PARENT SESSION
Oral Session #43: Soil Ecology: Mycorrhizae and Roots. Presiding: W. Stock.
Wednesday, August 8, 2001. 8:00 AM to 12:15 PM. Hall of Ideas F.
Architecture of Pinus strobus fine roots across upland and wetland ecosystems.
DEFOREST, JARED1, PREGITZER, KURT2, ZAK, DONALD1, 1 2
ABSTRACT- The production of fine roots represents a substantial portion of belowground net primary production in many forest ecosystems. Fine roots proliferate in response to localized resource availability through greater branching. First-order roots, which are primarily responsible for nutrient uptake, are less costly in terms of plant C investment, compared to the higher-order roots. It is not understood how C investment or the production of first-order roots, relative to higher-order fine roots, change with fine-root branching. Number, length, and specific root length (m/g C) were measured for first- through forth-order roots of Pinus strobus in a range of upland and wetland ecosystems in northern Michigan. Fine root branching (total number and length of first-order roots) varied across the range of ecosystems, but the proportion of first-order to higher-order root length was consistent across ecosystems. A proportional relationship suggests that fine root branching patterns are controlled genetically, whereas the environment determines the degree of branching. Additionally, P. strobus specific root length varied among ecosystems, ranging from 50 m/g C in a forested wetland to 110 m/g C in a northern hardwood forest. This pattern indicates that investment of C by P. strobus yields a greater length of first-order roots in northern hardwood forests than in poorer quality sites.
KEY WORDS: C, fine roots, Pinus strobus, specific root length