Carbon stocks in a tropical dry forest in Brazil

Abstract

-The dry forests are the type most widely distributed vegetation in the tropics, and studies aimed at quantifying the carbon stock in these forests are important for it to be quantified their participation as mitigating the effects of climate change. With that in mind, the aim of this research was to quantify the carbon stocks in the woody, herbaceous, litter and root components of a patch of dry tropical forest, with 30 years of regeneration in Iguatu-CE, Brazil. Initially the vegetation was inventoried by means of a floristic and phytosociological survey of the woody component in a 1 ha area which had been under conservation. The biomass was then estimated employing allometric equations, and the stored carbon was quantified. Stocks of carbon in the litter and the herbaceous plants were determined by monitoring their biomass over 24 months, with subsequent conversion into carbon. Carbon stocks in the roots were estimated as the product of their biomass and carbon concentrations, for this were collected 20 samples at a depth of up to 30 cm deep in the dry and rainy season. It was found that the carbon content varies with the chamber and evaluated by adding carbon stored in woody compartments (19,27 t ha Key words: Semi-arid. Caatinga. Biomass. RESUMO -As florestas secas são amplamente distribuídas nos trópicos, e estudos que visam quantificar o estoque de carbono nessas florestas são importantes para que possa ser quantificada sua participação como mitigadora dos efeitos das mudanças climáticas. Nesse sentido, objetivou-se com essa pesquisa quantificar o estoque de carbono nos componentes: arbustivoarbóreo, herbáceo, serrapilheira e raízes em um fragmento de floresta tropical seca, com 30 anos de regeneração, no município de Iguatú-CE. Inicialmente, realizou-se o inventário da vegetação, através de um levantamento florístico e fitossociológico do componente arbustivo-arbóreo. Posteriormente, estimou-se sua biomassa, empregando-se equações alométricas; em sequencia foi quantificado o carbono estocado. Já o estoque de carbono contido na serrapilheira e nas plantas herbáceas foi determinado através do monitoramento de suas biomassas, durante 24 meses, com posterior conversão dessas para carbono. O estoque de carbono contido nas raízes foi estimado através do produto entre suas biomassas e a concentração de carbono, para isso foram coletadas 20 amostras na camada de até 30 cm de profundidade no período seco e chuvoso, totalizando 40 amostras por ano. O teor de carbono varia de acordo com o compartimento avaliado, e somando-se o carbono estocado nos compartimentos arbustivo-arbóreo (19,27 t ha . Isso evidencia, portanto, a contribuição efetiva da floresta tropical seca na diminuição do CO 2 atmosférico. Palavras-chave: Semiárido. Caatinga. Biomasa.

Belowground Carbon and Nitrogen on a Thinned and Un-Thinned Seasonally Dry Tropical Forest

“…During the rainy months, from April to July 2013 and February 2014, the production of herbaceous dry biomass in the TC 5 was statistically higher than that seen in the RC 35 ). It can therefore be said that the TC 5 management expresses a greater sensitivity to the rainfall regime of the region.…”

“…The studies have shown that the concentration of fine roots throughout the soil profile in the TC 5 However, during the rainy period there was greater homogeneity in the concentration of fine roots along the vertical depth, with no significant difference (p > 0.05) ( Figure 5(b)). Although each type of vegetation has a different root architecture, use of the root to shoot ratio has been widely used to estimate the quantity of root biomass for the purposes of carbon accounting [20].…”

“…However, when the natural ground cover conditions were altered by the technique of thinning, significant differences in the production of dry biomass between the rainy and dry seasons became possible. As the vegetative stages in the phenological cycle of the species are short [4], within just two months from the end of the rains there is a significant reduction in the stock of dry matter in the vegetation, especially in the TC 5 . However, the occurrence of even small rainfall depths (66 mm) recorded during October and November, promoted the recovery of the net primary production in December ( Figure 2 and Figure 3).…”

“…It should be noted that throughout the experiment there was no grazing in either of the experimental watershed. To determine the variables being investigated, fifty 10 × 10 m sample units were distributed across the main course in both watersheds, RC 35 and TC 5 , marked out and identified in loco with metal plates according to [28] methodology.…”

“…Further, it should be noted that the SDFT located in the northeast of Brazil (approximately 900,000 km 2 ) has been little investigated as to the dynamics of fine roots or shoot biomass [5] [20] [21].…”