滇西北亚高山典型退化次生林土壤肥力状况特征研究

Study on Soil Fertility Status and characteristics of Typical Degraded SecondaryForests in Subalpine Areas of Northwest Yunnan Province

【目的】土壤肥力状况及分布特征直接影响土壤生产力的高低和生态恢复的途径和方向,探讨不同退化次生林土壤肥力状况特征,为实现维持和提高滇西北地区退化生态系统植被恢复土壤生产力提供理论依据。【方法】采用野外调查、室内分析并结合相关方法,对滇西北20世纪70年代、80年代、90年代采伐云杉、冷杉后自然生长的典型林分土壤pH、有机质,全量及速效氮磷钾含量进行分析。【结果】试验区土壤pH值范围为4.55~5.46,呈酸性,随着土壤深度加深,pH值无显著变化;不同退化林分类型和不同层次土壤有机质含量均存在显著差异,且随着土壤深度增加而逐渐降低;同一林分类型土壤速效养分含量随着土壤深度增加而逐渐降低,具有明显的“表聚性”,存在显著差异;同一林分类型土壤全氮、全磷含量差异显著,随着土壤深度的增加呈减少趋势,全钾含量在不同林型之间无明显规律;土壤肥力因子相关分析显示,不同退化林分类型各个土壤肥力因子之间存在较为紧密的相关关系,可以用来综合反映土壤肥力水平;6种退化林分类型土壤肥力综合得分分别为3.06、-2.27、-0.04、-0.13、0.14、-0.75,土壤综合肥力大小为退化高山栎灌丛>退化桦木林>退化大果红杉林>稀疏云杉+冷杉林>原始冷杉林>退化杜鹃灌丛。【结论】不同林分类型对土壤肥力状况影响差异显著,林分类型差异导致土壤肥力状况各异,其中退化高山栎灌丛土壤综合肥力最好,退化杜鹃灌丛土壤综合肥力最差。可根据不同退化林分类型的土壤肥力状况研究结果建立科学的土壤培肥及林分结构调控体系,为滇西北退化次生林的生态恢复合理配置与布局提供科学依据。

【Objective】The status and distribution of soil fertility have a direct impact on the level of soil productivity and the way and direction of ecological restoration.We discussed the soil fertility status and characteristics of different degraded secondary forests which provide basic data and theoretical basis for maintaining and improving the soil productivity of vegetation restoration of degraded ecosystems in Northwest Yunnan.【Method】By using field investigation,indoor analysis and related methods,the soil pH,organic matter,total and available NPK contents of typical forest stands in Northwest Yunnan after cutting spruce and fir in 1970s,1980s and 1990s was analyzed.【Result】The range of pH was from 4.55 to 5.46,which was acidic.With the deepening of soil depth,there was no significant change in pH value.There were significant differences among different degraded forest types and different levels of soil organic matter contents,which decreased gradually with the increase of soil depth.The content of available nutrient in soil of the same forest type decreased with the increase of soil depth,and had obvious surface aggregation,with significant differences.The contents of total N and total P in the same forest type decreased with the increase of soil depth,and there were significant differences,while there was no obvious regularity in total K in different forest types.The soil fertility factors of different degraded forest types had close correlation,which could be used to reflect the soil fertility levels comprehensively.The comprehensive scores of each degraded forest type were calculated by principal component analysis and the results showed that the comprehensive soil fertility scores of the six degraded forest types were 3.06,-2.27,-0.04,-0.13,0.14,and-0.75,respectively,and the soil comprehensive fertility was showed as follows:degraded Alpine oak shrub>degraded Betula forest>degraded potaninii var.macrocarpa forest>sparse Picea+Abies forest>virgin Abies forest>degraded Rhododendron simsii Planch shrub.【Conclusion】Different stand types had significant effects on soil fertility,and the differences in stand types led to different soil fertility conditions,among which the comprehensive soil fertility of degraded Alpine oak shrub was the best,and that of degraded R.simsii Planch shrub was the worst.Therefore,based on the soil fertility status of different types of degraded forests,a scientific system of soil fertility improvement and forest structure regulation can be established,which provides a scientific basis for the ecological restoration of the degraded secondary forest in Northwest Yunnan and the rational allocation and distribution of soil improvement.