Titus, Jonathan .
Douglas-fir seedlings show highest survival in barren sites at Mount St. Helens, Washington, USA.
Douglas-fir (Pseudotsuga menziesii) seeds were planted in barren, young and old lupine patch, and alder habitats in a variety of shade, site and soil treatments on the Pumice Plain of Mount St. Helens in September of 2002, 2003 and 2004. Seedling survival of each cohort was monitored until 2006. For each of the three years germination was highest in young lupine patches followed by barren habitats and significantly fewer seeds germinated in old lupine patches and alder thickets. Germination was higher under shade cloth in barrens and young lupine patches whereas pulling back the alder branches and exposing the substrate to light increased germination in alder thickets. For seedlings’ from seeds planted in 2002 first summer survival was >50% for all treatments in barren habitats whereas survival was <10% in the other habitats. For seedlings from seeds planted in 2003 and 2004, survival was high in barren and young lupine patch habitats and very low in old lupine patch and alder habitats. Seedling survival for each of the cohorts was higher in shade treatments than in unshaded treatments in barren and young lupine microsites, whereas mortality was too high in old lupine patch and alder habitats for this effect to occur. Soil moisture was usually higher in barren and young lupine patch habitats, perhaps due less vegetation in these sites, and may have contributed to the increased seedling survival these habitats.
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1 - Biology Department, SUNY-Fredonia, Fredonia, NY, 14063, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Boulevard A/Hilton
Date: Wednesday, July 11th, 2007
Time: 1:30 PM