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Transition Zone Baseline Map

Transition Zone Baseline Map

Averages were calculated by separately averaging the area of all transition zone polygons within the backshore, midmarsh or everywhere (Ďall typesí).

In November 2018, the San Francisco Bay Joint Venture’s (SFBJV) Science Program released the ‘SFBJV baseline Transition Zone GIS dataset. The dataset will serve as a baseline for tracking changes to the distribution and acreage of transition zone in SF, San Pablo, and Suisun Bays, and as a means for evaluating progress towards meeting habitat goals.

The SFBJV transition zone GIS dataset (see links below) represents the ‘baseline’ distribution and acreage of estuarine-upland transition zone elevations that are both (a) exposed to tides; and (b) adjacent to a saline marsh. The baseline data will be used to track changes to transition zone distribution and acreage over time and to evaluate the impact of restoration efforts. The GIS dataset not only represents the current distribution of transition zone, but also distinguishes between transition zone that is either in the ‘backshore’ (adjacent to both a tidal wetland and an upland) or in the ‘mid marsh’ (only adjacent to a tidal wetland). 

The SFBJV hired Brian Fulfrost to derive maps of ‘baseline’ transition zone from the existing ‘Bay Margin’ GIS datasets (Fulfrost and Thomson, 2015). The distribution and acreages of transition zone within the Bay Margin Decision Support System (DSS) are much larger because the Bay margin GIS data not only includes transition zone elevations that were exposed to tidal action (“actual”) but also  transitional elevations not currently exposed to tidal action (“potential”). In addition, the DSS includes rankings of restoration potential (e.g. habitat adjacency) based on indicators of habitat function.  We used the metrics of habitat function from the Bay Margin DSS to identify a subset of transition zone that could be used as a ‘baseline’ for the SFBJV Science Program. With the assistance of the SFBJV’s Science Steering Committee and other project partners, we identified two key metrics (tidal exposure and adjacency to a saline wetland), as well as additional data cleanup in San Pablo and Suisun bays, to produce a GIS layer that could justifiably serve as ‘baseline’ for the distribution and extent of estuarine-upland transition zone within greater SF bay.

More information can be found in this white paper about the project.

Baseline transition zone distributions in SF, San Pablo, and Suisun Bays can be downloaded and access at the following links:

1. GIS data (ESRI shapefile) w/ metadata (.xml) - https://bfa.egnyte.com/dl/ZtsKXQ67GA/SFBJV_transitionzone_baseline_July2018.zip

2. Interactive Map (viewing, querying, and exporting) Data Basin - https://databasin.org/datasets/09ef1c151c174c0cbf8f3f17c04de0dc

Questions about the datasets or report can be directed to Brian Fulfrost.