Drought Coincided with, but Does Not Explain, Late Holocene Megafauna Extinctions in SW Madagascar
Drought Coincided with, but Does Not Explain, Late Holocene Megafauna Extinctions in SW Madagascar
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DOI：
10.3390/cli9090138
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发表时间：
2021-09-01
期刊：
影响因子：
3.7
通讯作者：
Kennett, Douglas J.
中科院分区：
文献类型：
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作者：
Hixon, Sean W.;Curtis, Jason H.;Kennett, Douglas J.
近千年来，气候干燥可能导致马达加斯加南部的生态系统发生变化，导致当地巨型动物灭绝。然而，在过去的2000年中，区域干旱化的程度知之甚少，因为是地方性动物和经济上重要的牲畜干燥的反应。我们推断类似于1600年的气候变化周围的拉诺贝湖，西南马达加斯加，使用氧同位素分析的单种淡水介形类（Bradleystrandesia cf. fuscata）和元素分析。我们使用骨胶原稳定同位素和C-14数据集（n = 63）推断过去的栖息地和饮食的引进和灭绝的地方性大型食草动物的变化。灭绝的侏儒河马和多个巨大的狐猴物种消失在附近的Ranobe在干燥的间隔类似于1000-700卡年BP，但同时出现的引入牛，高木炭浓度，和其他人类活动的证据混淆干旱驱动的灭绝推断。与地方性巨型动物不同，牛中相对较低的胶原蛋白稳定氮同位素值表明，它们通过利用潮湿栖息地的斑块而在干旱期间生存下来。虽然巨型动物灭绝恰逢干旱在马达加斯加西南部，骨和湖泊沉积物的耦合数据不支持灭绝的巨型动物种群崩溃，仅仅是因为干旱的假设。鉴于牲畜的依赖，梅西奇补丁将变得更加重要，在面对预计的气候干燥，我们认为，可持续保护马达加斯加西南部的多刺森林应支持当地的生计，确保瘤牛获得梅西奇栖息地。此外，应研究目前畜牧业与河岸生境之间的相互作用，以帮助保护该岛的生物多样性。
Climate drying could have transformed ecosystems in southern Madagascar during recent millennia by contributing to the extinction of endemic megafauna. However, the extent of regional aridification during the past 2000 years is poorly known, as are the responses of endemic animals and economically important livestock to drying. We inferred similar to 1600 years of climate change around Lake Ranobe, SW Madagascar, using oxygen isotope analyses of monospecific freshwater ostracods (Bradleystrandesia cf. fuscata) and elemental analyses of lake core sediment. We inferred past changes in habitat and diet of introduced and extinct endemic megaherbivores using bone collagen stable isotope and C-14 datasets (n = 63). Extinct pygmy hippos and multiple giant lemur species disappeared from the vicinity of Ranobe during a dry interval similar to 1000-700 cal yr BP, but the simultaneous appearance of introduced cattle, high charcoal concentrations, and other evidence of human activity confound inference of drought-driven extirpations. Unlike the endemic megafauna, relatively low collagen stable nitrogen isotope values among cattle suggest they survived dry intervals by exploiting patches of wet habitat. Although megafaunal extirpations coincided with drought in SW Madagascar, coupled data from bone and lake sediments do not support the hypothesis that extinct megafauna populations collapsed solely because of drought. Given that the reliance of livestock on mesic patches will become more important in the face of projected climate drying, we argue that sustainable conservation of spiny forests in SW Madagascar should support local livelihoods by ensuring that zebu have access to mesic habitat. Additionally, the current interactions between pastoralism and riparian habitats should be studied to help conserve the island's biodiversity.