Soil and Geographic Distance as Determinants of Floristic Composition in the Azuero Peninsula (Panama)

Abstract

Many studies analyzing the relative contribution of soil properties versus distance-related processes on plant species composition have focused on lowland tropical forests. Very few have investigated two forest types simultaneously, to contrast ecological processes that assemble the communities. This study analyses-at the landscape scale-the relative contribution of soil and distance on lowland and submontane tropical forests, which co-occur in two reserves of the Azuero peninsula (Panama). Floristic inventories and soil sampling were conducted in 81 0.1-ha plots clustered in 27 sites, and data were analyzed using Mantel tests, variance partitioning and non-metric multidimensional scaling. The largest differences in floristic composition occurred between reserves in both forest types. Soil variation and geographic distance were important determinants of floristic composition, but their effects were highly correlated; together they explained 7-25 percent and 46-50 percent of the variation in lowland and submontane forests, respectively. Soil variables that had the best correlations with floristic composition were iron, zinc, and silt content in lowland, and calcium, copper, iron, potassium, magnesium, phosphorus, zinc, and sand content in submontane forests. The studied forests showed a high beta diversity that seems to be related primarily with soils and, secondarily, with dispersal limitation and stochastic events. The results reveal a response of tree assemblages to environmental gradients, which are particularly conspicuous in Panama. The effects of limited dispersal seem to be more important in submontane than in lowland forests, probably as a result of higher isolation.Abstract in Spanish is available in the online version of this article.

The role of recruitment and dispersal limitation in tree community assembly in Amazonian forests

“…Numerous studies have attempted to disentangle the respective roles of dispersal limitation and environmental filtering in the assembly of tropical plant communities (Tuomisto et al 2003;Jirka et al 2007;Damasco et al 2012;Garibaldi et al 2014). Most of them have used various types of variation partitioning techniques.…”

Correlates of plant β-diversity in Atlantic Forest patches in the Pernambuco Endemism Centre, Northeastern Brazil

“…Indeed, a lack of potenseed dispersers could enhance the turnover between more distant sites, although in our study site there is still a large number of birds and terrestrial mammals which may be able to carry seeds between the forest patches (Lobo-Araújo et al 2013;Mendes Pontes et al 2016;Pereira et al 2016;Campos et al 2018;Garbino et al 2018). The effect of geographical distance on species turnover is also explained by the fact that distant areas will likely have more contrasting environmental (e.g., soil, climate, topography) and anthropogenic (e.g., different disturbance regimes) contexts which will affect floristic composition (Pyke et al 2001;Arroyo-Rodríguez et al 2013;Garibaldi et al 2014).…”

Relación entre la composición florística y los nutrientes del suelo en comunidades de palmas del Chocó biogeográfico en Colombia y Ecuador

“…Nuestros resultados apoyan la hipótesis general de que la composición florística de los bosques tropicales está relacionada con los nutrientes del suelo. Si bien esto se ha demostrado en bosques amazónicos y en Panamá (Poulsen et al, 2006;Kristiansen et al, 2012;Garibaldi, Nieto-Ariza, Macía, & Cayuela, 2014;Tuomisto et al, 2014;Stevenson et al, 2018;Muscarella et al, 2018), nuestro estudio es el primero en resaltar que, en las tierras bajas del Chocó, la composición de las comunidades de palmas está relacionada con los nutrientes: los suelos con concentraciones bajas en bases intercambiables son más ricos en especies.…”

“…Nuestros resultados son consistentes con los de Garibaldi et al (2014) quienes, en la Península Azuero de Panamá, encontraron que la fertilidad y el P presentan una alta correlación con la composición florística.…”