PARENT SESSION
Oral Session #68: Nutrient Cycling. Presiding: D. Johnson.
Thursday, August 9, 2001. 1:00 PM to 5:00 PM. Hall of Ideas G.
Vernal nutrient retention by ground-layer vegetation and soil microbes in a Catskill northern hardwood forest.
Tessier, Jack1, Raynal, Dudley1, 1
ABSTRACT- The largest pulse of nutrient loss from northern hardwood forests occurs during spring in association with snowmelt and soil warming with potentially detrimental effects to aquatic ecosystems and drinking water quality. Both herbaceous plants and soil microbes may function as vernal nutrient sinks. We sought to quantify and compare the timing and magnitude of vernal nitrogen and phosphorus retention by ground-layer vegetation and soil microbes in a second growth stand over multiple years. Plants and soil microbes were sampled periodically over the spring seasons of 1999 and 2000 to quantify nitrogen and phosphorus pool sizes and nutrient uptake or loss. During the spring of 1999 soil microbes were neither significant sources nor sinks for nitrogen and phosphorus but lost 2.06 g N/m2 yet no phosphorus in 2000. Plants lost 1.08 g N/m2 and a net 0.10 g P/m2 in 1999 but gained 2.53 g N/m2 and 0.13 g P/m2 in 2000. Overall, plants were more biogeochemically active during both spring seasons than were soil microbes. Plants were more variable in nutrient retention patterns than were soil microbes and served as a nutrient source during the dry spring of 1999 but were a nutrient sink during the more typical spring of 2000. An additional year of sampling should help to more fully describe the vernal functioning of ground-layer vegetation and soil microbes in northern hardwood forests.
KEY WORDS: vernal-dam hypothesis, herbaceous plants, soil microbes , northern hardwood forest