GLOBAL CHANGE AND BRITISH COLUMBIA NATIVE FLORA Richard Hebda Botany Unit Royal British Columbia Museum Victoria, B.C. V8V 1X4 Presented at the "British Columbia Native Plants, their current Status and Future Colloquium at Botany Dept., University of British Columbia, May 12, 1990 ****************************************************************************** General Effects and Summary In the preceding sections I have identified some of the changes we might expect in specific vegetation zones and habitats. In this section I will make some general comments on the effect of global warming on our native flora: 1. Change in species distribution and in vegetation composition is natural and is well-demonstrated by studies of vegetation history. 2. The change associated with the global warming will be as rapid or likely more rapid than any change since the last glaciation. 3. Species will behave individualistically. Biogeoclimatic zones will not migrate, rather, new biogeoclimatic zones will arise. 4. Weedy adventive species will become more abundant and find permanent niches in new vegetation types. 5. Some rare species will be able to expand their populations whereas other will decline and disappear. 6. Moisture-and acid-loving species may decline in number, and drought resistant and alkaline-tolerant species increase. 7. Wetland and southern alpine species are potentially at greatest risk. 8. Re-equilibration of the flora into new vegetation units will be a lengthy process because the process of climatic change will continue for many years, as will the changes in distribution of species. 9. Loss of populations will likely be sudden rather than gradual, precipitated by climatic extremes or resultant effects. In general, this will lead to impoverishment of local and regional floras before re-establishment of new species. Recommendations 1. We must establish a long term project to inventory our flora and identify populations of rare plant species, especially in the south. 2. We must take steps to protect rare plant populations for they may/will serve as the reservoir for the new native vegetation to come (demonstrated by fossil record-i.e. western redcedar). Extant and new ecological reserves could function as sources from which new genetic strains, adapted to the new conditions can arise. 3. We must begin a program of ecological gradient conservation to provide opportunities for future dispersal. Climatic and hydrologic gradients must be conserved. 4. We must complete paleoecological studies for major biogeoclimatic regions to provide information on potential scenarios of change in species range, vegetation, hydrology and landscape process. These may help us develop a strategy to conserve land areas and environments to ensure that the native flora persists and the new vegetation types arise from as broad a base of native species as possible. In conclusion we must change our philosophy of conservation. By all means we must continue to preserve or set aside tracts of land to act as reservoirs of native species and vegetation, not only for economically valuables species, but especially for rare taxa and rare vegetation assemblages. However, we must also look at conserving the continuity of the natural setting from a much broader perspective. Rather than only trying to save or reserve small parcels, we must begin with the assumption that all of the provincial area merits a conservation strategy. Further disruptions to the natural environment must be sufficiently important to make withdrawals from our inherited portfolio of life forms and life assemblages. For unlike a financial investment portfolio we cannot buy and sell to meet our long term goals. When the life-form portfolio loses a species it is gone forever and we will never experience what it may have been, or benefit from what it may have to offer.