Key Laboratory of Grassland Ecosystem, Ministry of Education, Sino-U.S. Centers for Grazing Land Ecosystem Sustainability, Ministry of Science and Technology, Pratacultural Engineering Laboratory of Gansu Province, Pratacultural College, Gansu Agricultural University, Lanzhou 730070, China.
Qinghai Institute of Meteorological Sciences, Xining 810001, China.
Sci Total Environ. 2024 Apr 1;919:170900. doi: 10.1016/j.scitotenv.2024.170900. Epub 2024 Feb 13.
The sensitivity of grassland above- (AGB, gC m) and below-ground biomass (BGB, gC m) to climate has been shown to be significant on the Tibetan Plateau, however, the spatial patterns and sensitivity of biomass with altitudinal change needs to be quantitated. In this study, large data sets of AGB and BGB during the peak growth season, and the corresponding geographical and climate conditions in the grasslands of the Tibetan Plateau between 2001 and 2020 were analyzed, and modelled using a Cubist regression trees algorithm. The mean values for AGB and BGB were 61.3 and 1304.3 gC m, respectively, for the whole region over the two decades. There was a significant change in spatial AGB of 64.8 % on the Plateau (P < 0.05, with areas where AGB increased being twice as large as areas where AGB decreased), while BGB did not change significantly in majority the of the region (≥ 90.1 %, P > 0.05). In general, the areas where AGB showed positive partial correlations with precipitation were larger than the areas where AGB had positive correlations with temperature (P < 0.05). However, these trends varied depending on the climatic conditions: in the wetter regions, temperature had a greater effect on the size of the areas with positive AGB responses than precipitation (P < 0.05), while precipitation had a greater effect on the size of areas with positive BGB changes than temperature (P < 0.05). In the drier areas, however, precipitation affected the AGB response significantly compared to temperature (P < 0.05), while temperature influenced the BGB response greater than precipitation (P < 0.05). The response and sensitivity of grassland biomass to temperature and precipitation varied according to the altitude of the Plateau: the response and sensitivity were stronger and more sensitive at medium altitudes, and weak at the higher or lower altitudes. Likely, this phenomenon was resulted from the natural selection of plants to maintain the efficient use of resources during un-favourable and stressed conditions for maximum plant development and growth. These findings will help assess the ecological consequences of global climate change for the grasslands of the Tibetan Plateau, particularly in those regions with highly variable altitudes.
草原地上生物量（AGB，gC m）和地下生物量（BGB，gC m）对气候的敏感性已被证明在青藏高原上非常显著，然而，生物量随海拔变化的空间格局和敏感性需要量化。在这项研究中，分析了 2001 年至 2020 年青藏高原草原在生长高峰期的 AGB 和 BGB 大数据集，以及相应的地理和气候条件，并使用 Cubist 回归树算法对其进行了建模。在过去的二十年中，整个地区的 AGB 和 BGB 的平均值分别为 61.3 和 1304.3 gC m。高原上 AGB 的空间变化有显著变化（P < 0.05，AGB 增加的面积是减少的两倍），而大部分地区的 BGB 没有明显变化（≥90.1%，P > 0.05）。一般来说，AGB 与降水呈正偏相关的区域大于与温度呈正偏相关的区域（P < 0.05）。然而，这些趋势取决于气候条件：在较湿润的地区，温度对 AGB 正响应区域的大小影响大于降水（P < 0.05），而降水对 BGB 正变化区域的大小影响大于温度（P < 0.05）。然而，在较干燥的地区，降水对 AGB 响应的影响明显大于温度（P < 0.05），而温度对 BGB 响应的影响大于降水（P < 0.05）。草原生物量对温度和降水的响应和敏感性随高原海拔的变化而变化：在中海拔地区，响应和敏感性较强且较敏感，在较高或较低海拔地区较弱。这种现象可能是由于植物为了在不利和压力条件下最大限度地促进植物生长和发育，而对资源进行了有效的自然选择。这些发现将有助于评估全球气候变化对青藏高原草原的生态后果，特别是在那些海拔高度变化较大的地区。
