PS 26-132 - Moss Compostion on Nurse Logs Affects Tree Seedling Density in Temperate Rainforests

Tuesday, August 8, 2017
Exhibit Hall, Oregon Convention Center
Katy E. Maleta, Biology, University of Puget Sound, Tacoma, WA and Carrie L. Woods, Biological Sciences, Clemson University, Clemson, SC
Background/Question/Methods

Habitat heterogeneity is important because it is able to increase species diversity, which then can increase forest succession. . In old growth temperate rainforests, there are an abundance of nurse logs along the forest floor that can increase habitat heterogeneity by assisting in tree seedling germination. Furthermore, along each nurse log, there are various microhabitats created by different moss species as well as detritus and other epiphytes that may influence tree seedling germination. To determine what factors affect tree seedling germination on nurse logs, I examined how tree seedling density varied with moss depth, canopy cover, nurse log diameter, and moss species composition in the Hoh temperate rainforest, Olympic National Park Washington.

Results/Conclusions

I found that tree seedling density was affected by moss depth and moss composition. The mean seedling density was highest when moss depth was less than 3 cm, and lowest when moss depth was greater than 3 cm. The moss species, step moss had the highest percent cover where moss depth was thickest. Step moss gross vertically, creating layers with each year of growth. This increase in moss depth then inhibits seedling growth due to a potential decrease in light source. Seedling density was most abundant when slender beaked moss was present, which could be because slender beaked moss grows horizontally, allowing more light for the seedling. There were particular moss species found at high and low canopy cover, but there wasn’t an effect on seedling density. Seedling germination is affected by the microhabitats along a nurse log created by various moss species.