花江喀斯特峡谷地区不同小生境土壤水分的动态研究

对花江流域喀斯特石质山地人工造林地不同小生境（土面、石槽、石沟）的土壤物理性质和土壤水分动态变化规律进行了研究。研究结果表明:石沟的水分状况最好，土面的居中，石槽的最差；一年中不同小生境出现高墒期、低墒期的时段不一致；不同小生境水分胁迫频繁发生，但出现的次数、程度、持续时间各不相同；在持续干旱期，三种小生境中，失水最快的是石槽，其次是石沟，最后是土面，7天内损失水量分别为17．30％，14．49％，13．87％；土面、石槽、石沟出现轻度胁迫的时间分别为6d、6d、7d，土面、石槽在7天后出现中度胁迫。花江喀斯特峡谷地区不同小生境一般持续放晴7天就可能出现水分胁迫，这个数据可以作为生产上植物补水时间的依据。总体而言，石沟的土壤水分状况优于土面和石槽。针对不同小生境的水分动态特征，提出了树种选择、配置和林地土壤水分管理的建议。 

Studies on the regime of soil moisture under different microhabitats in Huajiang karst valley

Soil physical characters and soil moisture regime law under different microhabitats on afforestation land in karst stony hill area of the Huajing river valley are studied. The result shows that water condition of stone gully is best and soil surface is between stone gully and stone pit, but stone pit is worst. The time of high moisture condition period and that of low moisture condition period under different microhabitats obviously changes annually. Times, extent and dates of water stress under different microhabitats is also actually different in one year. Loss of soil moisture is fast in stone pit, but slow on soil surface, and in stone gully it is between stone pit and soil surface at three small sites within continuous drought dates, which is separately 17.30%, 14.49% and 13.87% in seven days. Time of slight stress on soil surface, in stone pit emerged in seven days. Therefore, soil water stress under different microhabitats emerged in Huajiang karst valley in seven days. This data may be regarded as the time for supplement of water to plants. In general, soil moisture condition in stone gully is superior to soil surface and stone pit. Directing at soil moisture regime character under different microhabitats, suggestion for choosing and allocating tree spices and management to soil water is put forth in the paper.