内蒙古呼伦贝尔南部沙带植被恢复进程中土壤理化特性变化

为了解呼伦贝尔沙漠人工植被恢复进程对土壤理化性状的改善效应,论文选取呼伦贝尔沙地人工和自然状态下植被恢复的2个系列、7种样地类型开展研究。结果显示：1）随植被恢复年份的增加及流动沙丘向固定沙丘的演进,地上植被生物量、盖度显著增加;2）2个系列样地土壤有机C含量均随植被的发展而显著增加,土壤上层显著高于中、下层;3）土壤全N、全P含量表现出与土壤有机C基本一致的同向变化规律,土壤全K含量在各样地间、各土壤层间基本相当;4）土壤速效养分含量一定程度上也出现增加,但总体上表现出较大的波动性。人工植被恢复1~3 a内,土壤养分含量与流动沙丘基本相当,但当恢复到5 a以上后,地上植被的发展对土壤特性的改良呈现出较为显著的正效应,沙漠化逆转程度显著提高。然而,拥有更高植被盖度及生物量的8 a人工植被恢复样地,有机C、全N等含量却显著低于自然状态下的固定沙丘样地,可见,当地人工植被恢复的同时,更应注重自然植被的保护。

Changes of Soil Physical and Chemical Properties with the Development of Artificial Planted and Natural Invaded Vegetation in Southern Hulunbeir Sandy Land

To understand the improving effect of vegetation restoration on soil properties in sandy land, a study was carried out in Hulunbeir sandy land of North China in 2014. Seven plots, named 8Y (vegetation restoration of 8 years), 5Y (5 years), 3Y (3 years), 1Y (1 years), MD (Moved Dune), SD (Semi-fixed Dune) and FD (Fixed Dune), were set for analyzing the physical and chemical properties of soil, such as content of soil water, pH, soil organic carbon (SOC), total nitrogen (N), total phosphorus (P), total potassium (K), available N, available P and available K. The seven plots belong to two series of vegetation types respectively, which are temporal pattern based on artificial vegetation (for 8Y, 5Y, 3Y and 1Y) and spatial pattern based on natural vegetation (for MD, SD and FD). The results show: 1) With the increase of restoration time, the biomass and vegetation coverage increased significantly at both types of plots. The biomass is 267.6 and 79.8 g/m² respectively on 8Y and FD, and the vegetation coverage is 75% and 50% respectively. 2) The content of SOC increased significantly with the development of the vegetation at both types of plot, and the content in upper layer of soil is significantly higher than that in middle and lower layer of soil. The SOC of upper layer soil is up to 3.85 and 3.22 g/kg respectively in 8Y and 5Y, but is up to 7.99 g/kg in FD. 3) The content of total N and total P show similar tendency as SOC, but the content of total K has no significant difference among plots or soil layers. The total N of upper layer soil ranges between 0.08 and 0.41 g/kg from 1Y to 8Y, between 0.16 and 0.61 g/kg from MD to FD, and the total P ranges between 0.21 and 0.48 g/kg from 1Y to 8Y, and between 0.29 and 0.50 g/kg from MD to FD. 4) The content of soil available nutrients also increases with the development of vegetation to a certain extent, however with an undulation. Generally, the contents of soil nutrients at the plots of 1Y and 3Y are similar with that of MD. When it is planted after more than 5 years, the artificial vegetation can have a significant effect on improving the physical and chemical properties of soil and mitigating the desertification. However, the contents of SOC and total N are significantly lower at the plot of 8Y than that at the plot of FD. Thus, when developing the human-planted vegetation, local government should pay more attention to the protection of natural vegetation.