Phase Decomposition upon Alteration of Radiation-Damaged Monazite-(Ce) from Moss, Ostfold, Norway

The internal textures of crystals of moderately radiation-damaged monazite-(Ce) from Moss, Norway, indicate heavy, secondary chemical alteration. In fact, the cm-sized specimens are no longer mono-mineral monazite but rather a composite consisting of monazite-(Ce) and apatite pervaded by several generations of fractures filled with sulphides and a phase rich in Th, Y, and Si. This composite is virtually a 'pseudomorph' after primary euhedral monazite crystals whose faces are still well preserved. The chemical alteration has resulted in major reworking and decomposition of the primary crystals, with potentially uncontrolled elemental changes, including extensive release of Th from the primary monazite and local redeposition of radionuclides in fracture fillings. This seems to question the general alteration-resistance of orthophosphate phases in a low-temperature, 'wet' environment, and hence their suitability as potential host ceramics for the long-term immobilisation of radioactive waste

The tree height estimated by non-power models on volumetric models provides reliable predictions of wood volume: The Amazon species height modelling issue.

Allometries that include height as independent variable usually provide greater accuracy on estimates of volume, biomass or individual carbon than other prediction strategies that rely only diameter at breast height as independent variable. However, when these models are applied in Amazon Forest Inventories, it is common to use estimated heights rather than measured heights to prepare volume, biomass or carbon estimates. This practice is common, but rarely discussed and the effect on predictions and precision is usually overlooked. The aim of this study was to examine hypsometric models and evaluate the effect of estimated height on merchantable volume prediction in Eastern Amazonian forests. The study area was a 3,786 ha Forest Management Unit owned by Jari Florestal S.A., in the Jari Valley Region of the State of Pará, Brazil. The data includes 16,099 trees of 25 species, measured and harvested in 2006. Ten percent of the data were reserved for validation of the hypsometric and volumetric estimates. Five hypsometric models and two modelling techniques (linear regression and mixed-effects model) were examined. The choice of best model was based on graphical analyses of residuals, distribution of residuals, heteroscedasticity of error and presence of outliers as assessed by h-values, DFFITS and Cook's distance. The hypsometric relationship and volumetric estimates using DBH and DBH with estimated height were validated with Graybill's test, Theil's error decomposition, Efficiency, Equivalence test and Tukey's test for species estimates level. Heights estimated using a semi-logarithmic mixed-effects model can improve predictions from volume equations. The results show that exploratory data analysis and validation process helped to provide estimates with greater efficiency and should be adopted in related studies. The prediction of height associated with volumetric models for six different species provided volumetric estimates with an error below 5% for the global average volume. The estimated height by the mixed-effect non-power law model should be included in double input models previously developed for volume prediction

Resiliência do volume de madeira de espécies comerciais em diferentes áreas experimentais na Amazônia Oriental.

O objetivo do estudo é avaliar o comportamento do volume de madeira em diferentes grupos de espécies arbóreas comercias ao longo do tempo em áreas experimentais na Amazônia Oriental Brasileira. Foram analisada a dinâmica do volume na Flona Tapajós, Floresta Monte Dourado-Jari, Floresta do Moju e Fazenda Rio Capim. Foram realizados inventários florestais de espécies arbóreas a partir de 20 cm diâmetro. Esses inventários foram realizados em diferentes anos antes e após a exploração florestal em cada área experimental. Para análise dos dados foram para as classes de diâmetro entre 20 e 49,9 cm, para caracterizar o estoque de madeira reservado para a futura exploração, e outra classe com árvores de DAP ≥ 50 cm para caracterizar o volume da presente colheita. Foram calculados os equações do volume. As categorias de grupos de espécies arbóreas comerciais foram G1, G2, G3, G4 e G5 e essa classificação foram realizadas através das espécies arbóreas comerciais encontradas nas áreas estudos comparadas com as espécies arbóreas comerciais encontradas em Pará (2016). Os volumes foram por categorias de grupos de espécies arbóreas comercias ao longo do tempo, tratamentos silviculturais e classe diamétrica. Os resultados encontrados variaram de acordo com tratamentos silviculturais, classe diamétrica e períodos. Através do estudo é possível afirmar que a floresta é capaz de ter sua resiliência volumétrica, pois se observou nessas áreas de estudos, que a maioria das espécies arbóreas comerciais nos diferentes tratamentos silviculturais aumentaram seu volume após 30, 26 e18 anos de exploração florestal de impacto reduzido

Rapid tree carbon stock recovery in managed Amazonian forests.

While around 20% of the Amazonian forest has been cleared for pastures and agriculture, one fourth of the remaining forest is dedicated to wood production [1] . Most of these production forests have been or will be selectively harvested for commercial timber, but recent studies show that even soon after logging, harvested stands retain much of their tree-biomass carbon and biodiversity [2,3] . Comparing species richness of various animal taxa among logged and unlogged forests across the tropics, Burivalova et al.[4] found that despite some variability among taxa, biodiversity loss was generally explained by logging intensity (the number of trees extracted). Here, we use a network of 79 permanent sample plots (376 ha total) located at 10 sites across the Amazon Basin [5] to assess the main drivers of time-to-recovery of post-logging tree carbon ( Table S1 ). Recovery time is of direct relevance to policies governing management practices (i.e., allowable volumes cut and cutting cycle lengths), and indirectly to forest-based climate change mitigation interventions