Cedrela odorata (Spanish cedar)

C. odorata is a large tree up to 40 m tall and 2 m in diameter which produces a light-weight timber. Its natural distribution range is confined to the New World, extending from northern Mexico to Argentina, including the Caribbean. It is widely planted throughout the tropics and its timber is well known for its use in cigar boxes and a broad range of other products, including musical instruments. It is also occasionally planted for shade and used as an ornamental tree on roadsides and in parks. C. odorata has great potential as a plantation species, due to its fast growing and timber producing characteristics. It is also used as an agroforestry species in cocoa and coffee plantations (Lemmens et al., 1995). C. odorata is highly vulnerable to attack by shoot borers (Hypsipyla spp.), whose larvae damage seedlings and saplings. There is some evidence that infestation can be controlled by planting C.odorata with other species, such as Leucaena leucocephala, Neolamarckia cadamba or (under light shade) with Eucalyptus deglupta (Lemmens et al., 1995).

Three widely distributed species, C. odorata, C. fissilis and C. angustifolia were observed to hybridize freely, and hybrids could explain the great phenotypic variability in these taxa (Smith, 1960), though there is still no experimental evidence to support or reject the hybridization hypothesis (Cintron, 1990). Recent cytological studies however, have indicated that at least two separate basic diploid chromosome numbers (2n= 50 and 56) occur in C. odorata; which seems widespread in the Meliaceae and may inhibit free hybridization (Styles and Khosla, 1976).

C. odorata begins flowering and fruiting when 10-12 years of age. Throughout its native range it begins flowering at the beginning of the rainy season when new leaves are expanding, being September-October in Argentina, and May-August in Mexico, the Caribbean and northern South America (Cintron, 1990). Trees are monoecious; male and female flowers are borne on the same inflorescence but the species is proterogynous (female flowers open first). Pollination is by small insects and moths (Ward et al., 2005). Fruit development takes 9-10 months and they ripen during the following dry season, with the large woody capsule borne near branch tips. Fruits ripen, split and shed seeds while still attached to the parent tree, opening from the top downward, each releasing 40-50 winged seeds in the dry season. Heavy seed crops are produced annually in some areas and biennially or irregularly in others.Seeds lose viability quickly unless stored very dry at reduced temperatures. Vigorous germination begins with the first rains, with seed viability reportedly up to 90% and rapid germination usually completed within 2-4 weeks, with no dormancy recorded (Cintron, 1990).

The following is taken from Cintron (1990). Early development of the seedling is rapid with optimal moisture and light. Seedlings can grow both in shade and full sunlight. In natural forests, large numbers of seedling are observed near fruiting trees during the beginning of the rainy season but most of these disappear by the middle or end of the rains. This high natural mortality may be due to shade or competition, or possibly pathogenic diseases such as damping off or other root problems (Cintron, 1990). Seedlings and saplings have extremely shallow root systems and are sensitive to uprooting and root trampling. Seedlings grow to approximately 100 cm tall with a stem diameter of 1 cm or more during the first year under favourable conditions. C. odorata does not coppice readily or produce root suckers though it will pollard and it can be grafted and air-layered (Cintron, 1990). Although tolerant of weeds during the seedling stage, it is considered intolerant of weeds and shade at the sapling stage and beyond. Its thin and spreading crown of light green leaves suggests it is a light demanding species, as does its fast growth and appearance after fire, in hedgerows and on ruins. It is best described as late successional, as it has a moderately long life span (Cintron, 1990).

In Puerto Rico, C. odorata is found in sub-tropical moist and sub-tropical wet zones but is commonest in the sub-tropical moist zone over limestone-derived soils, with other more locally common and frequent trees including Sideroxylon foetidissimum, Dipholis salicifolia, Andira inermis, Terebraria resinosa, Bucida buceras, Clusia rosea, Ochroma pyramidale, Montezuma speciosissima, Coccoloba diversifolia, Zanthoxylum martinicense,Bursera simaruba and Hyeronima clusioides. In continental moist and wet forests, it is also often associated with the more common and frequent mahogany (Swietenia spp.) (Cintron, 1990).

C. odorata is a climatic generalist, found over a wide geographic range of warm latitudinal belts, from sub-tropical dry forests through sub-tropical moist forest to sub-tropical wet forest, to tropical moist and wet and tropical premontane moist and wet zones in equatorial regions. It is most abundant in the lowlands and foothills, and other species such as C.montana and C. lilloi, replace it at higher elevations. Its distribution is within the frost-free tropics for the most part, although it has been collected at latitudes 26°N and 28°S where occasional light frosts can be expected. Mean temperatures of 23° to 26°C are found in the Caribbean part of its range; in tropical South America mean temperature is slightly higher, 28°C with a mean minimum of 23°C and a mean maximum of 32°C. At the southern limit of its range in Argentina the mean temperature is 24°C; mean maximum temperature is 30°C and mean minimum is 18°C (Cintron, 1990). It prefers seasonally dry climates as reflected in its deciduous habit and its formation of (presumably annual) growth rings, preferring annual rainfall of 1200-2400 mm with a dry season 2 to 5 months long, being stunted and slow-growing with 1000 mm, and is only sporadically in areas up to 3500 mm and only on very well-drained sites C. odorata is always found naturally on well-drained soils, often but not exclusively on limestone; or on sites with heavy or waterlogged soils. It may be exacting in its soil requirements but these are still imperfectly understood. In the West Indies it is most commonly found on limestone-derived clay soils but it also grows on well-drained sites over acid soils derived from volcanic rock (ultisols). The common denominators appear to be drainage and aeration of the soil, not soil pH, though no definitive studies of nutrient requirements in the forest has been performed (Cintron, 1990).