东北过伐林区不同林分类型土壤肥力质量评价研究

保持和提高森林土壤肥力质量是实现森林健康的基础。研究不同林型下土壤肥力质量对森林可持续经营具有重要意义。以东北过伐林区金仓林场中的落叶松Lartx gmelinii人工纯林、云杉Picea asperatax紫椴Tilia amurensis天然混交林、紫椴×白桦Betula platyphylla天然混交林、五角槭Acer monox白桦×落叶松天然混交林、五角槭×白桦×紫椴天然混交林、白桦×落叶松天然混交林和五角械×紫椴×青杨Populus pseudo-simonii天然混交林为研究对象，分析和比较了不同林分下的土壤物理和化学性质，并采用主成分分析与聚类分析相结合的方法评价了其土壤肥力质量。结果表明：①林分类型对土壤理化性质影响显著；随土壤深度增加，土壤密度和土壤pH值增大，而土壤含水量、物理性粘粒含量和养分质量分数减少，但其在不同林分下的变化程度不同；②土壤因子之间关系密切，物理性粘粒含量与含水量、全氮、速效钾质量分数呈极显著正相关，而与土壤密度和pH值呈显著负相关；土壤养分质量分数之间具有不同程度的显著正相关关系；③采用主成分分析法对不同林分下0～60cm的土壤肥力质量进行了评价，土壤肥力质量表现为天然混交林高于落叶松人工纯林；采伐降低了土壤的肥力质量；在落叶松人工纯林中，随着林龄的增加，土壤的肥力质量下降。通过对土壤肥力质量综合指标值的聚类分析，将研究区土壤肥力质量分为优、良、中、差4个等级，肥力质量属于中等以上（优、良、中等）的林地所占研究样地的比例为66．7％，研究区森林土壤肥力质量属于中等水平。建议在经营过伐林时，注意调整林分结构和树种组成，控制采伐强度，同时进行长期定位观测和比较，以改善林分整体的肥力状况。本研究结果为该地区林业可持续经营提供直接依据，也为东北地区森林土壤肥力质量评价提供参考。

Evaluation of soil fertility quality under different forest stands in over-logged forest region, northeast China

Preservation and improvement of forest soil fertility quality is the basic task for forest health, and it is of great importance to study forest soil fertility quality for the maintenance and sustainable management of forest health. The larch plantation and natural mixed forests of picea and linden, birch and linden, larix, birch and maple, birch, maple and linden, birch and larix, linden, maple and cathay poplar in Jincang forest farm, Jilin Province were selected for the determination and comparison of soil physico-chemical properties in different forest stands. Soil fertility quality of these forest stands was further assessed with principal component analysis and clustering analysis methods. The results were showed as the followings：①Types of forest stands had significant effects on soil physico-chemical properties. With the increase of soil depth, soil bulk density and soil pH increased, but soil water content, physical clay contents and nutrients content decreased with diverse variation degrees in different forest stands. ②There existed close correlations between soil properties. Soil water content, total N and rapidly available K had very significant positive correlations with physical clay content, but significant negative correlations with soil bulk density and soil pH. The correlations between soil nutrients content were significant positive, but with different degrees. ③The soil fertility quality assessment with principal component analysis showed better soil fertility quality in natural mixed forest than larch plantation in the depth of 0~60 cm. Cutting could reduce the level of soil fertility quality; and in larch plantation, as the stand age increased, soil fertility quality was lower. Through clustering analysis of comprehensive index, the soil fertility quality was classified into 4 levels, namely excellent, good, medium and poor. The soil fertility quality of the study area belonged to middle level in general with 66.7% of forest stands falling into excellent, good, medium levels. Therefore, adjusting stand structure and tree species composition and controlling thinning intensity with long-term and located observations are suggested to improve the general fertility quality of over-logged forest stands. The results provided direct supports for sustainable forest management of Jincang forest farm, and offered the references to the soil fertility quality assessment of forest ecosystems in northeastern region.