美国康奈尔大学的研究人员在新一期《科学》杂志上发表报告说,随着气候变暖,沙漠地区土壤中的氮会以气体的形式大量流失,从而导致生长在沙漠里的植物越来越少。
研究人员在美国莫哈韦沙漠地区选了几处试验点,通过精密测量仪器了解土壤中的氮是如何随着周围气温升降而变化的。研究发现,不管有没有光照,当温度达到40摄氏度至50摄氏度时,土壤中的氮会以气体形式从土壤中迅速释放出来。温度越高,释放的速度越快。研究人员由此推测,在世界任何高温干旱的地方都可能出现类似的情况,因此应该引起关注。
氮是植物生长过程中除水之外的第二大必需营养元素。研究人员指出,目前生长在沙漠地区的植物本来就很少,根据这一新发现,随着全球气候变暖加剧,沙漠土壤里的氮会大量流失,那么生长在沙漠里的植物就会越来越少,这将给沙漠地区的生态环境构成严重威胁。(生物谷Bioon.com)
生物谷推荐原始出处:
Science 6 November 2009:DOI: 10.1126/science.1178984
Abiotic Gas Formation Drives Nitrogen Loss from a Desert Ecosystem
Carmody K. McCalley* and Jed P. Sparks
In arid environments such as deserts, nitrogen is often the most limiting nutrient for biological activity. The majority of the ecosystem nitrogen flux is typically thought to be driven by production and loss of reactive nitrogen species by microorganisms in the soil. We found that high soil-surface temperatures (greater than 50°C), driven by solar radiation, are the primary cause of nitrogen loss in Mojave Desert soils. This abiotic pathway not only enables the balancing of arid ecosystem nitrogen budgets, but also changes our view of global nitrogen cycling and the predicted impact of climate change and increased temperatures on nitrogen bioavailability.
Department of Ecology and Evolutionary Biology, Corson Hall Room E149, Cornell University, Ithaca, NY 14853, USA.