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    Author(s): Richy J. Harrod; Charles B. Halpern
    Date: 2005
    Source: Natural Areas Journal. 25: 246-256
    Publication Series: Scientific Journal (JRNL)
    PDF: Download Publication  (1.9 MB)


    We examined the seed ecology of Iliamna longisepala as an aid to developing a conservation strategy for this rare endemic forb of northcentral Washington. We conducted field, greenhouse, and laboratory studies to quantify: (1) densities of buried viable seed among sites with different histories of burning, (2) post-fire spatial distributions of germinants relative to reproductive plants and bum severity, (3) seed production and its annual variation, and (4) germination requirements. Density of seed in the soil was not significantly related to history of burning, but sites that experienced fire 10 years before sampling averaged 10 times as many seeds as sites that burned recently and four times as many seeds as sites that had not burned within 50 years. Density of viable seeds in the soil did not correlate with density of reproductive plants. In a field experiment, germinants appeared after fall burning, but not after spring burning. Germinants were most abundant within 10 m of reproductive plants and were concentrated in areas of high burn severity. Seed production per plant was significantly correlated to crown diameter, but production varied dramatically from year to year. Experimental germination trials were largely unsuccessful due to low (8%) viability of seeds collected from mature plants. However, field studies illustrate that fire is sufficient to break the dormancy of seeds that have accumulated in the soil. Long-term exclusion of fire may lead to local extinction of populations as the longevity of reproductive plants and seeds are exceeded. However, burning more frequently than every 10 years could deplete local seed reserves.

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    Harrod, Richy J.; Halpern, Charles B. 2005. The seed ecology of Iliamna logisepala (Torr.) Wiggins, an east Cascade endemic. Natural Areas Journal. 25: 246-256


    fire effects, prescribed burning, rare plant, seed ecology

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