Seedling demography of Swida controversa: Effect of light and distance to conspecifics

Takashi Masaki, Tohru Nakashizuka

    Research output: Contribution to journalArticlepeer-review

    49 Citations (Scopus)

    Abstract

    Some shade-intolerant trees with soil seed banks also have advanced recruits under a closed canopy. To determine the relative roles of advanced recruits and seed banks in regeneration, we studied the demography of seedling cohorts of the deciduous canopy tree, Swida controversa, in an old-growth temperate forest in Japan. Five cohorts that germinated in 1988-1992 were followed for 10 yr, relating their survival and growth to the environment. We measured distance to the nearest conspecific adult, initial local density of conspecific seedlings, herbaceous plant coverage, light intensity, and soil water content. Seed production occurred only in 1988 and 1990, but seedlings emerged every year from 1988 to 1992. Only increasing distance to the nearest conspecific adult had a significant, positive effect on seedling survival. Damping-off by fungal pathogens was the most common cause of seedling mortality, especially near conspecific adults. Growth of seedlings was significantly and positively affected by light level; rapid growth occurred mostly in a large gap (∼200 m2). Even here, however, the growth rate of seedlings decreased over time. A stochastic simulation suggested that the relative importance of soil seeds and advanced recruits changes with the distance. In sites <25 m from conspecific adults, colonization of gaps should occur via the soil seed bank, because seedlings do not survive at these distances. In sites farther away, advanced recruits were more important than the seed bank in colonizing gaps. We hypothesize that, in sites with an abundant population of S. controversa, regeneration would most likely originate from the soil seed bank, but in other sites regeneration would most likely be from advanced recruits.

    Original languageEnglish
    Pages (from-to)3497-3507
    Number of pages11
    JournalEcology
    Volume83
    Issue number12
    DOIs
    Publication statusPublished - 2002 Dec 1

    Keywords

    • Canopy gap
    • Fungal pathogen
    • Light intensity
    • Ogawa Forest Reserve, Japan
    • Seed bank
    • Seedling bank
    • Swida controversa

    ASJC Scopus subject areas

    • Ecology, Evolution, Behavior and Systematics

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