Plant community, primary productivity, and environmental conditions following wetland re-establishment in the Sacramento-San Joaquin Delta, California

Abstract

Wetland restoration can mitigate aerobic decomposition of subsided organic soils, as well as re-establish conditions favorable for carbon storage. Rates of carbon storage result from the balance of inputs and losses, both of which are affected by wetland hydrology. We followed the effect of water depth (25 and 55 cm) on the plant community, primary production, and changes in two re-established wetlands in the Sacramento San-Joaquin River Delta, California for 9 years after flooding to determine how relatively small differences in water depth affect carbon storage rates over time. To estimate annual carbon inputs, plant species cover, standing above-and below-ground plant biomass, and annual biomass turnover rates were measured, and allometric biomass models for Schoenoplectus (Scirpus) acutus and Typha spp., the emergent marsh dominants, were developed. As the wetlands developed, environmental factors, including water temperature, depth, and pH were measured. Emergent marsh vegetation colonized the shallow wetland more rapidly than the deeper wetland. This is important to potential carbon storage because emergent marsh vegetation is more productive, and less labile, than submerged and floating vegetation. Primary production of emergent marsh vegetation ranged from 1.3 to 3.2 kg of carbon per square meter annually; and, mid-season standing live biomass represented about half of the annual primary production. Changes in species composition occurred in both submerged and emergent plant communities as the wetlands matured. Water depth, temperature, and pH were lower in areas with emergent marsh vegetation compared to submerged vegetation, all of which, in turn, can affect carbon cycling and storage rates.

Aridland constructed treatment wetlands I: Macrophyte productivity, community composition, and nitrogen uptake

“…The interaction of community composition and nutrient removal is obscured by 99 confounding factors (e.g., climate, wastewater type and quality, wetland design) and is generally 100 only examined by comparing the performance of two species to each other (Brisson & Chazarenc,101 2009). Nonetheless, there is reason to believe that community composition does influence CTW 102 performance (Brisson & Chazarenc, 2009;Miller & Fujii, 2010 Our research used a whole-system approach to study an operational CTW where vegetation 132 has been relatively unmanaged since planting, lending insights into how changes in plant 133 community composition may have impacted whole-system N uptake. Studying the impact of 134 community composition at this holistic scale provides a valuable context for extrapolating small-135 scale experimental findings to ecosystem-level management practices.…”

Engineering the global ecosystem

“…Focusing on the fundamental sustainability concepts and effective and sustainable approach to engineering design would include planning for ecosystem services, such as integrating engineered wetlands into the agricultural landscape to provide nitrogen processing and other ecosystem services. When ecosystem services are incorporated into the engineering design of larger projects, experience has demonstrated tangible benefits to engineered systems (Sommer et al 2001;Schemel et al 2004;Fleming-Singer and Horne 2006;Maynard et al 2009;Miller and Fujii 2010;Stringfellow et al 2010).…”

Water temperature differences by plant community and location in re-established wetlands in the Sacramento-San Joaquin Delta, California, July 2005 to February 2008

“…Differences in water depth in the wetlands affected carbon fluxes, biomass inputs, and accretion rates, in part, because deeper water slowed the colonization and spread of emergent marsh vegetation, which was a driver of productivity and elevation gain in the wetlands. Also, the spread of emergent marsh vegetation was associated with changes in local environmental conditions, including water pH, dissolved oxygen concentration, and temperature, all of which can affect decomposition rates, a primary factor in controlling preservation of carbon substrates and rates of accretion (Miller andFujii, 2010 and2011).…”

“…Decomposition rates increase in warmer water, in part, because the microbial population generally becomes more active as the temperature increases (Bachand and Horne, 2000;Kadlec and Reddy, 2001). Emergent marsh vegetation shades the water surface, decreasing the incidence of light, which is associated with cooler water temperatures (Miller and Fujii, 2010) that potentially slow decomposition and improve conditions for the preservation of organic matter (Miller and Fujii, 2011). In contrast, in areas of submerged vegetation, the water surface is exposed to sunlight, which warms the water column (Miller and Fujii, 2010).…”

“…Emergent marsh vegetation shades the water surface, decreasing the incidence of light, which is associated with cooler water temperatures (Miller and Fujii, 2010) that potentially slow decomposition and improve conditions for the preservation of organic matter (Miller and Fujii, 2011). In contrast, in areas of submerged vegetation, the water surface is exposed to sunlight, which warms the water column (Miller and Fujii, 2010). In a study in Sacramento County of wastewater-treatment wetlands with similar vegetation, water temperatures differed according to the length of time the water was in the wetland; water cooled as it travelled from inflows to outflows (Nolte Associates, Inc., 1999).…”