Intra-specific variation in carbohydrate reserves and sprouting ability in Eucalyptus obliqua seedlings

Seedlings of 13 provenances of Eucalyptus obliqua L'Her. grown under favourable moisture and nutrient conditions in a glasshouse for 9 months showed significant differences in seedling height, lignotuber size and carbohydrate reserve pools in roots and lignotubers. Lignotuber size was strongly and inversely correlated with mean annual rainfall of the source provenance, and larger E. obliqua lignotubers had higher concentrations and pools of carbohydrate reserves than smaller lignotubers. When seedling stems were clipped just above the lignotuber to simulate grazing or damage by fire, clipped seedlings showed significantly different responses to disturbance; seedlings with large carbohydrate reserve pools produced more sprouts of greater dry weight than seedlings with small carbohydrate reserve pools. The sprouting ability of lignotubers was related to carbohydrate reserves, such that plants with larger reserves in the lignotubers and roots supported production of a greater number of sprouts of greater total biomass than plants with smaller reserves. These results suggest that the sprouting mechanism provided by lignotubers is more important for seedling survival in areas of lower rainfall.