淮北土石山区不同土地利用方式对土壤团聚体组成的影响

Effects of Different Land Use Types on Soil Aggregate Composition in Rocky Mountain Area of Northern Huai River

为了探索经济林发展对土壤性质的影响,以赣榆区西北部小流域为研究区,选取具有代表性的三种经济林类型(板栗林、苹果林及山楂林,三者均为针阔混交林转变而来),并以无人为干扰的针阔混交林为对照,采用湿筛法研究了不同土地利用方式下土壤团聚体状况和变化规律,并基于非度量多维尺度分析(NMDS)探究了其影响机制。结果表明:(1)0～10 cm和10～20 cm土层上,随着粒级的增大,各土地利用方式团聚体百分含量呈先增大后减小的趋势,整体而言,不同土地利用方式下团聚体组分的差异主要表现为针阔混交林和经济林间的差异,团聚体百分含量存在差异的粒级主要为<0.25 mm和>1 mm的团聚体。(2)平均重量直径(MWD)在不同土地利用方式下差异性显著,0～10 cm,针阔混交林土壤MWD显著大于板栗林; 10～20cm,板栗林和山楂林土壤MWD显著大于苹果林; 20～30 cm,山楂林土壤MWD显著大于苹果林,几何平均直径(GMD)变化不明显。(3)NMDS轴分析显示土壤容重与NMDS1显著相关,土壤总有机碳、总氮和碳氮比与NMDS1略相关,土壤总有机碳与NMDS2略相关。研究表明经济林的营造影响了土壤团聚体状况,且主要表现为土壤中大团聚体比例的降低和微团聚体比例的上升,总体而言,经济林团聚体稳定性低于针阔混交林,其中苹果林土壤团聚体稳定性最差,土壤容重和土壤碳氮是影响土壤团聚体组分的重要因素。

In order to explore the effect of developing economic forest on soil properties, this paper took the small watershed in northwestern Ganyu district as the research area, selected 3 typical economic forest types ( chestnut forest, apple forest and hawthorn forest, which were all converted from conifer-broad leaf forest), took conifer-broad leaf forest with no human interference as the contrast, and studied the status and change law of soil aggregates under different land use types by the wet sieving method and explored the impact mechanism based on non-multidimensional scaling( NMDS). The results showed that:①With the increase of grain size in 0~ 10 cm and 10-20 cm soil layers, the percentage content of aggregates in different land use types increased first and then decreased. On the whole, the difference of aggregate composition in different land use types was mainly manifested as the difference between conifer-broad leaf forest and economic forest. The grain sizes with different percentage content of aggregates were mainly < 0.25 mm and > 1 mm.② The mean weight diameter (MWD) was significantly different under different land use types, 0~ 10 cm, the soil MWD value of conifer-broad leaf forest was significantly greater than that of chestnut forest;10-20 cm, the soil MWD value of chestnut forest and hawthorn forest was significantly greater than that of apple forest;20~30 cm, the soil MWD value of hawthorn forest was significantly greater than that of apple forest, and the geometric mean diameter ( GMD) did not change significantly.③NMDS axis analysis showed that soil bulk density was significantly related to NMDS1 , soil total organic carbon, total nitrogen and carbon-nitrogen ratio were slightly related to NMDS1 and soil total organic carbon was slightly related to NMDS2. The study indicated that the construction of economic forest affected the status of soil aggregates, which was mainly manifested by the decrease of large aggregate ratio and increase of micro-aggregate ratio in the soil. In general, the stability of economic forest aggregates was lower than that of conifer-broad leaf forest. The stability of apple forest soil aggregates was the worst. Soil bulk density and soil carbon and nitrogen were the important factors affecting the composition of soil aggregates.