PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Testing the association between tree species and soil properties: Do watershed patterns reflect those of individual trees?
Peterjohn, William*,1, Gress, Stephen1, 1 West Virginia University, Morgantown, West Virginia
ABSTRACT- Despite identical climate, geology, and land-use history, large differences in nitrate production and loss have been observed at the Fernow Experimental Forest (FEF) for forested watersheds receiving high amounts of N deposition. Plot-level data from these watersheds suggest that the species composition of canopy trees may make an important contribution to this variability. To test the strength of the association between tree species composition and N availability, we measured potential net nitrification rates and strong correlates of this process (pH & C:N ratio) in soils collected under fifteen canopy trees for each of six species. These species included three associated with high nitrate availability (Acer saccharum, Liriodendron tulipifera, & Prunus serotina) and three associated with low nitrate availability (Fagus grandifolia, Quercus prinus, & Nyssa sylvatica). Consistent with observations made at coarser spatial scales, we found that soils under A. saccharum, L. tulipifera, and P. serotina had higher pH values, lower C:N ratios, and higher net nitrification rates than did soils under Q. prinus. Soils under F. grandifolia and N. sylvatica had intermediate values for these variables that were often not statistically different from values measured in soils under some, or all, of the other species. An exception was that soil pH under N. sylvatica was higher than soil pH under either F. grandifolia or Q. prinus. Across the species examined, there was a strong association (r = -0.97) between the average soil C:N ratios and net nitrification rates. A weaker association (r = 0.51) was found between the average net nitrification rates and soil pH. The distinctive soil properties found under different tree species at the FEF, and at other locations, suggests that ecosystem properties at coarser spatial scales may strongly reflect, and may be reasonably inferred from, the species composition of dominant canopy trees.
Key words: N Cycling, Tree species, Forests