黄土丘陵区人工林地土壤水分平衡初探

在黄土丘陵区雨季,由于暴雨频繁,水土流失严重,地下水位很深,因而土壤水分生态条件是影响林木生长的主要限制因子。所以,定量地研究人工林生态系中的水分平衡状况,不仅是阐明林木生长状况与生产力形成规律所必需,而且也是合理布设水土保持造林措施的重要依据。一、试验区的自然概况试验区地处黄土丘陵沟壑区,位于延河支流杏子河下游的陕西安塞县沿河湾乡茶坊村。这里植被稀疏,气候干旱,年平均降水量549.1mm,但分布不均,7—9月降雨量占全年的61.1％,且多暴雨,水土流失严重,年侵蚀模数14,000T/km~2,多年平均水面蒸发1463.5mm。供试树种为14年生人工刺槐林,位于海拔1230—1280m的山坡上,坡度25°左右,土壤为黄绵土,土壤比重2.61,土壤物理性质见表1,土壤水分特征曲线见图1(离心

A PRELIMINARY STUDY ON THE SOIL WATER BALANCE OF ARTIFICIAL FORESTLAND IN LOESS-HILLY REGION

Soil water balance of the artificial forestland planted with locust trees has been studied quantitatively for years on the water balance plots sets in Ansai soil and water conservation station of loess hilly region in Shanxi province, based on the soil water balance equetion for the soil of artificial forestland. The analyse result shows that the soil is becoming dry because of intense evapotranspiration and the water-sucking effect due to the development of the root system in deep layer if the artificial forest is made on the loess hilly region with semi-arid climate. The providing function of the water stored in deep layer to adjust the need of water from trees will be vanished, thus, only could the trees grow depending on the precipitation in current year. From this point of view, it is thought that the artificial forests deteriorate their own soil water condition constantly, which makes the trees grow slowly and limits the growth amount with water.