青藏高原植被生态系统垂直分布变化的情景模拟

如何模拟和揭示青藏高原植被生态系统垂直分布在全球气候变化驱动下的时空变化情景，对定量解析青藏高原陆地生态系统对气候变化响应效应具有重要意义。该论文基于Holdridge life zone （HLZ）模型，结合数字高程模型（DEM）数据，改变模型输入参数模式，发展了改进型HLZ生态系统模型。结合1981-2010（T0）时段的气候观测数据和IPCC CMIP5 RCP2.6、RCP4.5、RCP8.5三种情景2011-2040（T1）、2041-2070（T2）、2071-2100（T3）三个时段气候情景数据，实现了青藏高原植被生态系统垂直分布的时空变化情景模拟。引入生态系统平均中心时空偏移趋势模型和生态多样性指数模型，定量揭示了青藏高原植被生态系统在不同垂直带上的时空变化情景。结果显示：青藏高原共有16种植被生态系统类型；冰雪/冰原、高山潮湿苔原和亚高山湿润森林为青藏高原主要的植被生态系统类型，其面积之和占到了青藏高原总面积的56.26%；高山干苔原、亚高山潮湿森林、山地灌丛、山地湿润森林和荒漠等对气候变化的敏感性总体上高于其它类型；在T0-T3期间，青藏高原的高山湿润苔原、高山干苔原、荒漠呈持续减少趋势，平均每10年将分别减少1.96×10⁴km²、0.15×10⁴km²和1.58×10⁴km²；亚高山潮湿森林、山地湿润森林和山地灌丛呈持续增加趋势，平均每10年将分别增加3.42×10⁴km²、2.98×10⁴km²和1.19×10⁴km²；RCP8.5情景下青藏高原的植被生态系统平均中心的偏移幅度最大，RCP4.5情景下的偏移幅度次之，而RCP2.6情景下的偏移幅度最小。另外，在三种气候变化情景驱动下，青藏高原植被生态系统的生态多样性呈减少趋势。总之，未来不同情景的气候变化将直接影响青藏高原植被生态系统的时空分布格局及其生态多样性，气候变化强度越高，影响就越大，而且气候变化对青藏高原植被生态系统的影响呈现出从低海拔到高海拔递增的影响效应。

Scenario simulation of vertical distribution changes of vegetation ecosystem in the Qinghai-Tibet Plateau

How to simulate and reveal the spatiotemporal change scenarios of vertical distribution of vegetation ecosystem in Qinghai-Tibet Plateau under the future global climate change is very beneficial for quantitatively explicating the response of terrestrial ecosystem to climate change. In this study, the improved Holdridge Life Zone (iHLZ) ecosystem model was developed by combing the HLZ model and Digital Elevation Model (DEM) data. Based on the climate observation data in the T0 (1981-2010) period, and the Intergovernmental Panel on Climate Change Coupled Model Intercomparison Project (IPCC CMIP5) RCP2.6, RCP4.5, and RCP8.5 climate scenario data in the T1 (2011-2040), T2 (2041-2070), and T3 (2071-2100) periods, the vertical scenarios of vegetation ecosystem distributed in Qinghai-Tibet Plateau were simulated. The spatiotemporal shifting model of ecosystem mean center and ecological diversity index were introduced to explicitly analyze the change of vegetation ecosystem in different vertical zones of Qinghai-Tibet Plateau. The results show that there are 16 mountain vegetation ecosystem types in Qinghai-Tibet Plateau. The ice snow/ice, alpine moist tundra, and subalpine moist forest are the major vegetation ecosystem types and covers 56.26% of the total area of Qinghai-Tibet Plateau. -The sensitivity of alpine dry tundra, subalpine moist forest, mountain shrub, and desert to the climate change would be generally more than other types in Qinghai-Tibet Plateau under the three scenarios of RCP2.6, RCP4.5, and RCP8.5. The areas of alpine moist tundra, alpine dry tundra and desert show a decreasing trend, which will be decreased by 1.96×10⁴ km², 0.15×10⁴ km² and 1.58×10⁴ km² per decade between T0 and T3, respectively. The areas of subalpine moist forest, mountain moist forest and mountain shrub show an increasing trend, which will be increased by 3.42×10⁴ km², 2.98×10⁴ km² and 1.19×10⁴ km² per decade between T0 and T3, respectively. The mean center in the vegetation ecosystem has the largest shift distance under the scenario RCP8.5, followed by the scenario RCP4.5, and that has the least shift distance under the scenario RCP8.5. The ecological diversity of vegetation ecosystem will be reduced generally in Qinghai-Tibet Plateau in the future. In general, the greater climate change will lead to the larger impacts of climate change on ecosystem diversity, which shows an increasing trend from low altitude to high altitude in the Qinghai-Tibet Plateau.