Understanding the gene flow patterns of tropical forests will enhance tree improvement and gene conservation efforts. Gene flow is mediated by pollen, seed and seedling dispersal, and factors affecting this gene flow include phenology, spatial distribution, population structures, seed predation, sexual and mating systems as well as physical and biological barriers to gene flow. This book discusses issues on tree improvement and gene conservation needs to be conducted for six forestry types practiced: conventional or traditional forestry, agroforestry, plantation forestry, short rotation forestry, urban and community forestry, and international forestry.