Document: DAV-3-90-1

Documenting the impacts of changing land use and land holding trends on vegetation patterns in the California Sierra Nevada using a geographic information system (GIS).

SAAH, D.*, T.BENNING and L.FORTMANN

University of California Berkeley, Berkeley, CA 94720 USA ¹

Abstract:
A geographic information system (GIS) was developed to record and analyze changes in land use, land holding patterns and forest cover in the Sierra Nevada of California. The Placer County sub-region of the Integrated Hardwood Range Management Program (IHRMP) in the central Sierra Nevada was the study area. Vegetation and parcel base GIS coverages created for 1957 and 1998 were examined and compared to determine change in forest cover, landholding and land use. This was accomplished by systematic transect sampling, which was spatially analyzed in the GIS. Two patterns emerged based on high and low elevation. 1) The high elevations can be generalized as having a net increase in forest cover on consolidated parcels with a notable increase in stand density between the two time points. Overall, there was a shift in forest cover from the lower to higher elevations. Forest cover patches in the higher elevations were more uniform and had larger extents. Parcel concentration followed the same polarizing trend, with land in the high elevations becoming more consolidated and low elevation more fragmented. Federal government land holdings, which are predominantly found in the higher elevations, have increased by 13.5% from 1957 to 54% of the total study area. There has been an observed net increase of forest cover on federal lands. Parcels classified as timberland have also been historically found in the higher elevations. The majority of 1998 parcels classified as timberland have been consolidated into fewer larger holdings, with a total net decrease in area of 35% from 1957. 2) The lower elevations can be generalized as fragmented both in parcel size and forest cover. This may be due to the increase in residential developments in the foothills as well as improvements to the major transportation corridors. Observed forest cover densities in the low elevations have increased but the average extent of each patch has decreased. Finally, local owners controlled relatively the same percentage of land between the two time periods (19.1% in 1957, 18.29% in 1998). There was a shift of absentee owners from the San Francisco Bay Area (-14.49% of the total study area from 1957 to 1998) to other parts of California (+5.42% in Southern California, +5.32% in the Northern Interior).

Keywords: GIS, Landscape Ecology, Vegetation Change, Land Holding, Forest Cover, Sierra Nevada

This abstract is being presented at: 2:30 PM in session:
Oral Session #64: Remote Sensing.