增温改变高寒草甸植物群落异速生长关系

以青藏高原高寒草甸为研究对象,采用红外线辐射器进行模拟增温试验,于2011-2013年、2016-2018年植被生长季进行群落生长特征调查,选取指数函数、线性函数、对数函数和幂函数4种常用基本函数进行最优方程拟合,以确定不增温对照和增温处理下植物群落生长关系的类型,进而探讨增温对高寒草甸植物群落生长关系的影响.结果表明:1)在不增温对照下,地上生物量与密度(P<0.05)、高度(P<0.01)、盖度(P<0.01)均呈显著正相关关系,而在增温处理下,地上生物量与频度(P<0.01)、盖度(P<0.01)呈极显著正相关关系,根冠比与密度(P<0.05)、盖度(P<0.05)呈显著负相关关系;2)在增温处理下,盖度对地上生物量的影响增强(P<0.01),频度对地上生物量的影响由不显著(P>0.05)变为显著正相关(P<0.01),密度和盖度对根冠比的影响也由不显著(P>0.05)变为显著负相关(P<0.05);3)在4种常用基本函数中,幂函数更符合植被的生长关系,说明高寒草甸植被符合异速生长理论;在对照处理下,高寒草甸植被地上部分表现为等速生长,地下部分表现为异速生长关系,整体表现为异速生长关系;而在增温处理下,地上部分和地下部分均表现为异速生长关系,整体也体现为异速生长.这说明在增温处理下高寒草甸植被地上部分由等速生长关系变为异速生长关系,地下部分的异速生长关系进一步增强.本研究结果对正确理解气候变化如何影响高寒草甸植物生长与群落结构具有理论意义.

Effects of simulated warming on the allometric growth patterns of an alpine meadow community on the Qinghai-Tibet Plateau

An alpine meadow on the Qinghai-Tibetan Plateau was chosen as the research object. In the meadow, simulated warming experiments were conducted using infrared radiators, and community growth characteristics were investigated during the plant growing seasons of 2011?2013 and 2016?2018. Four common basic functions (exponential, linear, logarithmic, and power functions) were selected to fit the optimal equations to analyze the allometric relationships of the plant communities under control and warming treatments and explore the effects of the simulated warming on the allometric relationships of the meadow plant communities on the plateau. The results showed that: 1) In the control treatment, the aboveground biomass was significantly and positively correlated with density (P < 0.05), height (P < 0.01), and cover (P < 0.01), whereas in the warming treatment, the aboveground biomass was significantly and positively correlated with frequency (P < 0.01) and cover (P < 0.01), and the root-shoot ratio was significantly negatively correlated with density (P < 0.05) and cover (P < 0.05); 2) The effect of cover on the aboveground biomass increased under the warming treatment (P < 0.01), the effect of frequency on the aboveground biomass changed from insignificant (P > 0.05) to significantly positive (P < 0.01), and density and cover effects on the root-shoot ratio changed from insignificant (P > 0.05) to significantly positive (P < 0.01). The density and cover effects on the root-shoot ratio also changed from insignificant (P > 0.05) to significantly negative (P < 0.05); and 3) Among the four common basic functions, the power function was more consistent with the vegetation growth relationship, indicating that meadow vegetation conformed to the allometry theory. In the control treatment, the aboveground part of the meadow vegetation was in agreeance with the isometric relationship, the belowground part with the allometric relationship, and the overall meadow vegetation with the allometric relationship. In the warming treatment, the aboveground part, belowground part, and overall meadow vegetation all conformed to the allometric relationship. Therefore, the aboveground part of the meadow vegetation changed from an isometric relationship to an allometric relationship, and the belowground part of the meadow vegetation further enhanced the allometric relationship under the warming treatment. The results of this study have theoretical significance for accurately understanding how climate change affects plant growth and community structure in alpine meadows.