Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Faith Inman-Narahari; Rebecca Ostertag; Stephen P. Hubbell; Christian P. GiardinaSusan Cordell; Lawren Sack; Andrew MacDougall
    Date: 2016
    Source: Journal of Ecology. 104(3): 773-780
    Publication Series: Scientific Journal (JRNL)
    Station: Pacific Southwest Research Station
    PDF: Download Publication  (293.0 KB)

    Description

    1. Conspecific density may contribute to patterns of species assembly through negative density dependence (NDD) as predicted by the Janzen-Connell hypothesis, or through facilitation (positive density dependence; PDD). Conspecific density effects are expected to be more negative in darker and wetter environments due to higher pathogen abundance and more positive in stressful, especially dry, environments (stress-gradient hypothesis). For NDD to contribute to maintaining diversity, it should be apparent at the community-wide scale as a negative correlation between seedling recruitment, growth or survival and conspecific adult abundance (community compensatory trend; CCT).
    2. We examined seedling survival in relation to con- and heterospecific adults within 10 m and con- and heterospecific seedlings within 1 m for 13 species within two 4-ha permanent plots located in dry and wet forests in Hawaii. We also examined interactions between conspecific density and light and species’ commonness.
    3. For all species pooled, adult conspecific effects were positive (PDD) in both dry and wet forests, though they were stronger in the dry forest. In contrast, seedling conspecific effects were negative (NDD), though only significantly so in the wet forest.
    4. The strength and direction of density effects varied with understorey light such that seedlings had the highest survival where both adult conspecific density and light were high but the lowest survival where seedling conspecific density and light were high.
    5. In the wet forest, the most common species showed positive effects of adult conspecifics, but the less common species showed negative adult conspecific effects. We found mixed evidence for a CCT: seedling survival was positively correlated with basal area, but negatively correlated with tree density (stems ha−1). Thus, it remains unclear whether NDD is a diversity-maintaining mechanism in these forests.
    6. Synthesis. Overall, we found that positive conspecific effects influenced seedling mortality patterns more than negative interactions did, even in tropical wet forest where NDD is predicted to drive species’ abundances. Additionally, the strength and direction of density effects varied with forest type, PAR, and species’ abundance, underscoring the need to consider abiotic factors and species’ life-history traits in tests of density dependence hypotheses.

    Publication Notes

    • You may send email to psw_communications@fs.fed.us to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

    Citation

    Inman-Narahari, Faith; Ostertag, Rebecca; Hubbell, Stephen P.; Giardina, Christian P.; Cordell, Susan; Sack, Lawren; MacDougall, Andrew. 2016.Density-dependent seedling mortality varies with light availability and species abundance in wet and dry Hawaiian forests. Journal of Ecology. 104(3): 773-780. https://doi.org/10.1111/1365-2745.12553.

    Cited

    Google Scholar

    Keywords

    community compensatory trend, density dependence, determinants of plant community diversity and structure, facilitation, Janzen-Connell hypothesis, regeneration dynamics, seedling ecology, tropical dry forest, tropical wet forest

    Related Search


    XML: View XML
Show More
Show Fewer
Jump to Top of Page
https://www.fs.usda.gov/treesearch/pubs/54428