Joy B. Zedler
Isa Woo
2002
<p><span>Where wetlands receive urban runoff, </span><i class="a-plus-plus">Typha</i><span> spp. and other invasive plants often displace the native vegetation. We tested the ability of nutrients (N and P) to increase vegetative growth of </span><i class="a-plus-plus">T. × glauca</i><span>(a hybrid of </span><i class="a-plus-plus">T. latifolia</i><span> and </span><i class="a-plus-plus">T. angustifolia</i><span>). In the greenhouse, 17 treatments revealed that </span><i class="a-plus-plus">T. × glauca</i><span> required both N and P for growth, and total leaf length was most stimulated where a higher proportion of P was added (7N∶1P vs. 14N∶1P, with N constant and P changed), regardless of concentration (the High treatment was 4× the Low treatment). In Gardner Marsh (Madison, Wisconsin, USA), we set up 28 plots (1×6 m) that bisected the boundary between sedge meadow (graminoids) and </span><i class="a-plus-plus">T. × glauca</i><span>, and we added a common lawn fertilizer (9N∶1P∶4K) at high (62.5 g/m</span><span class="a-plus-plus">2</span><span>), medium (31.3 g/m</span><span class="a-plus-plus">2</span><span>), low (15.6 g/m</span><span class="a-plus-plus">2</span><span>), and control (0 g/m</span><span class="a-plus-plus">2</span><span>) rates on five dates, with n=7 plots/treatment. After one growing season, fertilizer addition increased </span><i class="a-plus-plus">T. × glauca</i><span> ramet density, height, and biomass, especially where the sedge meadow graminoids were initially dominant. Aboveground biomass of </span><i class="a-plus-plus">T. × glauca</i><span> in the high nutrient addition treatment (1029±256.1 g/m</span><span class="a-plus-plus">2</span><span>) was more than double that for control plots (431±80.52 g/m</span><span class="a-plus-plus">2</span><span>) overall, with the greatest percent increase in sedge meadow subplots. In contrast, native graminoids (mostly </span><i class="a-plus-plus">Carex</i><span> spp.) did not respond to treatment, either in biomass or percent cover. </span><i class="a-plus-plus">Typha × glauca</i><span> allocated nutrients to both growth and storage, as indicated by higher N and P concentrations in leaves, shoot bases, and rhizomes in plots with high nutrient addition. Because fertilizing the marsh enhanced the shoot growth of </span><i class="a-plus-plus">T. × glauca</i><span> but not native graminoids, and because the 7N∶1P treatment stimulated growth in the greenhouse, we suggest that wetland managers focus on reducing P inflows to urban wetlands. Fertilizer additions below those recommended by the manufacturer for new lawns (5× that of our highest treatment) should be more economical and have fewer impacts on receiving wetlands.</span></p>
application/pdf
10.1672/0277-5212(2002)022[0509:CNASAS]2.0.CO;2
en
Springer
Can nutrients alone shift a sedge meadow towards dominance by the invasive <i>Typha × glauca</i>
article