六盘山4种典型林分林下草本细根生物量与土壤特性的关系

探究六盘山典型林分林下草本细根生物量分布及其与土壤特性的关系，为植物-土壤环境关系的理论研究和区域植被的可持续性管理提供科学依据。以六盘山国家级自然保护区4种典型林分（Ⅰ.辽东栎；Ⅱ.白桦；Ⅲ.华山松；Ⅳ.华北落叶松）为研究对象，采用根钻法测定林下浅层土(0~50 cm)中草本细根生物量、土壤含水量、土壤容重和土壤养分含量，并分析细根生物量与土壤特性的关系。结果表明，4种林分林下草本细根生物量主要集中在0~20 cm土层中，其中以林分Ⅲ林下草本植物细根生物量最多；土壤容重（0~20 cm）为林分Ⅰ最大，林分Ⅲ最低，表明土壤容重越小越利于细根生物量的积累；Pearson相关分析（未控制林分类型）和偏相关分析（控制林分类型）均表明，不同土层细根生物量主要与土壤容重、土壤含水量和土壤TP含量之间呈显著负相关(P<0.05)，与土壤C∶N、N∶P之间呈现显著正相关(P<0.05)。六盘山林下草本细根生物量因林分类型而异，但主要分布在土壤表层（0~20 cm），限制林下草本细根生物量积累的因素为土壤容重、土壤含水量、土壤TP含量、土壤C∶N、N∶P。适宜的土壤容重（0.87~1.10）、土壤含水量（14.50%~19.58%）和合适的土壤C∶N（约12∶1）、N∶P（约8∶1）及较低的土壤TP含量有利于林下草本细根生物量的积累，其中林分Ⅲ的林-草管理模式能够显著提高林下草本细根生物量，并且利于改善林下土壤理化特性，促进森林水养循环。

Relationship Between Fine Root Biomass of Understory Herb Layer and Soil Characteristics of Four Kinds of Stands in the Liupan Mountain

The objectives of this study were to understand the distribution of fine root biomass of herbs under forest in Liupan Mountain and its relationship with soil characteristics,so as to provide scientific basis for the theoretical study of plant-soil environment relationship and sustainable management of regional vegetation.Four typical stands in Liupan Mountain National Nature Reserve were selected as the research object (Ⅰ.Quercus wutaishanica; Ⅱ.Betula platyphylla; Ⅲ.Pinus armandii; Ⅳ.Larix gmelinii var.principis-rupprechtii).Using the method of soil core sampling,we measured the fine root biomass of understory herb layer,soil water content,soil bulk density and soil nutrient content in shallow soil layer (0-50 cm),and analyzed the relationship between fine root biomass and soil characteristics.The results showed that the fine root biomass of understory herb layer was mainly distributed at 0-20 cm soil layer,in which the fine root biomass of understory herbs was the highest in stand Ⅲ,and the soil bulk density (0-20 cm) was the highest in stand Ⅰ and the lowest in stand Ⅲ,indicating that the smaller the soil bulk density,the better the accumulation of root biomass.Pearson correlation analysis (uncontrolled stand type) and partial correlation analysis (controlled stand type) showed that fine root biomass in different soil layers was significantly and negatively correlated with soil bulk density,soil water content and soil total phosphorus content (P<0.05),and positively correlated with soil C∶N and N∶P (P<0.05).The fine root biomass of understory herb layer varied with stand types in Liupan Mountain,but mainly distributed in the soil surface (0-20 cm).The factors that limited the accumulation of herbaceous fine root biomass were soil bulk density,soil water content,soil total phosphorus content,soil C∶N and soil N∶P.Suitable soil bulk density(0.87-1.10),soil water content (14.50%-19.58%),soil C∶N(12∶1) and N∶P(8∶1),and lower soil total phosphorus content were all beneficial to the accumulation of the fine root biomass.Among them,the forest-grass management model of stand III was most conducive to the accumulation of fine root biomass of herbs under the forest,and was conducive to improving the physical and chemical properties of the soil under the forest and promoting the water and nutrient cycle of the forest.