Woodrow Wilson School, Princeton University, Princeton, NJ, 08544, U.S.A.
Wildlife Institute of India, Dehradun, Uttarakhand, 248001, India.
Conserv Biol. 2018 Dec;32(6):1313-1324. doi: 10.1111/cobi.13145. Epub 2018 Sep 6.
The Himalayas are a global biodiversity hotspot threatened by widespread agriculture and pasture expansion. To determine the impact of these threats on biodiversity and to formulate appropriate conservation strategies, we surveyed birds along elevational gradients in primary forest and in human-dominated lands spanning a gradient of habitat alteration, including forest-agriculture mosaics, mixed agriculture mosaics, and pasture. We surveyed birds during the breeding season and in winter to account for pronounced seasonal migrations. Bird abundance and richness in forest-agriculture and mixed agriculture mosaics were equal to or greater than in primary forest and greater than in pasture at local and landscape scales during both seasons. Pasture had greater abundance and richness of birds in winter than primary forest, but richness was greater in primary forest at the landscape scale during the breeding season. All 4 land-use types held unique species, suggesting that all must be retained in the landscape to conserve the entire avifauna. Our results suggest forest-agriculture and mixed agriculture mosaics are particularly important for sustaining Himalayan bird communities during winter and primary forests are vital for sustaining Himalayan bird communities during the breeding season. Further conversion of forest-agriculture and mixed agriculture mosaics to pasture would likely result in significant biodiversity losses that would disproportionately affect breeding species. To ensure comprehensive conservation, strategies in the western Himalayas must balance the protection of intact primary forest with the minimization of pasture expansion.
喜马拉雅山脉是一个受到广泛农业和牧场扩张威胁的全球生物多样性热点地区。为了确定这些威胁对生物多样性的影响，并制定适当的保护策略，我们沿着海拔梯度对主要森林和受人类主导的土地中的鸟类进行了调查，这些土地包括森林-农业镶嵌体、混合农业镶嵌体和牧场，涵盖了一系列生境变化梯度。我们在繁殖季节和冬季调查了鸟类，以考虑到明显的季节性迁徙。在繁殖季节和冬季，无论是在局部还是景观尺度上，森林-农业和混合农业镶嵌体中的鸟类丰富度和数量都与主要森林相当或更高，且高于牧场。在冬季，牧场的鸟类数量和丰富度大于主要森林，但在繁殖季节的景观尺度上，主要森林的鸟类丰富度更高。所有 4 种土地利用类型都拥有独特的物种，这表明为了保护整个鸟类群，所有类型都必须在景观中保留。我们的研究结果表明，森林-农业和混合农业镶嵌体在维持喜马拉雅山鸟类群落冬季方面特别重要，而主要森林在维持喜马拉雅山鸟类群落繁殖季节方面至关重要。进一步将森林-农业和混合农业镶嵌体转化为牧场可能会导致生物多样性的大量丧失，这将不成比例地影响繁殖物种。为了确保全面保护，喜马拉雅山西部的策略必须平衡保护完整的原始森林和最小化牧场扩张。
