Objetivou-se quantificar os teores de C nos reservatórios da biomassa vegetal de diferentes espécies da Caatinga, floresta tropical seca do Nordeste do Brasil. Foi realizado um estudo florístico e fitossociológico prévio e selecionadas nove espécies de maior densidade absoluta, que representou 87% do fragmento. Foram amostradas biomassa dos compartimentos folhas e lenho de cada uma das espécies para determinação do teor de C. Como resultado, houve diferença nos teores foliares de C entre as espécies. O teor de C foliar das espécies variou entre 448,0 e 454,3 g C por kg de biomassa seca e o teor de C do lenho das espécies variou entre 451,4 e 453,1 g C por kg de biomassa seca. Esses resultados sugerem a utilização de fator de conversão de biomassa para carbono específico por espécie em Caatinga, como alternativa ao fator genérico de 50% recomendado pelo IPCC. Esta pesquisa revela que o uso do fator recomendado pelo IPCC superestima estoques de C em Caatinga. Mais estudos são encorajados para confirmar esse resultado.

The relationship between soil attributes and spatial distribution variability of tree and shrub vegetation, specifically those in process of natural regeneration, can be an important tool for understanding the ecology of populations and communities while enabling the recommendation of species that can be used in restoration programs of degraded areas, as in this area from Atlantic Forest of Brazil. Thus, this work aimed to study soil chemical attributes as indicators of spatial distribution of forest species in natural regeneration with higher absolute density in the Lowlands Dense Ombrophilous Forest fragment in Pernambuco, Brazil. For soil chemical characterization, samples were collected at depths of 0.0-0.10 and 0.11-0.20 m. The natural regeneration species sampling was performed in 40 subunits of 25 m², implemented in 40 sampling units of 250 m². The individuals with diameter at breast height (DBH) < 15 cm and height ≥ 1.0 m were measured. Thus, the ten natural regeneration species with the highest Absolute Density were defined. Geostatistical analysis was used to characterize the spatial variability of forest species and soil attributes. Tovomita mangle may be indicated for soils with different chemical characteristics and natural fertility; Brosimum rubescens and Inga capitata for acidic soils with low natural fertility, but with moderate levels of exchangeable Al; Talisia retusa should be recommended for alic soils and Caraipa densifolia for non-alic soils; and Anaxagorea dolichocarpa and Protium arachouchini for high natural fertility soils.

Important for soil quality, the edaphic fauna is indicative of an environment in equilibrium. The study aimed to identify the macrofauna and mesofauna organisms of the soil in a fragment of riparian forest. The work was carried out in a fragment of ciliary forest on the farm Tamanduá, municipality of Santa Terezinha, Paraíba. The macrofauna was quantified in soil samples collected at different depths (0-5 cm and 5-10 cm) using the TSBF method. For the mesofauna was collected randomly in the same area, samples of soil + litter in the depths 0-5 cm and 5-10 cm using metal rings. The design was completely randomized in a 4 × 2 factorial scheme (4 seasons, 2 depths), with 5 replicates, the means being compared by the Tukey test. The main orders of the macrofauna were: Hymenoptera, Coleoptera, Isoptera, and Enquitreídeos being the order of greater proportion in the two depths to Hymenoptera. There were a higher population and diversity of soil macrofauna in the superficial layer (0-5 cm). For the mesofauna were found in the samples organisms belonging to the groups Acarina and Collembola, being the order Acarina the most representative in the two depths evaluated. The environment of riparian forest presents greater diversity and density of macrofauna and mesofauna of the soil in the layer of 0.0-5.0 cm of depth, which presents greater food supply and conditions favorable to the survival of these organisms.

This study aimed to estimate the redistribution of rainfall in a Caatinga vegetation fragment of about 50 years in fallow system, in late stage of regeneration. To quantify the throughfall, rainfall collectors were installed in six individuals of the species Croton blanchetianus, Mimosa tenuiflora, Cnidoscolus quercifolius, Aspidosperma pyrifolium and Poincianella bracteosa, totaling 30 rainfall collectors. For the stemflow, collecting system set around the stems of the six subjects in each of the five selected species was used, consisting of collecting gutters in a spiral. In addition, a rain gauge was installed in an open location to quantify the open precipitation, which during the study period was equal to 1173.56 mm. The C. quercifolius species had the highest average of throughfall; probably this may be related to the peculiarities in relation to architecture and canopy shape. The stemflow has lower shares in gross precipitation in A. pyrifolium and C. quercifolius species, representing 15.25 to 12.48% of the total rainfall, respectively. The values obtained for the interception losses were greater than 60% in all species. Key words: Forestal hydrology, throughfall, stemflow.

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≤DBsMg>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.

Through carbon fixation and nutrient cycling, forests support global biogeochemical dynamics, and the Amazon, the largest continuous tropical forest, constitutes one of Earth's most important carbon sinks worldwide. This study aimed to review the scientific literature on litter carbon stocks in the Amazon. For this purpose, a database was compiled from the Scopus and Web of Science platforms using a previously defined set of keywords, including publications up to 2023. Initially, 232 publications were identified and subsequently screened according to pre-established criteria, resulting in a final dataset of 32 studies. Brazil accounted for the highest number of studies on the subject, whereas no research was identified from Ecuador, Guyana, or Suriname. Within Brazil, a greater concentration of studies was observed in the state of Pará, while no scientific records were found for the states of Amapá, Roraima, and Tocantins. Fewer than half of the studies evaluated areas subjected to changes in vegetation cover. Additionally, approximately 4% of the publications did not report the type of litter assessment conducted, and about 22% did not specify the method used to determine carbon content. The findings of this review underscore gaps in the scientific literature, particularly regarding the spatial distribution of studies across the Amazon and the lack of methodological detail in the assessment of litter carbon stocks. Palavras-chave: litter input; bibliometrics; biogeochemical cycles; carbon sink; land-use change.