岷江上游典型油松人工幼林的生态环境效应

Eco-environment Effects of the Typical Young Pinus Tabulaeformis Plantation Rehabilitation in the Upper Reaches of Minjiang River

油松林是岷江上游和大渡河上游地区河谷与中山段灌丛地上恢复重建的代表性人工林类型之一,还缺乏深入研究。选择岷江上游典型的油松幼林,通过2a的定位监测,研究了油松林恢复重建的生态环境效应。1)与重建前的灌丛比较,油松幼林林下土壤物理性质(容重、土壤孔隙度、非毛管孔隙度、土壤重力水库容、土壤水向下渗透性速度、土壤通气度)得到明显改善,土壤持水能力提高了16%;2)油松幼林林冠对降雨的拦截和再分配作用明显。雨量等级低,拦截作用越大,尤其是当降雨量小,历时较长时,截留率越高,对降水的涵养比率越高。油松幼林生态系统能全部就地涵养全年降雨频率60%～70%的<10mm等级的雨量而不致产生明显的地表径流;对于占全年降雨频率35%～30%的10～50mm等级的降雨量,有至少30%～50%能被油松林生态系统就地涵养;3)重建的油松幼林林下土壤平均侵蚀模数36t·km-2·a-1,灌丛地表为713t·km-2·a-1,分别比裸地少99 55%和91 09%,而同期灌丛地表平均径流模数有38 90×104m3·km-2·a-1,油松幼林为7 23×104m3·km-2·a-1,分别比裸地减少79 47%和99 96%,油松林重建基本控制了土壤侵蚀和水土流失;4)油松林重建明显降低了不同深度的土壤温度。夏季降低的效果明显强于秋季。油松林内与林缘灌草丛5cm层土温较裸地分别平均?

Interception on rainfall by tree canopy, soil physical characteristics, and microclimate change were monitored in 14-years-old Chinese pine (Pinus tabulaeformis) forest plantation which had a density with (2 700) stems/hm^2, the crown density 90%, the average height with 6 m and DBH with 12cm, one of the typical plantation in the upper reaches of the Minjiang River and nearby shrubs. The eco-environmental effect of the artificial forest were studied and evaluated. Compared with the degraded shrubland, the soil physical properties (including soil bulk density, soil porosity, non-capillary porosity, volume of soil gravity water-holding, soil permeability, soil ventilative porosity) were significantly improved after 12 years rehabilitation, and soil moisture capacity increased 16%.The effect of the interception and redistribution of precipitation by Chinese pine plantation were quite evident. Young Chinese pine plantation ecosystem could intercept all rainfall(<10 mm class) which accounts for 60%～70% of all rainfall in the region and intercepted 30%～50% of rainfall (10～50 mm) that accounts for 30%～35%. The average erosion modulus is 36 t.km^(-2)·a^(-1) and 713 t·km^(-2) in the young Chinese pine plantation and in the nearby shrubs respectively, which respectively droped 99.55% and 91.09% than in the bared ground. In the meantime the average ground runoff modulus is 3.89×10~5 m^3·km^(-2)·a^(-1) and 7.23×10~4 m^3·km^(-2)·a^(-1), which are respectively lower 79.47% and 99.96% than that in the bared ground. Loss of soil and water had been controlled by the Chinese pine plantation. The soil temperature of varied depth (5 cm, 10 cm, 20 cm, 40 cm, 70 cm and 100 cm) decreased significantly in the Chinese pine plantation. The effects are more prominent in summer than in autumn. The soil temperature(5cm) in the young Chinese pine plantation and in the shrubs is respectively lower 4.4℃ and 3.8℃ than in the bared land. The air humidity in the Chinese pine plantation is higher 4%～9% than on the bare land during from May to September, the average is 6%. The air temperature in the Chinese pine plantation is lower 0.35℃ than on the bare land during from May to September. These results displayed that the effect of the Chinese pine plantation on eco-environment is significant in the upper reaches of the Minjiang River, implicating that forest restoration is one of the reliable and effective method to promote ecological function restoration.