鲁中山地不同密度侧柏人工林土壤质量特性

Soil quality characteristics of Platycladus orientalis plantations with different densities in central mountainous area of Shandong province

【目的】土壤质量是森林生态健康的重要组成部分。开展森林土壤质量研究,对于诊断林地土壤质量优劣具有重要意义,可为人工林的合理经营提供科学依据。【方法】以鲁中山地22块不同密度(1300~6400株·hm^-2)侧柏人工林样地土壤为研究对象,采用野外调查和室内分析相结合的方法,取样测定17个土壤指标,研究林地土壤的理化性质、生物学特性;采用相关性分析,探讨林分密度对侧柏人工林土壤质量的影响。【结果】1)供试的侧柏林地有40.90%的土壤容重处于“适中”等级,多数处于“较低”水平,供试样地的土壤粘粒含量也普遍较低。由于总孔隙度、毛管孔隙度和毛管持水量较高,林地土壤的透气性和保水性较好。2)林地土壤电导率普遍很低,72.72%土壤的阳离子交换量(CEC)处于“很高”或“较高”等级。土壤碱解氮和有效磷含量较低,分别只有13.64%和36.36%的样地达到“适中”等级,而有效钾含量均处于较高水平。3)林分密度与总孔隙度、毛管持水量、CEC、碱解氮、有效钾、过氧化氢酶、脲酶之间的关系均为显著负相关(P<0.05);在林分密度较低(<2500株·hm^-2)时,土壤质量明显高于其它密度组。【结论】鲁中山地侧柏人工林土壤理化性质和生物学性质较为稳定,各指标在不同样地间的变异均为中、低强度。林地土壤质量受林分密度影响较大,密度较低时有利于林地土壤质量的提升。对密度过高的侧柏人工林应采取间伐抚育措施,控制在2500株·hm^-2左右,有利于提高林地土壤质量。

【Objective】Soil quality of forest land is an important component of forest ecological health.The research on forest soil quality is of great significance for the diagnosis of forest soil quality,which can provide scientific basis for reasonable management of plantations.【Method】Based on field investigation and indoor analysis,17 soil indexes were measured by sampling and the physical,chemical and biological characteristics of soils from Platycladus orientalis plantations with different densities(1300-6400 trees·hm^-2)in central mountainous area of Shandong province were studied,and the effects of stand density on soil quality of plantations were discussedusing correlation analysis.【Result】1)Soil bulk density of 40.90%sample plots was in the“moderate”grade and most of them were at the“low”level.Soil clay content in the sample plots was also generally low.Because of the high porosity,capillary porosity and capillary moisture,the permeability and water holding capacity of forest soils were relatively good.2)The conductivity of soils was generally very low,and cation exchange capacity(CEC)of 72.72%of the soils was at the“very high”or“high”level.The contents of available N and P in soils were lower,with only 13.64%and 36.36%of sample plots at the“moderate”grade,respectively.However,the contents of available K were at at high level for all the soils.3)The relationship between stand density and soil porosity,capillary moisture,CEC,available nitrogen,available potassium,catalase activity and urease activity was significantly negatively correlated(P<0.05).When stand density was low(<2500 trees·hm^-2),soil quality was evidently higher than other density groups.【Conclusion】Soil physical,chemical and biological properties of Platycladus orientalis plantations in the central mountainous areas of Shandong province are relatively stable,because the variation of each index in different plots was moderate or low intensity.The soil quality of plantations was greatly affected by stand density.The low density is beneficial to the improvement of the soil quality of Platycladus orientalis plantation.In order to improve the soil quality of the forest land,thinning and tending measures should be taken for the high density Platycladus orientalis plantation.The stand density should be controlled at about 2500 trees hm^-2 to improve the soil quality of forest land.