Transcription of SUMMARY - Southern Research
1 SUMMARYWood density information for a large number of tropical treespecies is presented in units of ovendry weight in grams percubic centimeter of green volume. The data base includes 1,280entries from tropical America (40 percent), tropical Asia (36 per-cent), and tropical Africa (24 percent). The most frequent wooddensities were to g/cm3. In all three tropical continents,the most frequent class was the to g/cm3. These data areuseful for a wide variety of practical and scientific applications,including the estimation of forest stand biomass from woodvolume data were collected for a project related to estimatingthe biomass of tropical forests from inventory data.
2 The projectwas supported by subcontracts 19B-07762C with S. Brown atthe University of Illinois and 19X-43326(= with Lugo at theUniversity of Puerto Rico, under Martin Marietta EnergySystems, Inc., contract DE-AC05840R21400 with the of Energy. The department of agriculture ,Forest Service, Institute of Tropical Forestry, provided librarysupport to the Densities of Tropical Tree SpeciesGisel Reyes, Sandra Brown, Jonathan Chapman,andAriel E. LugoINTRODUCTIONI nformation on the biomass of tropical forests iscritical in order to answer many questions on therole of these forests in global phenomena, includingthe global carbon and other nutrient cycles, and onthe magnitude of the global wood biomass of tropical forests has been measuredfor a few sites scattered around the tropical world,but the area represented by these studies isextremely small (~30 ha) compared with the totalarea of tropical forests (about 18 million km2)(Brown and Lugo 1982).)
3 Furthermore, there isstrong evidence that the selection of these few siteswas biased toward high biomass forests (Brown andLugo 1984). A vast quantity of forest inventory datais available for the tropics. These data often reportstand and stock tables (number of trees per unitarea and volume per unit area, respectively) bydiameter class or total volume for areas that are rep-resentative of thousands of hectares of forests. Thedata are useful for estimating forest biomass by avariety of techniques (Brown and others 1989;Gillespie and others in press).
4 To use forest inventory data for biomass estima-tion, wood density values for species or speciesgroups are often needed. For example, the product ofgross commercial volume and wood density, byspecies or species groups, gives the biomass of thecommercial wood. Total biomass can then be esti-mated using biomass expansion factors (totalbiomass/commercial wood biomass) as reported inBrown and others (1989). Wood density data mayalso be useful for the study of forest structure andresponse to environmental factors ( , Chudnoff1984). However, Chudnoffs (1984) analysis of pat-terns in wood densities of tropical trees according tolife zone was not conclusive because the data basewas small.
5 Weaver (1987) demonstrated that theaverage wood density of montane forest stands inPuerto Rico increased with increasing age of thestand. Similar analyses for other ecologicallycontrasting conditions are not possible because wooddensity data are normally not readily available toecologists and studies of tropical forest biomass (Brown andLugo 1982, 1984; Brown and others 1989; Lugo andothers 19881, a large data base has been assembledon wood density of tropical tree species. Becausewood volume data, as reported in forest inventories,are given in units of green volume, and because vol-umes needed to be converted to oven dry weights,wood density is reported in ovendry weight gramsper cubic centimeter of green volume.)
6 This informa-tion is summarized here to help others in need of are encouraged to make the authors awareof additional sources of information so that the database can be updated and disseminated information is stored at the Institute of TropicalForestry and can be obtained from the senior list of species for which wood densities weregathered is based on the species encountered ininventories of the following regions and countries:1. Tropical moist forests of BrazilLowland to upland and wet, moist, and dryforests (as described in Holdridge 1967) ofVenezuelaGuyanaSurinam2.
7 Tropical Asiaa. Malaysiab. Sri LankaGisel Reyes is a technical information specialist, Jonathan Chapman is a biological technician, and Ariel E. Lugo is the project leader atthe Institute of Tropical Forestry, department of agriculture , Forest Service, Southern Forest Experiment Station, Rio Piedras,PR 00928-2500; Sandra Brown is an ecologist with the department of Forestry, University of Illinois, 110 Mumford Hall, 1301 W. Gregory,Urbana, IL Tropical forest regions of east India3. Tropical Africaa. Cameroonb.
8 GabonThe sources used for wood densities are listed byeach region (table 1). Difficulties were encounteredin finding sufficient wood density data in the desiredunits for forests of tropical Africa and Asia. Most ofthe data for these regions were in lb/f@ volume atla-percent moisture (air-dry weight). Because of thislimitation, a regression equation was developedusing data in Chudnoff (1984) for wood density withvolume at 12-percent moisture versus wood densityat green volume. There were no significant differ-ences among the regression equations for the threetropical regions; thus, only the equation based on allspecies is used.
9 The regression equation, based ondata for 379 trees, is as follows:Y = + (r2 = )whereY = wood density at ovendry weight/greenvolume; g/cm3X = wood density at air-dry weight/volume at12-percent moisture; g/cm3 All density data adjusted by this regression equa-tion are indicated in the data set (table 2) with anasterisk (* AND DISCUSSIONT able 2 lists the species as identified in the origi-nal source and the reported wood density (g/cm3) foreach species. All values cited in the sources (table 1)are reported without comment, although age of treefrom which the sample was derived may be a factorfor differences between bibliographic sources for thesame species (indicated by a plus sign [+I in table 2).)]
10 However, it is likely that most determinations arebased on mature are a total of 1,180 species listed in table Asia, tropical America, and tropical Africaare represented, respectively, by 428, 470, and 282species or 36,40, and 24 percent of the data set is summarized in figure 1 accordingto continent and frequency of occurence of wood den-sity classes. The most frequent wood densities arethe g/cm3 classes. The to class isdominant in the data sets of all three wood density of trees in the tropical America2data set were more evenly distributed across fourclasses ( to ).
