basal area in the tropics can be accounted for by the relatively simple metrics of MAP and DSL.En este estudio evaluamos las hipótesis de Gentry (1991) y Schnitzer (2005) que establecen que la densidad y el área basal de lianas en bosques tropicales varían negativamente con la precipitación promedio anual y positivamente con la estacionalidad. Estudios previos que correlacionan la abundancia de lianas con estas variables climáticas han encontrado resultados contradictorios, lo cual justifica un nuevo análisis de los factores que controlan la abundancia de lianas utilizando una base de datos diferente. Compilamos una base pantropical de datos que contiene 28.953 lianas (diámetro 2,5 cm) de estudios conducidos en 13 bosques neotropicales y 11 bosques paleotropicales, incluyendo bosques secos y húmedos. Los rangos de precipitación promedio anual y duración de la estación seca (número de meses con precipitación promedio < 100 mm) de los diferentes estudios fueron 860–7250 mm/yr y 0–7 meses, respectivamente. Pantropicalmente, la densidad y área basal de las lianas disminuye significativamente a medida que la precipitación anual aumenta, y aumenta a medida que la duración de la estación seca aumenta, apoyando las hipótesis de Gentry (1991) y Schnitzer (2005). Nuestros resultados sugieren que mucha de la variación en densidad y área basal de lianas en los trópicos puede ser explicada por las relativamente simples medidas de precipitación promedio anual y duración de la estación seca.