Do sprouting tree species on erosion-prone sites carry large reserves of resources?

Saplings of Euptelea polyandra were studied to determine whether tree species found on unstable hillslopes of temperate, old-growth forests in Japan carry substantial storage materials for sprouting replacement genets, as is the case with resprouter species of fire-prone areas, Concentrations (% d. wt basis) of carbohydrates (starch, sucrose, glucose and fructose) contained in roots, stems and leaves were measured in summer and winter. E. polyandra saplings were compared with those of Quercus serrata (a frequently sprouting tree), and those of Mallotus japonicus and Idesia polycarpa (rarely sprouting trees) in the same forest. Total concentrations of carbohydrates (the sum of starch, sucrose, glucose and fructose) in roots were lowest in E. polyandra in both summer and winter. In addition, E, polyandra had a lower ratio of root biomass to total plant biomass than Q. serrata, but similar to that of the nonsprouting species. M. japonicus and I. polycarpa. On the other hand, the total concentration of carbohydrates in the above-ground parts were similar in the four species in both summer and winter. These results indicate that E. polyandra had less long-term storage resources to implement sprouting, in spite of its apparent effectiveness in sprouting. We propose hypotheses to explain the reason why E. polyandra stores a relatively small amount of resources for sprouting.