上海市郊沿海防护林防护效应的研究

Study on protection effect of coastal windbreak in Shanghai suburb

为分析上海市郊沿海防护林的防护效应,于2009年夏季对人民塘水杉(Metasequoia glyptostroboides Hu et Cheng)基干林带前后不同观测点的风速、气温和空气相对湿度等气候因子进行了观测,并对该林带前后1 km处的防台风效应进行了比较;另外,以滨海森林公园的红叶椿(Ailanthus altissima‘Hongye’)林分为观测对象,比较分析了林带内不同垂直高度处的防风效应。结果表明,水杉基干林带具有明显的防风效果,林带内至林带后65 m范围内的风速较林带前均有不同程度的下降,以林带后25 m处的风速最低;在"莫拉克"台风登陆期间,水杉基干林带在较大尺度上具有明显的降低风速的作用;水杉基干林带在一定程度上能降低局部气温、提高空气相对湿度,以林带内的气温最低、空气相对湿度最高,从而达到改善林后小气候的作用。红叶椿林分内不同垂直高度处的防风效应有一定的差异,其中垂直高度2 m处的风速最大,而树冠处(垂直高度5 m)的风速最低。

To analyze the protection effect of coastal windbreak in Shanghai suburb,the climatic factors including wind speed,air temperature and air relative humidity at different observation points before or after forest belt of Metasequoia glyptostroboides Hu et Cheng in People Pond of Shanghai were investigated in the summer of 2009,and the windbreak effect on typhoon at 1 km before or after M.glyptostroboides forest belt was also compared.Otherwise,the windbreak effect at different vertical heights of stand was analyzed by taking the forest belt of Ailanthus altissima ＇Hongye＇ in Binhai Forest Park as investigation object.The results show that the forest belt of M.glyptostroboides in People Pond possesses obvious windbreak effect,and the wind speed in the range from inner to 65 m after forest belt decreases to a certain extent compared with that before forest belt,and the lowest wind speed at 25 m after forest belt.During the landing time of the typhoon ＂Morakot＂,the forest belt of M.glyptostroboides has an obvious effect on weakening the typhoon in a larger scale.The windbreak belt of M.glyptostroboides also has an effect on reducing local air temperature and increasing air relative humidity,especially the lowest air temperature and the highest air relative humidity appear in inner forest belt,thus achieving the role of improving microclimate after forest belt.The wind speed at different vertical heights of A.altissima ＇Hongye＇ stand is different,in which,the wind speed at 2 m vertical height is the highest while that at canopy（vertical height 5 m） is the lowest.