科研之友
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摘要
Nitrogen dynamics in riparian systems are often addressed within one land-use type and are rarely studied on watershed scales across multiple land uses. This study tested for temporal trends and watershed-wide spatial patterns in N mineralization and identified sire factors related to N mineralization. We measured net N mineralization in situ at monthly intervals for 1 yr at 32 riparian sites along the 124-km length of the Calapooia River, Oregon. We observed seasonal trends of mean net N mineralization with relatively low rates in the fall (29.8 kg N ha(-1) yr(-1)) and winter (30.1 kg N ha(-1) yr(-1)) and relatively high rates in the spring (122.1 kg N ha(-1) yr(-1)) and summer (99.7 kg N ha(-1) yr(-1)) when conditions for microbial activity and decomposition were likely enhanced. Annual net N mineralization on an area basis ranged from -13.5 to 234.0 kg N ha(-1) yr(-1) with a mean for all sites of 50.1 kg N ha(-1) yr(-1). Annual net N mineralization per kilogram of soil ranged from -16.2 to 207.1 mg N kg soil(-1) yr(-1), with a mean for all sites of 64.4 mg N kg soil(-1) yr(-1). Regression analysis revealed hardwood basal area and coverage of grass as significant positive predictors of kilograms of N mineralized per hectare. Location along the river explained 22% of the variability of N mineralization per hectare, indicating that riparian areas may function differently along the length of the river.
- 出版日期2011-4
- 单位Virginia Tech; 美国弗吉尼亚理工大学(Virginia Tech)
