Soils, Geoenvironments and Ecosystem Services of a Protected Area in Western Brazilian Amazonia

Abstract The Serra do Divisor National Park (SDNP) in the Westernmost Brazilian Amazonia possesses unique Mountain landscapes of sub-andean nature, with high geo-biodiversity and pristine environments, with a potential high contribution in ecosystems services. We studied and mapped the basic geo-environmental units of the main sector of the Park, evaluating soil carbon stocks as a key ecosystem service provided by the Protected Area. For the identification, characterization and mapping of the geoenvironmental units, we integrated pedological, geomorphological and vegetation data obtained by local soil survey and field campaigns, as well as secondary data. Eight geoenvironmental units were identified and mapped, distributed in three main compartments: the Serra do Divisor (SD) the upper Moa River and the medium Moa River. This region presents similar environments to the sub-Andean region, notably the Ceja Forest at the top surface of the SD. Soils at the SD have high organic carbon accumulation, with close association with the nutrient-poor, quartz-rich rocks, and shows organic matter illuviation indicating active podzolization. The SDNP encompasses important ecosystems and services linked with high geo-biodiversity, and high soil carbon stocks, representing a new frontier for scientific research in the only area of transitional sub-andean forested landscape in Brazil

Thermal monitoring of a Cryosol in a high marine terrace (Half Moon Island, Maritime Antarctica)

Abstract Active layer and permafrost are important indicators of climate changes in periglacial areas of Antarctica, and the soil thermal regime of Maritime Antarctica is sensitive to the current warming trend. This research aimed to characterize the active layer thermal regime of a patterned ground located at an upper marine terrace in Half Moon Island, during 2015-2018. Temperature and moisture sensors were installed at different soil depths, combined with air temperature, collecting hourly data. Statistical analysis was applied to describe the soil thermal regime and estimate active layer thickness. The thermal regime of the studied soil was typical of periglacial environment, with high variability in temperature and water content in the summer, resulting in frequent freeze-thaw cycles. We detected dominant freezing conditions, whereas soil temperatures increased, and the period of high soil moisture content lasted longer over the years. Active layer thickness varied between the years, reaching a maximum depth in 2018. Permafrost degradation affects soil drainage and triggers erosion in the upper marine terrace, where permafrost occurrence is unlikely. Longer monitoring periods are necessary for a detailed understanding on how current climatic and geomorphic conditions affect the unstable permafrost of low-lying areas of Antarctica (marine terraces)

Determinação de estoques totais de carbono e nitrogênio e suas frações em sistemas agrícolas implantados em argissolo vermelho-amarelo

Os estoques de C orgânico do solo são definidos pela interação dos fatores que determinam sua formação e aqueles que promovem sua decomposição. Este trabalho teve o objetivo de quantificar a recuperação nos estoques de C nos compartimentos de C orgânico de um Argissolo Vermelho-Amarelo distrófico latossólico em conseqüência do seu uso agrícola. Foram avaliadas áreas com seringal, pomar de citros, pastagem e mata secundária. Retiraram-se 20 amostras de solo em cada uso, nas profundidades de 0-10 e 10-20 cm. Para avaliar o efeito dos tratamentos, foram determinadas e calculadas as seguintes propriedades: C orgânico total (COT), N total (NT), C nas frações ácidos fúlvicos (AF), ácidos húmicos (AH) e humina (HN), C orgânico lábil (CL), C da biomassa microbiana (CMICR), matéria orgânica leve (MOL), C e N da MOL (CMOL e NMOL), C solúvel em água (CSA) e índice de manejo de C (IMC). Na profundidade de 0 a 10 cm, o teor de COT variou de 20,9 a 13,3 g kg-1 para mata secundária e pastagem, respectivamente, enquanto de 10 a 20 cm essa variação foi de 13,5 a 9,8 g kg-1, respectivamente. O IMC de 0 a 10 cm foi maior no seringal (69) e pomar de citros (70) e menor na pastagem (54), o que também ocorreu de 10 a 20 cm. Nas profundidades avaliadas, os sistemas com seringal e pomar de citros apresentaram maior potencial para preservar e, ou, recuperar os teores de COT e NT e os compartimentos lábeis, como o CMICR, CSA, MOL, CMOL e NMOL, bem como proporcionaram melhor qualidade da matéria orgânica humificada com o aumento do conteúdo de substâncias húmicas alcalino-solúveis mais condensadas, ao passo que a pastagem mostrou potencial limitado de preservação de C no solo. Isso posiciona o pomar de citros e especialmente o seringal como uma estratégia de manejo importante para conservação da qualidade do solo. Os teores CMICR, CSA, MOL variaram mais intensamente entre os sistemas de uso que o COT, razão por que podem ser considerados indicadores mais sensíveis das mudanças no estado da matéria orgânica do solo.Soil carbon stocks are the result of interaction of factors that determine their formation and decomposition. This study aimed to quantify the total organic recovery in various C pools under the following different land uses of an Ultisol: secondary forest, rubber tree plantation, pasture, and citrus plantation. The soil was sampled at depths of 0 to 10 cm and 10 to 20 cm and the following characteristics were determined: total organic carbon (TOC), total nitrogen (TN), fulvic acid fraction-C (FA), humic acid fraction-C (HA), humin-C (HN), labile organic matter-C (CL), microbial biomass-C (C-MICR), light organic matter (LOM), C and N of LOM (CLOM and NLOM), water-soluble C (WSC), and Carbon Management Index (CMI). The TOC values varied from 20.9 to 13.3 g kg-1 in the 0-10 cm layer for forest and pasture, respectively, and from 13.5 to 9.8 g kg-1 in 10-20 cm, respectively. The CMI was high in 0-10 cm under rubber cultivation (69) and citrus plantation (70) soils and low in the pasture soil (54). These results were similar in the 10-20 cm layer. In the studied layers, the capacity of preserving and/or recovering TOC and TN concentrations as well as the labile compartments such as CMICR, CSA, MOL, CMOL and NMOL was greater in the rubber and citrus systems. In these plantations the quality of humified fractions increased in parallel to an increment in the condensed alkaline-soluble humic substances. On the other hand, the potential for preservation of soil C under pasture was limited. Citrus and particularly rubber plantations are therefore important land uses to maintain the soil quality. Levels of CMICR, WSC, LOM varied more intensively among the land uses than TOC and can therefore be considered more sensitive indicators of alterations in soil organic matter