Dry forests in the southern interior of British Columbia: Historic disturbances and implications for restoration and management

We examine the hypothesis that low elevation, dry forests in southern BC evolved in the context of a low-severity, fire dominated disturbance regime, that fire suppression has led to ecological conditions which are radically different from the past, and that “restoration” initiatives are required to re-establish former ecological conditions. Three sources of information were used to infer historic disturbance regimes and the nature of disturbance since the early 1900’s: (1) accounts by early explorers and systematic timber surveys before extensive management, (2) fire scar data, and (3) records of wildfire, insect attack, timber harvesting and weather patterns. Our analyses consistently indicate that historic natural disturbances and management during the last century have been diverse, complex and episodic at multiple spatial and temporal scales. Several interacting factors including climate, harvesting, livestock grazing, fire suppression and changing geographic patterns of insect attack have been key drivers in creating the conditions observed today. Hence, it is not clear what state represents “natural” forest conditions, or what the target conditions for restoration activities should be if the objective is to “restore natural conditions”. We conclude that future management should avoid using “ecosystem restoration” as an objective when historical conditions are uncertain or there is no clear reference condition because of temporal variability.  Instead, managers should focus on clearly defining desired stand conditions, the commodity, social and ecological objectives that will be met or compromised with these conditions, and identifying the most effective (economical, social and ecological) tools for achieving these objectives.