Abstract: Study on relationship between populations diversity and its environments,such as light,water,soil,insects and weed in several farmlands ecosystems shows that there is a close connection between populations diversity and their environmental components.Suitable increase of biomass compositions will be more favorable for a better farmland environment,and will inturn improve the development of organisms and the productivity of the system,even if little operation space is existing in one ecosystem.It can also be concluded that the increase of population diversity for a farmland ecosystem is very possible only if the environment permitts.The modification of current farmland ecosystem still has much potentiality.

Key words: forest region of Northeast China, soil carbon pool, forest type, forest age, spatial variability.