Allometric models are necessary for estimating biomass in terrestrial ecosystems. Generalized allometric relationship exists for many tropical trees, but species- and region-specific models are often lacking. We devel...Allometric models are necessary for estimating biomass in terrestrial ecosystems. Generalized allometric relationship exists for many tropical trees, but species- and region-specific models are often lacking. We developed species-specific allometric models to predict aboveground biomass for 11 native tree species of the Sudanian savanna- woodlands. Diameters at the base and at breast height, with species means ranging respectively from 11 to 28 cm and 9 to 19 cm, and the height of the trees were used as predictor variables. Sampled trees spanned a wide range of sizes including the largest sizes these species can reach. As a response variable, the biomass of the trees was obtained through destructive sampling of 4 754 trees during wood harvesting. We used a stepwise multiple regression analysis with backward elimination procedure to develop models separately predicting, total biomass of the trees, stem biomass, and biomass of branches and twigs. All species- specific regression models relating biomass with measured tree dimen- sions were highly significant （p 〈 0.001）. The biomass of branches and twigs was less predictable compared to stem biomass and total biomass, although their models required fewer predictors and predictor interac- tions. The best-fit equations for total above-ground biomass and stem biomass bad R2 〉 0.70, except for the Acacia species; for branches including twig biomass, R2-values varied from 0.749 for Anogeissus leiocarpa to 0.183 for Acacia macrostachya. The use of these equations in estimating available biomass will avoid destructive sampling, and aid in planning for sustainable use of these species.展开更多
The seedling population structure of Pteleopsis suberosa and their regeneration mechanisms were investigated in four roadside environments （graded, adjacent, intermediate and ungraded areas） along paved and unpaved ...The seedling population structure of Pteleopsis suberosa and their regeneration mechanisms were investigated in four roadside environments （graded, adjacent, intermediate and ungraded areas） along paved and unpaved roads in West Africa. A total of 203 quadrats of 2 m × 5 m in size were surveyed and placed along transects parallel to the roads. Within each quadrat, the total number of seedlings and the number of living shoots per seedling base were recorded. Regeneration mechanisms were determined by assessing basal and aerial sprouts and excavating the root systems below ground level. The results show that the total seedling density and the densities of single- and multi-stemmed individuals varied significantly （p 〈 0.05） among the four roadside environments. However, all seedlings were produced asexually; root suckers were predominant （98%） compared to water sprout （1%） and coppices （less than 1%）. This study demonstrates that an intermediate level of soil disturbance from grading along paved and unpaved roads may stimulate P. suberosa regeneration by root suck- ering. Road type （paved and unpaved） did not affect seedling density, but was a highly significant variable in relation to the coppicing ability of P. suberosa populations in roadside sites. In conclusion, P. suberosa is a disturbance-tolerant species which can proliferate mainly by root suckering after roadwork disturbance.展开更多
基金provided by Swedish International Development Cooperation Agency (Sida)
文摘Allometric models are necessary for estimating biomass in terrestrial ecosystems. Generalized allometric relationship exists for many tropical trees, but species- and region-specific models are often lacking. We developed species-specific allometric models to predict aboveground biomass for 11 native tree species of the Sudanian savanna- woodlands. Diameters at the base and at breast height, with species means ranging respectively from 11 to 28 cm and 9 to 19 cm, and the height of the trees were used as predictor variables. Sampled trees spanned a wide range of sizes including the largest sizes these species can reach. As a response variable, the biomass of the trees was obtained through destructive sampling of 4 754 trees during wood harvesting. We used a stepwise multiple regression analysis with backward elimination procedure to develop models separately predicting, total biomass of the trees, stem biomass, and biomass of branches and twigs. All species- specific regression models relating biomass with measured tree dimen- sions were highly significant （p 〈 0.001）. The biomass of branches and twigs was less predictable compared to stem biomass and total biomass, although their models required fewer predictors and predictor interac- tions. The best-fit equations for total above-ground biomass and stem biomass bad R2 〉 0.70, except for the Acacia species; for branches including twig biomass, R2-values varied from 0.749 for Anogeissus leiocarpa to 0.183 for Acacia macrostachya. The use of these equations in estimating available biomass will avoid destructive sampling, and aid in planning for sustainable use of these species.
基金Swedish International Development Cooperation Agency (Sida).
文摘The seedling population structure of Pteleopsis suberosa and their regeneration mechanisms were investigated in four roadside environments （graded, adjacent, intermediate and ungraded areas） along paved and unpaved roads in West Africa. A total of 203 quadrats of 2 m × 5 m in size were surveyed and placed along transects parallel to the roads. Within each quadrat, the total number of seedlings and the number of living shoots per seedling base were recorded. Regeneration mechanisms were determined by assessing basal and aerial sprouts and excavating the root systems below ground level. The results show that the total seedling density and the densities of single- and multi-stemmed individuals varied significantly （p 〈 0.05） among the four roadside environments. However, all seedlings were produced asexually; root suckers were predominant （98%） compared to water sprout （1%） and coppices （less than 1%）. This study demonstrates that an intermediate level of soil disturbance from grading along paved and unpaved roads may stimulate P. suberosa regeneration by root suck- ering. Road type （paved and unpaved） did not affect seedling density, but was a highly significant variable in relation to the coppicing ability of P. suberosa populations in roadside sites. In conclusion, P. suberosa is a disturbance-tolerant species which can proliferate mainly by root suckering after roadwork disturbance.
