SHOOT DAMAGE EFFECTS ON STARCH RESERVES OF CEDRELA-ODORATA

The effects of shoot damage on starch concentrations in large roots an d lower boles of the tropical timber tree, Cedrela adorata, were measu red over a 30-day period following mechanical shoot removal. The degre e of damage was based on amounts typically destroyed by Hypsipyla gran della, a serious lepidopteran pest of C. odorata. From 14-month-old pl antations at La Selva Biological Station, Costa Rica, three treatments were established based on the length of shoot and number of leaves re moved: controls (no tissue removed), moderate damage, and severe damag e. Initial starch concentrations were compared with concentrations obs erved 18 to 30 days following shoot removal using enzymatic starch hyd rolysis and colorimetry. Root starch concentrations increased in undam aged trees, decreased slightly in the moderately damaged trees, and de creased markedly in severely damaged trees during the sampling period. Starch concentrations in lower boles did not decrease following shoot damage, suggesting a specific role of root search reserves in respond ing to aboveground carbon requirements. The dry weights of regrown sho ots were similar for the moderately and severely damaged trees, but se verely damaged trees produced numerous basal shoots while moderately d amaged trees produced only one or two terminal shoots near the point o f excision. Decreases in root search concentrations following shoot da mage and rapid shoot regrowth suggest that starch remobilization in ro ots of C. odorata might provide a survival mechanism after attack by H . grandella.