Monday, May 26, 2008 - 3:00 PM
485

Mechanisms of obtaining dominance by invasive plants in great lakes coastal marsh ecosystems

Nancy C. Tuchman, Daniel Larkin, Pamela Geddes, Kathi Jo Jankowski, Monika Freyman, and Lane Barham. Department of Biology and Center for Urban Environmental Research and Policy, Loyola University Chicago, 6525 N. Sheridan Road, Chicago, IL 60626

Mechnisms of obtaining successful dominance by the invasive cattail Typha x glauca in a northern Michigan coastal wetland were studied from physical and biogeochemical perspectives.  This synthesis of 5 years of field and controlled wetland mesocosm experiments demonstrates that the large stature of these cattails (300x greater biomass per plant than native plants) produces large amounts of litter (2,470 g/m2), which inhibits the growth of native plants and, through slow decomposition (> 4 years to decompose litter in situ), enriches the sandy soils with organic carbon (from 1.9% SOM in sandy soils to 36.7% in Typha associated soils).  Organic carbon enrichment, in turn, drives biogeochemical processes including N-fixation, mineralization, and denitrification, with a net accumulation of inorganic N (soil TIN in sandy soils associated with native plants is 0.013 μg N/g AFDM and 12.003 in Typha soils).  15N uptake experiments comparing Typha and the native plants suggest that Typha has the competitive advantage in sequestering soil N.  By producing vast amounts of litter that physically inhibits native plant growth and enriching the soils with organic C, Typha x glauca has produced a soil environment conducive to N-fixation and N availability which Typha exploits more efficiently than native plants.


Web Page: invasive species, biogeochemistry, nitrogen

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