Spatial heterogeneity of soil mineral oxide components in depression between karst hills,Southwest China

In karst regions,the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear.We investigated the spatial heterogeneity of SiO2,Al2O3,Fe2O3,CaO,MgO,P2O5,K2O,and MnO contents in the soils of slope land,plantation forest,secondary forest,and primary forest,as well as their relationships with environmental variables in a karst region of Southwest China.Geostatistics,principal component analysis(PCA),and canonical correlation analysis(CCA)were applied to analyze the field data.The results show that SiO2was the predominant mineral in the soils(45.02%–67.33%),followed by Al2O3and Fe2O3.Most soil mineral oxide components had a strong spatial dependence,except for CaO,MgO,and P2O5in the plantation forest,MgO and P2O5in the secondary forest,and CaO in the slope land.Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems.Soil mineral oxide components,the main factors in all ecosystems,had greater influences on vegetation than those of conventional soil properties.There were close relationships between soil mineral oxide components and vegetation,topography,and conventional soil properties.Mineral oxide components affected species diversity,organic matter and nitrogen levels.     

Effects of corridor networks on plant species composition and diversity in an intensive agriculture landscape

The development of modern agriculture has resulted in much homogenization of the landscape consisting of large patches of farmland,so small remnant non-crop habitats especially linear corridors play an important role in the conservation of species and the maintenance of ecosystem functions.However,little attention has been paid to the effects of corridors structural characteristics on the plant species restricted to such habitats.In this study,we selected three types of corridors including ditch,hedgerow and road,and ana-lyzed their structural characteristics.The plant species presented in these corridors were investigated,and the species diversity,abun-dance and frequency were estimated.Moreover,spatial arrangements of corridors were classified into different types to discuss whether there were significant effects of corridor network on plant distribution.The results show that three types of corridors have different ef-fects on plant species composition and diversity.The one-one combined corridor networks and total network associated by three corri-dors have more complex structural features than each single type of corridor.However,there is no strong correlation between the corri-dor networks with their plant species.We suggest that carrying out a pointed vegetation survey at corridor intersections to further test the relationships between structural features of corridor and plants is necessary.     

Denitrification potential of marsh soils in two natural saline-alkaline wetlands

Little information is available on denitrification potential of marsh soils in natural saline-alkaline wetlands. The denitrification potentials of an open wetland in the floodplain(Erbaifangzi wetland) and a closed wetland(Fulaowenpao wetland) in backwater areas in Jilin Province of Northeast China were monitored by an anaerobic incubation at 30℃ for 25 days. Our results showed that the relative denitrification index(RDI) increased gradually with incubation time, and showed a rapid increase in the first 5 days of incubation. The RDI values declined quickly from surface soils to subsurface soils and then kept a small change in deeper soils along soil profiles over the incubation time. Denitrification proceeded much faster in the top 20 cm soils of open wetland than in the closed wetland, whereas no significant differences in RDI values were observed in deeper soils between both wetlands. The RDIs were significantly negatively correlated with bulk density and sand content, while a significantly positive correlation with clay content, soil organic matter, total nitrogen and phosphorous. The maximum net NO–3-N loss through denitrification in 1 m depth were higher in the open wetland than the closed wetland with higher soil pH values. Future research should be focused on understanding the influencing mechanisms of soil alkalinity.     

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运用气象影视节目强化气象科普宣传

通过对目前气象科普知识宣传现状的分析,找出存在的问题和电视气象节目气象科普宣传的优势,提出强化电视气象节目气象科普宣传的建议,为我们搞好气象科技服务打下良好的社会基础.     

基于航摄影像的滇池捞鱼河湿地植物类型提取

为了获取滇池湿地的植物类型分布信息,以捞鱼河湿地为示范区,采用分辨率为0.15 m的航摄影像为影像数据源,利用人机交互和面向对象相结合的影像解译方法,实现捞鱼河湿地植物类型分布信息的提取.在植物类型边界提取过程中,发现过高的影像分辨率(≤0.3m)不利于成片具有空间异质性植物类型边界的正常提取,容易出现同一类型过度分割情况.通过邻域降分辨率重采样技术,将影像分辨率降至0.6m时,能有效解决过度分割问题.当分辨率降至更低时,虽然能解决过度分割问题,但会导致地物边界出现不同程度的锯齿而与地物边界不符的后果.研究所应用的基于Feature Extaction模块的植物类型边界提取方法,能有效减少人机交互方法中人工勾绘边界的工作量,在保证分类精度的同时减少人力投入,对航摄影像在大范围湿地植物类型的提取中具有重要借鉴意义.     

EMD方法在广西夏季降水量预测中的应用

对广西夏季降水量进行EMD分解后,利用均生函数相关法,比较不同IMF分量组合建模的预测,不同组合试验预测显示,用前二个IMF分量组合建模预测是最佳的组合方案。经对2001—2010年共10年广西夏季降水量实际预测检验表明,趋势预测准确率达70%以上,对夏季降水量预测较有参考价值。为基层台站的气候预测及服务提供一个客观预测方法。