Wieslander Vegetation Type Map Project

Composite photo of Temblor Range VTM photo 1936 by A.E. Wieslander and VTM retake 2013 by J. Gross. Mashup by H. Constable.

The Wieslander Vegetation Type Map (VTM) Project is a collection of vegetation maps, botanical plot sampling, plot maps, plant specimens and photos surveyed in the 1920s and 30s throughout California. In this remarkable effort, Forest Service crews mapped over 1/3 (16 million+ hectares) of the state. The data provide a snapshot of the state’s vegetation in the early 20th century, making the collection an invaluable resource for examining changes in land cover and use, and habitat restoration.

There are five main components to this collection: 1) vegetation maps, 2) plot data, 3) plot maps, 4) photos, and 5) botanical specimens. The digitation effort was a massive interdepartmental effort that involved two UC campuses and four departments.

Vegetation maps are USGS topo maps that were colored by hand in the field to indicate vegetation types. Dominant vegetation type maps were mapped with a minimum mapping unit of 16 hectares by direct observation. The vegetation mapping scheme was driven by the identification of overstory species. 

Researchers at the Information Center for the Environment at UC Davis, spearheaded by Jim Thorne, led the digitization of all the unpublished vegetation maps.

Original hand colored VTM Topo Quad Digitized Topo Quads

Plot data and Plot maps are the physical botanical sampling of subplots to ground-truth the vegetation maps. There were two types of plots per site, a brush/ground cover plot and tree plots. 

The brush and ground cover plots were roughly 40m x 10m divided into 100 equal sections. VTM biologists recorded the one herb or shrub species that was dominant in each subplot. They then calculated percent cover for each species by summing the number of subplots containing each dominant species. They also recorded the average height of each species and the depth of the litter. The tree plots were 40m x 20m, similiarly divided and calculated.

The plot data available in the Ecoengine have been summarized to show the dominant species at each location.

The Kelly Lab in Environmental Science, Policy and Management Department (ESPM) at UC Berkeley led the plot map digitization and georeferencing. The Allen-Diaz Lab in ESPM cataloged all of the plot data, which the original surveyors recorded by hand, in the field, on thin sheets of paper in faint pencil. 

Digitized locations of VTM Plots VTM botanists identifying plants


Photographs have locality data and vegetation data associated with them. The VTM photo digitization was led by the Marian Koshland Bioscience and Natural Resources Library, and is now complete. 

Partnering with the Biosciences Library, the Ecoengine team georeferenced 3,097 images and uploaded 3,347 photos as a collection into CalPhotos (a data source for the Ecoengine). Inspired by this rich archive, photographers have endeavored to take photo retakes, including Ecoengine programmer Joyce Gross, who has successfully located historic photo locations and has started the modern photo-retake collection.

VTM Photo 286720, Kernville, CA October 1931 

by Albert Wieslander

VTM Photo 286720 Retake, Kernville, CA 2013

by Joyce Gross

Herbarium specimens were collected for every species recorded on the vegetation maps and in the sample plots. See the Consortium of California Herbaria website to search for the records (http://ucjeps.berkeley.edu/consortium/). Many of the samples collected during the original VTM surveys are housed in Berkeley's University and Jepson Herbaria.

For more details of the methods of data and digitization methods, see the VTM Website's Data Description page.

The current VTM Project integrates the datasets to inform studies of global change. We have inititiated two such studies: 1) identifying 20th century changes in vegetation structure in coastal and southern California by comparing more recent USFS data to VTM data, and 2) identifying factors associated with vegetation diversity and identity.

Original Quercus agrifolia specimen collected during

VTM plot survey

Relevant Publications

Mcintyre, P.J., J.H. Thorne, C.R. Dolanc, A.L. Flint, L.E. Flint, M. Kelly and D.A. Ackerly. (2015). Twentieth-century shifts in forest structure in California: Denser forests, smaller trees, and increased dominance of oaks. Proceedings of the National Academy of Sciences. 122(5) pp 1-6. DOI: 10.1073/pnas.1410186112