Seeing the wood despite the trees: Exploring human disturbance impact on plant diversity, community structure, and standing biomass in fragmented high Andean forests

Abstract

High Andean forests harbor a remarkably high biodiversity and play a key role in providing vital ecosystem services for neighboring cities and settlements. However, they are among the most fragmented and threatened ecosystems in the neotropics. To preserve their unique biodiversity, a deeper understanding of the effects of anthropogenic perturbations on them is urgently needed. Here, we characterized the plant communities of high Andean forest remnants in the hinterland of Bogotá in 32 0.04 ha plots. We assessed the woody vegetation and sampled the understory and epiphytic cover. We gathered data on compositional and structural parameters and compiled a broad array of variables related to anthropogenic disturbance, ranging from local to landscape‐wide metrics. We also assessed phylogenetic diversity and functional diversity. We employed nonmetric multidimensional scaling (NMDS) to select meaningful variables in a first step of the analysis. Then, we performed partial redundancy analysis (pRDA) and generalized linear models (GLMs) in order to test how selected environmental and anthropogenic variables are affecting the composition, diversity, and aboveground biomass of these forests. Identified woody vegetation and understory layer communities were characterized by differences in elevation, temperature, and relative humidity, but were also related to different levels of human influence. We found that the increase of human‐related disturbance resulted in less phylogenetic diversity and in the phylogenetic clustering of the woody vegetation and in lower aboveground biomass (AGB) values. As to the understory, disturbance was associated with a higher diversity, jointly with a higher phylogenetic dispersion. The most relevant disturbance predictors identified here were as follows: edge effect, proximity of cattle, minimum fragment age, and median patch size. Interestingly, AGB was efficiently predicted by the proportion of late successional species. We therefore recommend the use of AGB and abundance of late successional species as indicators of human disturbance on high Andean forests.

Reconstructing Long Term High Andean Forest Dynamics Using Historical Aerial Imagery: A Case Study in Colombia

“…Six of the study localities are situated in an arc north of the city in the department of Cundinamarca (Tabio, Soacha, San Francisco, El Rosal, Guasca, and Guatavita) and three are located within the capital district Bogotá D.C. (Torca, Pasquilla, and Sumapaz). These localities were selected because they match a network of permanent plots that was established as a basis for various botanical and ecological studies between 2013 and 2019 [39][40][41]44]. The high Andean forests close to Bogotá reach a modest height (15-25 m) and are typically dominated by trees and tall shrubs of the genera Weinmannia, Miconia, Cavendisha, Myrsine, Myrcianthes, Xylosma, and Daphnopsis [38,41,44,56].…”

“…These localities were selected because they match a network of permanent plots that was established as a basis for various botanical and ecological studies between 2013 and 2019 [39][40][41]44]. The high Andean forests close to Bogotá reach a modest height (15-25 m) and are typically dominated by trees and tall shrubs of the genera Weinmannia, Miconia, Cavendisha, Myrsine, Myrcianthes, Xylosma, and Daphnopsis [38,41,44,56]. Around the city, the forest remnants appear as scattered and fragmented patches.…”

“…Detailed information related to the study localities is presented in Supplementary Table S1. information on the permanency of forest fragments, as well as the clear identification of regrown forest patches with corresponding age estimates (secondary succession) and their spatial configuration through time [44]. This study aims to investigate long-term changes in the extension and structure of high Andean forests by gathering detailed information on landscape history and patterns of landscape change through several decades.…”

“…The forests in the Eastern Andean Cordillera of Colombia experienced substantial human-induced modifications throughout the last centuries, leading to a drastic reduction of their extension [30,33]. The resultant urban-rural forest mosaic has been extensively studied with regard to species composition [34][35][36][37][38] and more recently, regarding the regeneration stadia of forest fragments [39][40][41], human impact on vegetation, and the provisioning of ecosystem services [42][43][44].…”

“…A better understanding of the main drivers of forest loss or recovery requires the precise monitoring of changes in forest cover at a small geographical scale. Recent studies on vegetation composition, structure, and the anthropogenic impact on biodiversity and biomass underpins the need for precise information on the permanency of forest fragments, as well as the clear identification of regrown forest patches with corresponding age estimates (secondary succession) and their spatial configuration through time [44].…”