Carbon balance of field grown apple (Malus domestica) trees

摘要

To be ecologically sustainable, productive tree ecosystems should be managed in order to enhance their potential to fix atmospheric carbon (C). The exchange of CO_2 between ecosystem and atmosphere reflects the balance between photosynthesis from plants (GPP or Gross Primary Production) and respiration by plants, animals and microbes (RE or Ecosystem Respiration). This balance is called Net Ecosystem Exchange (NEE) or Net Ecosystem Productivity (NEP = -NEE) and it is equal to the Net Primary Production (NPP) minus the heterotrophic component of RE (Rh). Therefore distinguishing the autotrophic and heterotrophic components of soil respiration and estimate the belowground C inputs from plants are crucial steps to determine if ecosystems are C-soureesor sinks.