Comparative effects of downslope water and nutrient movement on plant nutrition, photosynthesis, and growth in Alaskan tundra

• Published in: Ecography
• Main Authors: Oberbauer, S. F., Hastings, S. J., Beyers, J. L., Oechel, W. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1989
• Subjects: Ecology, Evolution, Behavior and Systematics; Arctic; Tundra
• Online Access: http://dx.doi.org/10.1111/j.1600-0587.1989.tb00853.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1600-0587.1989.tb00853.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0587.1989.tb00853.x

Changes in water and nutrient movement are common disturbances resulting from human activities in arctic regions. To assess the influence of water and nutrient movement on different plant growth forms, we added water and NPK fertilizer along 10 to 20 m linear transects across small natural drainages on an Alaskan tundra slope. Water was added by continuous‐flow emitters from a drip irrigation system at a rate of 450 L m −1 d −1 during the 1986 growing season and 110 L m −1 d −1 in the 1987 growing season. NPK in the form of Osmocote, a slow release fertilizer, was applied at 0.5 kg per linear meter in early and mid‐season of the 1985 growing season. Tissue N and P contents, light‐saturated photosynthetic rates, and aboveground biomass production were measured at peak season for key species 2 m above and 2 and 6 m below the water and nutrient applications in 1986 and 1987. Mean leaf N and P of the species tested increased slightly 2 m below the water addition sites and dramatically below the fertilizer addition sites. Increases in tissue N and P were also found 6 m below the fertilizer addition points. Leaf photosynthesis tended to increase 2 m below the water and nutrient additions for the species tested. Six meters below the treatment application points, photosynthesis was minimally affected in 1986 but increased in 1987. Increases in leaf area on the irrigation treatments were found only for the evergreen species, Ledum palustre and Vaccinium vitis‐idaea , 2 m below the site of addition. In contrast, fertilizer addition caused large increases in leaf area production for all species tested at 2 m below the treatment, and for some species at 6 m below treatment. The overall effects of the two treatments were similar, but were greater for the fertilizer addition.