High arctic heath soil respiration and biogeochemical dynamics during summer and autumn freeze-in - effects of long-term enhanced water and nutrient supply
High arctic heath soil respiration and biogeochemical dynamics during summer and autumn freeze-in - effects of long-term enhanced water and nutrient supply
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DOI：
10.1111/j.1365-2486.2012.02770.x
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发表时间：
2012-10-01
影响因子：
11.6
通讯作者：
Michelsen, Anders
中科院分区：
文献类型：
--
作者：
Christiansen, Casper T.;Svendsen, Sarah H.;Michelsen, Anders
在格陵兰岛东北部高纬度地区，预计本世纪气温和降水量将增加，然而，关于供水量增加对干燥高纬度北极生态系统中土壤CO 2 流出的影响的信息相对较少。我们测量了 2009 年夏季和秋季的土壤呼吸 (Rsoil)，并结合秋季冻结期间格陵兰岛东北部扎肯伯格干燥开放石南地区的微生物生物量和养分利用率。该苔原地点经过了全面的因子操作，包括 14 年来不断增加的土壤水供应，以及偶尔在豆类中添加氮 (N)。夏季浇水增强了夏季的土壤Rsoil，但降低了第二年秋季的Rsoil。我们推测这是由于土壤生物对最近固定的植物碳的消耗加剧。因此，秋季土壤微生物活动似乎通过植物相关碳库与生长季节植物生产紧密相关。单独添加氮持续增加 Rsoil，但当同时添加水和氮时，秋季 Rsoil 下降，与单独添加水时类似。尽管经历了几次冻融事件，微生物生物量碳（C）仍然保持不变，直到9月下旬最终减少了60%。尽管微生物生物量C和磷（P）显着减少，但微生物N没有变化。这表明死亡微生物释放的氮很快被幸存的微生物吸收。经过 14 年的环境控制，我们观察到土壤有机质含量没有变化，这表明生态系统对环境变化具有很强的抵抗力。
In High Arctic NE Greenland, temperature and precipitation are predicted to increase during this century, however, relatively little information is available on the role of increased water supply on soil CO 2 efflux in dry, high arctic ecosystems. We measured soil respiration (Rsoil) in summer and autumn of 2009 in combination with microbial biomass and nutrient availability during autumn freeze-in at a dry, open heath in Zackenberg, NE Greenland. This tundra site has been subject to fully factorial manipulation consisting of increased soil water supply for 14years, and occasional nitrogen (N) addition in pulses. Summer watering enhanced Rsoil during summer, but decreased Rsoil in the following autumn. We speculate that this is due to intensified depletion of recently fixed plant carbon by soil organisms. Hence, autumn soil microbial activity seems tightly linked to growing season plant production through plant-associated carbon pools. Nitrogen addition alone consistently increased Rsoil, but when water and nitrogen were added in combination, autumn Rsoil declined similarly to when water was added alone. Despite several freeze-thaw events, the microbial biomass carbon (C) remained constant until finally being reduced by 60% in late September. In spite of significantly reduced microbial biomass C and phosphorus (P), microbial N did not change. This suggests N released from dead microbes was quickly assimilated by surviving microbes. We observed no change in soil organic matter content after 14years of environmental manipulations, suggesting high ecosystem resistance to environmental changes.