The analysis of the systematic transitions in the forested landscape and the study of the forest fragmentation patterns allow us to deepen our understanding of the changes in the vegetation ground cover. The importanc...The analysis of the systematic transitions in the forested landscape and the study of the forest fragmentation patterns allow us to deepen our understanding of the changes in the vegetation ground cover. The importance of knowing the intricate patterns of the land usage of the upper basin of the Amazon region is widely recognized. This zone is one of the most diverse biological areas in the world, is home to large areas of mature tropical cloud forest and demonstrates high probabilities of stable climatic conditions in light of global warming. The research quan- tiffed systematic transitions through the ＂loss＂ and ＂gain＂ of the different categories of landscape during the eighteen-year study period of the Ecuadorian Amazon Region （EAR）, the forest fragmentation patterns were also analyzed based on a set of indicators. Therefore, with respect to the entirety of the landscape, the results registered for the ground coverage in forested areas during the first period （1990-2000）, show a decrease of 6.99% and an increase of 0.68%; and during the second period （2000-2008）, show a decrease of 3.99% and an increase of 2.14%. It demonstrated that forest and agricultural areas tended to replace or be replaced by herbaceous vegetation faster than expected fortuitously. Finally, the indices of fragmentation signaled intense changes during the 1990-2000 period with a reduction during the period 2000-2008. Per- centages registered in the Largest Patch Index （LPI） were between 79.58%; 52.39% and 49.99% respectively; while the Patch Density （PD） varied between 0.04; 0.06 and 0.07. This suggests the propensity of for- est cover to remain intact. The results of this investigation suggest a tendency towards stability in Ecuador＇s Amazon landscape. Within the framework for development and management of this area, the tendency is natural regeneration. This permits a consolidation of the conservation, reforestation, forestation and agricultural forestry plans, programs and systems for the protected areas in EAR.展开更多
Eu^3＋/Dy^3＋ single-doped and co-doped 6SrO-3Al2O3-91SiO2 and 12SrO-6Al2O3-82SiO2 glass and glass-ceramics were synthesized successfully by a sol-gel method. The prepared samples were characterized by the X-ray diffr...Eu^3＋/Dy^3＋ single-doped and co-doped 6SrO-3Al2O3-91SiO2 and 12SrO-6Al2O3-82SiO2 glass and glass-ceramics were synthesized successfully by a sol-gel method. The prepared samples were characterized by the X-ray diffraction, high-resolution transmission electron microscopy, photoluminescent spectra and X-ray photoelectron spectroscopy. The effect of annealing temperature, doped ions and matrix component on the structure and the photoluminescent characteristics was systematically studied. The higher temperature was helpful to form nanocrystals and the amount of SrO and Al2O3 could better disperse the rare earth ions in matrix at suitable temperature, and both of them could improve the luminescent intensity. Meanwhile, the doped ions could change the luminescent color by single, codoped and energy transfer. The Sr2SiO4 nanocrystals were observed in silicates glasses and became larger with the increase of the annealing temperature and the luminous efficiency of rare-earth（RE） ions could be enhanced when the samples changed from glass state to glass-ceramic state. The results indicated that the photoluminescent properties could be changed through controlling the doped ions, annealing temperature and matrix component.展开更多
基金supported by the National Secretary of Higher Education,Science,Technology and Innovation of Ecuador
文摘The analysis of the systematic transitions in the forested landscape and the study of the forest fragmentation patterns allow us to deepen our understanding of the changes in the vegetation ground cover. The importance of knowing the intricate patterns of the land usage of the upper basin of the Amazon region is widely recognized. This zone is one of the most diverse biological areas in the world, is home to large areas of mature tropical cloud forest and demonstrates high probabilities of stable climatic conditions in light of global warming. The research quan- tiffed systematic transitions through the ＂loss＂ and ＂gain＂ of the different categories of landscape during the eighteen-year study period of the Ecuadorian Amazon Region （EAR）, the forest fragmentation patterns were also analyzed based on a set of indicators. Therefore, with respect to the entirety of the landscape, the results registered for the ground coverage in forested areas during the first period （1990-2000）, show a decrease of 6.99% and an increase of 0.68%; and during the second period （2000-2008）, show a decrease of 3.99% and an increase of 2.14%. It demonstrated that forest and agricultural areas tended to replace or be replaced by herbaceous vegetation faster than expected fortuitously. Finally, the indices of fragmentation signaled intense changes during the 1990-2000 period with a reduction during the period 2000-2008. Per- centages registered in the Largest Patch Index （LPI） were between 79.58%; 52.39% and 49.99% respectively; while the Patch Density （PD） varied between 0.04; 0.06 and 0.07. This suggests the propensity of for- est cover to remain intact. The results of this investigation suggest a tendency towards stability in Ecuador＇s Amazon landscape. Within the framework for development and management of this area, the tendency is natural regeneration. This permits a consolidation of the conservation, reforestation, forestation and agricultural forestry plans, programs and systems for the protected areas in EAR.
基金Project supported by the National Natural Science Foundation of China(51562025)Graduate Student Innovation Special Funds(YC2016-S085) of Jiangxi Province
文摘Eu^3＋/Dy^3＋ single-doped and co-doped 6SrO-3Al2O3-91SiO2 and 12SrO-6Al2O3-82SiO2 glass and glass-ceramics were synthesized successfully by a sol-gel method. The prepared samples were characterized by the X-ray diffraction, high-resolution transmission electron microscopy, photoluminescent spectra and X-ray photoelectron spectroscopy. The effect of annealing temperature, doped ions and matrix component on the structure and the photoluminescent characteristics was systematically studied. The higher temperature was helpful to form nanocrystals and the amount of SrO and Al2O3 could better disperse the rare earth ions in matrix at suitable temperature, and both of them could improve the luminescent intensity. Meanwhile, the doped ions could change the luminescent color by single, codoped and energy transfer. The Sr2SiO4 nanocrystals were observed in silicates glasses and became larger with the increase of the annealing temperature and the luminous efficiency of rare-earth（RE） ions could be enhanced when the samples changed from glass state to glass-ceramic state. The results indicated that the photoluminescent properties could be changed through controlling the doped ions, annealing temperature and matrix component.
