The use of artificial intelligence to generate information of the savanna's energy capacity may support sustainable management of those areas. We assessed the efficacy of artificial neural networks (ANNs) combined with satellite data to estimate the energy potential (Pe) for cerradão, a dense savannah-like vegetation type in Brazil. We conducted a forest inventory for measuring dendrometric variables and sampling woody materials and barks in a cerradão area in the state of Tocantins, Brazil. The Pe of cerradão biomass was estimated based on the observed higher calorific power and drier biomass values. Six vegetation indices were retrieved from a RapidEye image and tested for correlation to choose the optimum vegetation index for biomass modeling. The basal area and the Normalized Difference Vegetation Index were used as predictors in the Pe modeling. We estimated an average of 19.234 ± 0.411 GJ ton-1 and 19.878 ± 1.090 GJ ton-1 for higher heating values of the wood species and barks, respectively, and an average Pe of 1022.660 GJ ha-1. The best ANN showed an error of 11.3% by using a structure of two, eight, and one neurons in the input layer, in the hidden layer, and in the output layer, respectively, as well as activation functions of the tangential and sigmoidal types. The validation tests showed no significant difference between the observed and ANNpredicted values. Based on our results, we concluded that Pe can be efficiently predicted by combining ANNs and remotely sensed data, which ultimately is a promising tool for forest sustainable management of the cerrado ecosystems.

The success of Eucalypt cultivation in Brazil was the result of decades of research, improvement of cultivation technologies, along with favorable edaphoclimatic properties. Nowadays, Eucalypt plantations are the main source of wood in the country. However, there are persisting doubts about the impacts on hydric, chemical and biological patters on the soil by this monoculture forest. For this reason, the understanding of the nutrient biogeochemical cycle linked to the litter dynamics contributes to elucidate the changes occurring in the physicochemical and biological properties of the soil. Thus, this work evaluated litterfall, litter layer and leaf decomposition in Eucalypt plantation 60 months-age in the Cerrado area, Distrito Federal. 360 days after experiment initiation, the remaining mass of leaves corresponded to 68.72%, indicating a highly recalcitrant litter. It was concluded that there is an intense production and accumulation of plant material, which undergoes decomposition at a slow rate. This longer time of permanence of litter on the ground provides a favorable niche for edaphic fauna, protecting the superficial layer of the soil by reducing the impact of the kinetic energy of raindrops and allowing for improvement in water infiltration and, consequently, maintenance of the soil hydric capacity.O êxito da eucaliptocultura no Brasil foi resultado de décadas de pesquisa, aprimoramento de tecnologias de cultivo, aliado às propriedades edafoclimáticas favoráveis. Atualmente, os plantios dessa espécie são a principal fonte de madeira no país. Entretanto, dúvidas a respeito de impactos nos padrões hídricos, químicos e biológicos do solo, advindos dessa monocultura florestal ainda carecem de elucidações. Por esta razão, o entendimento do ciclo biogeoquímico de nutrientes ligado à dinâmica da serapilheira contribui para elucidar as modificações que ocorrem nas propriedades físico-químicas e biológicas do solo. Assim, este trabalho avaliou a produção, acúmulo e decomposição de serapilheira em plantio eucalipto aos 60 meses de idade em área de Cerrado no Distrito Federal. Aos 360 dias após o início do experimento, a porcentagem de massa remanescente correspondia a 68,72% indicando uma serapilheira altamente recalcitrante. Conclui-se que há uma intensa produção e acúmulo de material vegetal, porém com uma lenta decomposição. Esse maior tempo de residência da serapilheira proporciona um nicho favorável à fauna edáfica e proteção da camada superficial do solo, por meio da redução do impacto da energia cinética das gotas de chuva, possibilitando assim, uma melhora na infiltração de água e consequentemente manutenção da capacidade hídrica no solo.Palavras-chave: biomassa remanescente, sacolas de decomposição, constante k de decomposição, solo distrófico.

Conserving the remaining savanna ecosystems in the Brazilian savanna (Cerrado) -a global biodiversity hotspot that stores carbon and provides water to a large portion of South Americarequires understanding the ecological processes maintaining their function. Nutrient cycling supports savanna function via plant litter production and decomposition by soil fauna, releasing nutrients for plant and soil organism uptake. Soil biodiversity and biogeochemistry linkages with litter dynamics in Neotropical savannas under a changing climate are poorly understood. Here, we combined two years of rainfall seasonality, leaf and wood litter production and decomposition with soil epigeic fauna abundancethe number of ground-surface dwelling invertebrates collected through pitfall trapstaxa richness, Shannon's diversity and Pielou's evenness, and 16 soil biogeochemical variables measured in 12 plots of preserved savanna. Rainfall seasonality modulated the mean soil epigeic fauna diversity and evenness across all plots, which were highest in the rainy season, in contrast to litterfall rates, which peaked in the dry season. In the dry season (April to September), the Formicidae family was the most abundant with 50% of all individuals, while in the rainy season (October to March), the Isoptera order was the most abundant with approximately 39% of individuals. Wood litter decomposition grouped with annual Hemiptera abundance, covarying with soil epigeic fauna diversity and evenness per plot and against soil fertility variables. Leaf litter decomposition co-varied with the total epigeic fauna abundance and soil pH. We speculate that the specific need to decompose wood litter may be associated with a greater need for diversity than an abundance of soil epigeic fauna. Our work highlights the role of rainfall seasonality on soil biodiversity and physicochemistry, which is also tightly linked with litter production and decomposition. This study advances our understanding of the mechanisms governing nutrient cycling in savanna ecosystems on nutrient-impoverished soils, with implications for achieving sustainable conservation and restoration goals.

The prediction of biological processes, which involve growth and plant development, is possible via the adjustment of mathematical models. In forest areas, these models assist in management practices, silviculture, harvesting, and soil fertility. Diameter, basal area, and height are predictors of volume and biomass estimates in forest stands. This study utilized different non-linear models for estimating biomass and nutrient values in the aerial biomass and roots of an unmanaged eucalypt stand in Cerrado dystrophic soil. It was hypothesized that the models would estimate the nutrients of the aboveground biomass and roots after meeting the selection and validation criteria. By statistical analysis of the parameters and subsequent validation, the Schumacher–Hall model was presented to be the best fit for biomass and nutrients. This result confirmed the ability of different variables, including diameter, basal area, and height, to be predicted. Estimating the nutrient values in the aboveground biomass and roots allowed a better understanding of the quality of the vegetal residues that remained in the soil. For dystrophic soils, which occur in the Cerrado, these estimates become even more relevant.

Em sistemas florestais, a forma natural de aporte de nutrientes se dá através da serapilheira, a qual compreende todo material vegetal depositado ao solo. Logo, vista a importância do tema, o presente trabalho objetivou realizar uma revisão sistemática sobre as diferentes metodologias utilizadas na temática da serapilheira e ciclagem de nutrientes nas diversas fitofisionomias do bioma Cerrado. Foram avaliadas todas as publicações, independentemente do período de publicação, e catalogadas as que se enquadraram na temática: quantificação da produção e decomposição da serapilheira no bioma Cerrado, por meio de buscas no portal periódicos CAPES. Foram selecionados 26 artigos com estudos nas seguintes formações florestais: Cerrado sentido restrito; Cerradão; Matas de Galeria; Florestas de transição Cerrado-Amazônia e plantios homogêneos. A respeito das metodologias, os coletores mais comuns nos trabalhos de produção foram os de formato quadrado (0,25 m²) e o número de coletores variou bastante entre os trabalhos (de 10 a 60 coletores). As folhas contribuíram em torno de 70% ou mais do total da serapilheira. A decomposição apresentou grande variação na massa acondicionada nas bolsas e nos tempos de coleta. Com exceção de um trabalho, os manuscritos avaliados não apresentaram estudos sobre a decomposição de outros componentes da serapilheira, que não a foliar, evidenciando assim a necessidade de estudos nesta temática. Os trabalhos apresentaram tempo total de um ano de avaliação em quase sua totalidade, o que evidencia a necessidade dos monitoramentos de longo prazo, pois estudos com breve duração não permitem avaliar os efeitos de alterações interanuais. As metodologias utilizadas nos trabalhos avaliados apresentaram alto grau de variação, evidenciando a necessidade de padronização que permita a comparação entre estes. Por fim, pôde-se observar que algumas fitofisionomias não possuem nenhuma publicação sobre os temas avaliados, o que reforça a necessidade de estudo da dinâmica da ciclagem de nutrientes nestes locais.

This study aimed to evaluate the natural regeneration of the Cerrado in the understory Eucalyptus sp. stands and investigate environmental factors that may be related to the establishment of the regenerative stratum. Three areas of reforestation of eucalyptus were selected: A1 (reform planting carried out in 2012, with occurrence of superficial fire in 2011), A2 (planting over 12 years old, established by seeding and affected by the occurrence of fire in 2011), and A3 (planting carried out in 2009, without the occurrence of fire); ten plots of 100 m² were marked in each area, and the natural regeneration, basal areas of eucalyptus and physical and chemical properties of the soil were evaluated. Chemical properties were similar for the three areas, where the results of analysis indicate acid and dystrophic soils. Physical properties indicate clay soils without limitations to plant growth. A variation was observed in the density and number of species regenerating between A2 (247 individuals from 28 species) and stands A1 and A3 (40 individuals from 20 species, and 32 individuals from 11 species, respectively), variation that can be explained due to the higher insolation in the understory, related to the lower basal area of Eucalyptus sp.Key words: fire; native species; soil properties Regeneração natural de Cerrado em sub-bosque de povoamentos de Eucalyptus sp., no Distrito Federal RESUMOO estudo teve como objetivo avaliar a regeneração natural de Cerrado no sub-bosque de povoamentos de Eucalyptus sp. e investigar fatores ambientais que podem estar relacionados ao estabelecimento do estrato regenerante. Foram selecionadas três áreas de reflorestamentos de eucaliptos: A1 (plantio de reforma realizado em 2012, com ocorrência de incêndio superficial em 2011), A2 (plantio com mais de 12 anos de idade, implantado por meio de semeadura e muito afetado pela ocorrência de incêndio em 2011), e A3 (plantio realizado no ano de 2009, sem ocorrência de fogo); demarcadas dez parcelas de 100 m² em cada área e avaliadas a regeneração natural, as áreas basais dos eucaliptos e propriedades físicas e químicas do solo. As propriedades químicas foram semelhantes para as três áreas, onde os resultados das análises indicam solos ácidos e distróficos. As propriedades físicas indicam solos argilosos e sem limitações. Foi verificada variação na densidade e número de espécies de regenerantes entre o povoamento A2 (247 indivíduos distribuídos em 28 espécies) e os povoamentos A1 e A3 (40 indivíduos distribuídos em 20 espécies; e 32 indivíduos distribuídos em 11 espécies, respectivamente), variação que pode ser explicada devido à maior insolação do sub-bosque, relacionada à menor área basal de Eucalyptus sp.

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The Brazilian federal law has established norms for vegetation protection in 2012 for the planting of exotic species for the restoration of altered areas. Given the large number of areas to be recovered in the savannah biome in Brazil (e.g., Cerrado), the use of fast-growing species and high biomass production (e.g., Eucalyptus spp.) has been earnestly considered. However, the recommendation of this exotic species must be scientifically supported. This work aimed to evaluate the decomposition process of eucalyptus leaf litter in three different phytophysiognomies in the Cerrado biome (Brazilian Savannah) with three different formation type: Typical Cerrado, Savannah Forest, and Gallery Forest. The leaf decomposition was evaluated by the litter bags that were collected from October 2017 to October 2018. The difference between the initial mass and the masses was evaluated at the different collection periods. After one year, we determined the decomposition rate and the constant k using the exponential equation proposed by Olson. The decomposition rate of eucalyptus leaves was high in the three Cerrado formations. The shortest decomposition time was observed in Gallery Forest. The results showed that the main types of Cerrado formation effectively assimilate the organic material to be deposited in the soil. Thus, the study demonstrated the feasibility and legal provision of using exotic species, e.g., eucalyptus in the arduous mission of recovering degraded forest environments