Temporal variability in plant and soil nitrogen pools in a high-Arctic ecosystem
Temporal variability in plant and soil nitrogen pools in a high-Arctic ecosystem
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DOI：
10.1016/j.soilbio.2007.03.016
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发表时间：
2007-08-01
影响因子：
9.7
通讯作者：
Dutton, Stephen
中科院分区：
文献类型：
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作者：
Bardgett, Richard D.;van der Wal, Rene;Dutton, Stephen
这项研究确定了斯瓦尔巴群岛斯匹次卑尔根岛高纬度地区（北纬 78 度）两个对比植物群落地上和地下氮库的时间变化。我们在生长季节期间四次测量了潮湿（以北看婆婆为主）和干燥（以八瓣仙女木为主）草甸群落的植物材料、土壤微生物生物量和土壤有机质中的氮库。我们发现植物、微生物以及溶解的无机和有机氮库受到显着但令人惊讶的低时间变化的影响，这种变化主要受短生长季节温度和水分可用性变化的控制。这种时间变化远小于其他季节性寒冷生态系统（例如高山苔原）所经历的变化，其中植物和土壤微生物库之间发生强烈的氮季节性分配。虽然微生物生物量只占生态系统总氮的一小部分，但它代表了潮湿和干燥草甸群落中最大的动态氮库（分别占生态系统总氮库的 3.4% 和 4.6%）。这表明土壤微生物群落动态对于北极生态系统中氮循环的重要性。在干燥草甸中，微生物氮与土壤温度呈强烈正相关，但这种关系在潮湿草甸中并不成立，因为潮湿的土壤条件等其他因素可能会限制生物活动。维管活地下植物部分代表了干燥和潮湿草甸中最大的单一植物氮库，平均占两个系统总氮库的 1.6%；该值在整个生长季节或植物群落之间没有变化。总体而言，我们的数据表明，北极高海拔生态系统中不稳定氮库的生长季节变化出人意料地低，我们认为这种变化主要由温度和湿度控制。 (C) 2007 Elsevier Ltd. 保留所有权利。
This study determined temporal variability in N pools, both aboveground and belowground, across two contrasting plant communities in high-Arctic Spitsbergen, Svalbard (78 degrees N). We measured N pools in plant material, soil microbial biomass and soil organic matter in moist (Alopecurus borealis dominated) and dry (Dryas octopetala dominated) meadow Communities at four times during the growing season. We found that plant, microbial and dissolved inorganic and organic N pools were subject to significant, but surprisingly low, temporal variation that was controlled primarily by changes in temperature and moisture availability over the short growing season. This temporal variability is much less than that experienced in other seasonally cold ecosystems such as alpine tundra where strong seasonal partitioning of N occurs between plant and soil microbial pools. While only a small proportion of the total ecosystem N, the microbial biomass represented the single largest of the dynamic N pools in both moist and dry meadow communities (3.4% and 4.6% of the total ecosystem N pool, respectively). This points to the importance of soil microbial community dynamics for N cycling in high-Arctic ecosystems. Microbial N was strongly and positively related to soil temperature in the dry meadow, but this relationship did not hold true in the wet meadow where other factors such as wetter soil conditions might constrain biological activity. Vascular live belowground plant parts represented the single largest plant N pool in both dry and moist meadow, constituting an average of 1.6% of the total N pool in both systems; this value did not vary across the growing season or between plant communities. Overall, our data illustrate a surprisingly low growing season variability in labile N pools in high-Arctic ecosystems, which we propose is controlled primarily by temperature and moisture. (C) 2007 Elsevier Ltd. All rights reserved.