有害植物孪花蟛蜞菊扩张对西沙岛屿陆生软体动物的影响

有害植物孪花蟛蜞菊(Wedelia biflora)的扩张对我国西沙群岛原生植物群落结构和功能产生了深刻影响,但陆生软体动物如何响应该扩张却未见报道。本文调查了西沙群岛永兴岛孪花蟛蜞菊不同扩张程度下褐云玛瑙螺(Achatina fulica)、钻头螺科、坚齿螺科和拟阿勇蛞蝓科等主要陆生软体动物的残体分布情况,测定了残体的分布密度和壳高、壳宽、壳重等可量化性状指标,研究了孪花蟛蜞菊扩张对陆生软体动物种群的影响。结果表明:(1)随孪花蟛蜞菊扩张程度增加,钻头螺科和褐云玛瑙螺的种群密度增加,坚齿螺科种群密度减小,拟阿勇蛞蝓科种群密度出现先增加后减少的趋势;(2)陆生软体动物类群的体型分布频率随孪花蟛蜞菊扩张呈现不同的变化趋势,褐云玛瑙螺较小个体数量增加,其他陆生软体动物体型分布变化不明显或较大体型残体分布增加;(3)孪花蟛蜞菊扩张对褐云玛瑙螺体型特征产生抑制作用,褐云玛瑙螺主要采用r策略来响应有害植物扩张的影响。综上,有害植物孪花蟛蜞菊在热带珊瑚岛屿植被中的扩张改变了陆生软体动物的形态、密度与种群结构,不同的软体生物类群表现出不同响应策略,在海岛有害生物的综合防治过程中应该引起足够重视。

Modeling of coal consumption rate based on wavelet neural network

In this paper,two wavelet neural network(WNN)frames which depend on Morlet wavelet function and Gaussian wavelet function were established.In order to improve the efficiency of model training,the momentum term was applied to modify the weights and thresholds,and the output of the network was summed up by function transformation of output layer nodes.When the Gaussian Wavelet Neural Networks(GWNN)and Morlet Wavelet Neural Networks(MWNN)were applied to coal consumption rate(CCR)estimation in a thermal power plant,the results confirmed their potency in function approximation.In addition,the influence of learning rate on the models was also discussed through the orthogonal experiment.