六盘山北侧叠叠沟小流域几种典型植被群落的水文功能研究

摘要

在宁夏六盘山北侧的半干旱区，研究了华北落叶松林、沙棘灌丛、虎榛子灌丛、草地植被类型的冠层截留与再分配、枯落物持水及土壤蓄水等水文功能。结果表明，不同植被类型的冠层截留能力相差较大，其中，沙棘灌丛的截留率最高（24．80％），华北落叶松林略低（21．40％），虎榛子灌丛最低（9．25％）；与此相反，树干茎流率以虎榛子灌丛为最高（33．18％），超出大多数干旱半干旱区灌木树干茎流范围（2％～10％）。从季节变化上看，不同植被群落的截留率均为6月份最大，7—9月份持续下降，10月份出现回升；但截留量均为7月份最大。枯落物持水性能以华北落叶松林样地为最高，其次为虎榛子灌丛、沙棘灌丛和草地，这与各植被类型枯落物层贮存量的大小排序一致。1 m土层的土壤容重以虎榛子样地为最小（1．03 g・cm-3），然后依华北落叶松（1．07 g・cm-3）、草地（1．08 g・cm-3）、沙棘（1．16 g・cm-3）的顺序增大。土壤总孔隙度、最大持水量以华北落叶松林样地为最高，毛管孔隙度、毛管持水量以虎榛子样地为最高，非毛管孔隙度以草地为最高；这几项指标均以沙棘样地为最低。综上所述，从林冠截持、枯落物持水性、土壤物理性质等总体来看，华北落叶松人工林的土壤存蓄水、调水能力最强，其次为虎榛子灌丛和草地，沙棘灌丛最差。%The hydrological functions ,in terms of canopy interception and water holding capacity of litters and soil layers ,were assessed in several vegetations in the semi-arid region in north part of Liupan Mountain ,Ningxia ,China . The results indicated that the canopy interception differed notably among different vegetations ,with the maximal value (24 .80% ) in the shrubs of Hippophae rhamnoides ,followed by the plantations of Larix principis-rupprechtii (21 .40% ) , and the minimal value (9 .25% ) in the shrubs of Ostryopsis davidiana .Conversely ,the maximal stem flow ratio (33 .1% ) appeared in the shrubs of Ostryopsis davidiana ,which exceeded the general range (2% ~10% ) of most shrubs in arid and semi-arid regions .From the aspect of seasonal variation ,the maximal interception ratio appeared in June ,then decreased from July to September ,and increased again in October .However ,the maximal interception amount appeared in July for all vegetations studied .The highest water holding capacity of litter layers was in the planta-tions of Larix principis-rupprechtii ,followed by the shrubs of Ostryopsis davidiana and Hippophae rhamnoides and the grassland ,being the same as the sequence of litter stock .The soil bulk density in 0~100 cm layer was minimal in the shrubs of Ostryopsis davidiana ,and maximal in the shrubs of Hippophae rhamnoides .The total porosity and water-hold-ing capacity were maximal in the plantations of Larix principis-rupprechtii ,while the capillary porosity and capillary wa-ter-holding capacity were maximal in the shrubs of Ostryopsis davidiana ,and the non-capillary porosity was maximal in the grassland ;the worst soil porosities was found in the shrubs of Hippophae rhamnoides .Considering comprehensively the canopy interception ,water holding capacity of litters and soil physical properties ,the best hydrological functions ap-peared in the plantations of Larix principis-rupprechtii ,then the shrubs of Ostryopsis davidiana and the grassland ,and the worst functions appeared in the shrubs of Hippophae rhamnoides .