Comparing the impact of cloudiness on carbon dioxide exchange in a grassland and a maize cropland in northwestern China
Comparing the impact of cloudiness on carbon dioxide exchange in a grassland and a maize cropland in northwestern China
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比较阴天对西北地区草原和玉米田二氧化碳交换的影响
DOI：
10.1007/s11284-012-0930-z
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发表时间：
2012-05-01
影响因子：
2
通讯作者：
Liang, Ji
中科院分区：
文献类型：
--
作者：
Bai, Yanfen;Wang, Jian;Liang, Ji
光的数量和质量对植物的生长有很大的影响。然而，不同的生态系统吸收太阳辐射的能力不同。利用2008年和2009年生长季中期（7 - 8月）的云量资料，比较了阿柔高寒草地（叶面积指数较低）和盈科绿洲玉米农田（叶面积指数较高）云量对生态系统CO2净交换的影响。结果表明，两个观测点的NEE对光合有效辐射（PAR）的响应在阴天比晴天更负（碳吸收）。在多云天气下，当晴空指数（CI）在0.4 ~ 0.7之间时，NEE最大。灌溉期前，草地在60-65°太阳高度角时，最大提高量为11.9%，玉米地在60-65°太阳高度角时最大提高量为34.9%，在35-40°太阳高度角时最大提高量为10.3%。与玉米地相比，草地NEE对CI的响应随太阳高度角的变化较小。结果表明，增强的NEE下多云的天空可以归因于越来越多的扩散PAR和环境因素（空气温度和蒸汽压赤字）的相互作用。
Light quantity and quality strongly influence plant growth. However, different ecosystems have different capabilities to assimilate solar radiation. In this study, the effects of cloudiness intensity on the net ecosystem exchange of carbon dioxide (NEE) were compared between an alpine grassland (with lower leaf area index) at A’Rou and an oasis maize cropland (with higher leaf area index) at Yingke, using flux data obtained during the middle of the growing season (July–August) in 2008 and 2009. The results showed that the response of NEE to photosynthetically active radiation (PAR) was more negative (carbon uptake) under cloudy than under clear skies at both sites. The maximum NEE occurred when the clearness index (CI) ranged from 0.4 to 0.7 under cloudy skies. The maximum enhancements were 11.9% for solar elevation angles of 60–65° in the grassland, and 34.9% for solar elevation angles of 60–65° and 10.3% for angles of 35–40° in the maize cropland before the irrigation period. The response of NEE to CI changed slightly with solar elevation angle in the grassland compared to the maize cropland. The results indicate that enhanced NEE under cloudy skies can be attributed to increasingly diffuse PAR and interactions with environmental factors (air temperature and vapor pressure deficit).