Total belowground carbon allocation(TBCA) is defined as that carbon allocated belowground by plants to produce coarse and fine roots,root respiration,and root exudates and mycorrhizae.TBCA can be a large fraction of gross primary production,sometimes exceeding aboveground net primary production.Quantifying the individual components of TBCA is challenging because belowground C processes are intimately associated with the soil matrix.Thus,our understanding of the factors that control TBCA is poor,though incre...