Impacto da degradação sobre o estoque total de carbono de florestas ripárias na Amazônia Oriental, Brasil

Abstract

* Autor correspondente: guilirous@yahoo.ca RESUMOAs florestas ripárias provêem serviços ecossistêmicos essenciais à humanidade, mas estão sendo degradadas em um ritmo acelerado na Amazônia. Esse estudo teve como objetivo quantificar os estoques de carbono acima e abaixo do solo de florestas ripárias com quatro níveis de degradação (muito alta, alta, média e baixa) em duas microbacias (Rio Pepital e Rio Grande) em Alcântara (Maranhão), na Amazônia Oriental. Foram instaladas 24 parcelas permanentes de 1.000 m 2 , onde a vegetação (árvores, arbustos, herbáceas, lianas e palmeiras), a necromasa (serapilheira, árvores mortas, galhos) e o solo (0-20 cm e raízes) foram amostrados. A biomassa foi estimada mediante modelos alométricos (vegetação com DAP > 1 cm e árvores mortas) e de forma destrutiva (herbáceas, serapilheira, galhos finos, raízes). O estoque total de carbono nas florestas ripárias mais conservadas variou entre 88 e 202 Mg(C) ha -1. A degradação reduziu significativamente o estoque de carbono em todos os compartimentos (até 97% na biomassa viva acima do solo, até 91% de necromassa e até 47% no solo). Nas áreas conservadas, a biomassa viva acima do solo tem a maior participação no estoque total de carbono (> 70%), principalmente devido às árvores de grande porte. O estoque de carbono nos diferentes compartimentos estão fortemente relacionados entre si e também com a abertura do dossel. A incorporação desses resultados em modelos regionais de carbono pode auxiliar na implementação e revisão do Código Florestal Brasileiro, em particular na restauração das florestas ripárias onde a agricultura está consolidada. PALAVRAS-CHAVE: Maranhão, mata ciliar, conservação florestal, serviços ecossistêmicos, sucessão ecológica. Impact of degradation on carbon stock of riparian forests in the eastern Amazon, Brazil ABSTRACTRiparian forests provide essential ecosystem services to humanity, but are being degraded at an accelerated rate in the Amazon. This study aimed to quantify carbon stocks above and below ground in riparian forests with four levels of degradation (very high, high, medium and low) in two watersheds (Pepital Rio and Rio Grande) in Alcântara, Eastern Amazon. Twenty-four permanent plots of 1,000 m 2 were installed, and vegetation (trees, shrubs, herbs, lianas and palms), necromass (litter, dead trees, branches) and soil (0-20 cm and roots) were sampled. The biomass was estimated using allometric models (vegetation with dbh> 1 cm and dead trees) and destructively (herbaceous, litterfall, branches, roots). The total carbon stock in the most conserved riparian forests ranged between 88 and 202 Mg(C) ha -1. Degradation significantly reduced carbon stock in all compartments (up to 97% in above-ground biomass, up to 91% of necromass, and up to 47% in soils). In conserved areas, the aboveground biomass is the largest compartment of the total carbon stock (> 70%), mainly due to large trees. The carbon stock in the different compartments are strongly correlated with each other and with the canopy opening. The incorpor...

Degradation of Riparian Forest Affects Soil Properties and Ecosystem Services Provision in Eastern Amazon of Brazil

“…The watersheds examined in this study are illustrative of this problem. The degradation process begins with the removal of large trees for timber and charcoal production (Zelarayán et al ., ); the impoverished forests are then cut and burned, and the cleared land is used for subsistence agriculture and then abandoned until a regenerated fallow is burned again (Celentano et al ., ), resulting in a mosaic of areas in different levels of degradation.…”

“…Soils are classified as Plinthosols, naturally poor in nutrients (Anjos et al, 1995). Young secondary forests dominate the landscape, but small fragments of old-growth forest also remain (Zelarayán et al, 2015). The rural population of the study area is very poor and relies mainly on slash-andburn subsistence agriculture, which is the main cause of riparian forest degradation (Celentano et al, 2014).…”

“…The rural population of the study area is very poor and relies mainly on slash-andburn subsistence agriculture, which is the main cause of riparian forest degradation (Celentano et al, 2014). Riparian vegetation varies from terra-firme forests in the highlands to flooded forests in the plains, with mangroves at the mouth of the Pepital River (Zelarayán et al, 2015). Our study was carried out closer to the headwaters, in non-flooded forests.…”

“…This study is part of a long-term research project that aims to achieve the restoration of the Pepital River watershed (Celentano et al, 2014;Triana et al, 2015;Zelarayán et al, 2015). In September 2012, we carried out a field assessment of the entire riparian zones of the Pepital River and Grande River.…”

“…According to the FAO (2009), canopy cover and tree height are suitable criteria for classifying different degrees of degradation along with professional judgment based on field observation. Indeed, the agents of degradation (such as loggers and farmers) usually leave highly degraded (or deforested) areas alongside other relatively well-and intermediately conserved forest habitats (Zelarayán et al, 2015).…”