Monitoring large herbivore diversity at different scales: comparing direct and indirect methods

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• 作者：Joris P. G. M. Cromsigt ; Susan J. van Rensburg ; Rampal S. Etienne and Han Olff
• 关键词：Direct observational counts ; Dung counts ; Ecological monitoring ; Hluhluwe ; iMfolozi Park ; Mammal diversity estimates ; Savanna ungulates ; Spatial scale
• 刊名：Biodiversity and Conservation
• 出版年：2009
• 出版时间：May, 2009
• 年：2009
• 卷：18
• 期：5
• 页码：1219-1231
• 全文大小：341.4 KB

文摘

Monitoring of large herbivores is central to research and management activities in many protected areas. Monitoring programs were originally developed to estimate (trends in) population sizes of individual species. However, emphasis is shifting increasingly towards conservation of diversity and communities instead of individual species, as a growing literature shows the importance of herbivore diversity for ecosystem functioning. We argue that the design of monitoring programs has not yet been adapted well to this new conservation paradigm. Using large herbivore census data from Hluhluwe-iMfolozi Park, South Africa, we studied how monitoring methodology (observational counts vs. dung counts) and spatial scale interact in influencing estimates of large herbivore species richness and diversity. Dung counts resulted in higher herbivore species richness and diversity estimates than direct observational counts, especially at finer monitoring resolutions (grid cells smaller than 25 km2). At monitoring resolutions coarser than 25 km2 both methods gave comparable diversity estimates. The methods also yielded different spatial diversity estimates, especially at finer resolutions. Grid cells with high diversity according to the dung count data did not necessarily have high diversity according to the observational counts, as shown by low correlation of grid cell values of both methods. We discuss these results in the light of estimates of the sampling effort of each method and, hence, suggest new monitoring designs that are more suitable for tracking temporal and spatial trends in large herbivore diversity and community composition.