Typha Control and Sedge/Grass Meadow Restoration on a Lake Ontario Wetland

Abstract

To identify control techniques for cattails (Typha angustifolia and the hybrid Typha x glauca) in a Lake Ontario drowned-rivermouth wetland, multiple physical and chemical treatment techniques were implemented over two years at Kents Creek, New York. Treatments included cutting (C), spraying (S) glyphosate (Rodeo) onto cut stalks, tilling (T) rhizomes, and wicking (W) cattail re-sprouts later in the growing season (August). Each treatment technique had year options; for example, the cut treatment could be applied in year 1 or in both years 1 and 2 (C1 or C12). All possible treatments yielded 24 treatment combinations, plus two control plots; these were randomly assigned to each of the five treatment replicates established in equivalent stands of cattail. Vegetation sampling occurred in early summer (late June) and again in late summer (August) before treatment in both years. Cattail stem counts and species percent cover data were collected to analyze the effects of the treatments. Environmental variables (soil moisture, sediment depth, water-table elevation, soil organic matter, and bulk density) were measured to assist in the explanation of treatment success and differences observed among replicates. In addition to looking at the direct effects the treatments had on cattails, I assessed how the treatments affected the growth and expansion of sedge/grass meadow community species (Carex lacustris and Calamagrostis canadensis). Treatments combinations C1W1, C1SW1, C1WT, C12SW1, C12W1T, and C12SW1T significantly reduced cattail stem counts from June 2010 to August 2011. The most important treatment technique was the wick (W) treatment, vi which was implemented in August; it was included in every successful treatment for reducing cattails. The C12W1T treatment significantly reduced cattail stem counts the most (mean of 15.9 stems per plot), while treatments C12SW1T (12.9) and C12SW1 (12.2) also caused large reductions in Typha stems. Eight treatments significantly increased the amount of C. lacustris, including C1, C1W1, C1SW1, C1WT, C1SW1T, C12W1, C12SW1, and C12W1T. Five treatments that significantly reduced Typha stems also significantly increased C. lacustris cover. Overall, C. lacustris increased an average of 18% for any plot that had treatments applied. Treatment replicate 3 had some significantly different environmental variables that likely led to more successful treatments. Replicate 3 was positioned at a slightly higher elevation compared to the other replicates, leading to lower soil moisture, which helps control cattails. Although application of the wick treatment in August was the most important treatment method, addition of other treatments earlier in the year increased stress on cattails and led to increased reductions. Reduction of cattails also led to increased growth of Carex lacustris if C. lacustris was present before treatments were implemented. For management implications, I suggest using the cutting (early summer) and wicking treatments (late summer), as these two treatments were the most effective at reducing Typha stems. If funds are available, the tilling treatment combined with cutting and wicking, could be implemented, as it helped increase stress on Typha and led to increased stem reductions.