民勤荒漠区草场植被对气温和降水的响应

Response of grassland vegetation to climate warming in the Minqin area

为了揭示荒漠草场植被响应气候变化的特征,本研究运用民勤荒漠区1974年以来的物候观测资料和2002年以来的植被样方观测资料以及同期气象资料,分析了荒漠草场植被对气温和降水变化的响应。用线性趋势线及其回归显著性表示变化趋势的显著性,用相关系数表示2组变量的相互关系。数据分析采用SPSS 13.0软件完成。结果表明,1)民勤荒漠区1961年以来的年平均气温升高速率大于全球水平和中国近百年来水平;2)植物对气温变化的响应主要表现春季物候提前,秋季物候推迟,生长季延长;植被对降水量变化的响应主要表现为植被盖度和纯盖度随降水量减少而降低;3)植被盖度及纯盖度主要与年降水量正相关;植株密度主要与9月份降水量正相关;4)春季气温的升高对植物物候的影响大于秋季。

The phenological data from 1974-2009 were analysed and data relating to vegetation samples and meteorology during 2002-2010 were gathered to elucidate the response of desertified rangeland to air temperature and precipitation variations.1） The rising rate of annual average temperature in the desert area since 1961 was greater than that at the global level or the national（China） level over the past century.2） The responses of desert plants to temperature variation were mainly displayed as： the advance of spring phenology,the delay of autumn phenology and the extension of growing duration,all of which were greater than those reported in the available literature.3） Both vegetation cover and pure cover were mainly positively correlated with the annual precipitation and the precipitations during June-July and April-May.Plant density was mainly positively related to the precipitations in August and September.4） The impact of rising temperatures in spring on plant phenology was greater than that in autumn.The advance of phenophases,from higher to lower in order was： bud-expansionbud-openingthe beginning of floweringthe beginning of leaf extension and leaf maturityflower-bud appearancepeak floweringthe end of floweringfruit maturity.The delay of phenophase,from higher to lower in order,was sequenced as： full leaf-discolorationthe beginning of leaf-fallthe beginning of leaf-discolorationend of leaf-fall.