Hydrologic controls on nitrogen availability in a high-latitude, semi-arid floodplain
Hydrologic controls on nitrogen availability in a high-latitude, semi-arid floodplain
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高纬度半干旱洪泛区氮可用性的水文控制
DOI：
10.2980/15-3-2998
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Jeremy B. Jones
中科院分区：
文献类型：
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作者：
N. Lisuzzo;K. Kielland;Jeremy B. Jones
过去的研究表明，阿拉斯加内陆地区Tanana河洪泛平原早期演替植物群落的表观氮供应与年生长需要量存在差异。由于先前的固氮、矿化和沉积测量只能占这些群落氮需求的约26%，因此其他的氮供应机制应该在起作用。本研究探讨了地下水文向早期演替植物群落生根区提供氮的潜力。沿河漫滩建立了3个地下水井样带，测量了2 y的水文特征和土壤/水化学。然后利用水文测量数据模拟了平流和毛细上升对氮的潜在贡献。利用离子交换膜和稳定同位素示踪剂研究了植物对低渗氮的利用。在2003年高水位期间，离子交换膜上的氮积累表现出大量的氮输入。植株在4个位置中的2个位置显示了对低渗15n标记氮的吸收。毛细管上升和平流模型估计地下水的氮供应等于或超过氮矿化和固氮的总氮供应。这些发现强调了深埋过程在控制塔纳纳河漫滩早期演替植被养分供应中的重要性。
Abstract Past research shows a discrepancy between apparent nitrogen supply and the annual growth requirements for early successional plant communities along the Tanana River floodplain in interior Alaska. Because previous measurements of nitrogen fixation, mineralization, and deposition can only account for approximately 26% of these communities' nitrogen requirements, other mechanisms of nitrogen supply should be operating. This study examined the potential for subsurface hydrology to supply nitrogen to the rooting zones of early successional plant communities. Three transects of ground water wells were established along the floodplain, and hydrologic characteristics and soil/water chemistry were measured for 2 y. Hydrologic measurements were then used to model the potential nitrogen contributions from advective flow and capillary rise. Ion exchange membranes and stable isotope tracers were used to identify the use of hyporheic nitrogen by vegetation. Nitrogen accumulation on ion exchange membranes showed a large input of nitrogen during a period of high water in 2003. Plants showed uptake of hyporheic 15N-labelled nitrogen at 2 of 4 locations. Models of capillary rise and advective flow estimated that nitrogen supply from subsurface water equalled or exceeded total nitrogen supply from nitrogen mineralization and nitrogen fixation combined. These findings underscore the importance of hyporheic processes in controlling nutrient supply to early successional vegetation on the Tanana River floodplain.