Lower Columbia River Historical Landcover Change
The Estuary Partnership compared historical landcover data to it's recent 2010 landcover data set using a GIS, to determine how lower Columbia River and estuary habitats have changed from the late 1800's to the present. Funding for this work was provided by the U.S. Environmental Protection Agency. The historical data was prepared by the University of Washington WET lab and Oregon Biodiversity Information Center (formerly Oregon Natural Heritage Institute), using information from detailed survey maps created in the late 1800's by the former Office of Coast Survey (now NOAA) and General Land Office (BLM), respectively.
Results from our analysis are consistent with previous studies, and show that more than 75% of historical lower Columbia tidal and fluvial wetlands have been lost due to human impact, with much of this loss resulting from agricultural and industrial development, and flood protection measures. These wetlands provide critical habitat for rearing juvenile salmonids as well as other species, and their extensive loss has prompted habitat restoration efforts that have been ongoing for the past few decades.
Results from the change analysis can help inform restoration efforts. Maps of habitat change show where critical habitats have been lost and where it might be practical to recover them. Historical and current acreages calculated in the analysis provide a baseline for establishing target recovery amounts, for different types of habitat that have seen extensive loss.
Lower Columbia River Historical Landcover Change Report & Publication
Click here for a version of the Final Report, including detailed methods and results, available from our website.
Click here to access the published version, from the Journal of Coastal Conservation.
Historical Landcover Change Results for Lower Columbia River Wetlands
The map below illustrates changes to historical wetlands that have occurred since the late 1800's. Despite the extensive loss of both herbaceous and wooded wetlands, some areas have seen increase in these habitats as well. Overall, the map shows a dynamic habitat regime with a shifting mosaic of habitat types.
Targeted Recovery of Priority Habitats
The Estuary Partnership is using results of it's Historical Landcover Change analysis to help establish target recovery goals for habitats that have seen extensive loss. More information on this effort can be found below the map.
Lower Columbia Habitat Restoration Recovery Targets
The Estuary Partnership is applying results from it's Historical Landcover Change analysis and Sea Level Rise Impacts analysis to develop regional habitat restoration and protection targets for the lower Columbia River and estuary. By knowing how much habitat has been lost, how much additional habitat is predicted to be lost due to climate-induced sea level rise, and how much habitat is required to maintain healthy populations of critical species, we can get a sense of how much habitat needs to be recovered to achieve this goal.
Our Ecosystem Classification System provides a basis for this analysis. For each of the eight management reaches in this Classification we have identified the critical habitat types that have seen significant loss and quantified these. Based on those results we established target recovery amounts required to restore these habitats to 30% and 40% of their historic levels. Established landscape ecology principles show that these levels may be sufficient for maintaining viable populations of native species. At the same time, these are achievable goals for the region, based on an analysis of how much available land might practically be restored.
Maps of these 'recoverable habitats' are available at the following links, for each of the eight management reaches.
Recoverable Priority Habitats:
We are currently in the process of adjusting our Habitat Targets based on our recent Sea Level Rise Impacts study. Sea level rise is expected to alter currently existing habitats as well as potential 'recoverable habitats'. These predicted impacts will be used to adjust our recovery targets needed to meet the 30% and 40% habitat goals under a future climate regime. We will provide updated Habitat Restoration Target Recovery information when this analysis is completed.