Marsh restoration in the presence of intense herbivory: The role of Justicia lanceolata (Chapm.) small
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Authors: D. W. Llewellyn, and G. P. Shaffer
Date: 1993
Journal: Wetlands
Volume: 13
Number: 3
Pages: 176-184
Summary of Methods: The potential use of Justicia lanceolata in wetland restoration was examined on Arrowhead and Hawk islands in the Atchafalaya Delta, Louisiana. Four paired islets of J. lanceolata were selected with one plot allowing grazing (control) and the other excluding nutria grazing. Vegetative cover was estimated with cover classes after plots were installed (fall 1991). Sediment profiles were collected, dried, and analyzed for total nitrogen (TN), total phosphorus (TP), electrical conductivity (EC), and particle density. A subsequent green house study was also conducted to determine the effect of light levels ranging from 60 to 500 µmol m-2 s-1on J. lanceolata production. Hurricane simulation with three storm-surge durations (72, 24 and 10 hours) was conducted followed by two flushing events (freshwater flushing and absence of freshwater flushing) and four levels of salinity (0, 5, 10 and 15 ppt). Dry weight was measured by clipping four weeks after simulations. An additional pilot study to determine the combined effects of salinity (0, 3 and 6 ppt) and flooding (10, 20 and 30 cm) was also conducted with different salinities and different levels of flooding. Every 3 weeks for 6 months, 2 pots were randomly harvested to measure above and belowground biomass.
Article Summary / Main Points: There was no difference in the vegetation cover between protected islets and unprotected islets fifteen months after the initiation of field trials. No differences were observed in TN, TP and EC among the islets. Nutrients were high and were not limiting at islet centers and EC increased with increases in islet size. Plants grown in greenhouse did not differ in the rate of carbon fixation under varying light levels. Salinity levels increased when hurricane waters were not followed by freshwater flushing. An increase in salinity and flooding levels decreased biomass production. One week following the simulation, the 72-hour storm surge decreased carbon fixation the most. Three weeks after the hurricane, salinity levels of 10 and 15 ppt severely depressed carbon fixation. J. lanceolata has the potential to be highly resilient to hurricane events followed by freshwater flushing and inhibit nutria herbivory.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 131A Southern Mississippi River Alluvium 151 Gulf Coast Marsh
Agrovoc Control Words: Wetlands Fresh marshes Restoration
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: lance-leafed water willow, justicia lanceolata, nutria, myocastor coypus, herbivore-resistant, louisiana, fresh marsh, wetlands restoration
Annotation: The results from this study are applicable to southeastern coastal wetlands of the United States. Use of J. lanceolata in wetland restoration efforts may be quite broad. The results are applicable to southeastern parts of USA since there is problem of wetland loss due to herbivory by nutria in marsh habitats.
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