Leiberg Vegetation Layer
In 1902, the U.S. Geological Survey published Forest Conditions in the northern Sierra Nevada, California, by John B. Leiberg. This book contains generalized vegetation information on about 3.5 million acres between 39º and 40º N latitude and between 120º and 121.5º west longitude. This information is in the form of both a written description and maps of the area. In an effort to utilize the maps in this book in a GIS, we digitized the maps using ArcMap 8.3.
There are four main themes in the Leiberg maps and in the final digital product.
1) Cover – In the “cover” theme, each polygon is labeled as either: < 2000, 2000-5000, 5000-10,000, 10,000-25,000, greater than 25,000 merchantable board feet/acre, chaparral, cultivable, cultivated, pasture, rock, water, or woodland.
2) Culled Timber – Polygons in this theme represent areas where cutting of trees has occurred, whether for timber, mining or fuel.
3) Species Distributions – Douglas fir, grey pine, mountain hemlock, red fir, sugar pine, western juniper, western white pine and yellow pine
4) Fire - These polygons represent fire perimeters and the intensity of those fires: 5-25%, 25-50%, 50-75% or 75-100% of timber burned
UTM nad83 projection