喀斯特地区土壤温度变化特征及其与环境因子的关系

喀斯特地区土壤温度变化特征对研究该区土壤活性及小气候变化具有重要意义。为探明喀斯特地区土壤温度变化特征及其与环境因子的关系，以喀斯特高原峡谷区四种典型土地类型（花椒地、金银花地、火龙果地、荒地）为研究对象，采用土壤含水量监测系统（ECH2O）对各样地土壤温度变化进行连续定点监测，分析土壤温度的动态变化特征及其与环境因子的关系。结果表明：10 cm处土壤温度日变幅最大，土层越深日变幅越小；土壤温度日变幅为夏季较大，秋、冬季较小。火龙果地、金银花地土壤温度日变幅明显大于花椒地、荒地；随着土层加深，土壤温度日变化出现滞后现象；不同季节土壤温度均为火龙果地 > 荒地 > 花椒地 > 金银花地。夏季土层越深，土壤温度越低；秋、冬季土层越深，土壤温度越高；土壤垂直温度变异系数表现为冬季大于夏季。相关分析表明，土壤温度与气温、太阳辐射及土壤含水量均呈显著正相关（P<0.05），土壤温度变化与容重、孔隙度、土壤质地、有机碳等土壤理化性质相关性显著。花椒地土壤温度日变幅最小，与其较高的土壤含水量和总孔隙度、容重小、土壤持水性强密切相关。综上，花椒地对土壤温度的调节效果较好，因此，在喀斯特地区生态恢复的过程中，种植花椒能在一定程度上改善土壤性质，提升土壤肥力。本研究为喀斯特地区的生态恢复提供了科学依据，为植被生态效益评价提供一定参考。

Characteristics of soil temperature variation in karst area and its relationship with environmental factors

Characteristics of soil temperature variation in karst area are of great significance to the study of soil activity and microclimate change. To verify the variation characteristics of soil temperature in karst areas and its relationship with environmental factors, four typical land types including Zanthoxylum bungeanum (HJ), Hylocereus undulates (HLG), Lonicera japonica (JYH) and wasteland (HD) in the Karst plateau canyon were taken as research objects. Soil moisture monitoring system (ECH2O) was used for continuous fixed-point monitoring of different sites. The dynamic change characteristics of soil temperature at different time scales and its relationship with environmental factors were analyzed. The results showed that the daily variation of soil temperature was characterized by the sharpest diurnal variation of soil temperature appeared at 10 cm, and the deeper the soil depth, the smaller the diurnal variation. There was a great diurnal variation of soil temperature in summer but a smaller in autumn and winter. The diurnal variation of soil temperature in HL and JYH were significantly greater than that in HJ and HD as the soil depth deepens. There was a hysteresis effect in the diurnal variation of soil temperature. The daily variation of soil temperature at 10 cm and 25 cm of different land types showed a cubic function. The variation of soil temperature in different seasons was as follows:HLG > HD > HJ > JYH. The vertical variation characteristics of soil temperature was that the deeper the soil layer in summer, the lower the soil temperature was. The deeper the soil layer in autumn and winter, the higher the soil temperature. The vertical variation coefficient of soil temperature was greater in winter than in summer. There was significantly positive correlation between soil temperature with atmospheric temperature, solar radiation and soil moisture content (P<0.05). There was also a significantly close correlation between soil temperature variation with soil properties such as soil bulk density, porosity, soil texture, and organic carbon. The diurnal variation of soil temperature in HJ was the smallest, which has a close relationship with the higher soil moisture content and porosity, the better soil water holding capacity and the smaller bulk density. The soil temperature regulation capacity of HJ was the best among the four land types, therefore, the land type of HJ can improve soil properties and soil fertility to a great extent in the process of ecological restoration in karst areas. This study provides a scientific basis for ecological restoration and some reference for ecological benefits evaluation of vegetation in karst areas.