黔中喀斯特山地不同森林类型的地表径流及影响因素

采用固定样地定位监测方法,于2001-2005年研究了黔中喀斯特山地不同森林类型对地表径流的影响。结果表明,不同林分类型的年地表径流量均值为11.108mm、林分类型间变幅为1.765-22.934mm、年际间变幅为10.553-11.699mm,退耕还林幼林(22.934mm)>针叶林(17.236mm)>针阔混交林(10.770mm)>阔叶林(8.876mm)。不同森林类型年地表径流量的季节变化为夏季>春季>秋季>冬季,同降雨量的季节变化趋势相一致。与同生物气候带、不同生物气候带森林相近类型的径流量规律相似,反映出黔中喀斯特山地森林与其它森林地表径流量规律的相似性。其中喀斯特山地森林中灌木林地表径流量与其它地带性和非地带性森林中灌木林地表径流量变化的相异性又反映出黔中喀斯特山地森林地表径流的特殊性,这种特殊性主要是成土母岩造成的。地表径流系数的季节变化趋势中,退耕还林幼林为夏季>春季>秋季>冬季,针叶林和针阔混交林为夏季>春季>冬季>秋季,灌木林和阔叶林为春季>夏季>冬季>秋季,这种差异与不同林分类型组成树种的生活型有关。旬地表径流量与反映温度和水分的气象指标间的单相关性达显著水平,多元回归方程模拟表明衡量温度的相关指标对地表径流量的贡献率高于降水,这反映了温度对近地气团的控制作用,进而影响区域降水和林地径流量。森林不同层片特征对地表径流量的影响具有互补性和抑制性,受森林群落组成、结构和发育的共同影响。年地表径流量受小生境和林地表层土壤特性的综合影响,地表径流量随坡度的增大而增加、随海拔的升高而降低,与毛管孔隙度和总孔隙度的负相关性达显著水平,多元回归方程模拟发现容重的贡献率达-96.54%。

Forest Surface Runoff and Its Influence Factors in Karst Mountainous Area in Center of Guizhou Province, China

Based on 5-year from 2001 to 2005 located observation in different types of forests in karst mountainous area in center of Guizhou Province, China, the annual surface runoff was from 1.765 to 22.934 mm in different forest types and from 10.553 to 11.699 mm in different observed years, with an average of 11.108 mm. The forest surface runoff changed in the order of young forest returned farmland (22.934 mm)> coniferous forest(17.236 mm)>needle and broad-leaved mixed forest (10.770 mm)>evergreen and deciduous broad-leaved forest (8.876 mm), which is similar to forests in the same or another bio-climate zones. And it is the common character of karst and nonkarst mountainous forests. The karst shrub forest was different from nonkarst in surface runoff due to mother rock properties. Surface runoff of the types was Summer>Spring>Autumn>Winter, coincided with seasonal distribution of precipitation. Seasonal changing rule of surface runoff coefficients in young forest returned farmland was as same as seasonal distribution of surface runoff, and the rule in coniferous forest and needle and broad-leaved mixed forest was Summer>Spring>Winter>Autumn, and the rule in shrub forest and evergreen and deciduous broad-leaved forest was Spring>Summer>Winter>Autumn, and this difference was made by species composition and precipitation distribution. There existed remarkable correlation, accorded to line, between surface runoff in ten days and hydrological factors include precipitation,evaporation and relative humidity, and temperature factors include Max. and Min. and average temperature in air and surface and soil deepth in 5 cm, 10 cm, 15 cm and 20 cm. Results of contribution ratio to surface runoff from multi-variances regression analyses was that temperature is higher than hydrology, and this indicated temperature affected flow of air mass near surface, and influenced further precipitation and forested surface runoff. Influence of layer characteristics in different forest types on annual surface runoff had mutual beneficent and repellency based on community component, structure and development. Annual surface runoff was affected complexly by micro-habitat and surface soil characteristics of plots, and increased by slope of plots rising, and decreased by altitude of plots rising, there had remarkable negative correlation between annual surface runoff and total porosity and capillary pore, and contribution ratio of volume weight to annual surface runoff was-96.54%, based on multi-variances regression analyses.