Western pine forests with continuing frequent fire regimes: Possible reference sites for management

In contrast to a few isolated forests in northern Mexico, most forests in the western Untied States have been significantly modified by fire suppression, harvesting, and livestock grazing. This has increased their fire hazards and many are in need of restoration. Understanding reference conditions is challenging because we have few intact forests functioning under the continuing influence of climate variation, insects, diseases, and frequent fires. This article summarizes information from reference sites and argues for incorporating natural heterogeneity in restoration targets across similar forests in the United States.