广州地区荷木夜间树干液流补水的影响因子及其对蒸腾的贡献

明确树木夜间水分补充现象有助于提高总蒸腾量和冠层气孔导度估算的精确度，进一步认识冠层蒸腾与树干液流之间存在的时滞关系.本研究采用热消散探针法测定了广州地区的荷木树干液流密度，同步监测了主要的环境因子，从不同时间尺度分析了树干夜间液流的水分补充现象.结果表明：与白天相比，荷木夜间液流密度较小，旱季变化幅度比湿季大；夜间水分补充的时间段主要在前半夜(18:00-22:00)；年内各季节夜间水分补充量之间没有显著差异，与环境因子之间的偏相关关系不显著，但与胸径、树高、冠幅、树干生物量、冠层生物量的回归曲线拟合很好，表明树形特征和生物量能更好地解释夜间补水的变化；各季节夜间水分补充量对总蒸腾量的贡献有显著差异，旱季明显高于湿季.

Effects of different land use types on mosquito community

From 2010 to 2011,an investigation was conducted on the mosquitoes in the construction land(Ⅰ),rural land(Ⅱ),wetland(Ⅲ),forest land(Ⅳ),and arable land(Ⅴ) at 21 sites of Wuxi,Jiangsu Province of East China,aimed to understand the effects of different land use types on mosquito community.A total of 10 mosquito species belonging to 5 genera were found,with an average density being 67.94 ind·lamp-1·h-1.The dominant species in the land use types were Culex pipiens pallens in Ⅰ,C.tritaeniorhynchus in Ⅱ,C.pipiens pallens and C.tritaeniorhynchus in both Ⅲ and Ⅳ,and C.pipiens pallens,C.tritaeniorhynchus,Armigeres subalbatus,and Anopheles sinoensis in V.The mosquito density was in the order of Ⅱ> Ⅲ > Ⅴ >ⅣIV >Ⅰ,with a significant difference(P<0.05) among the land use types except between Ⅳ and I.The mosquito biodiversity was in the order of Ⅴ > Ⅳ > Ⅲ > Ⅱ >Ⅰ,being significantly(P<0.05) higher in Ⅴ and Ⅳ than in Ⅲ,Ⅰ,and Ⅱ.At a similarity of 68%,all the land use types except Ⅳ and Ⅴ had an independent mosquito community.After the lands were transferred to constructed land,the dominant species became C.pipiens pallens only,and the mosquito density and biodiversity decreased significantly.Under urbanization,C.pipiens pallens and C.pipiens pallens-born disease should be controlled,and the importance of controlling C.tritaeniorhynchus and C.tritaeniorhynchus-born disease would decline.