Ontogeny affects response of northern red oak seedlings to elevated CO2 and water stress: II. Recent photosynthate distribution and growth

摘要: Northern red oak in the western Lake States area of USA exists on most xeric edge its distribution range. Future climate-change scenarios for this predict decreased water availability along with increased atmospheric CO2. We examined recent photosynthate and growth seedlings as a function CO2 mole fraction (400, 530 700 μmol mol−1 CO2), regime (well watered water-stressed), ontogenic stage. Water stress effects were largely offset by elevated CO2. Water root mass ratio without concurrently increasing allocation to roots. However, apparent sink strength water-stressed at completion third stage tended be greater than that well seedlings, shown continued high export, which may contribute carbon reserves support preferential under conditions. Elevated shoot associated rapid expansion flush. Carbon resources observed enhanced could provided photosynthetic rate over an leaf (Anderson & Tomlinson, 1998, volume). Increased LG conditions, together provide mechanisms offsetting CO2. Careful control ontogeny was necessary discern these changes provides further evidence need such careful mechanistic studies.