凋落物去除/保留对杉木人工林林窗和林内土壤呼吸的影响

Effects of removing / keeping litter on soil respiration in and outside the gaps in chinese fir plantation

为探讨去除/保留凋落物对林窗内外杉木人工林土壤呼吸的影响、明确去除/保留凋落物条件下杉木人工林林窗内外土壤呼吸主要影响因子,改进经营管理措施和保持杉木人工林的可持续发展,在福州白沙国有林场内选取本底基本相同和经营措施接近的12年生杉木人工林及其林窗,分别采用去除和保留凋落物处理,在每月晴好天气通过Licor-8100A对其凋落物量、土壤呼吸、土壤温度、湿度进行了1a(2014年3月—2015年2月)的定点观测,在此基础上分析不同凋落物输入量处理下杉木人工林窗内外土壤呼吸与环境因子的动态特征、土壤呼吸和环境因子关系,结合方差分析等解释土壤呼吸的拟合模型,结果表明:1)杉木林林窗、林内土壤呼吸速率年平均值分别为2.47μmol m^(-2)s^(-1)和2.13μmol m^(-2)s^(-1);去除凋落物后,分别减少了22.89%、25.89%;林窗内外均是7月份出现最大值,去除凋落物后分别为(3.65±0.14)μmol m^(-2)s^(-1)和(2.85±0.08)μmol m^(-2)s^(-1);保留凋落物分别为(4.26±0.34)μmol m^(-2)s^(-1)和(3.61±0.34)μmol m^(-2)s^(-1);1月值最小,去除凋落物分别为(0.9±0.04)μmol m^(-2)s^(-1)和(0.83±0.03)μmol m^(-2)s^(-1),保留凋落物分别为(1.02±0.041)μmol m^(-2)s^(-1)和(0.92±0.05)μmol m^(-2)s^(-1)。2)土壤温度和湿度共同解释了杉木人工林林窗内外土壤呼吸68.63%—77.28%;3)林窗、林内去除和保留凋落物处理的土壤呼吸与土壤5cm深的温、湿度间显著相关;4)林窗、林内土壤温、湿度的双因素模型均比单因素模型能更好地解释土壤呼吸的动态变化。林窗、林内去除凋落物的土壤呼吸温度敏感系数Q10值分别为1.39和1.37,差异不显著(P=0.634);保留凋落物的Q10值分别为1.40和1.55,差异显著(P=0.010)。研究结果为揭示杉木人工森林生态系统碳通量以及其驱动机制提供理论基础。

In this paper, in order to discuss the effects of removing/keeping litter on soil respiration（SR） in/out of the gaps, clearly put forward the major factors influencing SR under these situations, improve the managements, and keep sustainable development of Chinese fir plantation, 12 years-old Chinese fir plantations and their gaps in similar sites and with same managements at Fuzhou Baisha State-owned Forest were set up and chosen, respectively, to study SR differences, relationships between SR and other environments, SR fitting models in and outside of forest gaps under the circumstances of keeping or moving litter falls in the plots. SR, and soil surface temperature and moisture were measured in several fixed sample plots by Li-8100A during the fine days per month from March, 2014 to February, 2015 in order to analyze the month dynamic characteristics of SR, environment factors and the relations between the two with different carbon inputs in or out of the Chinese Fir forest gaps combining with variance analysis. The results showed that 1） the anural average values of SRs in and outside of Chinese fir plantations were 2.47 and 2.13 μmol m-2 s-1 respectively, and that it would decrease 22.89% and 25.89% respectively while removing the cover litter fall. In or out of the gaps of the forests, both the maximum values of SR appearing in July were （3.650.14） and （2.850.08） μ mol m-2 s-1 after removing litter respectively, and were （4.260.34） and （3.610.34） μmol m-2 s-1 by keeping litter, respectively. And the minimum ones contemporarily emerging in January were （0.90.04） and （0.830.03） μmol m-2 s-1 after taking off the liter respectively, and were （1.020.041） and （0.920.05） by holding litter respectively. 2） Soil temperature together with moisture could account for 68.63%-77.28% of the total SR totally; 3） the relationships between soil respirations and soil temperatures/moistures are significant correlations with large correlation coefficient in the depth less than 5cm in the soil; 4） all the two-factor models were better than the single-factor ones of soil temperature and moisture in explaining the dynamic variances of SR in/out the gaps in Chinese fir plantations; Soil sensitive coefficient （Q10） of SR when wiping off litters in/out Chinese fir forest were 1.39 and 1.37, respectively, which were not significant （P=0.634）, while Q10 were 1.40 and 1.55 when keeping litters in/out of gaps in Chinese fir plantations, respectively, which were significant （P=0.010）. The results could provide the thesis foundation for carbon flux and its mechanism in the ecosystem of Chinese fir plantation.