| The Soil temperature and moisture are the main factors that affect the soil fertility, and play an important role in the soil physical and chemical properties, biological processes and regional microclimate. The characteristics of land cover influence soil temperature and moisture strongly, especially in typical karst area with vegetation damaged seriously, soil and water lossed tempestuously, natural disasters occured frequently and development and conservation conflicted distinctly. In order to understand the characteristics of soil temperature and moisture in karst erea, the study was carried on in different communities(Form.Pinus yunnanesis, Form. Quercus variabilis and secondary bareland) in Shilin, China. The main results are as follows:(1) During the study period, the average temperature is 16.2℃ almost equaled to average annual temperature(16℃), and the annual rainfall is 695.8mm that less 272.1mm than the average annual rainfall(967.9mm). The average temperature of secondary bareland is 19.4℃, Form. Quercus variabilis is 17.5℃ and Form.Pinus yunnanesis is 15.3℃.The average moisture of Form.Pinus yunnanesis is 36.9%, secondary bareland is 35.4% and Form. Quercus variabilis is 24.6%.(2)Atmospheric temperature could explain 20 cm soil temperature changes of secondary bareland is 85%, Form. Quercus variabilis 82.5% and Form.Pinus yunnanesis 60% respectively. The 120 cm depth soil temperature of Secondary bareland, Form. Quercus variabilis, Form.Pinus yunnanesis are variation of 67%, 58% and 35%. The explain extent of atmospheric temperature on soil temperature in 3 habitats: secondary bareland>Form. Quercus variabilis>Form.Pinus yunnanesis.(3)The soil temperature in the study area showed:secondary bareland>Form. Quercus variabilis>Form.Pinus yunnanesis, but it changes with the time scales, soil profile and communities significantly. The diurnal amplitude of soil temperature appeared two peaks(Dec. and May) and two troughs(Mar. and Sept.) dunring the period, curved as roughly "M". We can infer that when the seasonal transition the soil temperature changed sharply. However, the inter-monthly soil temperature variation was changed with the season shifting. The rangeability of soil temperature in variation depth of spring, autumn and winter is relatively bigger than that of summer. In spring, the variability of soil temperature at 20 cm depth is medium and 120 cm weak. In summer,the variability of soil temperature is weak because of the high atmosphere temperatures. In autumn, the variability of soil temperature is mediun. In winter, the variability of soil temperature at 20 cm is medium, and in secondary bearland and Form. Quercus variabilis is equal and bigger than that of Form.Pinus yunnanesis. The small variation of Form.Pinus yunnanesis in winter,it provides a good environment for the seedling in the topsoil. The variation of soil temperature at 120 cm depth with a seasonal differences significantly and Form.Pinus yunnanesis(0.10) > Form. Quercus variabilis(0.08) > secondary bareland(0.07). The soil temperature of the rainy season was higher than that of dry season, and the difference with average was greater than dry season(4) Four special meteorological events(small to moderate rain, heavy rain, heavy rain and snow) were analyzed. In small to moderate rain intensity of precipitation, the soil temperature is stable. The soil temperature is diversity in heavy rain at different communities, and it can change the soil thermal directions and microhabitats in secondary bearland and Form. Quercus variabilis. The rainstorm can decrease the soil temperature rapidly but maintain shortly. During the rainstorm, the soil thermal gradient is decreased then increased with a big extent. In snowfall(December 12 to 20), secondary bareland soil temperature from 15.6 ℃ down to 12.6 ℃, 23.8% decline; Form. Quercus variabilis from 14.3℃ down to 11.4℃, 25.4% decline; Form.Pinus yunnanesis from 12.7℃ down to 10.2℃, a decline of 24.5%. Because of the short duration and little quantity in the snow, the snowflakes was melt quickly, so it just declines the soil temperature acceleratedly more than heat preservation.(5) The soil moisture is difference in communities. The moisture is relatively high Form.Pinus yunnanesis. With high rock patches persentage and loos soil, the secondary bareland soil moisture is less than that of Form.Pinus yunnanesis and bigger than that of Form. Quercus variabilis. Because of higher forest canopy interception(21.35%), the moisture is low and variability is weakly in Form. Quercus variabilis.(6)Soil moisture in Shilin Karst area has a strong temporal and spatial heterogeneity, In the time scale, secondary bareland 80 cm soil containing water maximum and minimum time is different from other sample plot, the remaining plots of each soil layer minimum value appeared in the late spring, maximum value appeared at the end of the summer, reflecting the distribution of precipitation time on soil moisture content influence. But on the whole features showing Form.Pinus yunnanesis(36.9%) > secondary bareland(35.4%) > Form. Quercus variabilis(24.6%). 20cm-80 cm, the characteristic of soil moisture is: Limestone bare land > Quercus variabilis forest > Form.Pinus yunnanesis, in the spatial scale. When the depth increases to 80 cm above, all kinds of soil containing the deviation of water is in Form.Pinus yunnanesis > Form. Quercus variabilis>secondary bareland, with the improvement of forest, deep soil moisture showed an increasing trend.(7) Due to the surface habitat differences larger, resulting in in the dry season, the rainy season, all kinds of soil moisture in infiltration capacity there is a great difference, but from the soil thermodynamic effect on the moisture change point of view, Yunnan Stone Forest in the dry season, the rainy season the soil water potential basically flat.(8) The special meteorological events, heavy rain weather, accept the Form. Quercus variabilis all soil depth and Form.Pinus yunnanesis 20 cm, rains of precipitation of other soil moisture variation coefficient of determination to 0.87, especially 80 cm deep layers are more than 0.91, continuous heavy rain, rain intensity of precipitation on soil moisture replenishment effect is the most significant, including snowfall events during the test period. Main contribution of Rainstorm in surface runoff, recharge rivers and lakes, in heavy rain, broad-leaved forest effective block erosion of precipitation on the forest humus. In addition, the continuous rain weather can also increase the soil moisture, supply soil moisture.(9) The relationship between soil temperature and moisture is complex. At 20 cm depth, the soil temperature and moisture shows an obvious negative correlation relationship, but a significant positive correlation between the two at the deeper soil layers. Because with the water infiltration leading the soil specific heat capacity increased, the deep soil layer temperature is raised.(10) In secondary bareland, the main controlling factors of soil moisture is temperature(air temperature and soil temperature) when lack of precipitation. The temperature(air temperature and soil temperature) and precipitation control the moisture commonly when rainfall is abundant, and the precipitation is more important than the temperature.
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