黄河三角洲不同林龄人工柽柳林生长季土壤微生物与土壤呼吸特征研究

Soil microorganism and soil respiration characteristics of Tamarix chinensis plantations of different ages in the Yellow River Delta during the growing season

为探讨人工柽柳林对滨海盐碱地的改善效果,以黄河三角洲滨海盐碱地区3种不同林龄(8 a、6 a、3 a)人工柽柳林为对象,采用多点混合采样法,对生长季土壤微生物量C、N及微生物数量变化进行了对比分析;同时利用LI-8100A土壤碳通量测量系统,原位监测了柽柳生长季内土壤呼吸速率的变化特征。结果表明:1)人工柽柳林土壤微生物微生物量C、N变化受林龄和季节影响明显,其中8 a林地含量最高,3 a林地最小,夏季较高,春季较低,且8 a与3 a差异显著,夏季与春季差异显著(P <0.05);不同林龄土壤微生物商生长季介于2.56～4.15%之间,其变化规律与微生物量一致。2)土壤3种微生物数量均随林龄的增大而增加,微生物数量关系为细菌>放线菌>真菌,而3种微生物数量季节变化规律不一致。3)3种林龄土壤呼吸速率的大小为8 a> 6 a> 3 a,土壤呼吸具有明显的季节变化和日变化,其中季节变化表现为夏季>秋季>春季,日变化则呈现出低-高-低的单峰曲线,最大值则出现在12:00―14:00。4)相关分析表明,土壤含盐量与土壤微生物量C和呼吸速率呈显著负相关,与细菌、真菌呈极显著负相关,是主要限制因子;土壤微生物量C、N与微生物商、土壤呼吸、土壤微生物数量均呈正相关;除土壤湿度外,土壤温度与其它指标均呈正相关;而土壤湿度与各指标间均不显著。5)综上所述,不同林龄人工柽柳林土壤微生物量、微生物数量及呼吸速率均可反映土壤环境状况,可为滨海盐碱地土壤改良和土壤质量演变规律提供理论依据。

In order to study the coastal saline soil improvement effects of Tamarix chinesis plantation,taking Tamarix chinensis plantations of different ages (8 a,6 a,3 a) in the saline and alkaline area of Yellow River Delta as the research object,the soil microbial biomass C and N and the quantity of microorganism during the growing seasons were contrastively analyzed by multipoint mixed sampling method.Meanwhile,the soil respiration rate in-situ monitoring was done during the growing seasons with LI-8100A soil carbon flux measurement system.The results indicate that:1) The soil microbial biomass C and N of T.chinensis were significantly affected by the tree ages and season;of the tested forests,C and N contents in eight-year forest land were the highest,3-year forest land was the smallest,summer was higher,spring was lower,and there was significant difference between 8-year and 3-year,and there was significant difference between summer and spring (P < 0.05);The growth season of soil microbial quotient of different forest ages ranged from 2.56% to 4.15%,and the variation law was consistent with the microbial biomass.2) The numbers of three microorganisms in soil increased with the increase of forest age,the relationship between the number of microorganisms was:bacteria > actinomycetes > fungi, and the seasonal variation of the three microorganisms was different.3) The soil respiration rate of different ages showed a descending order as below:eight year old > six year old > three year old.The soil respiration had obvious seasonal and daily variation,and the seasonal variation showed a descending order as below:summer > autumn > spring,while the daily variation showed a tendency of unimodal curve of low-high-low with the maximum appearing during 12:00-14:00.4) The correlation analysis indicated that the soil salinity,which was the main limiting factor,had a significant negative correlation with soil microbial biomass C and soil respiration rate,and a great significant negative correlation with bacteria and fungi;The soil microbial biomass C and N had a significant positive correlation with soil microbial quotient,soil respiration and the quantity of microorganism;The soil temperature had a significant positive correlation with all the other indicators except soil moisture,while the soil moisture had no significant difference with all the indicators.(5) In summary,the soil microbial biomass,microbial quantity and respiration rate of artificial T.chinensis forests at different forest ages can reflect the soil environmental conditions,which can provide a theoretical basis for soil improvement and soil quality evolution in coastal saline-alkali soils.