Betula glandulosa Michx. Response to burning and postfire growth temperature and implications of climate change

Abstract

Plants collected from eight fire-prone sites in western and northern Canada were tested in a greenhouse experiment for response to low fire severity and growing temperatures of 14-24˚C. The combined data showed that burning interacted with growth temperature during the first 42 days after treatment to significantly reduce sprout height at low temperatures and increase sprout height at the highest temperature. Burning significantly increased sprout height growth at all temperature treatments after 84 days although this effect was most apparent at the highest growth temperature. Burning significantly reduced sprout production after 42 days and had no significant influence on sprout production or aboveground biomass production after 84 days. Separate analysis of individual site data showed two populations with significant fire-stimulated sprout height growth and two other populations with similar, but slightly less significant response. The populations showed no geographic or topographic trend in fire response. The warmer growing conditions of postfire microsites appear to provide this shade intolerant plant with a competitive advantage over other invading pioneer and resprouting species by enhancing fire-stimulated height growth response. Due to its fire ecology, Betula glandulosa populations are expected to expand and thrive in this region under future climate change conditions.