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  • 1
    Electronic Resource
    Electronic Resource
    Limitations on Sphagnum growth and net primary production in the foothills of the Philip Smith Mountains, Alaska (1989)
    Springer
    Oecologia 80 (1989), S. 256-262 
    Details
    ISSN: 1432-1939
    Keywords: Tussock tundra ; Sphagnum ; Growth ; Tundra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the foothills of the Philip Smith Mountains, Brooks Range, Alaska, tussock tundra occurs on rolling hills and in valleys that were shaped by Pleistocene glaciations. During the 1986 and 1987 summer seasons, Sphagnum growth and production were determined in “water tracks” on tundra slopes that acted to channel water flow to the valley bottom stream and in “intertrack tundra” areas that were relatively homogeneous with respect to downslope drainage. Measurements were made under ambient environmental conditions and on mosses receiving supplemental irrigation in each area. Growth rate for Sphagnum spp. (cm shoot length increase/day) was low and relatively constant in intertrack tundra and highest but quite variable in water tracks. A strong negative correlation was found between Sphagnum spp. growth rate and solar irradiance in the shady environment below Salix canopies in the water tracks. Estimates of net annual dry weight (DW) production for Sphagnum spp. ranged from 0.10 g DW dm-2 yr-1 in intertrack tundra vegetation to 1.64 g DW dm-2 yr-1 in well-shaded water tracks. Experimental water additions had little effect on growth and production in intertrack tundra and well-developed water tracks, but significantly increased growth in a weakly-developed water track community. Low production over large areas of tundra slopes may occur due to presence of slow growing species resistant to dessication in intertrack tundra as opposed to rapidly growing less compact species within the limited extent of water tracks. We hypothesize that species capable of rapid growth occur also in weakly-developed water tracks, and that these are water-limited more often than plants occurring in well-developed water track situations. Where experienced, high light intensity may additionally limit growth due to photoinhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380160
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  • 2
    Electronic Resource
    Electronic Resource
    Competition for nitrogen in a tussock tundra ecosystem (1982)
    Springer
    Plant and soil 66 (1982), S. 317-327 
    Details
    ISSN: 1573-5036
    Keywords: Carbon ; Competition ; Isotope ; Mosses ; Nitrogen ; Soil microbes ; Tundra ; Vascular plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The objective was to measure the competition for nitrogen among vascular plants, mosses, and soil microbes along a continuum of nitrogen availability, induced by carbon and nitrogen amendments, in a tussock tundra ecosystem.15N was used as a tracer. Vascular plants showed an increasing15N recovery with increasing time and with increasing nitrogen availability; the latter suggests that nitrogen was limiting vascular plant growth. Green mosses took up15N initially, but showed no significant trends with either treatment or time. There was a higher15N recovery in the soil insoluble compartment for the carbon-amended treatment than in the nitrogen-amended treatments; this suggested that carbon as an energy source limited microbial activity. After two months, the relative15N recovery fell in the order: soil microbes (≈79%)〉vascular plants (≈16%) 〉green mosses (≈2%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183798
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