广西森林土壤主要养分的空间异质性

Abstract

通过对广西区7大森林片区的11个主要森林类型样地土壤养分含量进行分析，利用地统计学方法，研究了广西区森林主要土壤养分的空间变异状况及分布格局，探讨了其相关的生态学过程，以期为广西区森林分区与林间采取不同措施管理提供科学依据。结果表明：广西区森林土壤主要养分基本属于中等变异，速效养分变异大于全量养分，其中AP、AK变异程度最大；广西森林土壤主要养分的半变异函数均表现出一定的空间结构特征，TN、TP、AP表现为中等强度的空间自相关，TK、AN、AK表现为强烈的空间自相关；不同土壤养分空间结构不同，Kriging等值线图表明广西区氮素含量比较丰富、K含量中等、P含量较少，北部片区土壤养分含量普遍大于南部片区，这可能与气候、降雨、人工种植森林树种、地形、林地管理措施等有关。;Soil is a complex natural system with strong spatial heterogeneity of its internal properties. The properties of soil are strongly varied even at the centimeter scale and the changes in soil properties on a large scale have a pivotal role in the patterns of ecosystem growth. Soil fertility is one of the most important ecological functions of soil and its spatial layout and structure directly affects the ability of plants to recover from stress as well as affecting plant height and overall ecosystem productivity. In the fragile habitats of the Guangxi area, the spatial distribution characteristics of soil nitrogen (N), phosphorus (P) and potassium (K) are strongly related to the regional distribution of shrub vegetation. Studies on the nutrient variability in forest soil of this area will help to understand the plant community structure and ecosystem energy flows. Forest resources are very rich in the Guangxi area making it one of the most important forest areas in southern China. Located in the southwest of China, Guangxi's forest is obviously geographically different to the rest of China. In recent years, the forested area of Guangxi has substantially increased through the introduction of a variety of tree species. This abundant introduced forest type is beneficial to economic development, but a lack of understanding of the nutrient distribution in forest soils in Guangxi has led to poor decisions regarding which tree species to introduce. This, in turn, has led to a decline in the quality of forest soil, has wasted resources and has limited the development of the forestry industry in Guangxi. This research investigated the main soil nutrients (N, P and K) of eleven forest types in seven forest districts in Guangxi. Geostatistics is used to study the spatial variation and pattern of the soil nutrients, and then the ecological implications of this were discussed to provide a scientific basis for forest division and management decisions in Guangxi. The results showed that the main forest soil nutrients in Guangxi had an overall medium level of variability but the variability of the soil available nutrients was larger than soil total nutrients, among which the variability of available P and K were largest. All the semi-variable functions of forest soil nutrients in Guangxi showed distinct spatial structural features. Soil total N and P and available P performed moderate spatial autocorrelation, while soil total K and available N and K performed strong spatial autocorrelation. The spatial structures of forest soil nutrients were diverse. The kriging contour maps showed that the soil N pool was abundant, the K pool was medium and the P pool was relatively low in Guangxi forest soils, and that the main soil nutrient contents in the north district of Guangxi was larger overall than in the south district. The spatial pattern of the main soil nutrients in Guangxi forests may be related to climate, precipitation, plantation forest species, topography and forest management practices and the effect of these factors on soil nutrients requires further investigation.