This page provides an overview of the approach and methodology used to build the Native Landscape View of the EcoAtlas Baylands and its current status as a tool for use in ecosystem analysis.


The Native Landscape View of the EcoAtlas is a composite picture based upon hundreds of independent sources of data. These include eighteenth- and nineteenth-century maps, sketches, paintings, photographs, engineering reports, oral histories, explorers' journals, missionary texts, hunting magazines, interviews with living elders, and other sources. Documents were selected from about 10,000 materials examined at archives around the Bay Area and are catalogued in the project databases. Sufficient information about the natural Bay Area landscape is available from early European documents to discover the distribution and abundance of many habitat types fairly confidently. With a robust amount of data, historical sources overlap and confirm (or contradict) each other, strengthening their interpretation. The intersection of discrete sources is then mapped and recorded in a database. This is the basic procedure used to compile the Native Landscape View of the EcoAtlas.


Statement of Uncertainty: BEWARE

However, while the Native Landscape View likely approximates pre-European conditions at a regional scale, with substantial local detail, it must be emphasized that substantial uncertainty may be present at a local scale. The amount of uncertainty ranges from, in location, 100 ft to 1 mile, in size, from 10% to 100%, and in actual presence, from "definite" to "possible." As part of the process of integrating data to form the composite picture, the relative certainty of each feature (e.g. a creek, marsh, or pond) has been recorded according to quantitative or qualitative standards (see Table 1) for presence, size, and location.

These individually coded attributes will enable EcoAtlas users to query the estimated amount of uncertainty associated with different places in the map, based on SFEI's scholarship. However, these attributes have not been linked to the EcoAtlas at this time. As a result, a wide range of certainty levels exists in the Native Landscape View. Features may be as far as one mile from their true 1800 location, as much as half their true size, and/or not strongly supported (but suggested) by the evidence.



Table 1. Certainty Level Standards (not attached to GIS at this time)

Certainty Level

Presence of Feature

Size of Feature

Location of Feature


Presence well-supported:
" Definite"

Size well-controlled
(+/- 10%)

Location well-controlled
(within 500 feet)


Presence well-supported,
with some qualification(s):
" Probable"

Size not well-controlled but evidenced
(+/- 50%)

Location not well-controlled
(within 2000 feet)