报告题目：Perennial Vegetation Increases Soil Carbon Sequestration and Reduces Greenhouse Gas Emissions
报告人简介：Scott Chang（张小川）博士是加拿大阿尔伯塔大学可再生资源系教授。其主要研究方向为森林土壤，土壤养分循环和植物营养，以及土壤学在土地复垦，农业和林业中的应用。张博士现任国际土壤科学联盟土壤肥力和植物营养委员会主席，美国农学会环境质量研究奖委员会主席，曾任中国土壤与植物科学家协会主席。他还担任过美国土壤科学学会（SSSA）森林，草地和荒地土壤分部的主席，以及阿尔伯塔省土壤科学研讨会主席。张博士曾担任《Canadian Journal of Soil Science》、《Journal of Environmental Quality》、《Environmental Science and Pollution Research》、《Forests》、《Forest Ecology and Management》副主编/客座编辑，现任《Biology and Fertility of Soils》、《Pedosphere》杂志编辑。张博士发表了220余篇SCI文章，研究经费1300余万加元。他获得了诸如美国土壤科学学会会士（2016年），美国农学会会士（2016年），教师国际奉献奖（2015年）和Killam年度教授奖（2014年）等诸多荣誉。
摘要：Trees planted on the agricultural landscape are widely regarded as beneficial for reducing wind speed, minimizing erosion risks, and diversifying farm operations; however, the effect of trees (in the forested land-use) on soil carbon storage and greenhouse gas emission in agroforestry systems is not well understood. A large scale project was initiated in Alberta to investigate the effect of trees (perennial vegetation) on soil carbon storage, carbon distribution in particle size/density fractions, microbial composition, enzyme activities, and greenhouse gas emission in three agroforestry systems (shelterbelt, hedgerow and silvopasture). Within each agroforestry system, the forested land-use consistently had greater total organic carbon in the bulk soil, in particle size fractions and in density fractions than the agricultural land-use. The forested land-use had greater bacterial abundance and to some extent species richness as compared to the agricultural land-use; however, soil enzyme activities were not affected by trees in agroforestry systems during the mid-growing season when samples were collected. Forested land-use had lower heterotrophic respiration and N2O emission rates, and a greater CH4 sink. Our data suggest that agroforestry systems are effective in increasing carbon storage and the diversity of microbial communities, and in reducing greenhouse gas emissions in central Alberta. Including agroforestry in the agricultural landscape should be encouraged to realize the benefits of including trees on farm.