岩溶断陷盆地不同地貌部位土壤水时空分布规律及其影响因素

(1.中国地质科学院 岩溶地质研究所/自然资源部、广西岩溶动力学重点实验室, 广西 桂林 541004; 2.重庆市岩溶环境学重点实验室, 西南大学 地理科学学院, 重庆 400715)

土壤水; 时空异质性; 土壤质地; 降水; 植被; 裸岩

Spatiotemporal Dynamics of Soil Water and Its Influencing Factors Along Transect of Landform in Karst Graben Basin, Southwestern China
ZENG Rui1,2, ZHANG Tao1, PU Junbing1, LI Jianhong1, WANG Sainan1,2, CHEN Jinke1,2

(1.Key Laboratory of Karst Dynamics, MNR & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin, Guangxi 541004, China; 2.Chongqing Key Laboratory of Karst Environment, School of Geography Sciences, Southwest University, Chongqing 400715, China)

soil water; spatiotemporal heterogeneity; soil texture; precipitation; vegetation; bare rock

备注

云南蒙自岩溶断陷盆地作为典型的石漠化地区,对其土壤水文过程及其影响因素的揭示是土壤保护和植被恢复的必要条件。通过在盆地、坡面、高原面设置高分辨率长期监测站,探讨云南蒙自岩溶断陷盆地不同地貌部位不同深度土壤水分的时空动态及其影响因素。结果 显示:(1)研究区土壤水分含量的空间分布有两大趋势,一是随着海拔升高而增加,二是随着土层深度增加而降低;(2)土壤含水量雨季高于旱季,但土壤水变异程度的年内季节差异较小,属于弱变异及中等程度变异,表明研究区土壤水分的年内波动较为和缓,对植被的生长恢复有利。(3)盆地土壤水受前期土壤水分条件影响,在全年的变异程度强于坡面及高原面。同时受土壤质地及孔隙度等影响,盆地及高原面的下层土壤水分变异低于上层土壤。(4)各监测点土壤水分含量变化与降水变化的一致性较高,说明降水是影响该区土壤水分含量变化的重要因素,但由于土壤质地、植被、裸岩等因素的差异,盆地与降水之间的一致性要优于坡面及高原面。总之,云南蒙自岩溶断陷盆地不同地貌部位的土壤水分在土壤质地、植被及降水环境的综合影响下具有显著且规律的时空变化,这将有助于指导盆地的植被复建以及水资源调配工作,为岩溶断陷盆地的石漠化治理提供依据。

The hydrological process of soil moisture and its influence factors are the limitation for soil protection and vegetation restoration in the typical rocky desertification area. To explore the dynamic distribution and its influence factors of soil moisture in different slope positions and different depths, high-resolution and long-term monitoring stations were set up in basin, transitional slope, and mountainous area of the Mengzi karst basin in Yunnan Province. The results show that:(1)two major trends in the spatial distribution of soil moisture include that soil moisture increases with the elevation and decreases with the depth of the soil layer;(2)the soil moisture of the fault depression basin in the wet season is much higher than that in the dry season, but the seasonal difference of soil moisture variation is little and changes from weak to moderate variability, which is beneficial to the growth of vegetation;(3)with respect to spatial pattern, the soil moisture variation degree in the basin is higher than that of the slope and mountainous area in the whole year because the initial soil moisture condition; additionally, the soil moisture variation of lower subsoil in the basin and the mountainous area is lower than that in the upper soil due to the soil texture and porosity;(4)the soil moisture changes with precipitation in the three monitoring points, which indicates that precipitation is an important factor affecting soil water variation, and this homogeneity between soil water and precipitation in the basin is better than that of the slope and mountainous area due to soil texture, vegetation and bare rock. The soil moisture exhibits significant and regular spatiotemporal variations and is controlled by the combined influence of soil texture, vegetation and precipitation environment in the Mengzi karst graben basin, Yunnan, which will play the important roles in improving the vegetation restoration and water resources management, and provide the basic data for the control of rocky desertification in karst depression basins.