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Abstract
Factors contributing to poor establishment of blue oak (
Quercus douglasii) and valley oak (
Q. lobata) in California oak-grassland savannas were studied in a series of acorn seeding experiments initiated in 1985. Exclusion of large herbivores permitted examination of herbaceous interference and small mammal and insect depredation. Herbaceous interference was the most important factor. Average emergence in all blue oak seedings with and without herb control was 45 percent and 29 percent, respectively. The respective values for all valley oak seedings were 60 percent and 46 percent. Average first year survival, expressed as a percentage of acorns planted, was significantly improved by elimination of herbs in both blue oak (30 percent vs. 11 percent) and valley oak (45 percent vs. 25 percent) seedings. Limited data suggests the differential in survival is maintained over time as overall survival declines. With few exceptions, the addition of screen protection to discourage predation significantly enhanced survival and growth. Shade provided by window screen cages is suspected of making an unmeasured positive contribution. Interaction between herbaceous control and protection appears to develop with time.
Parent Publication
Citation
Adams Jr., Theodore E.; Sands, Peter B.; Weitkamp, William H.; McDougald, Neil K. 1991. Blue and Valley Oak Seedling Establishment on California''s Hardwood Rangelands. In: Standiford, Richard B., tech. coord. 1991. Proceedings of the symposium on oak woodlands and hardwood rangeland management; October 31 -November 2, 1990; Davis, California. Gen. Tech. Rep. PSW-GTR-126. Berkeley, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; p. 41-47
