青藏高原东北边缘云杉属-冷杉属林火烧迹地枯落物持水特征

Water Retention Characteristics of Litter in Fire-burned Land of Spruce and Abies Forests on the Northeastern Margin of Qinghai-Tibetan Plateau

以青藏高原东北边缘云杉属-冷杉属林火烧迹地为研究对象,基于典型抽样法于2020年8月和2021年7—8月在火烧迹地和未过火天然林采集枯落物样品,采用室内浸泡法测定分析枯落的蓄积量、持水量、有效拦蓄量等指标,探究林火干扰下不同坡位枯落物的水文效应,为更好地促进森林水源涵养以及水土保持功能提供依据。结果表明:(1)在植被恢复过程中,枯落物的厚度和蓄积量随着恢复年限的增加而增加,且厚度为3.75~8.31 cm,蓄积量为6.16~8.13 t/hm^(2)。恢复5,15年火烧迹地上、中、下坡枯落物厚度和蓄积量与天然林差异显著。(2)枯落物的最大持水量为20.94~26.22 t/hm^(2),恢复5,15年火烧迹地枯落物最大持水量与天然林差异达显著水平。在枯落物持水达到饱和前,不同恢复年限下各坡位枯落物持水量与浸水时间呈对数函数关系,吸水速率与浸水时间呈幂函数关系。(3)枯落物的有效拦蓄量为14.58~16.95 t/hm^(2),有效拦蓄深为1.44~1.78 mm。恢复5年火烧迹地枯落物有效拦蓄量表现为中坡>上坡>下坡,恢复15年火烧迹地和天然林有效拦蓄量均为下坡>中坡>上坡。综上所述,在植被恢复过程中,枯落物的厚度、蓄积量、持水性能都随着恢复年限的增加而提高,呈现天然林>恢复15年>恢复5年;火烧迹地枯落物的持水性能及持水过程呈现中、下坡大于上坡,即枯落物的水文效应受坡位和火烧干扰的影响。

Taking the spruce-fir forest fire sites on the northeastern margin of the Qinghai-Tibet Plateau as the research object,the samples were collected from the burned sites.Ubed unburned natural forests in August 2020 and July-August 2021 based on the typical sampling method and indoor immersion method.Litter samples were measured and analyzed for indicators such as storage volume,water holding capacity,and effective storage capacity,to explore the hydrological effects of litter at different slope positions under the disturbance of forest fires,and to provide a basis for better-promoting forest water conservation and soil and water conservation functions.The results show that:(1)During the vegetation restoration process,the thickness and accumulation of litter increased,with the longer restoration years,and the thickness was 3.75~8.31 cm,and the accumulation iss 6.16~8.13 t/hm^(2).The more thickness and volume of litter on the above-up-slope,mid-slope,and down-slope in the recovery 5 and 15 years fire sites were significantly different from those in the natural forest.(2)The maximum water-holding capacity of litter is 20.94~26.22 t/hm^(2),and the difference between the maximum water-holding capacity of the litter in the 5 and 15 years of recovery and the natural forest reaches a significant level.Before the water-holding capacity of the litter reaches saturation,the water-holding capacity of the litter at each slope position has a logarithmic function relationship with the water immersion time,and the water absorption rate has a power function relationship with the water immersion time under different recovery years.(3)The effective storage capacity of litter is 14.58~16.95 t/hm^(2),and the effective storage depth is 1.44~1.78 mm.The effective interception of litter in the restored 5 years burmed are shows the order of mid-slope>up-slope>down-slope,and the effective intercepted amount of the restored 15-year-burned area and the natural forest is down-slope>mid-slope>up-slope.To sum up,in the process of vegetation restoration,the thickness,volume and water-holding capacity of litter improved with the increase of the restoration period,showing that natural forest>restoration 15 years>restoration 5 years;The water performance and water holding process showed that the middle and lower slopes were larger than the upper slopes,that is,the hydrological effect of the litter was affected by the slope position and the disturbance of fire.