Variability of heterotrophic metabolism in small stream corridors of an early successional watershed
Variability of heterotrophic metabolism in small stream corridors of an early successional watershed
复制标题
DOI：
10.1029/2010jg001516
复制
发表时间：
2011-06
影响因子：
--
通讯作者：
Linda Gerull;Aline Frossard;M. Gessner;M. Mutz
中科院分区：
文献类型：
--
作者：
Linda Gerull;Aline Frossard;M. Gessner;M. Mutz
[1]河流廊道中的代谢活动受到多种因素的复杂组合的调节，这些因素在成熟的生态系统中很难理清。鸡溪在德国，实验创建的流域在早期的演替阶段，提供了一个简化的系统，以评估代谢活动的时空变化的机会。我们测量了土壤和沉积物中的微生物呼吸沿着水文流动路径从陆地高地到短暂的三条河流走廊的多年生站点。干燥的土壤和沉积物进行再湿润呼吸测量之前，模仿期间和降雨后的活动。土壤和沉积物的呼吸速率和有机质含量普遍较低。藻类的存在和血管植物片段在常年流的吸积达到增加呼吸速率，指出颗粒有机物的重要性。与预期相反，再湿润的土壤和沉积物从干流渠道的呼吸速率与常年渠道部分收集的沉积物测得的速率相似。这表明，永久性的水的可用性不是一个主要因素，决定代谢潜力在早期演替鸡溪流域。常年渠道的碳周转率比短暂渠道和陆地站点高四到八倍，因为水是永久可用的。然而，这一幅度是不够的常年渠道，以弥补陆地土壤的大表面积：外推到一年，整个流域，河流渠道贡献只有5%的总碳周转，95%是由于降雨事件期间和之后的土壤。
[1] Metabolic activity in stream corridors is regulated by a complex combination of factors that are difficult to disentangle in mature ecosystems. Chicken Creek in Germany, an experimentally created watershed in an early successional stage, offers the opportunity to assess the spatiotemporal variation in metabolic activity in a simplified system. We measured microbial respiration in soils and sediments along the hydrologic flow path from upland terrestrial to ephemeral to perennial sites of three stream corridors. Dry soils and sediments were rewetted before respiration measurements to mimic periods of activity during and after rainfall. Respiration rates and organic matter contents of soil and sediment were generally low. The presence of algae and accretion of vascular plant fragments in the perennial stream reaches increased respiration rates, pointing to the importance of particulate organic matter. Contrary to expectation, respiration rates of rewetted soil and sediment from dry stream channels were similar to rates measured with sediments collected in the perennial channel sections. This suggests that permanent water availability was not a main factor determining metabolic potential in the early successional Chicken Creek watershed. Carbon turnover in perennial channels was fourfold to eightfold higher than in ephemeral channels and terrestrial sites, as water was permanently available. However, this magnitude was insufficient for perennial channels to compensate for the large surface area of terrestrial soils: extrapolated to a year and the whole watershed, stream channels contributed only 5% to total carbon turnover, 95% being due to soils during and after rainfall events.