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Dryad

Spatial variation in human disturbances and their effects on forest structure and biodiversity across an Afromontane forest

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Apr 04, 2022 version files 78.89 KB

Abstract

Context

Human disturbances can have large impacts on forest structure and biodiversity, and thereby result in forest degradation, a property difficult to detect by remote sensing.

Objectives

To investigate spatial variation in anthropogenicdisturbances and their effects on forest structure and biodiversity.

Methods

In 144 plots of 20 x 20 m distributed across a forest area of 750 km2 in Southwest Ethiopia, we recorded: landscape variables (e.g., distance to forest edge), different human disturbances, forest structure variables, and species composition of trees and epiphyllous bryophytes. We then first assessed if landscape variables could explain the spatial distribution of disturbances. Second, we analysed how forest structure and biodiversity were influenced by disturbances.

Results

Human disturbances, such as coffee management and grazing declined with distance to forest edges and penetrated at least a kilometer into the forest. The slope was not related to disturbance levels, but several types of disturbances were less common at higher elevations. Among human disturbance types, coffee management reduced liana cover and was associated with altered species composition of trees. The presence of large trees and basal areas was not related to any of the disturbance gradients.

Conclusions

Although most anthropogenic disturbances displayed clear edge effects, surprisingly the variation in the chosen forest degradation indices was only weakly related to these disturbances. We suggest that the intersection between edge effects and forest degradation is very context-specific and relies much on how particular societies use the forests. For example, in this landscape coffee management seems to be a key driver.