Publication
The effect of natural disturbances on forest biodiversity: an ecological synthesis
Publisher:
Wiley
Date:
08-07-2022
DOI:
10.1111/BRV.12876
Abstract: Disturbances alter bio ersity via their specific characteristics, including severity and extent in the landscape, which act at different temporal and spatial scales. Bio ersity response to disturbance also depends on the community characteristics and habitat requirements of species. Untangling the mechanistic interplay of these factors has guided disturbance ecology for decades, generating mixed scientific evidence of bio ersity responses to disturbance. Understanding the impact of natural disturbances on bio ersity is increasingly important due to human‐induced changes in natural disturbance regimes. In many areas, major natural forest disturbances, such as wildfires, windstorms, and insect outbreaks, are becoming more frequent, intense, severe, and widespread due to climate change and land‐use change. Conversely, the suppression of natural disturbances threatens disturbance‐dependent biota. Using a meta‐analytic approach, we analysed a global data set (with most s ling concentrated in temperate and boreal secondary forests) of species assemblages of 26 taxonomic groups, including plants, animals, and fungi collected from forests affected by wildfires, windstorms, and insect outbreaks. The overall effect of natural disturbances on α‐ ersity did not differ significantly from zero, but some taxonomic groups responded positively to disturbance, while others tended to respond negatively. Disturbance was beneficial for taxonomic groups preferring conditions associated with open canopies (e.g. hymenopterans and hoverflies), whereas ground‐dwelling groups and/or groups typically associated with shady conditions (e.g. epigeic lichens and mycorrhizal fungi) were more likely to be negatively impacted by disturbance. Across all taxonomic groups, the highest α‐ ersity in disturbed forest patches occurred under moderate disturbance severity, i.e. with approximately 55% of trees killed by disturbance. We further extended our meta‐analysis by applying a unified ersity concept based on Hill numbers to estimate α‐ ersity changes in different taxonomic groups across a gradient of disturbance severity measured at the stand scale and incorporating other disturbance features. We found that disturbance severity negatively affected ersity for Hill number q = 0 but not for q = 1 and q = 2, indicating that ersity–disturbance relationships are shaped by species relative abundances. Our synthesis of α‐ ersity was extended by a synthesis of disturbance‐induced change in species assemblages, and revealed that disturbance changes the β‐ ersity of multiple taxonomic groups, including some groups that were not affected at the α‐ ersity level (birds and woody plants). Finally, we used mixed rarefaction/extrapolation to estimate bio ersity change as a function of the proportion of forests that were disturbed, i.e. the disturbance extent measured at the landscape scale. The comparison of intact and naturally disturbed forests revealed that both types of forests provide habitat for unique species assemblages, whereas species ersity in the mixture of disturbed and undisturbed forests peaked at intermediate values of disturbance extent in the simulated landscape. Hence, the relationship between α‐ ersity and disturbance severity in disturbed forest stands was strikingly similar to the relationship between species richness and disturbance extent in a landscape consisting of both disturbed and undisturbed forest habitats. This result suggests that both moderate disturbance severity and moderate disturbance extent support the highest levels of bio ersity in contemporary forest landscapes.