【摘要】 为探究坝上高原不同退化程度杨树人工林对枯落物及土壤水源涵养功能退化的影响,于2016年7—9月在张北县进行样地调查,对不同退化程度杨树人工林地枯落物及土壤水源涵养功能进行定量分析。结果表明:(1)林下枯落物储量表现为轻度退化(24.68t/hm~2)>中度退化(13.43t/hm~2)>重度退化(3.66t/hm~2),枯落物有效拦蓄量表现为轻度退化(29.28t/hm~2)>中度退化(23.18t/hm~2)>重度退化(3.30t/hm~2),最大持水量为轻度退化(34.90t/hm~2)>中度退化(24.13t/hm~2)>重度退化(3.86t/hm~2),最大持水率表现为轻度退化(228.80%)>中度退化(228.70%)>重度退化(119.94%),枯落物持水量、持水速率与浸水时间分别符合对数函数与指数函数;(2)不同退化程度土壤容重范围为1.65～1.80g/cm~3,毛管孔隙度为27.42%～33.64%,总孔隙度为29.97%～38.57%;(3)林地土壤入渗速率与入渗时间呈幂函数关系,稳渗速率表现为中度退化(3.32mm/min)>轻度退化(2.58mm/min)>重度退化(2.44mm/min)。坝上高原退化杨树人工林的枯落物及土壤的水源涵养能力处在较低水平,随退化程度增大而显著下降。因此,在森林经营中应注意合理的树种选择,对退化较严重的林地通过补植其他树种或促进更新进行修复。研究结果可为当地杨树人工林退化评价及相关恢复重建提供一定的理论依据及参考。更多还原

【Abstract】 To investigate the water conservation function of litter and soil in degraded poplar plantation in Bashang plateau,a sample plot survey was conducted in poplar plantation with three degradations(light degradation,medium degradation and heavy degradation)in Zhangbei from July to September,2016,and water conservation characteristics of litter and soil were quantitatively analyzed.The results showed that:(1)Litter storage was sorted as light degradation(24.68t/hm~2)>medium degradation(13.43t/hm~2)>heavy degradation(3.66t/hm~2),and the effective retention capacity listed in the order of light degradation(29.28t/hm~2)>medium degradation(23.18t/hm~2)>heavy degradation(3.30t/hm~2),the maximum water-holding capacity followed the order of light degradation(34.90t/hm~2)>medium degradation(24.13t/hm~2)>heavy degradation(3.86t/hm~2),the maximum water-holding rate followed the order of light degradation(228.80%)>medium degradation(228.70%)>heavy degradation(119.94%).There was an logarithmic function relationship between water-holding capacity and immersion time,while a exponential function relationship was found between water-holding rate and immersion time.(2)The soil bulk density of the three poplar plantations ranged from 1.65 to 1.80g/cm~3,capillary porosity ranged from 27.42%to 33.64%,and the range of total porosity ranged was 29.97% ～ 38.57%.(3)There was a power function relationship between soil infiltration rate and infiltration time.The stable infiltration rate followed the order of medium degradation(3.32mm/min)>light degradation(2.58mm/min)>high degradation(2.44mm/min).The water conservation capacity of soil and litter of degraded poplar plantations in Bashang Plateau was at a poor level and decreased significantly with the increasing of degradation degree.Therefore,reasonable tree species selection should be paid attention to during forest managemen,and the seriously degraded forest land should be restored by replanting other tree species or promoting regeneration.The results could provide some theoretical basis and reference for the degradation evaluation and the restoration and reconstruction of local poplar plantation.更多还原