高寒草甸植被特征对模拟增温的响应——以青藏高原多年冻土区为例

采用红外辐射灯(infrared heater)模拟气候变暖背景,研究青藏高原多年冻土区高寒草甸优势植物种珠芽蓼(Polygonum viviparum)、美丽风毛菊(Saussurea superb)和黑褐苔草(Carex atrofusca)的生长发育及光合特性对气候变暖的短期响应及其差异性,旨在为评价草地生态系统的敏感性和脆弱性提供科学依据。结果表明,模拟增温W1(1.88℃)和W2(3.19℃)均可改变高寒草甸物种分布的频度和季节分布格局,并显著影响植被高度和光合色素含量,影响程度存在种间差异性。与不增温对照相比,W1增温下物种具有不同的响应,美丽风毛菊的高度、频度和叶绿素含量均呈下降趋势,而珠芽蓼和黑褐苔草均呈增加趋势。W2增温显著增加了珠芽廖和黑褐苔草的高度、频度和叶绿素含量(P0.05),却显著降低了美丽风毛菊的叶绿素a/b值(P0.05)。物种间光合特性存在显著差异(P0.05),样地间差异性表现更为突出,但增温处理间变化不明显。这说明增温可促进高寒草甸牧草类植物的生长发育,延长青草期,有利于牧业生产,但斑块状分布明显。

Response of vegetation characteristics in the alpine meadow ecosystem to simulated temperature enhancement---A case study of permafrost regions on the Qinghai-Tibet Plateau,China

Infrared heater was used to simulate temperature enhancement in the field focusing on the effects of temperature enhancement on the growth and photosynthetic characteristics of three alpine plants:Polygonum viviparum,Saussurea superb,and Carex atrofusca in order to provide basis for estimating the sensitivity and friability of the meadow ecosystem in the permafrost region on the Qinghai-Tibet Plateau,China.The results showed that the simulated warming W1(1.88 ℃)and W2(3.19 ℃)could all alter the distributing frequency and season pattern of the alpine plant species.Compared with the CK,the W1 temperature enhancement brought differ-ent changes to different plants under which the height,frequency and chlorophyll contents of the S.pulchra were de-creased but the values of the P .viviparum and C.atrofusca were increased.The W2 warming evidently in-creased the height,frequency,and chlorophyll content of the P .viviparum and C.atrofusca but significantly (P<0.05)decreased the ratio of chlorophyll a to b of the S.pulchra resulted in its decreases in the height,fre-quency,and chlorophyll content.It showed significant differences in the photosynthesis indicators among the plant species,especially among the plots.All above indicates that the warming can improve the growth and de-velopment of the grazing plants in the alpine meadow and prolong their green grass duration resulting in benefit to the livestock production but the vegetation distribution evidently variegated.