作 者 ：刘增文,段而军,刘卓玛姐,冯顺煜
期 刊 ：生态学报 2009年 29卷 10期 页码：5696~5707
Keywords:pure forests, soil degradation, soil polarization,
摘 要 ：在由单一树种组成的纯林内土壤性质偏离原平衡态并朝某个方向极端化发展的趋势被称为极化。采用多样地多样点混合采土法对陕北半湿润黄土丘陵区进入后期成熟生长期的不同树种纯林和混交林土壤性质测定结果表明： （1）几乎所有树种纯林的土壤性质均发生了中度（P＞0.10）以上的极化，其中属于极强度极化（P＞0.20）的性质分别为：落叶松和白桦林地的化学、生物学性质和微量元素；侧柏林地的化学和生物学性质；华山松和辽东栎林地的化学性质和微量元素；刺槐林地的生物学性质和微量元素；小叶杨林地的物理和化学性质。（2）不同树种纯林土壤的极化趋势分别为：油松林地发生贫养化和微量元素亏损；落叶松林地发生微量元素富集但却贫养化；侧柏林地发生富C、N和生物学性质改善；华山松林地发生物理性质改善但却贫养化和生物学性质恶化；刺槐林地发生富养化、生物学性质改善但却微量元素亏损、物理性质恶化；小叶杨林地发生贫养化、微量元素亏损和物理、生物学性质恶化；白桦林地发生物理性质改善、微量元素富集但却贫养化；辽东栎林地发生微量元素富集。（3）相对林木抗极化能力，土壤的绝对综合极抗比属于中等以上（I ＞0.40）的性质分别为：小叶杨林地的物理性质； 侧柏林地的物理、化学性质和微量元素；落叶松、刺槐和白桦林地的所有性质。
Abstract:Soil polarization refers to the shift of soil properties away from equilibrium toward unbalanced or extreme conditions due to the presence of a single tree species in pure stands of planted forests. In this study, we measured a broad range of soil properties in mature stands of pure and mixed forests at multiple sites in the semi-humid loess hilly region of northern Shaanxi Province, China. The results indicated that soil polarization reached the level of moderate or higher（P＞0.10）in almost all pure forests that were examined in this study and in which very strong polarization（P＞0.20）was observed for the following soil properties: chemical properties, biological properties and trace element content of Larix principis-rupprechtii and Betula platyphylla forests; chemical and biological properties of Platycladus orientalis forest; chemical properties and trace elements of Pinus armandii and Quercus liaotungensis forests; biological properties and trace element content of Robinia pseudoacacia forest; physical and chemical properties of Populus simonii forest. The results also indicated the following trends in soil polarization. Pinus tabulaeformis forest depleted the soil nutrient and trace element content. L. principis-rupprechti forest increased the soil trace element content but decreased the soil nutrient content. P. orientalis forest increased soil C and N content and improved soil biological properties. P. armandi forest improved soil physical properties, but depleted soil nutrient levels and caused a deterioration in soil biological properties. R. pseudoacacia forest increased soil nutrient content and improved soil biological properties, but decreased soil trace element content and caused a deterioration in soil physical properties. P. simonii forest decreased soil nutrient and trace element content and caused a deterioration in soil biological and physical properties. B. platyphylla forest improved soil physical properties and increased soil trace element content, but depleted soil nutrient content. Q. liaotungensis forest increased the soil trace element content. When we compared the level of soil polarization to the anti-polarization capacity of trees, we found more than moderate levels of polarization (I >0.40) for the following soil properties: soil physical properties of P. simonii forest ; soil physical properties, chemical properties, and trace element content of P. orientalis forest; all soil properties of L. principis-rupprechtii, R. pseudoacacia and B. platyphylla forest.
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