Growth of Coastal Backbone Shelterbelt and Its Soil Improvement in Yuyao City

Investigations were carried out in October and November of 2018 on growth and soil improvement in coastal backbone shelterbelt constructed from 2007 to 2015 in Yuyao city, Zhejiang province.The results showed that conservation rate of surveyed forest was up to 85%, and the average canopy density was over 0.65.The mean stand volume and biomass of the shelterbelt built in 2010 were the highest, and that in 2010 and 2013 had the fastest growth.Among planted tree species, Populus sp., Salix fragilis and Metasequoia glyptostroboides had the fastest growth, but Casuarina equisetifolia and Ailanthus altissima slower.The investigation indicated that afforestation could increase the content of soil total nitrogen and organic matter, and could effectively reduce salt content.Each tree species could effectively increase the content of total nitrogen and organic matter in rhizosphere soil, and significantly reduce the content of soil salt.Sapium sebiferum could effectively increase the total phosphorus content in rhizosphere soil.Comprehensive analysis demonstrated that P.sp., S.sebiferum, Pistacia chinensi and Nerium indicum could be selected for afforestation of coastal shelterbelt.