Climate severity and land‐cover transformation determine plant community attributes in Colombian dry forests

Abstract

Tropical dry forests (TDF) are known to be resource‐limited due to a marked seasonality in precipitation. However, TDF are also shaped by factors such as solar radiation, wind speed, soil fertility, and land‐cover transformation. Together, these factors may determine different gradients of environmental harshness that are likely to drive changes in plant community attributes. Here, we evaluated the effects of environmental harshness on plant community diversity and structure of Colombian TDF, based on floristic and environmental data from 15 1‐ha permanent plots. We also analyzed these effects on legumes species only (including both deciduous and non‐deciduous species), deciduous species only (including both legumes and non‐legumes species), and on the whole community excluding either legumes or deciduous separately. Drier conditions and higher land‐cover transformation had the strongest negative effects on species diversity, basal area (BA), and canopy height. Soil fertility, on the contrary, did not have a significant effect on any of the evaluated response variables. Interestingly, legumes maintained their diversity and BA along the climatic gradient, while deciduous species were negatively affected by drier conditions and by an increase in secondary vegetation at the landscape level. Our results suggest that although TDF are limited by water availability, land‐cover transformation strongly increases environmental harshness. Yet, both legumes and deciduous species were differentially impacted by climatic and land transformation variables. Thus, to better understand TDF plant community attributes, it is necessary to consider these gradients and to disentangle their effects on different plant functional groups. Abstract in Spanish is available with online material.

Biogeographic regionalization by spatial and environmental components: Numerical proposal

“…Some studies have shown that precipitation and soil properties affect current patterns of species diversity in the tropical dry forest (e.g., [35,70,71]); in this sense, our results also indicate that precipitation seasonality is the most important variable for explaining species…”

“…Some studies have shown that precipitation and soil properties affect current patterns of species diversity in the tropical dry forest (e.g., [ 35 , 70 , 71 ]); in this sense, our results also indicate that precipitation seasonality is the most important variable for explaining species richness in the SDTF. Therefore, the highest Asteraceae richness values concentrate in relatively high and stable humidity conditions, such as those found in the Upper Balsas district.…”

Limited evidence of coupling between above and belowground functional traits in tropical dry forest seedlings

“…Tropical dry forest is an ideal model for understanding how tree species cope with drought. First, it presents a strong dry season where soil water deficit limits tree species' growth and establishment (Murphy & Lugo, 1986;González-M et al, 2019). Second, strategies to cope with water deficit have been wellstudied in adult individuals, but it is unclear whether these strategies are fully developed from the seedling ontogenetic stage.…”

“…Second, strategies to cope with water deficit have been wellstudied in adult individuals, but it is unclear whether these strategies are fully developed from the seedling ontogenetic stage. And third, high fragmentation rates in this ecosystem can amplify the climatic severity due to the edge effects with effects on its structure and diversity (González-M et al, 2019). Understanding the functional mechanisms that determine seedling establishment will strengthen our ability to predict and understand these forests' future under climate change scenarios in which greater seasonality and reductions in rainfall are expected (Dai, 2013;Feng et al, 2013).…”

Building a socio‐ecological monitoring platform for the comprehensive management of tropical dry forests

“…This information has shown that species diversity, forest basal area, and canopy height decrease as drought and landscape transformation increase (González‐M. et al., 2019). Data have also provided insights on patterns of TDF tree species' abundance and spatial distribution, showing that almost half of the species recorded in permanent plots are extremely rare and as much as 80% exhibit a restricted distribution (Norden et al, 2019).…”