坡位对阴山北麓油松人工林表层土壤理化性质的影响

Effects of Slope Position on Physical and Chemical Properties of Surface Soil of Pinustabulaeformis Plantation in Northern Foot of Yin Mountains

坡位是影响林木的最重要的立地因子之一,对树木的生长、营养状况以及生态功能均会产生直接或间接的影响。以呼和浩特市武川县哈乐镇油松人工林为研究对象,比较了不同坡位间(坡上、坡中、坡下)油松人工林木,在0~20 cm深度的各表层土壤的物理化学性质,并分析了对土壤各指标的影响,为油松人工林经营提供依据。结果表明:多数表层土壤指标整体呈现出坡下>坡中>坡上;土壤孔隙度呈现出坡上最大,坡下最小,与土壤容重和土壤含水量刚好相反,说明坡下孔隙度紧密,因而水分也就越多;油松人工林林下土壤呈碱性,pH值范围在7.33~8.96;土壤有机质、土壤碱解氮、土壤速效磷和土壤速效钾含量均呈现出坡下最大,说明由于坡位原因,坡下土壤养分出现聚集现象,植被的生长状况也最好,多数的表层土壤养分指标高于底层含量,可能是由于上层土壤的枯枝落叶较多,分解后产生了大量养分;不同坡位下,油松人工林的表层土壤理化性质呈现出的相关性及相关性大小也各不相同,但在总体上存在一些较相似的变化规律,如:坡位与容重和速效钾呈极显著正相关(p<0.01),相关系数分别为0.926和0.974,坡位与土壤孔隙度呈极显著性负相关(p<0.01)相关系数为0.948,其他指标关系不紧密。为此,提出了在种植油松人工林时应充分考虑坡位因素,因地制宜,将有助于油松人工林的生长。

Slope position is one of the most important site factors,which has direct or indirect effects on the growth,nutrition and ecological functions of trees.Taking Pinustabulaeformis plantation in Hohhot town of Wuchuan County as the research object,the characteristics of Pinustabulaeformis plantation in different slope positions at a depth of 0~20 cm between different slope positions(on slope,in slope and under slope)were compared.The influence on soil indexes was analyzed to provide basis for the management of Pinustabulaeformis plantation.The results show that most of the topsoil indexes show a trend of slope-down>slope-middle>slope-up,and the soil porosity is the largest on slope and the smallest on slope-down,which is opposite to soil bulk density and soil water content,indicating that the soil porosity is close under slope.The soil under the Pinustabulaeformis plantation is alkaline,and the Ph value ranges from 7.33 to 8.96.The contents of soil organic matter,soil alkali-hydrolysable nitrogen,soil available phosphorus and soil available potassium are the highest under the slope.Under the slope,the soil nutrient accumulates and the vegetation grows best.The nutrient index of the surface soil is higher than that of the bottom soil,which may be due to the fact that there are more litter and leaves in the upper soil and a lot of nutrients are produced after decomposition.The physical and chemical properties of the surface soil of Pinustabulaeformis plantation were different,but there were some similar changes in the whole.For example,the slope position was positively correlated with bulk density and available potassium(p<0.01).The Correlation Coefficient was 0.926 and 0.974,respectively.The correlation coefficient between slope position and soil porosity was 0.948(p<0.01).Therefore,the slope position should be considered in planting Pinustabulaeformis plantation in the future,which will be helpful to the growth of Pinustabulaeformis plantation.