The effect of landscape composition, complexity, and heterogeneity on bird richness: a systematic review and meta-analysis on a global scale

Context

Birds, as indicators of biodiversity, are experiencing habitat reduction and loss due to landscape changes. Evidence is mounting that the response of bird richness to landscape patterns remains controversial on a global scale. In this study, we conducted a quantitative global synthesis to gain a comprehensive understanding of this relationship. Our findings contribute to the development of bird conservation strategies that align with the objectives of SDG15.

Objective

Through a quantitative review, this study investigated the effects of landscape patterns on bird richness and analyzed the sources of heterogeneity in the results.

Methods

A random-effects model was utilized to merge the impacts of landscape metrics on bird richness, and a meta-regression analysis was performed to investigate the origins of heterogeneity.

Results

The review encompassed 101 articles from 51 countries worldwide. Field sampling emerged as the primary method for acquiring bird data, with multiple linear regression and generalized linear models as the main analytical approaches. The meta-analysis results highlighted landscape area as a crucial factor influencing bird richness. Regarding landscape composition, the proportions of forests, shrublands, and water bodies positively impacted bird richness, while agricultural land and urban land had negative effects. The relationship between landscape complexity and bird richness is influenced by factors, including net primary productivity (NPP) and precipitation. Landscape heterogeneity was identified as a contributing factor to increased species richness.

Conclusion

Compared to landscape complexity, indicators of landscape composition and heterogeneity are more suitable as reference tools for bird conservation. The results of landscape complexity exhibit variation. Moreover, our findings underscore the crucial role of preserving forested areas in supporting bird diversity, emphasizing the necessity to account for regional variations when establishing forest cover thresholds.