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Stand structure and vegetation dynamics of a subalpine wooded fen in Rocky Mountain National Park, Colorado
Author(s) -
Johnson J. Bradley
Publication year - 1997
Publication title -
journal of vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 115
eISSN - 1654-1103
pISSN - 1100-9233
DOI - 10.2307/3237322
Subject(s) - ecotone , vegetation (pathology) , abies lasiocarpa , peat , montane ecology , ecology , subalpine forest , mire , picea abies , national park , picea engelmannii , habitat , deserts and xeric shrublands , forestry , geography , environmental science , biology , medicine , pathology
. The tree population size structure and relationship between tree diameter and age were examined in a subalpine fen and surrounding Picea‐Abies forest in northern Colorado. The fen grades from a sedge fen, through an ecotone, to a treed fen. Tree growth rate varies across the vegetational gradient, with the sedge fen having the slowest growth, and the upland forest having the fastest growth. Differences in growth rate are related to the average size of peat hummocks, with areas containing tall hummocks exhibiting the highest tree growth rates. Size structures display the characteristic reverse‐J distribution generally indicative of stable populations, but forest vegetation is expanding into the open regions of the fen, and within the treed fen an increase in Abies lasiocarpa is occurring. These changes are primarily attributed to a positive feedback situation wherein the fen's surface is built up by peat accumulation. Distinct hummocks form first on the open fen but then coalesce to form raised peat islands in the treed fen. This new substrate provides habitat with a comparatively low water table and allows the growth of mesophytic forest vegetation. A pathway for this vegetational development is proposed.