Abstract: Soil samples were collected from the depressions between karst hills by grid sampling method (5 m×5 m), and the spatial heterogeneity of soil nitrogen and phosphorus in surface layer (0-20 cm) under different land use patterns (burned land, mowing land, grassland, and fenced land) were investigated by classic statistics and geo-statistics. In the study area, the soil total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), and available phosphorus (AP) under the four land use patterns showed a moderate variation, with the contents being 5.40-6.26 g·kg^-1, 1.24-1.44 g·kg^-1, 365.87-507.32 mg·kg^-1, and 3.91-8.04 mg·kg^-1, respectively. The soil quality of fenced land and burned land was superior to that of grassland and mowing land. The soil AN of burned land, AP of burned land, AN of mowing land, and TN of fenced land were fitted well by spherical model; the soil TN of burned land, TN of mowing land, and AP of mowing land were fitted well by exponential model; and the other soil nutrient variables were fitted well by Gaussian model. A strong spatial autocorrelation occurred for the soil TP of mowing land, TP of burned land, TP of grassland, and TN of mowing land, AP of burned land, AP of grassland, and TN of fenced land, while a moderate spatial autocorrelation existed for the other variables. The soil TN and AN as well as the soil TP and AP under the four land use patterns showed the similar spatial distribution pattern. The soil TN and AN of burned land and mowing land presented a concave distribution, while the TP and AP showed a unimodal distribution. The soil TN, TP, AN, and AP in grassland all decreased with slope position, while these soil nutrients in fenced land presented concave distribution. Land use pattern changed the soil nutrient quality in the depressions between karst hills, and caused different spatial patterns of soil nutrients. Therefore, in the ecological restoration and reconstruction of karst region with broken landform and shallow soil, it should adopt rational land use pattern, protection, and moderate development to improve the soil quality of degraded ecosystems.

Key words: drought resistance, physiological characteristics., spring drought stress, relationship between root and leaf