In tropical regions where forests have been replaced by agriculture, the future of biodiversity is increasingly dependent on the presence of remnant forest patches and on-farm tree cover within agricultural landscapes. While there is growing evidence of the importance of tree cover within agricultural landscapes, most studies have been conducted in a single landscape, making it difficult to ascertain whether the conservation value of different types of tree cover can be generalized across landscapes. To explore whether use of different forms of tree cover by birds is consistent across landscapes, we compared the number of individuals, species richness, and diversity of birds associated with different forms of tree cover in four agricultural landscapes in Central America, using a standardized methodology and sampling effort. In each landscape, we compared bird assemblages in six tree cover types (secondary forests, riparian forests, forest fallows, live fences, pastures with high tree cover, and pastures with low tree cover). We observed a total of 10 723 birds of 283 species, with 83-196 species per landscape. The specific patterns of bird species richness, number of individuals, and diversity associated with tree cover types varied across the four landscapes, but these variables were consistently higher in the forest forms of tree cover (riparian forests, secondary forests, and forest fallows) than in non-forest habitats. In addition, forest forms of tree cover had distinct species composition from non-forest forms in all landscapes. There was also consistency in the use of different types of tree cover by forest birds across the four landscapes, with higher richness and number of individuals of forest birds in forested than non-forested forms of tree cover, and more forest bird species in pastures with high tree cover than in pastures with low tree cover. Our findings indicate that riparian and secondary forests are consistently of higher value for bird conservation (particularly for forest species) than live fences and pastures with tree cover. Consequently, agricultural and land use policies that promote the retention of secondary and riparian forests and increase tree cover within pastures would greatly benefit bird conservation, regardless of the landscape in which they are applied.

Introducción. En Centroamérica, los pequeños caficultores están amenazados por el aumento en las temperaturas y los cambios en los patrones de lluvia. Una estrategia para apoyar a las comunidades de pequeños agricultores a adaptarse al cambio climático es el uso de prácticas de Adaptación basada en Ecosistemas (AbE), las cuales integran la conservación, restauración y manejo sostenible de ecosistemas y biodiversidad. Sin embargo, existe poca información de cómo los productores utilizan estas prácticas. Objetivo. El objetivo de este estudio fue describir el uso de once prácticas de AbE entre pequeños agricultores de café, de cinco paisajes ubicados en Costa Rica, Honduras y Guatemala, así como comparar las características biofísicas y frecuencia de uso de las mismas entre paisajes. Materiales y métodos. La caracterización de las prácticas de AbE se realizó utilizando mapeo participativo, entrevistas, y mediciones de área y estructura y composición de la vegetación, entre julio 2014 y junio 2015. La comparación entre paisajes se realizó mediante un análisis de varianza. Resultados. Los resultados indican que muchos pequeños agricultores de café están implementando activamente el uso de prácticas AbE, entre ellas el uso de árboles de sombra en cafetales, los surcos en contorno, los huertos caseros y las cercas vivas. Sin embargo, existieron diferencias importantes entre paisajes en cuanto al uso y las características de AbE implementadas. Conclusión. Estas diferencias sugieren que los productores adaptan el uso de dichas prácticas en respuesta a los contextos sociales y biofísicos del medio en donde viven, y que existe valor en hacer intercambio de productores de diferentes regiones para compartir su conocimiento sobre estas prácticas.

Stand dynamic rates in Earth's vitally important tropical mountain rain forests are a central component of the response of these forests to global change, but their relationships to environmental gradients are poorly understood. We worked in mature forests on a 440-2810 m asl altitudinal gradient on Costa Rica's Talamanca Cordillera, making five censuses of 29 0.25-ha permanent sample plots during 2012-2019. We determined mortality and recruitment rates, as well as basal area (G) increments, for individuals ≥10 cm diameter at breast height. Our main hypothesis was that stand dynamic rates decrease with altitude (therefore temperature); we also tested the hypotheses that rates increase with plot community-weighted mean specific leaf area (CWM SLA) and decrease with CWM wood specific gravity (WSG). We developed regressions using generalized additive models to test our hypotheses. Mortality and recruitment rates decreased with altitude in line with our main hypothesis, though the strongly non-linear mortality trend may be driven by extreme weather and temperature. Also, the best model for recruitment rates included plot CWM SLA with a negative relationship. Gross basal area increment ΔG gross , the annual basal area increment of trees that survived the study period, had a hump-shaped relationship to altitude, possibly related to the low CWM WSG of mid-altitude forests. ΔG gross was indeed negatively related to CWM WSG. However, net basal area growth (ΔG net , the annualized difference between initial and final plot basal areas) was positively related to altitude due to low mortality in montane forests, in a model with CWM WSG with a negative relationship. ΔG net was negative in nine of the 29 plots at <1500 m asl. Patterns of rain forest stand dynamics on this long altitudinal gradient go beyond a direct response to temperature, and further work is required to improve scenarios of forest response to climate change. CWM traits should be measured to improve understanding. The effects of storms and lightning on low-and middle-altitude forest and the potentially high resilience of montane Fagaceae-dominated forests require attention. Diversity, not generality, should be expected on comparing tropical forest altitudinal transects.