Abha Panda
Shane C. Lishawa
Beth A. Lawrence
Olivia Fayne Johnson
2021
<p><span>Invasive species management typically aims to promote diversity and wildlife habitat, but little is known about how management techniques affect wetland carbon (C) dynamics. Since wetland C uptake is largely influenced by water levels and highly productive plants, the interplay of hydrologic extremes and <a class="topic-link" title="Learn more about invasive species from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/invasive-species" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/invasive-species">invasive species</a> is fundamental to understanding and managing these ecosystems. During a period of rapid water level rise in the Laurentian Great Lakes, we tested how mechanical treatment of invasive plant </span><i>Typha × glauca</i><span> shifts plant-mediated wetland C metrics. From 2015 to 2017, we implemented large-scale treatment plots (0.36-ha) of harvest (i.e., cut above water surface, removed biomass twice a season), crush (i.e., ran over biomass once mid-season with a tracked vehicle), and </span><i>Typha</i><span>-dominated controls. Treated </span><i>Typha</i><span> regrew with approximately half as much biomass as unmanipulated controls each year, and </span><i>Typha</i><span> production in control stands increased from 500 to 1500 g-dry mass m</span><sup>−2</sup><span> yr</span><sup>−1</sup><span> with rising water levels (~10 to 75 cm) across five years. Harvested stands had total in-situ methane (CH</span><sub>4</sub><span>) <a class="topic-link" title="Learn more about flux rates from ScienceDirect's AI-generated Topic Pages" href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/flux-rate" data-mce-href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/flux-rate">flux rates</a> twice as high as in controls, and this increase was likely via transport through cut stems because crushing did not change total CH</span><sub>4</sub><span> flux. In 2018, one year after final treatment implementation, crushed stands had greater surface water diffusive CH</span><sub>4</sub><span> flux rates than controls (measured using dissolved gas in water), likely due to anaerobic decomposition of flattened biomass. Legacy effects of treatments were evident in 2019; floating </span><i>Typha</i><span> mats were present only in harvested and crushed stands, with higher frequency in deeper water and a positive correlation with surface water diffusive CH</span><sub>4</sub><span> flux. Our study demonstrates that two mechanical treatments have differential effects on </span><i>Typha</i><span> structure and consequent wetland CH</span><sub>4</sub><span> emissions, suggesting that C-based responses and multi-year monitoring in variable water conditions are necessary to accurately assess how management impacts ecological function.</span></p>
application/pdf
10.1016/j.scitotenv.2021.147920
en
Elsevier
Repeated large-scale mechanical treatment of invasive Typha under increasing water levels promotes floating mat formation and wetland methane emissions
article