Determining the pattern of oak woodland regeneration for a cleared watershed in northwest California: A necessary first step for restoration

Historically, oak woodlands of northern California have been subject to int ensive tree and brush removal efforts to improve land for livestock grazing . As a result of this tree removal, these watersheds are susceptible to soi l erosion and stream degradation. Therefore, planting woody vegetation is o ften required to restore watershed function. Prior to such actions, a thoro ugh understanding of natural vegetation regeneration patterns is essential. The physical and biological attributes of natural vegetation regeneration in a cleared watershed were characterized using remote sensing, a Geographi c Information System, and field surveys. A 79-ha watershed at the Universit y of California's Hopland Research and Extension Center was examined becaus e the clearing of vegetation was part of a well-documented experiment in th e early 1960s, providing essential baseline data. The results of this study reveal that significantly more oak regeneration, consisting mostly of ever green oaks, occurred on moister and steeper northerly slopes. Deciduous oak s, located primarily on drier and less steep southerly slopes, have not reg enerated. Hardwood regeneration was associated with Josephine, Les Gates, a nd Maymen soils. The distribution of hardwood regeneration is clustered, su ggesting that the presence of other trees may promote regeneration. These r esults also suggest that without active restoration efforts such as tree pl anting and seedling protection, southerly slopes will most likely remain ba rren and erosion will continue, while northerly slopes and riparian areas w ill recover under the current land management practices. Despite some woody plant regeneration, the once densely forested watershed is now predominant ly grassland, emphasizing the need to minimize clearing of California oak w oodlands.