Habitat restoration success is often gauged by assessing a few prominent plant canopy characteristics. However, these structural canopy features may not correspond with the recovery of ecological functions in the restored habitat. To fully assess restoration success it is necessary to determine the relationship between habitat structure and ecosystem function, but this relationship is not well understood in brackish marshes. The objective of our study was to evaluate whether plant canopy development corresponded with the recovery of ecological functions in a restored brackish marsh. We augmented the standard practice of measuring dominant plant characteristics (e.g., percent plant cover) by concurrently documenting the development of animal communities and ecological functions in restored and reference sites within a brackish marsh in the Lower Neches Wildlife Management Area in Texas, USA. Emergent marshes were constructed in 2008, and we conducted five surveys of emergent marsh and aquatic communities in restored and reference sites in 2009.
Many structural features of the restored sites were similar to the reference area. For emergent plants, restored and reference sites had similar cover, canopy complexity, and aboveground biomass. Aquatic plant biomass (Ruppia maritima and Myriophyllum spicatum) was also comparable between reference and restored sites. Some functional metrics also suggested restoration success. Emergent plant photosynthetic rates tended to be higher in restored sites. Spartina alterniflora leaf nitrogen and phosphorus content were similar between restored and reference sites, suggesting comparable nutrient limitation patterns. However, many other metrics had lower scores in restored sites. These lower-performing metrics included plant species richness, plant stem density, belowground plant biomass, aquatic animal density, and soil organic content. These habitat features can be linked to important ecosystem functions like trophic support, productivity, ecosystem resilience, and carbon sequestration. Our study suggests that despite the apparent rapid structural development of the plant canopy in the restored site, recovery of ecological functions is occurring at a slower rate.