华北土石山区土壤水分蒸发特性

为了研究华北土石山区阴坡油松林、阴坡裸地和阳坡侧柏栎类混交林土壤水分蒸发特性。降水量与水面蒸发由Campbell气象自动观测系统测得。利用PVC管自制的微型蒸渗仪(Microlysimeter),直接钉入林地土壤,取原状土,放在原位,测定不同条件下的土壤蒸发规律。试验地多年的蒸发变化趋于一致,4~6月蒸发量大且变化不大,7~10月蒸发量明显下降。5月的日平均蒸发量最大,7月出现低谷,9月出现第2个高峰,10月降低。降雨量的变化与蒸发量相反。土壤蒸发总体规律是阳坡侧柏栎类混交林>阴坡油松林,林外>林内,阳坡侧柏栎类混交林林外无枯落物>阳坡侧柏栎类混交林林外有枯落物>阴坡油松林林内无枯落物>阴坡油松林林内有枯落物。

Soll Water-evaporation Characteristics of Mountainous Area in North China

The purpose was to study the soil water-evaporation characteristics in pine forests in shady slope and the mixed forests of Platycladus orientalis and oak in bare land of shady slope and sunny slope in mountainous area of north China.Rainfall and water-surface evaporation were determined with Campbell meteorologic automatic observation system.The soil evaporation law under different conditions was determined with self-made Microlysimeter made of PVC tubes,by directly nailing into forest soil,fetching original soil and putting in the original place.The evaporation changes tended to be identical in test field for many years.The evaporation was high from April to June with little change.The evaporation was reduced obviously from July to October.The average evaporation per day was highest in May and,smallest in July,and showed the second peak in September was showed and was reduced in October.The rainfall change was opposite to the evaporation change.The general law of soil evaporation was that Platycladus orientalis and oak mixed forests in sunny slope>pine forests in shady slope,evaporation out of forest>evaporation inside the forest,Platycladus orientalis and oak mixed forests in sunny slope without litter outside >P.orientalis and oak mixed forests in sunny slope with litter outside > pine forests in shady slope without litter inside > pine forests in shady slope with litter inside.