Multi-taxa ecological responses to habitat loss and fragmentation in western Amazonia as revealed by RAPELD biodiversity surveys

Jennifer Guevara,Marina Rodes-Blanco,Karima G López,Nereida Guerra-Arévalo,Pablo Meneses,Emmanuel Ambriz,H Mauricio Ortega-Andrade,Gabriel M Moulatlet

doi:10.1590/1809-4392202004532

Jennifer Guevara, Marina Rodes-Blanco + Show 6 more

Open Access

https://doi.org/10.1590/1809-4392202004532

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Abstract

ABSTRACT Habitat loss and fragmentation caused by deforestation are important anthropogenic drivers of changes in biodiversity in the Amazon rainforest, and has reached its highest rate in recent decades. However, the magnitude and direction of the effects on species composition and distribution have yet to be fully understood. We evaluated the responses of four taxonomic groups − birds, amphibians, orchid bees, and dung beetles - to habitat loss and fragmentation at both species and assemblage level in the northern Ecuadorian Amazon. We sampled fifteen 250-m long plots in terra-firme forest remnants. We calculated one landscape fragmentation index (fragindex), which considers the proportion of continuous forest cover, edge density and isolation in the landscape, and nine landscape configuration metrics. Logistic regression models and multivariate regression trees were used to analyze species and assemblage responses. Our results revealed that over 80% of birds, amphibians or orchid-bee species, and 60% of dung beetles were negatively affected by habitat loss and fragmentation. Species composition of all taxonomic groups was significantly affected by differences in forest cover and connectivity. Less than 5% of all species were restricted to landscapes with fragindex values higher than 40%. Landscape metrics related to the shape and area of forest patches determined the magnitude and direction of the effect on species responses. Therefore, changes in the landscape configuration of Ecuadorian Amazonia should be minimized to diminish the effects of habitat loss and fragmentation on species occurrence and assemblage composition.

Highlights

Between 2000 and 2012, more than 250,000 km2 of South American tropical forests were replaced by agriculture, cattle pastures and affected by other economic activities like mining and oil exploitation (Lewis et al 2015; Hansen et al 2020)
We examined the occurrence of four taxonomic groups in 15 plots in a fragmented landscape in the northern Ecuadorian lowland Amazonia
Our results revealed that over 80% of birds, amphibians, or orchid bee species were negatively affected by habitat loss and fragmentation, with a lower proportion for dung beetles (60%)

Summary

Introduction

Between 2000 and 2012, more than 250,000 km of South American tropical forests were replaced by agriculture, cattle pastures and affected by other economic activities like mining and oil exploitation (Lewis et al 2015; Hansen et al 2020). Most land transformation occurs in privately-owned lands, which are more vulnerable to transformations and degradation (Laurance et al 2002, 2009; Zimbres et al 2018). In the western portion of the Amazon basin in Ecuador, deforestation is the main driver of habitat loss and fragmentation, mainly for cattle pasture and silviculture (Bonilla-Bedoya et al 2014). Between 2010 and 2015, 2% of the total deforestation in the Amazon basin occurred in Ecuador, with an accumulated deforestation of 12,120 km (Borja et al 2017)

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