Disturbance, Diversity, and Invasion: Implications for Conservation

TLDR

Disturbance shapes ecosystem structure and species diversity, with the intermediate disturbance hypothesis predicting peak diversity at moderate levels, yet disturbance also increases invasibility and its effects are amplified by regime modifications and interactions, especially as natural regimes are altered by fragmentation and human activity. The authors aim to review how disturbances such as fire, grazing, soil disturbance, and nutrient addition influence plant species diversity and invasion in grassland ecosystems to inform conservation management. They conduct a literature review of disturbance impacts on grassland vegetation, synthesizing evidence on fire, grazing, soil disturbance, and nutrient addition.

Abstract

Disturbance is an important component of many ecosystems, and variations in disturbance regime can affect ecosystem and community structure and functioning. The “intermediate disturbance hypothesis” suggests that species diversity should be highest at moderate levels of disturbance. However, disturbance is also known to increase the invasibility of communities. Disturbance therefore poses an important problem for conservation management, Here, we review the effects of disturbances such as fire grazing, soil disturbance and nutrient addition on plant species diversity and invasion with particular emphasis on grassland vegetation. Individual components of the disturbance regime can have marked effects on species diversity, but it is often modifications of the existing regime that have the largest influence. Similarly, disturbance can enhance invasion of natural communities, but frequently it is the interaction between different disturbances that has the largest effect. The natural disturbance regime is now unlikely to persist within conservation areas since fragmentation and human intervention have usually modified physical and biotic conditions. Active management decisions must now be made on what disturbance regime is required and this requires decisions on what species are to be encouraged or discouraged.