Managing multi-ungulate systems in disturbance-adapted forest ecosystems in North America

Abstract

Understanding how interactions among ungulate populations and their environmental dynamics play out across scales of time and space is a principal obstacle to managing ungulates in western North America. Morphological similarity, forage-base homogeneity and increasing animal density each enhance the likelihood of competitive interactions among sympatric populations. Competition is an interspecific relationship with mutually negative effects, and it is often confused with amensalism. Although competition or amensalism is commonly assumed, they have been very difficult to confirm in applied management settings, perhaps because field research has not typically examined relationships across temporal and spatial scales sufficient to linking short-term or small-scale interactions with longer-term reproductive performance. Perhaps by default, neutral coexistence has been concluded in many studies, and experimental research has suggested that facilitative relationships, in which resource overlap is actually beneficial, are possible as well. Forage-mediated relationships among ungulates can be strongly influenced by disturbance-induced landscape dynamics, through which forage composition (diversity), production, quality and pattern mosaics are modified. Unfortunately, different management entities are responsible for ungulate populations and landscapes, respectively, and these entities often approach their respective problems at differing temporal and spatial scales. These scales of management may or may not align with the scales at which interactions between herbivores and plants play out. The overarching challenge facing managers is to develop information systems through which multi-species management can be planned so as to demonstrably contribute to long-term ecosystem sustainability while also maintaining its socio-economic viability. © 2010 Institute of Chartered Foresters, All rights reserved.