Soil-atmosphere exchange of N2O, CO2 and CH4 along a slope of an evergreen broad-leaved forest in southern China
Soil-atmosphere exchange of N2O, CO2 and CH4 along a slope of an evergreen broad-leaved forest in southern China
复制标题
中国南方常绿阔叶林坡地N2O、CO2和CH4的土壤-大气交换
DOI：
10.1007/s11104-008-9847-2
复制
发表时间：
2009-06-01
期刊：
影响因子：
4.9
通讯作者：
Zhang, Tao
中科院分区：
文献类型：
--
作者：
Fang, Yunting;Gundersen, Per;Zhang, Tao
在大多数站点，二氧化氮（N2O）、二氧化碳（CO2）和甲烷（CH4）的土壤-大气交换量是基于位于有限区域的几个室来估算的。地形已被证明影响温带生态系统中这些气体的产生和消耗，但这方面在热带地区往往被忽视。在本研究中，我们研究了中国南方常绿阔叶林沿100 m长的坡面全年净通量的空间变异性。由于水分和养分的有效性不同，我们预计斜坡下部释放的N2O和CO2会比斜坡上部多，而吸收的大气CH4会比斜坡上部少。结果表明，土壤水分（水填充孔隙空间，WFPS）沿坡面自下而上呈递减趋势，但3种气体中只有N2O的排放符合这一规律。坡内WFPS的年平均值为27.7% ~ 52.7%，N2O的年排放量为2.0 ~ 4.4 kg N ha（-1）年（-1）。这两个变量在坡度上呈高度正相关。在实验室培养的土壤中，净氮矿化和硝化的潜在速率以及N2O排放都没有随坡位而变化。在本研究中，土壤CO2释放和CH4吸收似乎与坡位无关。我们的研究结果表明，即使在短坡中，土壤含水量和相关的N2O排放也可能受到地形的影响，这可能需要在现场测量和建模中考虑到。
At most sites the magnitude of soil-atmosphere exchange of nitrous dioxide (N2O), carbon dioxide (CO2) and methane (CH4) was estimated based on a few chambers located in a limited area. Topography has been demonstrated to influence the production and consumption of these gases in temperate ecosystems, but this aspect has often been ignored in tropical areas. In this study, we investigated spatial variability of the net fluxes of these gases along a 100 m long slope of a evergreen broadleaved forest in southern China over a whole year. We expected that the lower part of slope would release more N2O and CO2, but take up less atmospheric CH4 than the upper part due to different availability of water and nutrients. Our results showed that the soil moisture (Water Filled Pore Space, WFPS) decreased along the slope from bottom to top as we expected, but among the three gases only N2O emissions followed this pattern. Annual means of WFPS ranged from 27.7% to 52.7% within the slope, and annual emissions of N2O ranged from 2.0 to 4.4 kg N ha(-1) year(-1), respectively. These two variables were highly and positively correlated across the slope. Neither potential rates of net N mineralization and nitrification, nor N2O emissions in the laboratory incubated soils varied with slope positions. Soil CO2 release and CH4 uptake appeared to be independent on slope position in this study. Our results suggested that soil water content and associated N2O emissions are likely to be influenced by topography even in a short slope, which may need to be taken into account in field measurements and modelling.