| It is well known that atmospheric CO2 concentration and temperature areincreasing as a consequence of human activities. Atmospheric CO2 concentration arepredicted to increase from 350μmol·mol-1 now to 570μmol·mol-1 2030. Andtemperature will continue to increase for several centuries as a result of CO2enrichment. Vegetation play a key role in reducing atmospheric CO2 and adapting andcontrolling warter and energy process in a certain region, while the underlyingmechanism are not clear, yet. Betula albo-sinensis, as the dominating tree species ofsubalpine dark coniferous forest in west Sichuan province, play an important role indeterming structure and function of forest ecosystem. In our study, effects of elevatedatmospheric CO2 concentration (ambient±350±25μmol·mol-1), increased temperature(ambient±2.0±0.5℃) and their combination on contents and allocation of solubleprotein were studied in independent and enclosed-top chamber system underhigh-frigid conditions. Chambers with ambient CO2 concentration and temperatureare taken as control. The results are as the following,1) Elevated atmospheric CO2 increased the accumulation of total weight of soluble protein in whole plant and changed allocation of soluble protein in red birchby increasing its allocation to roots and reducing its allocation to stem. This causedmuch more accumulation of soluble protein in roots which might help to promptgrowth, development and nutrient absorption ability of roots.2) Treatment EC increased content of albumin in roots and stems, reduced thecontent of albumin in leaves, and increased the content of globulin, promalin andglutenin in leaves. That is to say EC increased the accumulation of albumin in rootsand accumulation of globulin, promalin and glutenin in leaves. The reduced solubleprotein contents in plant leaves by EC, as reported by former researchers, are mainlyresulted from the reduced content of albumin in leaves.3) Elevated temperature increased the total of soluble proteins, but its allocationwas dependent on organs. In treatment ET, roots, stems, leaves and branches take27.74％, 35.57％, 23.00％and 13.68％of total weight of soluble protein. In treatmentCK, roots, stems, leaves and branches take 21.01％, 41.41％, 23.08％and 14.50％.Elevated temperature changed allocation of soluble proteins in that it stimulatedsoluble proteins accumulation in roots and improved the uptake of water in roots.4) Treatment ET increased the content of albumin and globulin in roots, andreduced the content of albumin and globulin in stems, leaves and branches. Thecontent of promalin in roots and leaves was increased significantly, and the content ofglutenin in stems was reduced significant. This suggested that ET stimulated theaccumulation of albumin and globulin in roots and accumulation of promalin in leavesand roots; that treatment ET increased content of soluble protein in leaves was mainlyresulted from the increased promalin content in leaves.5) Regarding treatment ETC, the total of weight of soluble proteins increased,but not significantly; but increased in stems. So the combination of elevatedatmospheric CO2 and temperature had not changed the allocation of soluble proteinsin red birch seedling and reduced soluble proteins in branches were not the result of increased carbohydrate.6) Treatment ETC reduced the content of albumin and promalin in roots, stems,leaves and branches, reduced the content of globulin and glutenin in rootssignificantly. That is to say elevated atmospheric CO2 and temperature reduced thecontent of soluble proteins in roots significantly which might help to prompt growth,development and nutrient absorption ability of roots.7) The effects of elevated atmospheric CO2 and temperature on soluble proteincannot be simply interpreted through their mechanism that obtained when they wereimposed on plant separately.
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