Compatibility of livestock grazing with stand regeneration in Mediterranean holm oak parklands

Successful regeneration of holm oaks is the key to the conservation of the outstanding biodiversity levels in Spanish dehesa parklands. However, low densities of regeneration were measured in this study. The threshold for livestock stocking levels supporting regeneration was below all figures presently found in the dehesas. In the analysis of stand structure, a positive relationship between tree age and the age of agro-silvo-pastoral use of the dehesas was detected. This suggests that the forest cycle has been disrupted, and stands may dissolve gradually. Regeneration failure is an implicit component of this agroforestry system. An analysis of long-term abandoned dehesas situated at roadsides showed that holm oak stands are able to recover if grazing and cultivation are set aside. In a mail survey, managers of private large landholdings highly appreciated having holm oaks on their land, both for income- and non-income-related motivations, e.g. for the preservation of real estate value or family tradition. Land managers identified over-maturity of stands and regeneration failure among the top five problems of dehesas. Conservation policy should be directed towards incentive schemes, environmental education, and technical assistance.