PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Canopy and herbaceous cover effect on survival and growth of cork and holm oak.
Caldeira, Maria *,1, Lecomte, Xavier1, Nogueira, Carla1, Moreira, Andreia1, Bugalho, Miguel2, Pereira, Joao1, 1 Dept of Forestry, Instituto Superior de Agronomia, Lisbon, Portugal2 Center for Applied Ecology, Instituto Superior de Agronomia, Lisbon, Portugal
ABSTRACT- Tree regeneration is scarce in the montado, a mediterranean savanna-type of ecossystem. The balance between processes such as facilitation and competition can drive the successful establishment of these species in systems where drought and high temperatures dominate during late spring and summer. We studied the effect of canopy and herbaceous cover in the survival and growth of the two major species in the montado systems, cork oak ( Quercus suber) and holm oak (Quercus rotundifolia). We randomized 18 plots of 2 by 4 meters, 10 and 8 of which were established under the canopy of adult trees and in open areas, respectively. Plots were divided in sub-plots (2 by 2m): one with and another without herbaceous vegetation. Acorns of both species were sown in each sub-plot. Survival of cork and holm oak were 27% and 16% higher in open areas, respectively. Holm oak survival was higher when herbaceous vegetation was present (31% in open area and 8% under canopy). Herbaceous vegetation increased cork oak survival (14%) under the canopy but decreased it (11%) in open areas. There were no significance differences in the relative growth rate of cork oak growing under the canopy and in open areas although herbaceous vegetation suppressed growth in both situations. Relative growth rate of holm oak was higher under the canopy with no significant effects of the herbaceous vegetation. The results on survival and growth of oak seedlings were dependent on the interaction between canopy and herbaceous cover. This interaction, along with oak species identity, affected the outcome of facilitation and competition.
Key words: oak seedlings, facilitation, competition, tree regeneration