The objective of this study was to evaluate the litterfall deposition, the decomposition rate (K L ) and the water holding capacity (WHC) of litter stored in the soil in two areas degraded by mining submitted to different methods of forest restoration: induction of natural regeneration (NR) and planting seedlings of native forest species (PS) with a forest fragment (FF) used as reference. The litterfall deposition was collected monthly over 12 months in collectors of 0.25 m 2 . The KL was estimated by the relation between annual litter production and litter stock in the soil surface. WHC was determined in the rainy and dry period. The litterfall deposition was lower in PS with values of 6.61 ± 0.20, 10.75 ± 0.52 and 11.83 ± 0.72 Mg ha -1 yr -1 for PS, NR and FF respectively. The K L and WHC were significantly lower in PS when compared to NR and FF, and WHC decreased significantly from the rainy season to the dry season. The induction of natural regeneration was the more effective restoration method for degraded areas regarding litterfall deposition, decomposition and water retention capacity, surpassing planting native tree species and approaching a native forest fragment.Fluxo, estoque e capacidade de retenção hídrica de serapilheira em ecossistemas de restauração florestal pós mineração, Amazônia Oriental RESUMO: O objetivo deste estudo foi avaliar a deposição da serapilheira, a taxa de decomposição (K L ) e a capacidade de retenção hídrica (CRH) da serapilheira estocada no solo em duas áreas degradadas por mineração submetidas a diferentes métodos de restauração florestal: indução de regeneração natural (RN) e plantio de mudas de espécies florestais nativas (PM) e um fragmento de floresta (FF) usado como referência. A deposição de serapilheira foi coletada mensalmente ao longo de 12 meses em coletores de 0,25 m 2 . O KL foi estimado pela relação entre a produção anual de serapilheira e o estoque de serapilheira na superfície do solo. A CRH foi determinada no período chuvoso e seco. A deposição de serapilheira foi menor no PM, com valores de 6,61 ± 0,20, 10,75 ± 0,52 e 11,83 ± 0,72 Mg ha -1 ano -1 para o PM, RN e FF respectivamente. O K L e CRH foram significativamente menores no PM quando em comparação com RN e FF, sendo que, a CRH diminuiu significativamente da estação chuvosa para à estação seca. A indução da regeneração natural foi o método mais eficaz de restauração de áreas degradadas quanto à deposição, decomposição e capacidade de retenção de água da serapilheira, superando o plantio de espécies arbóreas nativas e se aproximando de um fragmento de floresta nativa.Palavras-chave: mineração de bauxita; recuperação ambiental; indicadores de restauração florestal; regeneração natural; plantio de mudas nativas Litterfall, litter stock and water holding capacity in post-mining forest restoration ecosystems, Eastern Amazon Rev. Bras.
The lack of technological options for forest concessionaires to produce seedlings of native tree species in the Peruvian Amazon is a bottleneck for reforestation in the region. In this study, a new technology for seedlings production of low cost and accessible to producers was developed. Thus, the objective of this study was to evaluate the efficiency of using buckets as microenvironments under different substrates for the initial growth of Bertholletia excelsa seedlings. Forty days after germinating, the seedlings were transplanted to 115 cm³ tubes containing a standard substrate composed by sand + sawdust + charred sawdust in the proportion of 1:1:1 v/v. Afterwards, the tubes were settled in buckets (microenvironments) under a 100% shade net. The experimental design used in this study was fully randomized and the treatments were T1 = sand, T2 = sand + sawdust, T3 = decomposed Brazil nut shell and T4 = forest soil. The substrate T2 promoted the shoot length, root length, leaves number, shoot dry mass, root dry mass, total dry mass, and slenderness index in B. excelsa seedlings. Quality of B. excelsa seedlings produced in microenvironments was similar among treatments, regardless of the used substrate.Produção de mudas de Bertholletia excelsa Humb. & Bonpl., (Lecythidaceae) em microambientes e diferentes substratos RESUMO: A falta de opções tecnológicas de concessionários de florestas para a produção de mudas de espécies nativas na Amazônia peruana é um gargalo para o reflorestamento na região. Neste estudo, uma nova tecnologia de produção de mudas de baixo custo e acessível a produtores foi desenvolvida. Assim, o objetivo neste trabalho foi avaliar a eficiência do uso de baldes como microambientes e substratos para o crescimento inicial de plântulas de Bertholletia excelsa. Aos 40 dias após a emergência, as plântulas foram repicadas para tubetes com capacidade de 115 cm³, contento um substrato padrão composto por areia + serragem + serragem carbonizada na proporção (1:1:1 v/v). Posteriormente, os tubetes foram acondicionadas em baldes (microambientes) com telado a 100% de sombra. O delineamento experimental foi inteiramente ao acaso e os tratamentos foram: T1 = areia, T2 = areia + serragem, T3 = casca de castanha decomposta e T4 = solo de floresta. O substrato T2 favoreceu o comprimento de parte aérea, raiz, número de folhas, massa seca da parte aérea, raízes e total, além do índice de esbeltez de mudas de B. excelsa. A qualidade das mudas de B. excelsa produzidas em microambientes foi semelhante entre os tratamentos, independente do substrato utilizado.Palavras-chave: castanheira-do-brasil; concessionários florestais; Amazônia peruana; reflorestamento; qualidade de mudas Production of Bertholletia excelsa Humb. & Bonpl., (Lecythidaceae) seedlings in microenvironments under different substrates Rev. Bras.
The usage of spatial tools might be helpful in the optimization of decision-making regarding soil management, with technologies that assist in the interpretation of information related to soil fertility. Therefore, the present study evaluated the spatial variability of chemical attributes of the soil under an agroforestry system compared to a native forest in the municipality of Tomé-açu, Eastern Amazon, Brazil. Soil samples were performed at 36 points arranged in a 55 x 55 m grid. The soils were prepared and submitted to analysis in order to determine pH in H2O, exchangeable calcium, magnesium, potassium and aluminium, available phosphorus, potential acidity, organic matter, bases saturation and aluminium saturation. For each soil attribute, the spherical, gaussian and exponential models were adjusted. After the semivariograms fitting, data interpolation for assessment of spatial variability of the variables was performed through ordinary kriging. The spherical and gaussian models were the most efficient models in estimation of soil attributes spatial variability, in most cases. Most of variables presented a regular spatial variability in their respective kriging maps, with some exceptions. In general, the kriging maps can be used, and we can take them as logistical maps for management and intervention practices in order to improve the soil fertility in the study areas. The results principal components indicate the need for integrated management of soil chemical attributes, with localized application of acidity correctors, fertilizers and other types of incomes, using the spatial variability of these fertility variables.
At a moment when the importance of planted forests in the Amazon region is increasing, hypsometric models become highly relevant tools as they allow monitoring of and planning for tree plantations in a way that is practical and economic for the producer. Thus, the objective of the current study was to select and adjust a model of hypsometric relationships for a clonal plantation of Tectona grandis Linn F., submitted to selective thinning, located in Capitão Poço municipality, Pará state, Brazil. Data were collected from permanent plots in five-year-old stands using the fixed area method and systematic process. The best adjusted model was selected with an adjusted determination coefficient (R²aj.%), residual standard deviation of the percentage estimate (Syx%), recalculated residual standard error (Syxr%), diagnosis of distribution of residuals as a percentage and the Percent Average Deviation (PAD%). Hyperbolic models 2 and 3 had the highest determination coefficients (83.42 and 83.40%) and lowest PAD (-0.006 and -0.154%). The polynomial (1) and hyperbolic models (2 and 3) showed the smallest errors in related to the estimates. Model 2 (hyperbolic) was found to generate the best estimate of total T. grandis clonal plantation height. Use of this hypsometric model will allow a significant reduction of costs and time in forest inventory studies.
The seed bank is essential for the initiation of natural forest regeneration, especially in ecosystems in the early stages of development, where there have been anthropogenic or natural disturbances. The objective of the current study was to evaluate seed bank dynamics in three forest ecosystems, two in Utinga State Park (PEUt) and one on the Federal Rural University of Amazonia (UFRA) campus, both in Belém, Pará, Amazonian Brazil. The ecosystems were: primary forest (PF), early successional forest (ESF), and late successional forest (LSF). For seed bank evaluation, five plots were installed in each forest ecosystem, and in each plot 5 soil samples were removed at a depth of 0-0.05 m. In the three ecosystems, the most abundant species in the seed bank were Cecropia obtusa, Phyllanthus tenellus and Vismia guianensis. Zoochoria was the dominant dispersion syndrome with 1,041 (67.8%) individuals. In the PF and LST ecosystems the predominant life form was tree, followed by shrub, whereas in the ESF the shrub life form predominated, followed by tree. Thirtyone species were recorded in PF, 26 in ISF, and 32 in LSF. In general, pioneers were most frequent ecological group, with 289 individuals (93.2%) in PF, 288 individuals (88.7%) in LSF, and 188 (75.06%) in ESF. Thus, all ecosystems possessed a high potential for resilience in case of possible forest disturbances, and the PF seed bank was considered the most diverse in terms of arboreal species.
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