Flowering Phenology of River Red Gum (Eucalyptus camaldulensis Dehnh.) Associations in Homs Province, Syria

Abstract

Flowering phenology, ecology and stand characteristics of Eucalyptus camaldulensis Dehnh. were described in response to rainfall and temperature at a plantation site in Northwestern province of Homs, Syria. Flowering observations were carried out for one year on a bi-monthly basis as time of flowering, duration and intensity were recorded. Analysis of 30-year rainfall and temperature revealed that the area has a typical Mediterranean climate of cool thermal variant. The area experiences a decreasing trend in rainfall with a recurrent 6- months climatic drought. Trees registered 9.6 m in heights and 18.4 cm in diameter at 29 years of age. Trees started to set flower buds in the first week of June where cumulative annual rainfall (CAR) and mean temperature were 391 mm and 24.2ºC, respectively. Flowering occurred in two periods with varying percentages of flowering trees in each. Autumn flowering started in the first week of November and extended for 107 days. On the other hand, Spring flowering commenced in the first week of April and continued for 92 days. A significant negative relationship (r = -0.39) was observed between the percentage of flowering trees and average monthly rainfall. However, a weak but positive correlation (r = 0.33) existed between the percentage of flowering trees and average monthly temperature. The percentage of flowering trees were higher in dry months compared to wet months because of low temperature associated with wet period. Flowering intensity was ranked 0.7 in December and 3.3 in June. Fruit setting started in the onset of January and mid June for Autumn and Spring flowers, respectively. Knowing timing and duration of flowering contribute significantly towards understanding the species biology, managing associated fauna and rearing of honey bees in the area.