【摘要】 以大伙房水库流域4种不同水源涵养林植被类型为研究对象,研究土壤微生物量碳(MBC)、氮(MBN)含量以及土壤理化性质和凋落物养分的变化特征,运用通径分析模型,探讨土壤微生物量对土壤理化性质和凋落物养分的响应。结果表明:1)不同植被类型土壤有机碳(SOC)、全氮(TN)、铵态氮(NH4+-N)、硝态氮(NO3--N)含量表现为0～10 cm> 10～20 cm土层,且刺槐天然次生林显著高于其他植被类型;土壤C/N变化范围在11. 17～16. 42,土壤无机氮以NH4+-N为主,占77%。2)土壤MBC和MBN质量分数分别为92. 69～562. 55 mg/kg和64. 10～193. 42mg/kg,均表现为刺槐天然次生林>油松人工林>落叶松人工林>红松人工林,0～10 cm土壤MBC、MBN质量分数分别是10～20 cm土层的1. 83～2. 55、1. 18～1. 62倍。3)土壤MBC/MBN变化范围在1. 40～3. 15之间,土壤微生物量碳熵、氮熵的变化范围分别0. 38～0. 81%、3. 26～3. 59%。4)相关分析表明,土壤理化性质、凋落物养分质量分数与土壤MBC、MBN质量分数显著正相关;通径分析结果表明,土壤全氮、无机氮、有机碳、土壤含水量是直接影响该区域不同植被类型土壤微生物量碳氮的主导因素。研究结果表明刺槐天然次生林土壤质量较优于针叶人工林,建议今后在大伙房水库流域应减少人为干扰,加强对刺槐天然次生林水源涵养林的建设和保护。更多还原

【Abstract】 [Background] Soil microbial biomass is the most active part of soil organic matter,which can be used to characterize soil property,and plays an important role in the process of biogeochemical cycling of carbon and nitrogen. Investigating the character of soil microbial biomass under different water conservation forests could be helpful in the construction of water conservation forest in Dahuofang Watershed. [Methods]In order to clarify the effect of vegetation type on soil microbial biomass,a field experiment was conducted in 4 different vegetation types(Larix gmelinii,Pinus koraiensis,Pinus tabuliformis,and Robinia pseudoacacia) of water conservation forests in Dahuofang Watershed. We measured soil microbial biomass carbon(MBC) and microbial biomass nitrogen(MBN) and analyzed the response of soil microbial biomass to soil physical-chemical properties and litter nutrient content by path analysis model. [Results] 1) The content of soil organic carbon(SOC),total nitrogen(TN),ammonium nitrogen(NH4+-N), and nitrate nitrogen(NO3--N) were significantly higher in R.pseudoacacia natural secondary forests than other three vegetation types(P < 0. 05),which decreased gradually with increasing soil depth. The range of C/N was 11. 17-16. 42,and the content of soil NH4+-N accounted for 77% of soil total inorganic nitrogen. 2) The content of MBC and MBN were 92. 69 ～562. 55 mg/kg and 64. 10-193. 42 mg/kg,respectively,which were in the order of R. pseudoacacia natural secondary forests > P. tabuliformis plantation > L. gmelinii plantation > P. koraiensis plantation.The content of MBC and MBN in 0-10 cm soil layer were 1. 83-2. 55、1. 18-1. 62 times more than those in 10 ～ 20 cm soil layer,respectively. 3) The ration of MBC/MBN was 1. 40-3. 15,and soil microbial biomass carbon entropy(q MBC) and nitrogen entropy(q MBN) were 0. 38%-0. 81% 、3. 26%-3. 59%,respectively. 4) There was a significant positive correlation between microbial biomass and soil physical-chemical properties and litter nutrient content. Path analysis showed that the TN,NH4+-N,NO3--N,SOC and SWC(soil water content) were the most important factors affecting soil microbial biomass in different vegetation types of water conservation forests in Dahuofang Watershed.[Conclusions] The content of MBC,MBN and litter nutrient content in R. pseudoacacia natural secondary forests was higher than other three vegetation types,which suggests that R. pseudoacacia natural secondary forests better improves soil quality than coniferous plantations. Our results impliy that we should pay more attention to the protection of R. pseudoacacia natural secondary forests in the Dahuofang Watershed in order to improve soil quality.更多还原