ARE HEART ROT FUNGI MAJOR FACTORS OF DISTURBANCE IN GAP-DYNAMIC FORESTS

Heart rot fungi cause substantial economic loss in many forests, but t heir ecological roles in altering the speed or direction of succession are frequently overlooked. As heart rot induces trees to die standing or, more commonly, by bole breakage, the fungi that cause heart rot c an be viewed as both pathogens and agents of disturbance. Many forests that do not experience frequent, large-scale disturbance, such as tho se where fire is rare, are composed of old trees. Heart rot fungi are abundant in these old forests and are important ecologically as distur bance agents by initiating and sustaining canopy gaps. Heart rot fungi also have profound influence on numerous structures and processes suc h as nutrient cycling, vegetation composition, and wildlife habitat. T his paper uses the temperate rainforest of southeast Alaska to explore ecological consequences of heart rot, including the role of heart rot fungi in canopy gap formation. A thorough understanding of disturbanc e ecology in such forests must involve closely integrated research amo ng ecologists, mycologists, and pathologists.