Great Valley Ecoregion Vegetation Map Compilation

A vegetation map tile for California's Great Valley Ecoregion, compiled from four distinct source datasets including the 2024 Suisun Marsh update. The compilation uses an erase tool to resolve overlaps, ensuring the most recent data is displayed. Vegetation is attributed to the Group, Alliance, or Macrogroup level of the state and national vegetation hierarchy.

Use Cases

• Train a computer vision model to classify vegetation 'Group' or 'Alliance' from aerial imagery using the manually digitized polygons as ground truth.
• Analyze changes in vegetation composition by comparing this compiled layer with its constituent source datasets like 'Great Valley Ecoregion [ds2632]' and 'Delta Vegetation and Land Use Update - 2016 [ds2855]'.
• Assess mapping accuracy for different ecoregion sections using the reported 'users’ accuracy' metrics of 90.2% and 89% for the Central and Sacramento Valley maps.
• Model habitat connectivity by analyzing the spatial distribution of vegetation 'Alliance' polygons with a minimum mapping unit of 1.0 acre for natural features.

Strengths

• Integrates four detailed source datasets, including a 2024 update for Suisun Marsh, ensuring temporal relevance.
• Vegetation classification follows the state and national hierarchy, attributed to 'Group' and 'Alliance' levels.
• Portions of the map have high reported accuracy, with an average users’ accuracy of 90.2% and 89% for specific areas.

Limitations

• The San Joaquin Valley portion was field-verified but not formally assessed for accuracy, unlike other sections.
• Minimum mapping units vary (e.g., 1.0 acre for natural vegetation, 10 acres for agricultural/urban), which may omit smaller features.
• Some polygons are attributed only to the 'Group' or 'Macrogroup' level where the 'Alliance' could not be determined, reducing specificity.

Provenance

Source

State of California

Collection Method

Manual digitizing (heads-up digitizing) of vegetation polygons from NAIP aerial imagery (2009, 2012, 2014) and 2024 true color imagery, compiled from four source geodatabases.

Time Range

Primary source imagery spans 2009 to 2024.

Freshness

Includes data from a 2024 survey (Suisun Marsh) and was last updated on the platform in March 2026.

Geography

Great Valley Ecoregion, California, United States.