作 者 ：张文娟,张志强*,李湛东,张晓放,董克宇,陈立欣,王国玉
期 刊 ：生态学报 2009年 29卷 11期 页码：5942~5952
Keywords:urban forest, transpiration, sapflux, thermal dissipation probe,
摘 要 ：城市树木与森林作为城市生态系统的重要组成部分，充分发挥其生态环境服务、景观美化和休闲娱乐等功能得到了社会各界越来越广泛的重视。配置合理的城市树木与森林，建设节水型城市森林是水资源短缺地区城市生态建设必须重视的问题之一。以大连市劳动公园4种主要乔木树种雪松（Cedrus deodara）、榉树（Zelkova serrata）、丝棉木（Euonymus bungeanus）及水杉（Metasequoia glyptostroboides）为研究对象，应用TDP（Thermal Dissipation Probe）技术分别对每个树种3个径阶的单株树木蒸腾耗水进行了研究，并测定同期气候环境因子及0~25cm，25~50cm，50~75cm，75~100cm土壤含水量的动态变化。研究结果表明：不同树种生长季内蒸腾耗水具有明显的昼夜变化规律，3个径阶雪松夜间蒸腾量占全天的6.3%~33.9%；榉树占 124%~30.8%；丝棉木占6.5%~27.6%；水杉占6.0%~21.1%。受气候环境因子、土壤含水量以及树木生长节律的影响，各树种日蒸腾耗水量从9月以后表现为递减的变化。晴天、雨天与阴天3种典型天气条件下树木液流速率表现出不同的变化特征：晴天液流速率曲线较平缓且峰值范围较宽，液流开始升高时间最早，开始降低时间最晚，液流通量最大；雨天，峰值陡且窄，液流开始升高时间最晚，开始降低时间最早，液流通量最小；阴天表现居中。对各树种在整个生长季内蒸腾量从大到小的排序，径阶为10cm的树种为：丝棉木>榉树；径阶为14cm的树种为：丝棉木>榉树>雪松>水杉；径阶为18cm的树种为：雪松>丝棉木>榉树>水杉；径阶为24cm的树种为：雪松>水杉。
Abstract:Urban forests play a significant role in urban development because it provides valuable ecological and environmental services, landscape integrity, and recreation opportunities for urban residents. However, water saving approaches for urban forest development must be adopted in the cities that are facing water resources shortage. Many studies suggested that forests have much higher water demand than shorter plants. Therefore, it is critically important to select water\|saving trees in urban forestry practices in order to achieve the sustainable urban greening and landscaping. We selected four major urban tree species including Cedrus deodara，Zelkova serrata，Euonymus bungeanus，Metasequoia glyptostroboides.to quantify whole tree water use in the Labor Park of Dalian City, Liaoning Province, China. Thermal Dissipation Probes were deployed to monitor the sap\|fluxes continuously for 12 trees, three DBH classes of each species, from June through October in 2008. Climatic variables and soil moisture at the depth of 0-25cm, 25-50cm, 50-75cm, and 75-100cm were also measured by an automatic weather station and EMS70 soil moisture probes at the same time, respectively. The remarkable diurnal\|nocturnal variation of sapflux for different species was observed during the growing season and the nocturnal water loss accounted for a certain proportion of the total transpiration: 6.3%-33.9% for Cedrus deodara, 12.4%-30.8% for Zelkova serrata, 6.5%-27.6% for Euonymus bungeanus, and 6.0%-21.1% for Metasequoia glyptostroboides across three diameter classes. Due to compounding impact of climatic factors, soil moisture regime, and the tree growth patterns, the diurnal transpiration rate declined since September for all trees. Contrasting characteristics of daily sapflux pattern were found under three typical weather conditions. Sapflux curves of clear sunny days were relatively flat with wide range of peaks, showing an earliest start time of sap\|flow, an latest declining time with the highest daily sap\|flux volume. Sapflux curves of raining days showed steep and narrow peaks accompanied by a latest sap\|flow start time, and earliest declining time along with lowest sap\|flux volume. The performance for cloudy days stood in between. The whole tree water use ranking from high to low during the entire growing season was as follows: Euonymus bungeanus> Zelkova serrata within the 10 cm diameter class, Euonymus bungeanus> Zelkova serrata> Cedrus deodara > Metasequoia glyptostroboides within the 14 cm diameter class, Cedrus deodara >Euonymus bungeanus> Zelkova serrata > Metasequoia glyptostroboides within the 18 cm diameter class, and Cedrus deodara > Metasequoia glyptostroboides within the 24 cm diameter class.
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