Host composition, light, and nitrogen effects on ectomycorrhizal communities from Quercus seedlings grown in soils from regional hardwood -hemlock forests
Mycorrhizal fungi are an integral component of soil communities influencing host composition, productivity, and ecosystem processes. Ectomycorrhizae (ECM) are predominant in temperate and boreal forests where they may vary in soils between contrasting host species. Forest trees, their canopies, and soils may differ in biotic and abiotic factors such as host specificity, irradiance, and nutrient availability, which can affect ECM colonization and community structure. Studies have examined the influence of these factors on ECM, but few have examined how these factors may influence ECM communities from contrasting host species between regional forests and seedling ages. To address these issues, four studies were conducted to examine whether ECM abundance and diversity from seedlings grown in soils from two contrasting host species (i.e., oaks and hemlocks) differ: (1) between soil sources and different bait seedling species from one forest, (2) between contrasting soils from three regional forests and across seedling ages, (3) in response to variable irradiances, and (4) in response to variable nitrogen supplies. Seedlings were grown in a greenhouse in soil cores removed from beneath red oak ( Quercus rubra) and eastern hemlock (Tsuga canadensis) trees found in hardwood- and hemlock-dominated stands, respectively, located in forests in northern New Jersey and Pennsylvania, and southern New York. Q. prinus, Q. rubra, and Q. velutina were used as host species since they are common in these forests. In the first study ECM abundance and diversity were all greater on seedlings grown in oak compared to hemlock soils. There were no differences between host bait seedling species. The second study found that ECM abundance was greater on 12- and 24-week old seedlings from oak and hemlock soils, respectively, and that diversity was greater on seedlings from oak compared to hemlock soils, across forests. The third study found that ECM abundance was greater on seedlings grown under 100% and 45% full sun irradiances compared to 10% irradiance in oak and hemlock soils, respectively. ECM richness and diversity increased with increasing irradiance. Finally, in the fourth study, ECM abundance was found to decrease with increasing nitrogen. ECM richness decreased with increasing nitrogen. ^
Biology, Botany|Biology, Ecology|Biology, Microbiology
Gregory Douglas Turner,
"Host composition, light, and nitrogen effects on ectomycorrhizal communities from Quercus seedlings grown in soils from regional hardwood -hemlock forests"
(January 1, 2003).
ETD Collection for Fordham University.