黄土丘陵小流域沟坡水热条件及其生态修复初探

在黄土丘陵沟壑区,沟坡是小流域尺度上水土流失最为活跃的部分,对其水热条件的了解是进行综合治理的基础。论文以黄土丘陵区甘肃定西安家沟小流域为例,观测了沟坡不同地形部位和植被类型土壤水分季节动态和剖面变化特征,同时观测了光照、大气湿度、温度和风速等小气候条件,并探讨了沟坡生态修复方式。结论与建议如下。①历次取样中,0～100cm平均土壤水分均以沟道灌木林地最高,沟坡中的阳坡和阴坡的草地和灌木林地次之,梁峁坡农地最低,且6种类型样地间有显著差异(P<0.01);对于相同的植被类型来说,阳坡的林草植被土壤水分均要小于阴坡,但没有显著差异(P>0.05);而在同一坡向,草地的土壤水分要显著高于灌木林地(P<0.01);和梁峁坡农地的土壤水分季节变化特征相比,沟坡植被土壤水分的季节变化不明显。②对于梁峁坡农地和阴坡的灌木林地来说,土壤水分在剖面内随着深度变化平缓,而其它4种类型样地土壤水分在剖面内随着深度呈增加的趋势。对于这6种类型样地,土壤水分剖面差异格局与0～100cm平均含水量相似;且随着深度的增加,6种类型样地间土壤水分的差异性增大。③对于梁峁坡和沟坡来说,4～5月份风速均是观测期内最大的,但沟坡风速要小于梁峁坡坡面;在观测期内,高湿期出现在5月,且沟坡大气相对湿度高于梁峁坡;和

The water and heat condition and the ecological rehabilitation in the hilly-gully catchment of Loess Plateau

Gully region is the most severe place of soil and water erosion in the catchment scale of Loess Plateau.Knowledge of water and heat condition is the base of harnessing soil and water erosion of gully.Based on fixed and consecutive measurements of soil moisture,sunshine,air humidity and temperature,wind speed in gully and hillslope,the changing characteristics of soil moisture and climate condition were analyzed.The results and advises were as following:(1)the shrubland of gully bed had the highest time-averaged soil moisture of0～100cm.The grassland and shrubland in the udbac and adret of gully slope were the middle.The time-averaged soil moisture of cropland in hillslope was the lowest.The difference in time-averaged soil moisture among the six types plot was significant (P<0.01).The time-averaged soil moisture in adret of gully slope was slight lower(P>0.05)than udbac of gully slope for the same vegetation types.The grassland had significant (P<0.01)higher time-averaged soil moisture than shrubland for the same slope aspect of gully.The time-averaged soil moisture of gully plots had insignificant seasonal characteristics compared with cropland in hillslope.(2)The profile-averaged soil moisture of cropland in hillslope and shrubland in udbac of gully was expressed as steady-type.The other four types were expressed as increasing-type.The different patterns of profile-averagedsoil moisture were similar to the0～100cm time-averaged soil moisture among the six types of plots.And the difference increased with the increasing of depth.(3)The wind speed of April and May were the highest during the measured period.Gully had lower wind speed and less sunshine than hillslope.Gully had higher air humidity and temperature than hillslope also.(4)We can adopt “upper dam and lower pond”etc engineering measure and vegetation measure to solve the eco-environment of gully region.