不同林龄兴安落叶松枯落物及土壤水文效应研究

Hydrological Effects of Forest Litters and Soil in Xing'an Larch Forest at Different Stand Ages

林地植被和枯枝落叶层共同发挥着森林生态系统所特有的水文生态功能。对大兴安岭兴安落叶松（Larix gmelinii（Rupr.）Kuzen.）中龄林、近熟林、成熟林、过熟林四种林下枯落物及土壤进行野外实地取样和室内样品处理进行分析,结果表明：兴安落叶松林下枯落物层表现为随林龄增加总存储量增加,变化在18.02～21.65 t·hm^-2,半分解层的存储量为未分解层的4.8～5.9倍,其中近熟林枯落物半分解层蓄积量所占比例最大为85.3%。不同林龄枯落物最大持水量和最大持水率均表现为半分解层大于未分解层,且以过熟林最大。最大持水量为过熟林〉近熟林〉成熟林〉中龄林,变动在40.13～75.60 t·hm^-2之间,最大持水率为过熟林〉近熟林〉中龄林〉成熟林,变动在5.94%～7.93%之间。不同林龄枯落物有效拦蓄率差异很大,变化在30.18%～422.98%,林龄越大,分解程度越大,有效拦蓄越强,总体未分解层均小于半分解层。有效拦蓄能力也有差异,过熟林表现为最强,总有效拦蓄量达70.57 t·hm^-2,相当于拦蓄7.26 mm的降雨,不论从最大持水量、最大持水率还是有效拦蓄量过熟林一致表现为最强。不同林龄枯落物持水过程,在浸泡0.5 h内吸水速率最大,4 h之后减小,8 h时持水量基本达稳定,在整个持水过程中半分解层持水能力均高于未分解层。不同林龄土壤透水性、通气性均比较好。10～20 cm土层表现为随林龄增加而减小,变化在0.48～0.88 g·cm^-3;20～40 cm土层则表现为随林龄增加而增加,变化在1.03～1.41 g·cm^-3之间;各层土壤毛管孔隙度均表现为中龄林〉近熟林〉成熟林〉过熟林。各土层持水性能无论是毛管持水量、最小持水量还是最大持水量都表现为中龄林最大,随林龄增加而减小的趋势,并且持水能力浅层均较深层的大。中龄林在10～20 cm土层分别达是162.16、122.07和213.00 t·hm^-2,20～40 cm土层分别达是77.22、58.13和86.43 t·hm^-2;过熟林在10～20 cm土层为100.36、68.43和156.98 t·hm^-2,20～40 cm土层只有31.09、24.26和37.83 t·hm^-2,不同林龄各层土壤质量含水量、体积含水量也表现出相同的变化规律。该研究可为制定科学合理有效的经营管理方式和砍伐措施提供理论依据。

Under the impact of global climate warming,forests as the main terrestrial of ecosystems will undoubtedly be affected,especially the forest hydrological cycle will become more apparent.Precipitation will be reallocated by different forest vegetation and the enrichment litter of surface,which forms a feedback effect on climate change and also affects the soil water content of the forest.So forest vegetation and litter layer play unique forest ecosystems＇ hydrological and ecological function that largely regulated the global water cycle and water balance.A study of hydrological effects of litters layer and soil layer was carried out through field sample collection and treatment on different ages of Larch in Greater Xing＇an Mountains forest,middle-aged forest,near mature forest,mature forest,overmature forest.Results showed that the increment of litter layer accumulation increased with forest age,ranging from 18.02 to 21.65 t·hm^-2,and the total storage of semi-decomposed is 4.8～5.9 times of decomposed; Semi-decomposed layer accumulated amount of near mature forest was 85.3% at most.For all age of the forests,the water holding ratio and capacity were largest in over mature forest and semi-decomposed 〉 decomposed, the order of the water holding capacity was over mature forest 〉 nearly mature forest 〉 mature forest〉mid-maturation forest between 40.13 and 75.60 t·hm^-2, the water holding ratio was over mature forest 〉 nearly mature forest 〉 mid-maturation forest 〉 mature forest between 5.94% and 7.93%. The modified interception rate was great different,varied from 30.18% to 422.98%.It increased with ages and decompositions.On the whole un-decomposed layer is less than semi-decomposed layer.The modified interception showed different,the total modified interception of over mature forest was up to 70.57 t·hm^-2,equivalent to 7.26 mm of rainfall.Over mature forest was the strongest in the water holding ratio,the water holding capacity and the modified interception.Different Age of litter water-holding process,the maximum water absorption rate is in soaking 0.5 h,it decreases after 4 h,and basically reached stable at 8h.The water-holding of half-decomposed layer was higher than un-decomposed layer in whole process.Forest soil has good water permeability and air permeability in different ages.In 10～20 cm soil layer,it decreases with increasing forest age,ranging between 0.48 and 0.88 g·cm^-3,For 20～40 cm soil layer,it increases with the increase of forest age ranging from 1.03 to 1.41 g·cm^-3.Each layer soil capillary porosity-presented that mid-maturation forest 〉 nearly mature forest 〉 mature forest 〉 over mature forest.Water-holding capacity of mid-maturation forest is maximum concerning capillary water capacity,minimum moisture capacity and maximum moisture capacity for each layer and it decreases with increasing forest age,with shallow layer larger than deep layer.Regarding mid-maturation forest,capillary water capacity,minimum moisture capacity and maximum moisture capacity for 10～20 cm soil layer are 162.16 t·hm^-2,122.07 t·hm^-2 and 213.00 t·hm^-2 respectively and 77.22 t·hm^-2,58.13 t·hm^-2 and 86.43 t·hm^-2 for 20～40 cm soil layer.For over mature forest,the above parameters are 100.36 t·hm^-2,68.43 t·hm^-2 and 156.98 t·hm^-2 at 10～20 cm soil layer,while at 20～40 cm layer,values decreased to 31.09 t·hm^-2,24.26 t·hm^-2 and 37.83 t·hm^-2.Soil water and bulk density show the same changing regulation at each layer for different age forests.This article about hydrological effects of forest litters and soil in Xing-an larch forest at different stand ages can provide theoretical basis guide for making effective management and felling measures,while beneficial to the healthy growth and development of Sustainable water conservation and ecological environment in the Greater Xing＇an Mountains forest regions.