Moderate land use shifts plant diversity from overstory to understory and contributes to biotic homogenization in a seasonally dry tropical ecosystem

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• 作者：Lisa Mandle ; ^{lisa.mandle@gmail.com} ; Tamara Ticktin ^{ticktin@hawaii.edu}
• 关键词：Savanna woodland ; Western Ghats ; Non-timber forest product (NTFP) ; Livestock grazing ; Ground fire ; Plant diversity
• 刊名：Biological Conservation
• 出版年：2013
• 出版时间：February, 2013
• 年：2013
• 卷：158
• 期：Complete
• 页码：326-333
• 全文大小：450 K

文摘

Most of the world¡¯s remaining terrestrial biodiversity exists in tropical ecosystems affected by human activities. Despite the threats to seasonally dry tropical ecosystems, little is known about the impact of human land use change on their conservation value. We used savanna woodlands within the Western Ghats biodiversity hotspot as a case study to understand the effects of human land use on plant diversity. We investigated the effects of three common land-use activities - biomass extraction, livestock grazing and ground fire - on species richness and diversity, as well as species composition in terms of the breadth of geographic ranges of species present. We found that total species richness increased with livestock grazing due to increased understory richness. Overstory diversity and tree sapling diversity and richness decreased with more recent fire. Greater canopy openness was associated with increased understory richness and reduced overstory richness. The combination of fire and livestock grazing are likely to increase canopy openness, leading to a shift in diversity from the overstory to the understory. Although we found no change in species richness or diversity with biomass extraction, areas with biomass extraction had more widely distributed species and fewer narrowly distributed species, indicating land use may lead to biotic homogenization. Our results suggest that a mosaic of protected areas along with areas managed for biomass extraction and livestock grazing would be an effective way to balance the conservation of plant diversity with local communities¡¯ needs while maintaining overall levels of plant species diversity in these savanna woodlands.