Plant diversity changes at the southeastern Tibetan Plateau during the last 21 ka and its drivers

保护独特的藏族植物多样性需要了解其驱动因素。CLI-Mate、自然干扰和土地利用，潜在的多样性驱动因素在空间上高度相关。因此，应用以空间梯度为目标的现代生态学方法，它们对植物α多样性的具体影响及其相互作用很难分开。因此，我们建议开展一项以晚冰期和全新世植物α多样性变化为重点的古生态研究。我们假设青藏高原东部的(H1)植物α多样性指标(丰富度、优势类群数量)在晚冰期和全新世期间显示出复杂的时空趋势。我们预计(H2)丰度与景观结构有关，而景观结构本身是自然干扰(野火、侵蚀)和人类影响的函数。此外，我们假设(H3)优势类群数量主要与气候变化和人类影响驱动的植被类型有关。我们的研究将利用从湖泊沉积物分析中获得的替代信息。它将结合收集三个关键地点(位于青藏高原东南缘高地样带)的新的古环境数据和青藏高原东部及周边地区(25-40°N，90-105°E)的古环境数据。对古环境数据的解释将基于现代环境信息和替代信息之间的关系，这些信息来自由234个地点组成的湖泊沉积物训练集。在关键地点，将研究花粉和沉积古DNA(植物代谢编码)，作为过去植物α多样性和植被类型的替代模式。关于过去气候变化的独立信息将从沉积硅藻硅藻的稳定氧同位素测量和替代气候数据合成中推断出来。自然干扰和土地利用将从多代理方法中推断出来，包括对火灾、土壤侵蚀和土地利用的代理分析。关于综合研究，将使用已有的花粉数据集，并辅之以其他替代数据。最后，通过开发一种新的建模方法，我们的目标是理清阿尔法多样性措施、植被类型和景观结构、气候、自然干扰和土地利用之间的关系。我们的研究有可能确定植物潜水驱动因素的临界阈值，当超过这些阈值时，会导致巨大的和/或不可逆转的多样性损失。

The preservation of the unique Tibetan plant diversity requires an understanding of its drivers. Cli-mate, natural disturbances and land use, the potential diversity drivers are spatially highly correlated. Thus, their specific effects on plant alpha diversity and their interactions can hardly be separated ap-plying a modern ecological approach that targets spatial gradients. Accordingly, we propose to perform a palaeoecological study focusing on the Late Glacial and Holocene plant alpha diversity change.We hypothesize that (H1) plant alpha diversity measures (richness, dominant taxa num-ber) on the eastern Tibetan Plateau shows complex spatio-temporal trends during the Late Glacial and Holocene. We expect that (H2) richness is related to landscape structure, which itself is a function of natural disturbances (wildfire, erosion) and human impact. Furthermore, we hypothesize that (H3) the dominant taxa number is mainly related to vegetation type driven by climate change and human im-pact.Our study will make use of proxy information gained from the analyses of lake sediments. It will combine the collection of new palaeoenvironmental data at three key sites (located along altitudi-nal transect at the southeastern Tibetan Plateau margin) and palaeoenvironmental data synthesis from the eastern Tibetan Plateau and surrounding area (25-40°N, 90-105°E). Interpretation of palaeo-environmental data will be based on relationships between modern environmental information and proxy information as derived from a lake sediment training set comprising 234 sites. At key sites, pol-len and sedimentary ancient DNA (plant metabarcoding) will be investigated as proxies for past pat-tern in plant alpha diversity and vegetation type. Independent information on past climate change will be inferred from stable oxygen isotopes measurements of sedimentary diatom silica and proxy-climate data synthesis. Natural disturbances and land use will be inferred from a multi-proxy approach including the analyses of proxies for fire, soil erosion, and land use. With respect to the synthesis study, an already available pollen data set will be used and complemented with further proxy data. Finally, by developing a novel modelling approach we aim to disentangle the relationship between alpha diversity measures, vegetation type and landscape structure, climate, natural disturbances and land use.Our research has the potential to identify critical thresholds in drivers of plant diver-sity that when crossed cause a tremendous and/or even irreversible diversity loss.