民勤荒漠植被对气候变化的响应

运用民勤荒漠区1974-2009年物候观测资料和2002-2010年植被样方观测资料以及同期气象资料,分析了荒漠植被对气候变化的响应.结果表明:1961-2010年,民勤荒漠区气温升高,空气湿度增大,年均气温升高速率大于全球水平和中国近百年平均水平;植物对气温变化的响应主要表现在春季物候提前、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,植株密度、植物多度随降水量变化而波动;植被盖度和纯盖度与年降水量的相关性较高,然后依次为6-7月和4-5月的降水量;植株密度和植物多度与9月降水量呈正相关;植物春季物候提前的次序是芽初膨大期＞芽开放期＞开花始期＞展叶始期和展叶盛期＞花蕾序出现＞开花盛期＞开花末期＞果实成熟期;秋季物候推迟的次序是叶全变色期＞落叶始期＞叶初变色期＞落叶末期.春季气温升高对民勤荒漠区植物物候的影响大于秋季气温升高对物候的影响.

Responses of vegetations in Minqin desert area to climate change

Based on the phenological data in 1974-2009 and the plot vegetation data in 2002-2010 as well as the meteorological data, this paper analyzed the responses of the vegetations in Minqin desert area to climate change. In 1961-2010, the air temperature and air humidity in the study area increased, and the increasing rate of the mean annual air temperature was greater than the global level and China's level over the past century. The responses of the vegetations to the air temperature change were mainly manifested in the advance of spring phenology, delay of autumn phenology, and lengthening of growing duration, whereas the responses of the vegetations to precipitation change were mainly manifested in the decrease of vegetation coverage and pure coverage with the decreasing precipitation. The plant density and richness fluctuated with the variation of precipitation, and the vegetation coverage and pure coverage were positively correlated with the annual precipitation firstly, and the precipitation in Jun-July and in April-May secondly. The plant density and richness were positively correlated with the precipitation in September. The advance of the spring phenology was in the order of bud-expansion > bud-opening > beginning of flowering > beginning of leaf-extension and leaf flourish > flower-bud appearance > flower flourishing > end of flowering > fruit-maturity, whereas the delay of autumn phenology was in the order of full leaf-discoloration > beginning of leaf-fall > beginning of leaf-discoloration > end of leaf-fall. As compared with the increase of air temperature in autumn, the increase of air temperature in spring had greater effects on the plant phenology in Minqin desert area.