Document: GER-3-63-9

Control of fine root dynamics in a northern hardwood forest.

TIERNEY, G.* and T.FAHEY

Cornell University, Ithaca, NY 14853 USA ¹

Abstract:
Snow is an important regulator of winter soil temperatures at northern latitudes, and variation in snow depth has important consequences for root dynamics and belowground ecosystem processes. Over the past two years, we have used minirhizotrons to monitor the effects of an experimental snow removal treatment on the fine root dynamics of a northern hardwood forest plots at Hubbard Brook Experimental Forest, New Hampshire. Snow was removed from experimental plots dominated by either sugar maple or yellow birch for 6 week periods in early winter 1997-98 and 1998-99. Snow removal caused soil freezing in all experimental plots, but relatively mild winter temperatures during both winters prevented soil temperatures from dipping below -4 degrees Celsius. Soil freezing caused increased over-winter root mortality, and fine root production during the subsequent growing season peaked earlier in experimental vs. control plots. Fine root dynamics of both species reacted similarly to the experimental freeze treatment. The marked response of root dynamics to two relatively mild freezing treatments was surprising and indicates that even mild freezing events may have larger effects on biogeochemical cycling and nutrient loss in temperate forests than previously thought. More detailed study of the interactions between fine root dynamics and nutrient availability in these plots may improve understanding of the effects of soil freezing on ecosystem nutrient retention. Furthermore, our examination of the relationship between fine root dynamics and the soil environment in these plots has provided insight into controls on fine root dynamics in this system.

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This abstract is being presented at: 3:30 PM in session:
ROOT PROCESSES