东祁连山灌-草群落交错带土壤呼吸动态及影响因子分析

为探究高寒灌-草交错带土壤呼吸动态及影响因素,应用LI-8100A土壤呼吸自动测定系统,对东祁连山典型灌丛-草地交错带土壤呼吸动态及土壤因子进行测定,分析呼吸速率与土壤因子的相互关系。结果表明,整个交错带内土壤呼吸速率的均值介于2.3~7.2 μmol/(m²·s),各样地间土壤呼吸速率大小顺序为珠芽蓼草甸中心(S₁)>草甸-金露梅灌丛交错区(MSC₁)>金露梅灌丛中心(S₂)>金露梅-杜鹃灌丛交错区(MSC₂)>杜鹃灌丛中心(S₃),S₁和MSC₁样地的土壤呼吸日变化呈单峰型,峰值出现在14:00,S₂、MSC₂、S₃样地峰型不明显,且日变幅较小,仅为0.3~1.1 μmol/(m²·s);交错带内土壤物理性质和养分储量呈明显的垂直分异规律,土壤呼吸速率与土壤温度、全磷储量呈极显著的正相关(P<0.01),与土壤含水量极显著负相关(P<0.01),与0~20 cm土壤有机碳储量呈显著负相关(P<0.05);拟合分析显示,土壤温度、含水量和全磷储量是土壤呼吸速率的主要限制因子,土壤呼吸与土壤温度拟合系数最高,可解释土壤呼吸空间变异的79.9%。

Soil respiration dynamics and impact factor analysis of a shrubland-grassland eco-tone in the Eastern Qilian Mountains

This research explored the factors influencing soil respiration dynamics of an alpine Shrubland -Grassland ecotone.The soil respiration dynamics were measured using a LI-8100A automated soil CO2 flux system,and relationship between soil respiration and soil factors was analysed for an eastern Qilian Mountain typical Shrubland-Grassland ecotone.The mean soil respiration rate was 2.3 -7.2 μmol CO2/(m2 ·s).The rankings of soil respiration rate at different sampling points were:Polygonum viviparum meadow center (S1 )>Polygonum viviparum meadow - Potentilla fruticosa shrub ecotone (MSC1 )> Potentilla fruticosa shrub center (S2 )>Potentilla fruticosa -Rhododendron shrub ecotone (MSC2 )>Rhododendron shrub center (S3 ).The diurnal variation of soil respiration of S1 and MSC1 had a unimodal pattern,with the peak at 14:00. For S2 ,MSC2 and S3 respiration rates were only 0.3-1.1 μmol CO2/(m2 ·s)and the peak was not obvious. Soil physical properties showed a significant vertical gradation within ecotones.Soil respiration rate was signifi-cantly and positively correlated with soil temperature and total phosphorus (P <0.01),significantly negatively correlated with soil moisture (P <0.01),and significantly positively correlated with soil organic carbon in the 0-20 cm soil layer (P <0.05).Analysis of the relationship between soil respiration and soil temperature,soil moisture,total phosphorus,and organic carbon showed that soil temperature,soil moisture and total phos-phorus were the main limiting factors for soil respiration rate.The highest fitted coefficient was soil tempera-ture,which explained 79.9% of the spatial variability in soil respiration.