冷荒漠草本植物数量特征对不同水分输入和气象因子的响应

草本层是古尔班通古特沙漠植被的重要组成部分，在维持沙漠稳定、养分循环等方面具有重要意义。水分通常以积雪和降雨形式输入到土壤，输入方式及数量变化对荒漠植物的存活和生长有重要影响。本文以古尔班通古特沙漠南缘草本层为研究对象，利用人工增减积雪的方法，共设置4个积雪处理(0，50%，100%，200%积雪，其中100%积雪为对照)，于2009—2016年春季调查草本植物的数量特征和物种丰富度，分析草本植物数量特征对水分变化的响应；同时结合气象数据，分析不同年份一年生荒漠草本植物数量特征与主要气象因子的关系。结果表明：表层土壤含水量与积雪厚度成正比，相应的草本植物的幼苗密度与积雪水当量、表层土壤含水量成正比关系；2009—2016年，年内积雪量的变化对物种丰富度没有显著影响，各积雪处理间物种丰富度差异不显著；2009—2016年自然处理下年际间物种丰富度差异显著，2015年物种丰富度显著小于其余年份。结合气象数据分析发现，物种丰富度年际变化主要受幼苗建成期的降雨调控，并且干旱年份过后的湿润年份物种丰富度不受前一年降水的影响，说明荒漠草本植物层片具有较强的自我调节能力；自然处理下，不同年份草本植物旺盛期的存活数量与大气干旱程度(空气饱和差)呈显著负相关关系（R²值为0.611，P<0.05），与生长季的降雨量呈正相关关系（R²值为0.162, P>0.05），说明大气干旱程度更能表征荒漠草本植物生长峰值期的存活情况。

Responseof Herbaceous Plant Quantity to Different Water Input and MeteorologicalFactors in a Cold Desert#br#

Rainfalland atmospheric dryness play an important role in plant growth, especially inarid area. The herbaceous layer is an important component of the plantcommunity in the Gurbantunggut Desert, China, and it generally depends on snow meltwater in early spring for germination and development, resultant with a shortlife span. However, few studies focused on the relationship between the growthof desert annual herbaceous plants and rainfall and atmospheric dryness. Therefore,our objectives were to determine how snow cover, precipitation and atmosphericdryness affected the ecological traits of the herbaceous plants in this typicalarid zone. From 2009 to 2016,we applied four treatments of snow cover thickness(0,50%,100%,and 200% as well as 100% natural snow cover thickness) toinvestigate the species richness and density in 1 m ×1 m quadrats. The meteorologicaldata and field data were used to analyze the relationship between the growth ofdesert annual herbaceous plants and rainfall and atmospheric dryness. It wasfound that thick snow cover could result in a high topsoil moisture content andthen high seedling density. Although the snow cover regulated the seedlingdensity, there was no significant difference between species richness and snowcover thickness within a year. During the period of 2009-2016,however,thespecies richness fluctuated inter annually. It was inferred through theanalysis of meteorological data that the species richness was mainly regulatedby the rainfall during the seedling construction period. Moreover, the speciesrichness in wet year would return to the normal level after a drought year. Vaporpressure deficit (VPD) of the atmosphere reflected the degree of atmosphericdryness, and there was a significant negative correlation between the number ofsurvival herbaceous plants and VPD under the 100% snow cover treatment from2009 to 2016,with the R² value at 0.611 (P<0.05).There wasan opposite trend between the number of survival herbaceous plants and rainfallin growing season with R² at0.162 (P>0.05).Obviously, atmosphericdryness was more likely to determine the survival of herbaceous plants.