Nutritional Efficiency of Forest Species in Natural Regeneration of Tropical Forest in Brazil

Abstract

The knowledge of the nutritional aspects of native species, mainly in natural regeneration, may be important for understanding their establishment, particularly in areas with low nutrient availability soils, such as tropical soils. This study aimed to determine the biological utilization efficiency (BUE) of the nutrients N, P, K, Ca, and Mg of forest species of natural regeneration in a Lowlands Dense Ombrophilous forest fragment in Pernambuco, Brazil. A phytosociological study of the fragment was carried out and were defined the ten species with the highest absolute density (AD). Three individuals per species were selected. The N, P, K, Ca, and Mg contents were determined in the sample leaves of the species, and the foliar biomass was determined "in loco". Nine individuals of each species were collected according to the following diameter intervals at the base (DBs): DBs<5 cm; 5≤DBs<10 cm and 10≤DBs<15 cm. The content, stock and BUE of nutrients were calculated per species. The BUE of nutrients by species varied according to the following decreasing order: P>Mg>K>Ca>N. The highest BUE of nutrients was of the species Protium heptaphyllum. In tropical soils of low natural fertility, the use of these species can be recommended in environmental reforestation projects. The difference in the nutritional demand of the forest species can indicate the planting of those with greater capacity of absorption and BUE of nutrients, being more efficient in areas of soils with low natural fertility like in the tropical forests. P content foliar biomass of the species varied from 1.33 to 2.45 g kg -1 , with a mean of 1.49 g kg 1 . P content in A. dolichocarpa was higher than of the other species (Table 4).Nutrient stock in the foliar biomass of natural regeneration species followed the decreasing order: N>Ca>K>Mg>P. This decreasing sequence varied according to species: T. spruceanum was N>Ca>Mg>K>P; C. densifolia was N>K>Ca>Mg>P; and P. heptaphyllum was N>Ca>K>P>Mg (Table 3). The highest nutrient stock were observed in B. rubescens (Table 4), due to the amount of biomass per area of the species (Table 3) N was the nutrient that presented the highest stock in the foliar biomass of the highest AD species, varying from

Emergência e morfologia da plântula de Thyrsodium spruceanum Benth. a partir de diásporos coletados na chuva de sementes em Floresta Atlântica

“…é uma espécie de porte arbóreo, podendo atingir 20 m de altura, pertencente à família Anacardiaceae, ocorrendo na Floresta Amazônia, nas fitofisionomias Floresta de Terra Firme e Floresta de Várzea; e Floresta Atlântica, nas Floresta Estacional Semidecidual e Floresta Ombrófila (Silva-Luz & Pirani, 2015). É comumente identificada como uma das espécies com maior densidade em estudos desenvolvidos com florística e análise fitossociológica do componente arbóreo adulto e regenerantes (Silva et al, 2018a;Lima et al, 2017;Lima et al, 2019). Conhecida popularmente como caboatã-de-leite, mangabrava, mututurana, amaparana e tutuzuba-davárzea, T. spruceanum é uma espécie semidecídua, secundária, com comportamento de espécie ciófita até heliófita que produz frutos com pericarpo carnoso, o que facilita sua dispersão pela fauna (Lorenzi, 2008;Barroso et al, 2012).…”