南京城郊栎林与草地不同层次土壤含水量的变化规律

Variation of Soil Volumetric Water Content in Grassland and an Oak Forest at Different Depths in a Forest Farm in Nanjing

土壤水作为水资源的重要组成部分,是陆地生态系统中的最重要因素之一,土壤水分的研究一直是土壤-植被-大气系统领域的热点。表层土壤水分可能通过陆地-地表大气的反馈机制来调控地表水分分布过程（Kosheretal.,2003）。在中国黄土高原区,由于干旱缺水,广泛开展了植物与土壤水分关系研究,普遍认为植被覆盖度与土壤水分之间具有显著的相关关系（张晶晶等,2011;黄琳琳等,2011;梁超等,2011;颉登科等,2011）。

On an oak forest and grassland in the Tongshan forest farm in Nanjing,4 sets EM50 were installed to measure the soil volumetric water content with which the Daily Average Soil Volumetric Water Content（DASVWC） was calculated at depths of 5,15,30 cm,respectively.Simultaneously air humidity was measured at the height of 2 m.By analyzing the vertical-temporal variable quantity,variations of DASVWC and their correlation with meteorological factors were found to be affected by precipitation,air temperature and humidity and DASVWC.The variation pattern was different from that in the Yellow River watershed,where variability of DASVWC at the 0-5 cm layers was lower than that at the 15 cm and 30 cm soil layers,while variability of DASVWC at the 0-5 cm layers in this study sites was higher than that at the 15 cm and 30 cm soil layers regardless of types of land use.DASVWC at the 0-30 cm soil layers in the oak forest was lower compared with that in the grass land,indicating that DASVWC at the surface soil layer decreased with increase of plant coverage.During rain intervals in different seasons,DASVWC exponentially decreased with time very significantly.The daily decrease in DASVWC showed multifactor linear regression with DASVWC,air temperature,humidity in each period.