Large uncertainties in tree and forest carbon estimates weaken national efforts to accurately estimate aboveground biomass (AGB) for their national monitoring, measurement, reporting and verification system. Allometric equations to estimate biomass have improved, but remain limited. They rely on destructive sampling; large trees are under-represented in the data used to create them; and they cannot always be applied to different regions. These factors lead to uncertainties and systematic errors in biomass estimations. We developed allometric models to estimate tree AGB in Guyana. These models were based on tree attributes (diameter, height, crown diameter) obtained from terrestrial laser scanning (TLS) point clouds from 72 tropical trees and wood density. We validated our methods and models with data from 26 additional destructively harvested trees. We found that our best TLS-derived allometric models included crown diameter, provided more accurate AGB estimates (R2 = 0.92-0.93) than traditional pantropical models ( R2 = 0.85-0.89), and were especially accurate for large trees (diameter > 70 cm). The assessed pantropical models underestimated AGB by 4 to 13%. Nevertheless, one pantropical model (Chave et al. 2005 without height) consistently performed best among the pantropical models tested (R2 = 0.89) and predicted AGB accurately across all size classes-which but for this could not be known without destructive or TLS-derived validation data. Our methods also demonstrate that tree height is difficult to measure in situ, and the inclusion of height in allometric models consistently worsened AGB estimates. We determined that TLS-derived AGB estimates were unbiased. Our approach advances methods to be able to develop, test, and choose allometric models without the need to harvest trees.
Tag: sampling
Determination of inorganic monomeric Aluminium with the 60 s Pyrocatechol violet technique
A method for measuring the concentration of inorganic, monomeric Al in fluid samples was tested. The technique was found suitable as Al-organic acid complexes (malate) and polymeric Al (as calculated on the basis of sample pH and total Al concentration) did not interfere. A much simpler calibration procedure than in the original description by Kerven et al. (1989) was found satisfactory. Application of the technique to sample from a nutrient solution experiment show the importance of tight pH control in such experiments.
Farmer-led community institutions: key to reversing land degradation in the 21st century
Reversing global land degradation is about better and simpler technologies, better national policies and much more. But ultimately it is about rural people and their institutions. The greatest prospect for reversing land degradation in the next century is the evolution of real farmer-led community institutions that take charge and transform the way research and extension in land management are done. Broad-based evidence for this is emerging. This paper will examine this as part of a process of people taking back greater control of their furures through decentralization, democracy and local leadership. Examples of locally-led processes in natural resource conservation suggest two successful streams: (1) institutions that are developed independently by local communities and managed by them, whose subsequent activities may not be assisted by outside stakeholders, and (2) local conservation institutions that are initiated and guided by the public sector.
Measuring crop yields in on-farm agroforestry studies
The paper describes the agronomic and statistical principles that form the basis for measuring crop yields in on-farm agroforestry studies. Agroforestry systems differ from agricultural systems because of the presence of tree/crop interfaces and the need for large plots, large borders and long-term monitoring. These differences accentuate the variability of crop performance on farms. Crop yield estimation per unit area in any agroforestry system involves essentially i) stratification of the plot into different, clearly distinguishable crop zones such as those under and free from the influence of trees, those on sloping and flat areas, and those on areas affected by pests, ii) drawing representative samples from each stratum, and iii) weighting the sample yields with weights proportional to the stratum area. The tree/crop interface areas may require further stratification and determination of yields of individual crop rows at different distances away from trees based on the nature and extent of tree/crop competition. The precision of yield estimation depends on how well one is able to define the strata as well as the variance of crop yields in space and time in each stratum. Studies that provide this information are urgently needed for developing practical recommendations for crop-yield measurements on farms.
Collecting germplasm from trees-some guidelines’
There are many reasons for collecting tree germplasm.There may bea need for planting material that will be distributedimmediately to users-farmers or horticul- :turists or extensionworkers. With the rapid rate of deforesta- tion throughout thetropics, many species of trees-and their: genetic wealth-areendangered and the collection may be.to conserve their germplasm for posterity. In addition, : germplasm may be collected because it is needed for tree-.improvement programmes. Germplasm collection is a key step in anyprocess to do-.mesticate trees;the genetic variation of a speciesshould be : present in the collected germplasm, and this is needed for. the selection and improvement that are part ofdomestica-:tion. Many tropical trees have undergone little or nodomes-.tication,so the best source of germplasm for improvement:of these species is wild populations.However,collecting is . also often done in exotic stands, because theyare relatively :easy to get at and they provide a good comparative base in.trials to assess the performance ofdifferent sources of . germ plasm
Bats as environmental service providers in Bungo, Jambi, Indonesia. Bogor, Indonesia
Findings 18 species of bats from 5 families were found in different land use systems (mixed garden, young rubber, old rubber, disturbed forest and primary forest)
Preliminary evidence for domestication effects on the genetic diversity of Guazuma crinita in the Peruvian Amazon
Guazuma crinita, a fast-growing timber tree species, was chosen for domestication in the Peruvian Amazon because it can be harvested at an early age and it contributes to the livelihood of local farmers. Although it is in an early stage of domestication, we do not know the impact of the domestication process on its genetic resources. Amplified fragment length polymorphic (AFLP) fingerprints were used to estimate the genetic diversity of G. crinita populations in different stages of domestication. Our objectives were (i) to estimate the level of genetic diversity in G. crinita using AFLP markers, (ii) to describe how the genetic diversity is distributed within and among populations and provenances, and (iii) to assess the genetic diversity in naturally regenerated, cultivated and semi-domesticated populations. We generated fingerprints for 58 leaf samples representing eight provenances and the three population types. We used seven selective primer combinations. A total of 171 fragments were amplified with 99.4% polymorphism at the species level. Nei’s genetic diversity and Shannon information index were slightly higher in the naturally regenerated population than in the cultivated and semi-domesticated populations (He = 0.10, 0.09 and 0.09; I = 0.19, 0.15 and 0.16, respectively). The analysis of molecular variation showed higher genetic diversity within rather than among provenances (84% and 4%, respectively). Cluster analysis (unweighted pair group method with arithmetic mean) and principal coordinate analysis did not show correspondence between genetic and geographic distance. There was significant genetic differentiation among population types (Fst = 0.12 at p < 0.001). The sample size was small, so the results are considered as preliminary, pending further research with larger sample sizes. Nevertheless, these results suggest that domestication has a slight but significant effect on the diversity levels of G. crinita and this should be considered when planning a domestication program.