Ruiz-Jaen, Maria C. & T. Mitchell Aide. 2005. “Restoration Success: How Is It Being Measured?” In Restoration Ecology
, Vol. 13, No. 3, pp. 569-577, September 2005.
The authors investigated all restoration projects reported in the journal Restoration Ecology from 1993-2003. Their goal was to compare the reported methods of evaluating restoration success to the guidelines set out by the Society for Ecological Restoration (SER). Specifically, they examined what measures researchers use to assess ecosystem attributes and how researchers use these measures to determine restoration success.
The authors offer several definitions and explanations to frame their discussion. These include:
- SER’s 2004 definition of ecological restoration: “Ecological restoration is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed”
- SER’s 2004 Primer of nine guidelines for assessing restoration success:
- Similar species diversity and community structure in comparison with reference sites
- Presence of indigenous species
- Presence of functional groups necessary for long-term stability
- Capacity of the physical environment to sustain reproducing populations
- Integration with the landscape
- Elimination of potential threats
- Resilience to natural disturbances
- The three ecosystem attributes most often assessed by researchers:
The authors found that of the 468 articles investigated, only 68 monitored restoration success (14.5%). Wetlands, grasslands, and montane forests were the most common restored habitats, and the most common previous land uses were mining and agriculture. The most frequently used re-vegetation technique was planting seedlings, followed by direct seeding. The breakdown of the ecological assessment was as follows:
Diversity only - 3%
Diversity and Vegetation Structure - 41%
Diversity and Ecological Processes - 9%
Vegetation Structure and Ecological Processes - 9%
Diversity, Vegetation Structure, and Ecological Processes - 38%
Plants (79%) and arthropods (mainly insects) (35%) were the most common taxa studied in diversity assessment. Common methods of vegetative assessment were plant cover, density, biomass, and height. The common measurements of ecological processes were biological interactions, nutrient pools, and soil organic matter. The presence of mycorrhizae was a commonly assessed biological interaction.
The authors offer explanations for their findings. They argue that arthropods are used in diversity assessments because they represent many different functional groups (pollinators, decomposers, etc.) and because they play a critical role in nutrient cycling. Thus the presence or absence of arthropod taxa can play a large role in ecosystem function and sustainability. Vegetation diversity and structure is assessed because it is assumed that the recovery of fauna and ecosystem processes will follow the establishment of vegetative structure. Other contributing factors for vegetative assessments include relative ease of assessment and legal obligations for vegetative monitoring. Ecological processes are the least often studied, which the authors attribute to the length of time, difficulty, and expense of ecological processes assessments.
The three SER Primer attributes most rarely measured in restoration projects are:
- the capacity of the physical environment to sustain reproducing populations
- the integration with the landscape
These measurements all require long-term monitoring to be assessed. Significance for Designers
The article offers a good summary of current restoration monitoring methods and rationales for their use. The authors argue that assessment of the nine SER Primer goals is the ideal for monitoring restoration success, but that the most realistic goal is for restoration projects to assess diversity, vegetation structure, and ecosystem processes.
Landscape architects can help achieve this goal by including provisions for monitoring in the budgets and plans for their projects. Considering that less than 15% of all the published restoration projects in this study included monitoring of restoration success, it would seem that any level of monitoring and long-term accountability that can be incorporated into restoration projects would be an improvement over current conditions.
The authors advocate that those concerned about restoration success push for legal requirements for the monitoring of restoration projects, arguing that without legal incentives, it is difficult to make monitoring commonplace.