Abstract:
Through the classical statistics and the geological statistics method, the spatial variation patterns of soil water of rehabilitated forest and natural restoration grassland in different recovery time (15 a, 25 a) and different soil layer (0-20 cm, 20-40 cm) in the degraded red soil region, Taihe, Jiangxi Province was compared and analyzed. The results show that the soil moisture of rehabilitated forest and natural restoration grassland were uniformly distributed at the beginning. With the growing years, the soil moisture would rise and discrete degree would also increase in different extent for moderate variability. The distribution of soil moisture was the normal distribution, matched a spherical model (
R2 > 0.804). The data showed the significant spatial correlation and spatial variation characteristics, which mainly came from soil parent materials, topography and other structural variation. There was a significant increase in the nugget, sill and nugget/sill. The total variation had increased and caused by random factor according to the time alignment. The sill in the 0-20 cm soil layer of natural restoration grass was higher than that in the 20-40 cm soil layer at the same year, but the nugget and nugget/sill showed the contrary, so the random variation of under layer soil moisture was stronger than upper layer. For the rehabilitated forest, the 3 indexes showed that upper soil layer higher than under layer, and the random variation in surface layer was stronger. The spatial heterogeneity of surface soil moisture in rehabilitated forest increased with the restoration years, and displayed serious fragmentation. The variation range of the 2 layers (0-20 cm and 20-40 cm) in natural restored grass significantly increased with the change of time. The increased sampling density and extend slope would reveal spatial variation characteristics of soil moisture in degraded red soil region.