金沙江干热河谷银合欢人工林的土壤水分变化特征

Soil Moisture of Leucaena leucocephala Plantations in the Dry-hot Valley of Jinsha River,Yunnan

土壤水分是植物耗水的主要来源,对植物的生理活动有着重大影响。通过对金沙江干热河谷地区银合欢人工林的土壤含水量进行研究,分析其时间和空间上的动态变化特征及影响因素,结果表明:银合欢林的土壤含水量在雨季时期较高,旱季时期较低;随土层深度增加,土壤含水量也逐渐增加,且上层土壤含水量变化幅度大于下层;银合欢林土壤含水量的年际变化随着降雨量的增大而增加,但存在滞后效应;银合欢林在雨季阶段可以有效地降低0~40 cm土层的水分蒸发,起到良好的涵养水源作用;银合欢林种植对土壤理化性质产生了重大的影响,使得土壤容重下降,土壤孔隙度增加,土壤有机质增加,对土壤蓄水能力和持水性产生积极作用;土壤砂粒含量与土壤含水量呈显著正相关关系(P<0.05),土壤粉粒、粘粒含量与土壤含水量呈显著负相关关系(P<0.05)。总之,在金沙江干热河谷地区,合理发展银合欢人工林种植能有效地改良土壤物化性质,提高土壤持水、保水能力,具有良好的保持水土、涵养水源等生态作用。

Soil moisture is known to have a major impact on the physiological activities of plants,and is the main water source for plants.The soil moisture content of Leucaena leucocephala plantations or artificial forests in the dry-hot valley of Jinsha River was observed to analyze its temporal and spatial dynamic changes and influencing factors in the plantations.The results showed that the soil moisture content of L.leucocephala plantations was higher during the wet season and lower during the dry season.The soil moisture was increased with the soil depth,and its change was greater in the upper layer of the soil than in the lower layer of the soil.The annual changes of the soil moisture content increased with the rainfall,but there existed a hysteresis effect between the soil moisture content and the rainfall.L.leucocephala plantations effectively reduced the transpiration of moisture in the 0-40 cm soil layer during the wet season and hence had a good water conservation function.The L.leucocephala plantations gave great impact to the physical and chemical properties of the soil by reducing soil bulk density and increasing soil porosity and soil organic matter content,which produced positive effect on the capability of water holding and conservation.The soil sand content of L.leucocephala plantations was significantly positively correlated with the soil moisture content（P〈0.05）,but significantly negatively with the silt content and the clay content（P〈0.05）.Therefore,rational development of L.leucocephala plantations in the dry-hot Valley of Jinsha River can effectively improve the physical and chemical properties of the soil,and the water retention and conservation of the soil,and hence have an ecological function of soil and water conservation.