RESOURCE-BASED NICHES PROVIDE A BASIS FOR PLANT SPECIES DIVERSITY AND DOMINANCE IN ARCTIC TUNDRA

• Main Authors: R McKane, L Johnson, G Shaver, K Nadelhoffer, E Rastetter, B Fry, A Giblin, K Kielland, B Kwiatkowski, J Laundre, G Murray
• Format: Text
• Language: unknown
• Published: 2005
• Subjects: Arctic; Tundra
• Online Access: http://oaspub.epa.gov/eims/eimsapi.dispdetail?deid=64427

Ecologists have long been intrigued by the ways co-occurring species divide limiting resources, and have proposed that such resource partitioning, or niche differentiation, promotes species diversity by reducing competition. Although resource partitioning is an important determinant of species diversity and composition in animal communities, its importance in structuring plant communities has been difficult to resolve. This is due mainly to difficulties in studying how plants compete for belowground resources5. Here we provide evidence from a 15N-tracer field experiment showing that plant species in a nitrogen-limited, arctic tundra community were differentiated in timing, depth and chemical form of nitrogen uptake, and that species dominance was strongly correlated with uptake of the most available soil nitrogen forms. That is, the most productive species used the most abundant nitrogen forms, and less productive species used less abundant forms. To our knowledge, this is the first documentation that the composition of a plant community is related to partitioning of differentially available forms of a single limiting resource. Our results also suggest that tundra species composition is sensitive to natural and human-induced changes in availabilities of different nitrogen forms.