武夷山不同林龄甜槠林土壤呼吸特征及影响因素

Abstract

为揭示中亚热带常绿阔叶林群落优势种一甜槠天然林不同林龄林下土壤呼吸（Soil respiration，R_S）差异及影响因素，采用LI-8100开路式土壤碳通量系统对武夷山自然保护区不同林龄（18、36、54、72 a）天然甜槠林进行了1年的野外原位测定。结果表明：（1）不同林龄甜槠林R_S季节动态呈现明显的单峰趋势，林龄对冬季R_S影响并不显著（P>0.05），秋季18 a甜槠林R_S与其他3种林龄差异显著（P<0.05），林龄对土壤含水率的季节变化没有显著影响（P>0.05）；（2）不同林龄甜槠林5 cm深土壤温度与R_S拟合R²明显高于土壤含水率与R_S拟合R²，随着林龄增大，R_S温度敏感性指数Q₁₀值呈上升趋势，依次为1.551、1.589、1.640、1.664，且54、72 a甜槠林R_S温度敏感性指数Q₁₀值显著高于18、36 a（P<0.05）；（3）土壤含水率与5 cm深土壤温度共同解释了R_S变异的86%-90.3%；0-60 cm土层根系生物量与5 cm深土壤温度共同解释了R_S变异的88.3%-91.8%，由此可见，生物因子与非生物因子双因素拟合可以更好地解释不同林龄R_S差异。在对未来森林植被土壤呼吸及碳汇功能进行研究时，应在考虑林龄及季节差异的基础上，加强对生物因子的测定。;Soil respiration, as an important ecological process of material cycle and energy flow in forest ecosystem, is one of the main fluxes in the global carbon cycle, and plays an important role in the global carbon cycle and carbon balance. There are many factors that affect forest soil respiration, mainly non-biological factors such as soil temperature, water content and air temperature, etc. However, with different climatic zones and forest types, forest age has an important impact on carbon storage and carbon distribution in forest ecosystems, and there is also great uncertainty of the impact on soil respiration. In this paper, soil carbon flux system LI-8100 was used to measure soil respiration and its components in Castanopsis eyrei forests (18 a, 36 a, 54 a, and 72 a) of different forest ages in Wuyishan Nature Reserve. Meanwhile, soil temperature of 5 cm depth and soil water content were simultaneously measured. The results showed that: (1) the seasonal dynamics of soil respiration in Castanopsis eyrei forests with different forest ages presented a single peak trend, and the effect of forest age on soil respiration in winter was not significant (P>0.05). The soil respiration in 18 a Castanopsis eyrei forests in autumn was significantly different from that of the other three forest ages (P<0.05), and the forest age had no significant effect on the seasonal changes of soil water content (P>0.05). (2) Fitting R² of soil temperature of 5 cm depth and soil respiration in different forest age Castanopsis eyrei forest was significantly higher than fitting R² of soil water content with soil respiration. With the increase of forest age, the Q₁₀ value of soil respiration temperature sensitivity index showed an upward trend, which was 1.551, 1.589, 1.640 and 1.664 in turn, while the Q₁₀ value of soil respiration temperature sensitivity index of 54 a and 72 a Castanopsis eyrei forest was significantly higher than that of 18 a and 36 a Castanopsis eyrei forest (P<0.05). (3) Soil water content and soil temperature of 5 cm depth together explain 86%-90.3% of soil respiration variation. The root biomass of 0-60 cm soil layer and soil temperature of 5 cm depth jointly explain 88.3%-91.8% of soil respiration variation. Thus it can be seen that the two-factor fitting of biological factor and abiotic factor can better explain the soil respiration variation of different forest ages. When studying the soil respiration and carbon sink function of forest vegetation in the future, the determination of biological factors should be strengthened on the basis of considering the difference of forest age and season.