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矿质土壤呼吸是森林生态系统土壤碳库损失的重要途径之一,也是森林生态系统碳(C)平衡估算中的关键因子。了解矿质土壤呼吸在不同时间尺度上的变化,对理解森林生态系统C循环应对全球变化的响应至关重要,而高频观测是探讨矿质土壤呼吸在不同时间尺度变化的重要手段之一。通过高频自动观测系统与Li-8100土壤CO2通量测量系统,对福建省三明市陈大镇国有林场的米槠(Castanopsis carlesii)次生林在不同森林经营方式下(CK对照,RR皆伐,RB火烧)的矿质土壤呼吸与土壤温度和含水量的昼夜动态进行分析,并比较2种采样策略下矿质土壤呼吸的年、日均通量差异。结果表明:1)不同森林经营方式的矿质土壤呼吸与土壤温度和土壤含水量均存在着明显的季节动态,矿质土壤呼吸速率年均值表现为CK(2.18μmol m~(-2)s~(-1))>RB(1.93μmol m~(-2)s~(-1))>RR(1.89μmol m~(-2)s~(-1))。2)在不同森林经营方式下,采用手动观测的矿质土壤呼吸年平均日通量显著低于高频观测结果,而采用高频观测09:00—11:00时间段内观测数据计算日通量与高频自动观测系统全天(24h)结果无显著差异;3)不同森林经营方式下的林地,土壤水热条件的变化是影响矿质土壤呼吸的重要因素之一。双因子模型拟合结果表明,土壤温度和含水量共同解释了CK、RR和RB矿质土壤呼吸速率的年变化的96.8%,62.8%,95.4%,拟合结果明显优于以温度为单因子的指数模型。因此,未来气候变化背景下,为准确评估和预测不同森林经营方式对土壤与大气间碳通量交换的影响,采用高频自动观测技术观测矿质土壤呼吸,将有利于提高碳通量估算精度。
Mineral-soil respiration is one of the important ways of soil carbon pool loss in forest ecosystems, and also a key factor in estimating carbon (C) balance in forest ecosystems. Understanding the changes of mineral soils respiration on different timescales is of crucial importance in understanding the response of forest ecosystems to C cycling in response to global changes. High-frequency observations are one of the most important ways to explore the changes of mineral soils respiration at different timescales. Through the high-frequency automatic observation system and Li-8100 soil CO2 flux measurement system, the secondary forest of Castanopsis carlesii in the state-owned forest farm of Chen Dali Town, Sanming City, Fujian Province under different forest management modes (CK control, RR clear cutting, RB Fire) and the diurnal dynamics of soil temperature and water content were analyzed. The annual and daily flux of mineral soil respiration under two sampling strategies were compared. The results showed as follows: 1) There were obvious seasonal dynamics of mineral soil respiration, soil temperature and soil water content under different forest management modes. The average annual respiration rate of mineral soils was CK (2.18μmol m ~ (-2) s ~ (- 1> RB> 1.93μmol m -2 s -1> RR> 1.89μmol m -2 s -1. 2) Under different forest management modes, the daily average daily flux of mineral respiration in the soil observed by hand was significantly lower than that of the high-frequency observation, and the daily flux was calculated by observing the data from 09: 00-11: 00 during high-frequency observation And the high frequency automatic observation system did not show any significant difference in the whole day (24h); 3) The change of soil moisture and heat condition under different forest management modes was one of the important factors affecting the mineral soil respiration. The two-factor model fitting results showed that the soil temperature and water content together explained 96.8%, 62.8% and 95.4% of the annual variation of soil respiration rate of CK, RR and RB, and the fitting result was obviously better than the one with temperature Index model. Therefore, under the background of future climate change, in order to accurately evaluate and predict the impact of different forest management modes on carbon flux exchange between soil and atmosphere, using high-frequency automatic observation technology to observe the mineral soil respiration will be helpful to improve the carbon flux estimation accuracy.