Equações alométricas, estoque de biomassa e teores de carbono e nitrogênio de campinaranas da Amazônia central

Abstract

The campinarana is a heath vegetation type of the Amazon rainforest. They occur on sandy soils and represent the transition from dense forest to campina forest, or occur isolated amongst the dense forest. The ecological understanding and quantification of environmental goods and services of campinaranas are key steps in its conservation. The main objective of this work was to develop allometric equations for biomass above and below ground and also get the contents of carbon and nitrogen of a campinarana in central Amazonia. The use of allometric equations is considered the most accurate and fast method of getting the forest biomass, which should be studied on issues that concern forest management and climate change. The study of carbon and nitrogen is mainly the understanding of cycling of organic matter. Data collection was done in the campinarana Experimental Station ZF-2, which is located between the geographical coordinates 02 º 37 'and 02 º 38' south latitude and 60 º 09 'and 60 º 11' west longitude, or 90 km from the city of Manaus -AM. In total, one hundred trees were felled down, and their main components (coarse roots, stems, coarse branches, fine branches and leaves) were weighed separately. The adjustment of the allometric equations was performed with the regression of the weights of fresh mass of trees. In addition, we used fixed plots of 100 meters square where all biomass above ground was collected and weighed. This was done in order to understand their composition between vines, seedlings, palms and trees. Water, carbon and nitrogen contents were also determined from samples taken from different components of the felled trees. Thus it was found that 94% of the total biomass of campinarana consists on trees with DBH greater than or equal to 5 cm. The best fitted allometric equation for the total fresh biomass (above-ground + coarse roots) was: ln (Total Biomass) = -1.373 + 2.546 * ln (DBH) (R ² = 0.98, Sxy% = 4.19%). The water content of vegetation averaged 0,42 ± 0,008 (CI 95%). The carbon content averaged 47,5% ± 0,2 (CI 95%), and the nitrogen content averaged 7,0 g.kg-1 ± 0,6 (CI 95%). The C:N rate averaged 110 ± 5,6 (CI95%). The soil type and C / N ratio of leaves of Campinarana ZF-2 were different from a campinarana in the Reserva da Campina, located 60 km from Manaus, showing that there clearly is a difference between campinaranas in the Central Amazon, thus it needs further investigation.