* 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...

The possible benefits of molybdenum (Mo)-enriched seeds for grain legumes have yet to be addressed in sub-humid tropical areas, where cowpea (Vigna unguiculata L.) is an important crop. In 2016, seeds with 0.014 (low), 0.674, or 1.987 (high) μg seed −1 of Mo were harvested from plants sprayed with 0, 250, or 850 g ha -1 of Mo, respectively. These seeds were combined with either Bradyrhizobium inoculation (with or without) in 2017 or nitrogen (0 or 60 kg ha −1 ) in 2018 and evaluated under small farmer management in Maranhão State, Brazil. Maximum nodules plant −1 in these trials was 5.2. In 2017, inoculation acted synergistically with Mo-enriched seeds by increasing nodule weight. Averaged across inoculation levels, plants originated from high-Mo seeds had 36% higher leaf N concentration than those raised from low-Mo seeds. Inoculation did not affect yield, but plants grown from high-Mo seeds yielded 42% more than those raised from low-Mo seeds. In 2018, seed Mo content did not affect nodule and yield where urea was applied. However, without urea, plants raised from high-Mo seeds had 3.5-fold greater values for nodule number and weight and yielded 70% more than those grown from low-Mo seeds. We conclude that using Moenriched seeds associated with Bradyrhizobium inoculation would improve cowpea N nutrition and yield in a sustainable way.How to cite this article: Barbosa EPA, Sodré DN, Braun H, Vieira RF. Seeds enriched with molybdenum improve cowpea yield in sub-humid tropical regions of Brazil.