Definition
Structural components or structural aspects of an ecosystem include the biotic (living) and abiotic (physical) features of that ecosystem.
Representative Components
Key structural components discussed as particularly important metrics were trophic complexity, habitat composition, and biodiversity. Research needs are identified below each bullet point.
- Complexity
- Trophic complexity/foodwebs
- Inherently connected to function of trophic support and productivity
- Broken down into trophic groups
- Habitat complexity
- The role of anthropogenic structures in providing habitat complexity is an interesting aspect to consider in the discussion because they provide non-natural function and could be removed as mitigation.
- Trophic complexity/foodwebs
- Habitat composition at a landscape scale is needed to assist with regional, county or state-wide scale. In the discussion of out-of-kind mitigation, the regional or county-wide scale seems most appropriate. This might start with a description of what habitats are present in a given area, and a goal setting process could be to determine the expected relative percentage goals of a habitat for an area. For example, a guiding principle of Southern CA Wetland Recovery Project states “actions that influence the distribution of wetland archetypes consider the historic, current, and possible future extent, diversity and relative proportion of wetland types within the region.”
- Another need might be for a habitat classification system that creates groups of coastal habitats that are based on processes and functions rather than habitat types. An archetype is a group of ecosystems that are similar in terms of form, function, and processes. It currently exists for wetlands in southern California in the Southern California Wetland WRP Regional Strategy (2018). For wetlands, the physical conditions used to develop the archetype classifications included catchment properties (levels of water and sediment inputs), wetland area, proportion of subtidal and intertidal area, inlet dimension and condition, and tidal volume.
- Biodiversity
- A key need for additional research is regarding weighted biodiversity indices and metrics in the habitats under consideration. These indices would need to be scaled to be relative to the habitat type (e.g. salt marsh versus eelgrass) and in regional context (e.g. urbanization, climate). In addition, biodiversity can be done at many levels including species (most common) but additional levels should be considered including functional groups.
- It also seems important to evaluate the issue of how native versus overall biodiversity (including non-native species) should be evaluated as a goal. Some opinions advocate for provision of native biodiversity as a functional goal or as one in a suite of multiple benefits.
- Finally, there is the question of baseline data both in time and in location. Datasets in some regions might be limited without appropriate comparison datasets (e.g. undisturbed Baja marshes are not a good reference).
Utility
These structural aspects are typically used as metrics of habitat quality or metrics on which to evaluate restoration success (e.g. performance standards). Assessment of structural components is required on both the impact evaluation and restoration sides of the mitigation process. A key need for the effective application and evaluation of mitigation projects (regardless of the type of mitigation) is the development of crosswalks between these structural aspects/metrics and ecosystem functions and services. Ideally this might be conducted for rocky reef habitat, kelp, vegetated salt marsh, oyster beds, intertidal rocky shores, unvegetated mudflats, sandy beach, and coastal dunes.
Relevance/Importance
Coming soon…
Research Needs & Hurdles
Coming soon…
Example/Representative Metrics
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