Equações de biomassa e estoques de carbono de seis espécies em plantios mistos no noroeste do Mato Grosso

Henrique Simionato Robortella

During this time of discussion about global warming and climate change, environmental restoration projects thought as a CO2 sink in its plant biomass are essential in the fighting the increasing concentration of global warming greenhouse gases. One very eficient method to sequester atmosphere carbon is through reforestation and quantifying the resulting stands carbon. This work aimed at developing biomass uantification techniques of differents tree species, at understanding the within trees biomass carbon distribution and storage, at identifying how different species allocate biologic energy produced by photosynthesis and at assessing São Nicolau Farm reforestation potentiality. This reforestations were estabilished within the Forestry Carbon Sink Project a Peugeot/PSA initiative with the support of ONF,UFMT and SEMA-MT. It concerns large scale forest plantations, recovering forests in 1.742 ha large old pastures with almost 50 forest species. To reach this goal, different allometric models were tested, and specific equations were generated for the tree species Syzygium cumini (L.) Skeels Jambul, Cedrela odorata L. Spanish Cedar, Tabebuia chrysotricha (Mart. ex A.DC.) Standley Golden Trumpet Tree, Tabebuia aurea (Manso) Benth. &Hook.f. ex S.Moore Caribbean Golden Trumpet Tree , Schinus terebinthifolius Raddi Brazilian Peppertreee and Ceiba speciosa (A.St.-Hil.) Ravenna Silk Floss Tree. Allometric models for all the six species together were also tested. Different independent variables were evaluated: DBH, total height, trunks height and canopy width against total biomass. Ten specimens per species, with minimum DAP of 10 cm and age between 7 and 10 years, were felled to collect the samples and the weight from each compartment (leaves, thin branches,thick branches, stem and roots) were measured. Each compartment s moisture content,density, nitrogen and carbon content was determined. The biomass equations were applied to the farm s Anual Forestry Inventary, and then the biomass total stock was quantified for six species in the reforestation. A biomass-carbon conversion factor was calculated based upon their carbon content, so to quantify the species carbon stock (in CO2-equivalent). Among the results it was found that the best total biomass equations for the species were based on the model B=aDBHb (power function). Carbon content means were, generally, similar both within compartments and within species, except for S.terebinthifolius, whose carbon content was larger. The general mean carbon content was 47,2% of the biomass. After analysing the compartment s C/N ratio it was found low values for leaves, followed by thin branches and the highest values in stems and thick braches. The stocks of total biomass and carbon of the six species, which represents 11.72% of total basal area of the 10 years old reforestation and 1,742 ha, were, respectively, 3.798 t and 1.799 t. Each species biomass was assessed for its distribution on tree compartments, and three distinct behaviors were indentified between the six species. Some species allocated biomass preferencially in the canopy, others in the wood,and, this last group, secondarilly in canopies or roots. Finally, hypothetic situations of pure stands of the species were created, to be possible to compare their biomass per hectare with pure stands of the most commonly used planted species. The species S. cumini and S.terebinthifolius presented the best stocks per unit area. The conclusion is that the 10 years old reforestation these species stocks only 5% of total tropical forest biomass, and the main stocks is related to the species Syzygium cumini and Schinus terebinthifolius. Different effects of the tested independent variables on the specific equations and different tree architectures among species were also identified.

Equações de biomassa e estoques de carbono de seis espécies em plantios mistos no noroeste do Mato Grosso

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