Cedrela odorata

Abstract: Spanish Cedar (Cedrela odorata L.) is a globally important timber species which has been severely exploited in Mesoamerica for over 200 years. Using polymerase chain reaction–restriction fragment length polymorphisms, its chloroplast (cp) DNA phylogeography was studied in Mesoamerica with samples from 29 populations in six countries. Five haplotypes were characterized, phylogenetically grouped into three lineages (Northern, Central and Southern). Spatial analysis of ordered genetic distance confirmed deviation from a pattern of isolation by distance. The geographically proximate Northern and Central cpDNA lineages were genetically the most differentiated, with the Southern lineage appearing between them on a minimum spanning tree. However, populations possessing Southern lineage haplotypes occupy distinct moist habitats, in contrast to populations possessing Northern and Central lineage haplotypes which occupy drier and more seasonal habitats. Given the known colonization of the proto-Mesoamerican peninsula by South American flora and fauna prior to the formation of the Isthmus of Panama, it seems most likely that the observed population structure in C. odorata results from repeated colonization of Mesoamerica from South American source populations. Such a model would imply an ancient, pre-Isthmian colonization of a dry-adapted type (possessing the Northern lineage or a prototype thereof), with a secondary colonization via the land bridge. Following this, a more recent (possibly post-Pleistocene) expansion of moist-adapted types possessing the Southern lineage from the south fits the known vegetation history of the region.

Abstract: Cedrela odorata L. (Spanish cedar), an economically important timber species native to the American tropics, is the focus of increasing conservation concern due to high rates of deforestation within its native range. To assess the extent of the genetic diversity within and between populations of this species, samples were obtained from 10 widely dispersed populations within Costa Rica and analysed for random amplified polymorphic DNA (RAPD) variation. Fourteen 10-mer primers were used to generate 97 polymorphic RAPD bands. Presence/absence data for all bands were subjected to a pairwise genetic distance analysis, according to Jaccard's coefficient, then neighbour-joining cluster analysis was performed on these distances, as was an analysis of molecular variance (AMOVA), to assess levels of differentiation between populations and regions, and Shannon's Diversity Index was used to quantify levels of diversity within and between populations. Results indicated highly significant genetic differentiation (P < 0.004, AMOVA) between populations originating from the North Pacific and Atlantic/South Pacific regions of Costa Rica, with 35.3% of the total variation attributable to a difference between these areas. Little differentiation was recorded between populations from within the same region (P= 0.757, AMOVA), and 65.1% of the total variance was attributable to variation within populations. Estimated values for within-population diversity, calculated as Hpop/Hsp by means of Shannon's Diversity Index, were found to vary greatly between primers, but the overall within-population component of genetic diversity was 0.45. Possible reasons for the high degree of intraspecific genetic variation within this species are discussed and the implications of these results for the conservation and use of its genetic resources are described.

Abstract: The diversity of plant life forms in tropical forests affords the opportunity for assembly of plant combinations, both natural and managed, that make full use of resources and sustain high productivity. The influence of combining life forms on productivity and resource use was evaluated using three fast-growing tree species (Hyeronima alchorneoides, Cedrela odorata, and Cordia alliodora); each species was grown alone and with two perennial, large-stature, self-supporting monocots (Euterpe oleracea and Heliconia imbricata). Aboveground net primary productivity was extremely high in all stands. The monocots did not contribute significantly to the productivity of the Hyeronima polycultures, which was 4.5–8.4 g·m−2·d−1 between 18 and 36 mo. In contrast, the monocots accounted for 57% of the productivity (9.7 g·m−2·d−1) of Cedrela polycultures and 67% of the productivity (6.8 g·m−2·d−1) of the Cordia polycultures, by age 3 yr. The leaf area and density of fine roots in the Cedrela and Cordia polycultures were ...

Abstract: Elevated CO(2) concentrations ([CO(2)]) affect plant water relations and photosynthesis, and the increase in atmospheric [CO(2)] over the past 100-200 years has been related to changes in stomatal density and the carbon isotope ratio (delta(13)C) in tree rings and leaves from herbarium specimens. Because many tropical trees do not produce annual growth rings and their wood is therefore difficult to date, no trends in delta(13)C of tropical trees have been reported. Wood from Cedrela odorata L. (tropical cedar) and Swietenia macrophylla King (bigleaf mahogany), which do produce annual rings, was collected from a primary rain forest in Aripuana, Brazil (10 degrees 09' S, 59 degrees 26' W). We measured wood cellulose delta(13)C in 10-year growth increments from 37 Cedrela trees (between 11 and 151 years old in 2001) and 16 Swietenia trees (48-126 years old). A comparison of delta(13)C in cellulose of trees from different decades and of trees of different cambial ages showed that the amount of delta(13)C was largely related to the decade the wood was produced in, and not, or only to a minor extent, to tree age. Cellulose delta(13)C decreased from -26.0 to -27.3 per thousand in Cedrela and from -25.7 to -27.1 per thousand in Swietenia, with the largest changes occurring during the past 50 years. Based on these data and the trends in atmospheric [CO(2)] and delta(13)CO(2), we calculated that the internal [CO(2)] increased from about 220 to 260 ppm and that intrinsic water-use efficiency increased by 34% in Cedrela and by 52% in Swietenia. This may have implications for the water cycle and may explain the trend toward increased tree growth and turnover observed in some tropical forests.