秦岭北山几种典型人工纯林土壤性质极化问题研究

Soil Polarizations of Several Typical Artificial Pure Forests in North Mountain of Qinling

由于人工纯林中树种生物生态学特性的单一性、对养分吸收利用的选择性和对环境效应的特殊性,土壤性质往往呈现偏离原平衡态并朝某个方向非平衡或极端化发展的趋势被称为土壤极化,它是导致土壤退化的根本原因之一。根据对秦岭北山日本落叶松(larix kaempferi)、油松(Pinus tabulaeformis)、灰楸(Catalpa fargesii)和锐齿栎(Quercus.aliena var.acuteserrata)等几种典型人工纯林土壤性质的测定结果表明,在由天然草地向针叶林地的发展过程中,土壤物理性质在恶化,并且有偏酸化的趋势,土壤养分发生贫瘠化,土壤微生物数量减少,但部分酶活性有所改善;而在由天然草地向阔叶林地的发展过程中,土壤物理性质和生物学性质呈改善的趋势,酸碱性偏向中性化,土壤养分出现富集化或两极分化。在由天然草地向人工林地的发展过程中,各种土壤性质的绝对综合极化程度一般表现为酶活性>微生物量>养分含量>物理性质>酸碱性的规律。其中,土壤物理性质极化程度一般表现为针叶林地大于阔叶林地,微生物量极化程度一般表现为针叶林地小于阔叶林地,而土壤养分含量和酶活性的极化程度因林地而异,并以灰楸林地为最大,锐齿栎林地为最小。

The singularity of biological characteristic, selectivity of nutrient absorption and utilization and particularity of environmental effect under the artificial pure forests usually result in the polarization of soil properties, which is one of the basic reasons leading to soil degradation. The measurements of soil properties of several typical artificial pure forests （larix kaempferi, Pinus tabulaeformis, Catalpafargesii, Quercus. aliena var. acuteserrata） in north mountains of Qinling showed that： 1） in the development from the natural grassland to the artificial conifer forests, soil properties generally worsened, such as acidification, decreases of soil nutrients and microorganism biomass, but partial enzyme activities improved. Meanwhile, in the development from the natural grassland to the artificial broadleaf forests, soil properties generally improved, such as neutrolization of acidity, enrichment or polarization of soil nutrients. 2） in the development from the natural grassland to the artificial pure forests, the order of absolute comprehensive polarizations of soil properties was： enzyme activity 〉 microorganism biomass 〉nutrient contents〉physical properties 〉 pH, thereinto, the order of absolute comprehensive polarizations of soil physical properties was： conifer forest〉broadleaf forest, and the order of absolute comprehensive polarizations of soil microorganism biomass was： conifer forest〈broadleaf forest, but the polarizations of soil nutrient contents and enzyme activity varied with the types of artificial forests, and C. fargesii forest showing the greatest polarization, while Q. aliena forest the lest.