内蒙古典型草原枯落物的生态水文效应

Hydro-ecological Effects of Litter in Typical Steppe of Inner Mongolia

枯落物是影响干旱和半干旱地区草原生态系统水文过程中重要的因素。本研究利用野外监测和室内试验结合的方法探究内蒙古典型草原枯落物的生态水文效应。结果表明:大针茅(Stipagrandis)群落的枯落物蓄积量显著高于羊草(Leymus chinensis)群落和克氏针茅(S.krylovii)群落的。糙隐子草(Cleistogenes squarrosa)的枯落物最大持水量最高,羊草的最低,均与大针茅的和克氏针茅的有显著差异;羊草群落的枯落物最大持水量显著低于克氏针茅群落的和大针茅群落的。3种群落保留枯落物的土壤水分含量高于去除枯落物的,在春季和夏季尤为明显,但在秋季具有趋同化的特征。降雨时,枯落物会降低小雨对2.5cm处土壤水分的补充,但对中雨和大雨无显著影响。降雨后,枯落物可使土壤保持较高水分。综合枯落物的截留作用与保水效应,枯落物可以间接增加降雨的有效性。

Litter plays an essential role in affecting hydro process of arid and semiarid grassland ecosystem.To explore hydro-ecological effect of litter in grassland ecosystem of Inner Mongolia,we conducted a field controlled experiment and then measured water-holding capacity of different litter types in laboratory.The results were as follows：The litter stock of Stipagrandis steppe was significantly higher than that of Leymus chinensis steppe and Stipa krylovii steppe.Water-holding capacity of litter in Cleistogenes squarrosa and L.chinensis was the highest and lowest,respectively,and they had significant difference with that in S.grandis and S.krylovii.Moreover,water-holding capacity of litter in L.chinensis steppe was obviously lower than that in S.grandis steppe and S.krylovii steppe.Compared with the control,soil moisture covered by litter was greater,especially in spring and summer,but soil moisture dramatically tended to consistency among different treatments in autumn.During rainfall process,litter decreased replenishment of light rain to 2.5 cm soil depth but moderate rain and heavy rain were not affected.It showed that litter kept soil moisture at a high level after rainfall.It concluded that litter indirectly increased effectiveness of precipitation through intercepting rainfall and decreasing water evaporation.