Alder (Alnus crispa) effects on soils in ecosystems of the Agashashok River valley, northwest Alaska

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At the northern limit of the boreal forest biome, alder (Alnus crispa [Ait.] Pursh) shrubs occur in a variety of ecosystems. We assessed the effects of individual alder shrubs on soil properties and understory plant tissue nitrogen in floodplain terraces, valley slopes and tussock tundra ridges. The three ecosystems differed with respect to soil properties and abiotic conditions and supported distinct plant communities. Alder increased resin-exchangeable soil N and NO3 production significantly in each ecosystem. The greatest difference between alder canopy and surrounding soil NO3 measured both under field and laboratory conditions occurred in floodplain sites. The shrub effect on soil pH and soil organic matter was greatest on tundra ridges. Alder shrubs also influenced the nitrogen nutrition of plants growing beneath their canopies. Plants growing below alder canopies had higher foliar nitrogen concentration and natural abundance 15N composition and lower carbon to nitrogen ratio than open-grown plants. Similar to soil N availability, understory plant leaf chemistry responded more to alder on floodplains than on slope or tundra ecosystems. This pattern suggests that understory plants rely more heavily on alder-fixed-N in this resource-poor ecosystem.

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Publication type Article
Publication Subtype Journal Article
Title Alder (Alnus crispa) effects on soils in ecosystems of the Agashashok River valley, northwest Alaska
Series title Écoscience
DOI 10.1080/11956860.2001.11682634
Volume 8
Issue 1
Year Published 2001
Language English
Publisher Taylor and Francis
Description 7 p.
First page 89
Last page 95
Country United States
State Alaska
Other Geospatial Agashashok River valley
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