ABSTRACT
Biological legacies are the type, quantities, and patterns of biotic structures and organisms present before and after a disturbance. In the Pacific Northwest USA, tree mortality within a forest stand triggers gap-phase dynamics that produce keystone legacies such as snags and down logs. Large fires of mixed severities, including patches of severely burned areas, in dry fire-dependent mixed conifer and Ponderosa pine (Pinus ponderosa) forests generate pulses of legacies at landscape scales. Wildlife also may act as legacy populations for recolonization of post-disturbance forests. In contrast, industrial-scale logging, including roads, are chronic disturbances that remove nearly all legacies at rates and scales typically exceeding disturbance thresholds of many native species and ecosystems. Retention of legacies (wherein quantity, quality, scale and context matter) at the stand level, and management of large fires for landscape heterogeneity (i.e., pyrodiversity in this context) is ecologically beneficial to fire-adapted forests. However, management for biological legacies is often constrained by over-reliance on fire suppression, forest economics, and a lack of appreciation for the ecosystem benefits of large-scale disturbances.
