该研究采用珠三角典型森林植被生态系统的鼎湖山南亚热带常绿阔叶林通量观测站2012年CO_2通量资料和气象资料,分析了CO_2通量、净生态系统CO_2交换量及CO_2浓度的变化特征,及其与气象因子的关系。结果表明:(1)CO_2浓度日变化呈"一峰一谷"变化形态,在夜间或日出前后出现最大值,在午后到达最小值;CO_2通量日变化呈"单谷"曲线,在白天中午前后到达最小值(负值),夜间和早晨较高(正值)。(2)CO_2通量季节平均值的高低依次为春季>夏季>冬季>秋季,CO_2浓度季节平均值的高低次序则为冬季>春季>秋季>夏季,即非生长季高于生长季节,这可能与植物物候的季节变化所引起的CO_2源汇强度改变有关。(3)2012年鼎湖山森林生态系统的CO_2年均浓度为664.7 mg·m~(-3),CO_2通量年均值为-0.079 mg·m~(-2)·s~(-1),NEE为-611 g C·m~(-2)·a~(-1),表明鼎湖山针阔叶混交林近年来处于快速生长过程中,具有较强的碳汇功能。(4)CO_2通量及浓度与气温、饱和水气压差均成显著负相关关系,其中CO_2浓度与气温的相关性最高,其次为饱和水汽压差,表明气温和饱和水汽压差是影响CO_2浓度和通量的关键气象因子。受人类活动及气候变化的影响,近年来鼎湖山森林生态系统的碳汇功能有所增强。
英文摘要:
We analyzed the variation characteristics of the CO_2 flux, net ecosystem CO_2 exchange (NEE), CO_2 concentration and the relationship with meteorological variables on the basis of the CO_2 flux data and meteorological data of the southern subtropical evergreen broad-leaved forest flux observation station of Dinghu Mountain, a typical forest vegetation ecosystem in the Pearl River Delta. The research results were as follows: (1) The diurnal variation of CO_2 concentration appeared to be in the form of "peak-valley". Specifically, the CO_2 concentration variation was nearly at its peak at night or around sunrise. And the CO_2 concentration variation was nearly at its valley in the afternoon; Diurnal variation of CO_2 flux generally appeared to be a "valley" curve, approaching minimum value (negative) around noon and reaching maximum (positive) in the morning and at night. (2) The seasonal average of CO_2 flux could be shown as the following order: spring> summer> winter> autumn. The order of the seasonal average of CO_2 concentration could be shown as the following order: winter> spring> autumn> summer, from which we could find that the non-growth season was higher than the growth season in that it was related to the seasonal variation of CO_2 source/sink intensity caused by the seasonal variation of plant phenology. (3) In 2012, the average annual concentration of CO_2 in Dinghushan forest ecosystem was 664.7 mg·m~(-3). The annual mean value of CO_2 flux was-0.079 mg·m~(-2)·s~(-1), and net ecosystem CO_2 exchange capacity (NEE) was-611 g C·m~(-2)·a~(-1), which indicates that mixed confer-broadleaf forest at the Dinghu Mountain has strong carbon sink function in rapid growth during recent years. (4) CO_2 flux and CO_2 concentration had a significantly negative correlation with the temperature and the pressure difference of saturated water, of which the correlation between CO_2 concentration and the temperature was the highest, and the second was the saturated vapor pressure difference, which indicates that the temperature and saturated vapor pressure difference are the key meteorological factors that affect CO_2 flux and CO_2 concentration. We found that carbon sink function of Dinghu Mountain forest ecosystem had been enhanced in recent years, which could be influenced by human activities and climate change.