Grantee Research Project Results
1999 Progress Report: Applying Ecological Succession Theory to Evaluate Wetland Restoration in Urbanizing Coastal Watersheds
EPA Grant Number: R826111Title: Applying Ecological Succession Theory to Evaluate Wetland Restoration in Urbanizing Coastal Watersheds
Investigators: Craft, C. B. , Stevenson, R. Jan , Megonigal, J. P. , Broome, S. W.
Institution: Indiana University - Bloomington
EPA Project Officer: Hahn, Intaek
Project Period: June 1, 1998 through May 31, 2001 (Extended to May 30, 2002)
Project Period Covered by this Report: June 1, 1998 through May 31, 1999
Project Amount: $534,239
RFA: Ecosystem Restoration (1997) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Hazardous Waste/Remediation , Land and Waste Management , Aquatic Ecosystems
Objective:
The objective of this project is to assess the degree of full or complete restoration of wetland structure and function on restored salt marshes and other ecologically similar restored wetlands.Progress Summary:
The second year of field work was completed as the three Virginia sites (6 marshes) were sampled in June and October 1999. Samples collected during 1999 included algae (for diversity, biovolume, and productivity), above- and below-ground macrophyte biomass, soil cores (for nutrients, texture, organic matter quality, radioisotope dating, denitrification, and decomposition?CO2 and CH4), and benthic invertebrate cores.
Except for the benthic invertebrate identification, we completed most of the laboratory analyses from the 1998 field campaign in North Carolina. Some of the findings from our North Carolina and Virginia datasets are presented below.
Primary Producers (Diatom Species Composition and Diversity). Four hundred diatom taxa were found in all of the sediment and epiphyte samples. When analyzing the similarity of restored and reference sites using diatom taxa in sediments and epiphytes, we found that the similarity in diatom species composition between restored and reference marshes increased with age of restored wetlands during both spring and summer.
Surprisingly, the similarity in species composition between restored and reference wetlands for algae in sediments and epiphytic algae, both in Virginia and North Carolina, were similarly related to age (Figure 1). The similarity of diatom species composition between restored and reference wetlands in sediment samples showed a highly significant tendency of increase (Y= -0.139+1.325X, R2 = 0.915). Snow's Cut was an outlier, perhaps because the source and salinity of the water in the restored and reference marshes were so different. Epiphytic algal communities showed the same increase in similarity between restored and reference marshes with increase in age of restored marshes (Y=0.366+0.016X, P=0.000, R2 = 0.851) (outlier Snow's Cut).
Similarity of diatom species composition from sediments in restored and reference marshes along age gradient of restored marshes for both NC and VA summer samples, combined.
Biogeochemical Cycling (Soil Development). There exists a clear trend of organic carbon accumulation with time in the surface soil layer (0?10 cm) of created marshes. There is a 27-fold increase in soil carbon from the newest to the oldest marsh. Equivalence of the created with the natural marsh with respect to soil carbon may be estimated by comparison with nearby natural marshes. Soil carbon levels for each of the five most recently created marshes (DT through DC), were significantly lower than in nearby natural marshes (Figure 1). These marshes ranged in age from 1 to 14 years. In contrast, two of the three older created marshes (PK and ML) had soil carbon levels that were either higher or not significantly different from their natural reference marshes. These created marshes ranged in age from 24 to 28 years. This indicates that with regard to surficial soil organic carbon content, the created marshes require greater than 14 years to attain parity with natural marsh and in some cases may reach parity at some time between 14 and 24 years. The exception to this pattern occurred in the oldest created marsh (SC) which, 28 years after establishment, had soil carbon levels in the 0-10 cm layer only half that of its reference marsh. This failure to achieve equivalence does not reflect any deficit in organic carbon accumulation relative to the other older marshes but rather is due to the fact that the reference marsh in this case is a high organic matter Histosol (8 percent organic carbon). Organic carbon accumulation proceeds less readily in the subsurface (10-30 cm) layer where there is only an eight-fold increase from the lowest to the highest organic carbon levels of created marsh soils. The oldest created marsh (SC) had only 0.59 percent organic carbon while its reference marsh had 9.51 percent organic carbon at this same depth. In general, the created marshes, regardless of age, had significantly lower organic carbon levels in the subsurface layer than their natural reference marshes. Only the 24-year-old marsh (PK) had organic carbon levels that were not lower than the reference marsh. In this case, the reference marsh was in a highly stressed condition, which lowered its primary productivity and hence, its organic carbon level relative to most natural marshes of the area. This aspect of soil development is occurring much more slowly in the subsurface soil and equivalent conditions to natural marshes do not appear likely in the foreseeable future. With sea-level rise and an upward building of the marshes, organic carbon accumulation at the subsurface depths may occur eventually. However, created marshes presently function to sequester carbon only within a thin surface horizon.
Table 1. Potential denitrification rates measured in July 1999. All samples were amended with glucose and nitrate. Values are means?SD in units of ng/gdw soil/d. | |||||
Approximate Age | Name |
Natural Site |
Planted Site |
Absolute Difference1 | Percent Difference |
2 | Consultant | 98.0?61.4 | 14.1?21.4 | -83.9 | -85.6 |
3 | DOT | 37.4?49.7 | 7.3?4.4 | -30.1 | -80.5 |
9 | Dill | 5.9?8.0 | 10.8?9.0 | 4.9 | 83.1 |
14 | Port | 8.4?6.1 | 12.7?9.9 | 4.3 | 51.2 |
27 | Marine Lab | 47.7?48.0 | 70.3?85.5 | 22.6 | 47.4 |
29 | Snows Cut | 160.4?118 | 105.0?87.1 | -55.4 | -34.4 |
1Absolute Difference = planted - natural.
2Percent Difference = [(planted - natural)/natural]*100. |
Future Activities:
We are in the process of completing our laboratory analyses and summarizing our findings from the North Carolina and Virginia restored salt marsh sites. We expect to submit a manuscript to BioScience that summarizes the key findings of the project, including trajectories that describe the rate of development of various ecological attributes over time following salt marsh restoration. Additional manuscripts focusing on specific aspects of the project (e.g., algae, macrophytes, soils, biogeochemical cycling, benthic invertebrates) will be forthcoming in the next year.Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 9 publications | 6 publications in selected types | All 5 journal articles |
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Type | Citation | ||
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Craft C, Reader J, Sacco JN, Broome SW. Twenty-five years of ecosystem development of constructed Spartina alterniflora (Loisel) marshes. Ecological Applications 1999;9(4):1405-1419. |
R826111 (1999) |
Exit Exit |
Supplemental Keywords:
estuary, sustainable development, public policy, decision making, monitoring., RFA, Scientific Discipline, Geographic Area, Water, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Restoration, State, Southeast, Mid-Atlantic, Ecological Risk Assessment, Aquatic Ecosystem Restoration, Watersheds, wetlands, ecological succession theory, biodiversity, watershed, Virginia (VA), tourism, regional economies, sustainable development, decision making, coastal environments, conservation, ecological recovery, marshes, aquatic ecosystems, urbanizing coastal watershed, North Carolina (NC), water quality, watershed restorationRelevant Websites:
http://www.indiana.edu/~speaweb/
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.