BIOGEOCHEMICAL DIVERSITY ALONG A RIVERSIDE TOPOSEQUENCE IN ARCTIC ALASKA
BIOGEOCHEMICAL DIVERSITY ALONG A RIVERSIDE TOPOSEQUENCE IN ARCTIC ALASKA
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DOI：
10.2307/2937049
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发表时间：
1991-12-01
影响因子：
6.1
通讯作者：
MCKERROW, AJ
中科院分区：
文献类型：
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作者：
GIBLIN, AE;NADELHOFFER, KJ;MCKERROW, AJ
氮和磷库的大小，分布和循环速率进行了描述和比较发生在沿着一个单一的地形序列在北方阿拉斯加的六种不同的生态系统类型。地形序列位于布鲁克斯山脉北方山麓的萨加瓦尼克托克河的一系列旧洪泛平原上。从草丛苔原的高地，地形序列通过一个相对干燥的山顶石南带，山坡灌木/羽扇豆/Cassiope区，一个footslope木贼区，潮湿的莎草苔原，和河岸灌木区。6月上旬晚融的雪坡覆盖在山坡上，土壤温度、土壤湿度、融化深度和土壤融化的季节性变化规律一致，这6种生态系统类型土壤中N、P和C的现存量沿地形序列变化显著，但不是沿着单调的，这些元素的周转率也是如此。几种措施被用来比较N和P的可用性，包括土壤溶液浓度，在原位积累的离子交换树脂，和KCl提取的N和P的水平。年净N矿化率进行了测定，使用埋袋法，和生态系统呼吸测量捕获CO2在碱石灰[NaOH + Ca（OH）2]。土壤磷库的特点是连续提取方法分为四个主要的池，包括松散结合的P，铝和铁结合的P，主要矿物P，和有机P。N和P的可用性低，在所有6个生态系统相比，温带森林或湿地。然而，在生态系统中，有相当大的变化，在相对可用性的N与P，在硝酸盐作为氮源的明显相对重要性。
Nitrogen and phosphorus pool sizes, distribution, and cycling rates were described and compared for six different ecosystem types occurring along a single toposequence in northern Alaska. The toposequence was located on a series of old floodplains of the Sagavanirktok River, in the northern foothills of the Brooks Range. From tussock tundra in the uplands, the toposequence passed through a relatively dry hilltop heath zone, a hillslope shrub/lupine/Cassiope zone, a footslope Equisetum zone, a wet sedge tundra, and a riparian shrub zone. A late-melting snowbank covered the hillslope site in early June of each year, and the sites consistently varied in soil temperature, soil moisture, thaw depth, and the seasonal pattern of soil thaw.The standing stocks of N, P, and C in soils of these six ecosystem types varied dramatically but not monotonically along the toposequence, as did the turnover rates of these elements. Several measures were used in comparisons of N and P availability, including soil solution concentrations, in situ accumulation on ion-exchange resins, and levels of KCl-extractable N and P. Annual rates of net N mineralization were assayed using a buried bag method, and ecosystem respiration was measured by trapping CO2 in soda lime [NaOH + Ca (OH)2]. Soil P pools were characterized by sequential extraction methods into four major pools, including loosely bound P, Al- and Fe-bound P, primary mineral P, and organic P.Both N and P availability were low in all six ecosystems when compared with temperate forests or wetlands. Among ecosystems, however, there was considerable variation in the relative availability of N vs. P, and in the apparent relative importance of nitrate as a nitrogen source.