EFFECT OF LIGHT AND SIMULATED HERBIVORY ON GROWTH OF ENDANGERED NORTHEASTERN BULRUSH, SCIRPUS-ANCISTROCHAETUS SCHUYLER

The independent and interactive effects of light and simulated herbivo ry on growth and biomass allocation in the endangered emergent sedge, Scirpus ancistrochaetus Schuyler, were examined in a 15-week common ga rden experiment. Light level was manipulated through the use of shade cloth to attain shading levels of 0%, 30%, 63% and 90%, while herbivor y was simulated by reducing plant height by 50% six weeks into the exp eriment. Multivariate Analysis of Variance (MANOVA) of final total (sh oot + root) plant mass, leaf width and root to shoot ratio (R:S) indic ated overall significant effects of both light and the interaction of light and clipping. Means of these Variables decreased with decreasing light level. Furthermore, means of these variables were generally hig her for clipped plants than unclipped plants in 0% shade, while they t ended to be lower in clipped plants in all other levels of shade. Maxi mum leaf height was also significantly affected by light. Leaf height was similar in all treatments for the first ii weeks. For the last fou r weeks of the experiment, however, leaf height was lowest in plants g rown in 0% shade, highest in plants grown in 63 and 90% shade, and int ermediate in plants grown in 30% shade. Clipped plants tended to be ta ller than unclipped plants at lower levels of shade, while the opposit e was true at higher levels of shade, although effects were marginally significant. Both light and the interactive effect of Light and clipp ing were important determinants of growth of S. ancistrochaetus in thi s experiment and therefore may be important influences on its distribu tion within and among pond habitats.