祁连山不同混交度青海云杉林细根形态特征及与土壤理化性质的关系

目的]揭示祁连山青海云杉中龄林细根分布与土壤环境的互作关系，明晰不同混交度下土壤养分对细根发育的贡献因子，为祁连山天然林抚育经营提供理论依据。方法]采用根钻法对混交度为0,0.2,0.4,0.6的青海云杉中龄林进行细根取样，揭示不同土层细根形态特征，剖析了与土壤理化性质的关系。结果]细根生物量集中分布在0—20 cm土层，0—20 cm的土层细根生物量密度、根长密度、根表面积密度、比根长、比表面积显著高于20—40 cm土层(p<0.05),混交度0.4的林分各土层细根形态指标最大。4种混交度林分各土层中全氮含量、全磷含量、速效钾含量、有机质含量随土层深度的增加呈降低趋势，且各土层均以混交度0.4为最高。细根的总生物量密度、根长密度、根表面积密度、比根长、比表面积与0—40 cm土层中土壤全氮、全磷、碱解氮、速效磷、有机质、速效钾含量呈正相关，与全钾呈负相关关系。结论]细根生物量密度变化主要受土壤全氮含量的影响，混交度0.4的青海云杉中龄林有较强的细根贡献和较好土壤肥力，更有利于群落稳定效益的发挥。

Relationships of Fine Root Morphology and Soil Physicochemical Properties in Different Mingling Intensity of Picea crassifolia in Qilian Mountains

Objective]The interaction between fine root distribution and soil environment of middle-aged Picea crassifolia forests was revealed, and the contribution factors of soil nutrients to fine root development under different mingling intensity were clarified in order to provide theoretical basis for the rehabilitation and management of natural forests in Qilian Mountains. Methods] The root samples were collected in P. crassifolia middle-aged forests with different mingling intensities(0, 0.2, 0.4, and 0.6)by using soil coring method. The relations between root parameters(fine root biomass density, specific root length, specific root surface area, root surface area density and root length density)and soil properties(soil total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen, available phosphorous, available potassium and organic matter)were analyzed. Results] The fine root biomass was concentrated in the upper 0—20 cm soil layer, and decreased with soil depth. Values of fine root biomass density, root length density, root surface area density, specific root length, and specific root surface area in the soil layer of 0—20 cm were significantly higher than those in 20—40 cm soil layer(p<0.05). The fine root morphology indices of each soil layer of P. crassifolia forest were all peaked in the mingling of 0.4. Total nitrogen, total phosphorus, available potassium and organic matter in each soil layer decreased with the increase of soil depth, while they peaked at the mingling of 0.4. In the soil layer of 0—40 cm, there were the positive correlations between indices of fine root biomass fine root biomass density, root length density, root surface area density, specific root length, and specific root surface area and soil properties such as total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen, available phosphorous, organic matter, available potassium. Conclusion] The change of fine root biomass density is mainly affected by the total nitrogen content, mixed P. crassifolia forest with mingling intensity of 0.4 has remarkable fine root contribution and better soil fertility, which is more conducive to the development of community stability benefits.