黔中喀斯特地区5种林型冬季土壤呼吸研究

Winter Soil Respiration of 5 Forest Types in the Karst Areas of Central Guizhou Province

以黔中喀斯特地区的柏木林、灌木林、阔叶混交林、针阔混交林和马尾松林5种林型为对象,采用LI-6400-09便携式土壤呼吸叶室对其冬季土壤呼吸速率进行了测定和分析。结果表明,土壤呼吸速率的日变化幅度大小因林型和月份而存在差异,以灌木林2月份的土壤呼吸日变幅最大1.65～2.37μmol/(m2.s),以柏木林12月的土壤呼吸日变幅最小0.41～0.53μmol/(m2.s),大部分林地不同月份最大土壤呼吸速率是最小土壤呼吸速率的1.2～1.5倍;5种林型的土壤呼吸速率基本表现为1月<12月<2月,最大土壤呼吸速率是最小土壤呼吸速率的1.46～2.85倍,且同一林型不同月份间和不同林型同一月份间的土壤呼吸速率差异显著;几种林型的冬季土壤呼吸速率均与5,10和15cm处土温都呈较高的指数正相关;各林型的土壤呼吸速率与各土层的土壤体积含水率的关系较复杂;凋落物层对土壤呼吸的贡献率均表现为1月<2月<12月,占土壤总呼吸速率的比重为6%～36%。

LI-6400 portable photosynthesis measurement system and its soil respiration fitting 6400-09 are employed to measure and analyze the soil respiration rate of the Cupressus funebris forests, shrubs, mixed broadleaf, mixed conifer and broadleaf, and Pinus massoniana forests in the karst areas of central Guizhou in winter. Results indicate that there are differences in the diurnal change range among the different forest types and different months. The diurnal change range of shrubs in February is the highest, froml. 65 to 2. 37 μ mol/（m^2·s）, and that of the Cupressus funebris forests in December is the lowest, from 0. 41 to 0. 53μmol/（m^2·s）. The maximum soil respiration rate is 1.2 to 1.5 times as much as the minimum respiration rate of most of the forest types in different months. The general features of soil respiration of the 5 forest types are that the soil respiration rate of the 5 forest types is the smallest in January, the middle in Decem- ber, and the biggest in February; the maximum soil respiration rate is 1.46 to 2.85 times as much as the minimum respiration rate; and there is a great difference in soil respiration rate among different months of the same forest type and among different forest types in the same month. There are significant positive exponential correlations between soil respiration rate and the soil temperature at the 5, 10, and 15 cm depths. Relations between soil respiration rate and soil volumetric moisture at different soil depths for all the forest types are considerably complex. The contribution percentages of litter to the total soil respiration rate are from 6% to 36 %, with that of January being the smallest, February, the middle, and December, the biggest.