CH4 and N2O fluxes in the Colorado shortgrass steppe .1. Impact of landscape and nitrogen addition
CH4 and N2O fluxes in the Colorado shortgrass steppe .1. Impact of landscape and nitrogen addition
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DOI：
10.1029/96gb01454
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发表时间：
1996-09-01
影响因子：
5.2
通讯作者：
Delgado, JA
中科院分区：
文献类型：
--
作者：
Mosier, AR;Parton, WJ;Delgado, JA
每周，全年一氧化二氮（N2 O）和甲烷（CH 4）通量测量计划在9个地点内的中央平原实验范围内的科罗拉多短草草原在1990年开始，并持续到1994年。本文报道了观测到的站点间，年际和季节变化的这些通量沿着与土壤和空气温度和土壤水和矿质氮含量的变化。结果表明，冬季通量贡献了年N_2O排放量的20-40%和CH_4消耗量的15-30%。N_2O排放量最大值出现在冬季，这似乎是由于表层土壤解冻时的反硝化作用。N2 O最大年平均通量的年际变化是最小的2.5倍，在4年的测量期间，而最大年平均CH 4吸收率是最小年平均吸收率的2.1倍，观察网站内。一般情况下，站点平均年通量最大值为CH 4吸收对应于最小N2 O通量，反之亦然，这支持了水控制的一般概念的气体在土壤中的扩散和土壤含水量对微生物活性的限制。我们还观察到，具有相似的使用历史和土壤质地的牧场表现出相似的N2 O和CH 4通量，以及相似的季节和年度变化。桑迪壤土在施氮5-13年后，与未施氮土壤相比，消耗的CH 4减少了30-40%，产生的N2 O更多。相反，13年前施氮并不影响CH 4吸收，但在质地较好的土壤中，N2 O排放量继续增加。我们的长期数据还表明，土壤矿质氮浓度不是观测变化的可靠预测因子，或者没有变化。N2 O排放或CH 4吸收。最后，根据我们的数据，我们估计，每年全球天然，温带草原的N2 O排放率约为0.16 Tg N2 O-N yr（-1），而CH 4消费总量约为3.2 Tg CH 4-C yr（-1）。
A weekly, year-round nitrous oxide (N2O) and methane (CH4) flux measurement program was initiated in nine sites within the Central Plains Experimental Range in the Colorado a shortgrass steppe in 1990 and continued through 1994. This paper reports the observed intersite, interannual, and seasonal variation of these fluxes along with the measured variation in soil and air temperature and soil water and mineral nitrogen content. We found that wintertime fluxes contribute 20-40% of the annual N2O emissions and 15-30% of CH4 consumption at all of the measurement sites, Nitrous oxide emission maxima were frequently observed during the winter and appeared to result from denitrification when surface soils thawed. Interannual variation of N2O maximum annual mean fluxes was 2.5 times the minimum during the 4-year meas urement period, while maximum annual mean CH4 uptake rates were 2.1 times the minimum annual mean uptake rates observed within sites. Generally, site mean annual flux maxima for CH4 uptake corresponded to minimum N2O fluxes and vice versa, which supports the general concept of water control of diffusion of gases in the soil and limitations of soil water content on microbial activity. We also observed that pastures that have similar use history and soil texture show similar N2O and CH4 fluxes, as well as similar seasonal and annual variations. Sandy loam soils fertilized with nitrogen 5-13 years earlier consumed 30-40% less CH4 and produced more N2O than unfertilized soils, In contrast, the N addition 13 years ago does not affect CH4 uptake but continues to increase N2O emissions in a finer-textured soil, Our long-term data also show that soil mineral N concentration is not a reliable predictor of observed changes, or lack of changes, in either N2O efflux or CH4 uptake. Finally, from our data we estimate that annual global N2O emission rates for native, temperate grasslands are about 0.16 Tg N2O-N yr(-1), while CH4 consumption totals about 3.2 Tg CH4-C yr(-1).