准噶尔盆地南缘荒漠草地土壤温、湿度分层变化特征

干旱-半干旱区荒漠草地分布广,土壤温度变化剧烈,土壤湿度低,极大地影响了荒漠植被的生长及区域气候环境。本研究基于对新疆准噶尔盆地古尔班通古特沙漠南缘荒漠灌丛草地站点2017年5月-2019年4月地下10层的土壤温、湿度探头自动观测数据,分析了荒漠灌丛草地不同深度土壤温、湿度的变化特征,及其与气象数据的相关性。结果表明:1)荒漠灌丛草地各层土壤温、湿度随着季节变化存在明显的周期性变化特征,且不同深度土壤温、湿度垂直梯度明显,均在表层波动最大。浅层土壤温度随季节变化波动明显,且在18:00左右达到最大值。浅层土壤湿度波动大于深层,5 cm土壤湿度表现为春季>夏季>秋季>冬季,且基本表现为土壤湿度随着土层深度的增加升高的趋势。2)在该干旱-半干旱荒漠灌丛草地研究区,土壤温度与气象因子相关性较好,其中与0 cm地温、气温、蒸发呈显著正相关关系,相关系数高达0.955、0.942、0.823(P<0.01),且土壤温度与气象因子的相关性优于土壤湿度与气象因子的相关性。本研究明确了该区不同季节长时间序列的土壤温、湿度变化特征,可以为荒漠-绿洲过渡带植物生长、繁殖以及演替提供理论依据,为陆面过程的模拟研究提供基础模型初始化数据。

Soil temperature and moisture stratification characteristics in the marginal desert grassland of the Dzungaria basin

The wide distribution of arid and semi-arid desert grasslands,low soil temperature,and low soil moisture greatly affect the growth of desert vegetation and regional climate environment.The automatic observation data of soil temperature and humidity probes were obtained at a desert grassland site on the southern edge of the Gurbantonggute desert,Dzungaria basin,Xinjiang,from May 2017 to April 2019.The variation in the soil temperature and humidity at different depths and their correlation with meteorological data were analyzed.The results showed that:1)The soil temperature and humidity of each layer had obvious periodic change characteristics with the seasonal change.The vertical gradients of soil temperature and humidity at different depths were obvious,and the surface layer had the biggest fluctuation.The shallow soil temperature obviously fluctuated with the seasons and reached a maximum value at 18:00.The trend in the soil moisture at 5 cm was spring>summer>autumn>winter,and soil moisture increased with the increase in depth.2)The correlation between the soil temperature and meteorological factors was stronger than that with the soil moisture.The soil temperature was positively correlated with the ground temperature,air temperature,and evaporation,for which the correlation coefficients were 0.955,0.942,and 0.823,respectively(P<0.01).This paper presents the changes to the soil temperature and humidity in a desertoasis zone,to provide a basis for the model simulation of land surface processes using initialization data.