PROGNOSIS OF THE DIAMETER DISTRIBUTION AND CARBON STOCK IN A SECONDARY ATLANTIC FOREST BY MARKOV CHAIN

Abstract

ABSTRACT Growth and yield modeling at the diameter distribution level is an important tool to understand forest dynamics and to predict whether a forest will act as a CO2 emissions source or sink. Therefore, the objective of the present study was to determine the diameter distribution and carbon stock of a forest fragment using the Markov chain to evaluate the impact of growth dynamics on forest carbon capture. Twenty plots of 10x50m were inventoried, between 2010 and 2015, counting the stems with dbh > 5 cm. Diameter distribution was projected for 2015 and 2020, considering the whole fragment and the ecological groups (pioneer and non-pioneer tree species). The volume was determined using allometric equation while biomass and carbon was determined by multiplying the volume by the basic wood density and the carbon content, respectively. The diameter distribution estimated for the fragment and ecological groups did not differ statistically from the values observed using the Kolmogorov-Smirnov test (p-value < 0.05). The number of stems ha-1 estimated in the fragment was from 1,692 in 2015 to 1,841 in 2020. For the pioneer and non-pioneer species, the number of stems ha-1 was from 476 and 1,203 in 2015 to 472 and 1,362 in 2020, respectively. The carbon stock increased 5.69 MgC ha-1, with the greater contribution coming from the non-pioneer species. Therefore, it was concluded that the diameter distribution would remain “J-inverted” and the forest fragment would continue to act as a carbon sink over the coming years.