Native Stand Mapping

Robert L. McNitt

The purpose of the native stand-mapping project was to identify the location of existing native stands. It was the belief that the native Willamette Valley ponderosa pine race was threatened and it was important to identify and hopefully conserve some of these remaining fragments. It turned out that there is a great deal more Valley ponderosa pine than anticipated. As a result the focus of the project was adjusted to indicate not just the location of the pine stands but the tree density. The fieldwork was completed in the fall of 2002.

Picture by ODF GIS

The stand mapping project included identifying parent tree locations. 
This map shows the distribution of parents in the Willamette Valley

Over 950 stands were recorded throughout the Willamette Valley from Beaverton to Cottage Grove. The project is not comprehensive in that all stands were not located. The study is meant to give a general indication of stand locations and tree density as an overview to be presented on a small-scale map.

GPS points identify stands. Recorded data was restricted to stand locations, number of trees, species composition and tree size range. GPS points were usually taken in the center of a tree group, but not always. Sometimes it is hard to know a stand center, a landowner may not permit access, or the time required is too much for the benefit of added accuracy. In such cases location was based on the best estimates.

Identifying what stands to record is sometimes a challenge. Native stand identification is subjective. Rows of trees along drives and fence lines were considered non-native. Isolated single trees were considered suspect. Several older, very large trees in planted rows are another case. Several known non-Valley source stands were recorded. These stands consisted of large vigorous trees at least 60 years old. Examples are located on the Clackamas Co. Fairgrounds; a patch south of McMinnville, and another south of Rickreall. Further research on seed origin for these stands is warranted.

In the Molalla area there appears to be many scattered very large alligator barked individual trees. These are probably remnants of large native stands of pine in the area. The Molalla Area was very likely similar to the reported extensive stands around Monroe.

The stands were classified into five different number of trees groups. The number of trees ranged from 1 to 100 and over. There are more than a few stands of over 100 trees. If there were more than two hundred trees in a stand then two locations were noted. In the case of small stands and scattered trees mapping designations are subjective. Some times widely scattered trees are lumped as a medium size group and other times broken into smaller groups throughout the area. The objective is to identify the stands to create a sense of tree/stand density on a composite map.

Anticipated uses for the information include historical documentation, cone collection certification and soils correlation for site adaptability.


Last Updated 02/24/08