CO2浓度和温度升高对川西亚高山红桦幼苗根系结构的影响

CO2浓度和温度升高对植物产生了深刻的影响，为从多角度对这种影响进行研究，该文利用封闭式生长室系统控制CO2浓度和温度，以红桦幼苗为材料，研究了CO2浓度升高、温度升高以及二者同时升高对川西亚高山红桦幼苗根系结构的影响。结果显示:①与对照相比，CO2浓度升高处理显著增加了红桦细根的生物量（最大增幅达152％）、根 幅（增幅为10％～22％）、0～10 cm土壤层根系总长度、5～10 cm层根夹角。②温度升高处理使红桦细根生物量2004年6、10月增加，8月减少，但只有0～5 cm土壤层与对照相比差异显著；根幅6、8、10月分别减少16％、7％、30％；5～15 cm土壤层根系总长度、0～10 cm土壤层根夹角显著(P0.05)减少。③二者同时升高处理使红桦各层细根生物量８月增加最多，0～5 cm、5～10 cm、10～15 cm土壤层分别比对照增加237％、51％、107％；根系总长度减少，但0～10 cm土壤层根夹角增加。表明CO2浓度和温度升高均改变了红桦根系结构, 且对浅层根系结构影响较大，这是红桦对气候变化的一种有利适应。 

Effects of elevated CO2 concentration and temperature on root structure of subalpine Betula albo-sinensis seedlings in western Sichuan, southwestern China

In order to provide further insight to the response of plant to climate changes,the effects of elevated atmospheric CO_2 concentration,increased temperature and their interactions on root system structure of Betula albo-sinensis seedlings were researched with artificial enclosed-top chamber system. The results showed that: 1) fine root biomass(the largest increased range reached 152%),root range (increased by 10%-22%),total root length in 0-10 cm soil layer and root growth angle in 5-10 cm layer of B. albo-sinensis significantly increased under elevated CO_2 concentration. 2) Increased fine root biomass was observed in June and October but decreased in August of 2004 compared to the control under elevated temperature,and only the changes of fine root biomass in 0-5 cm layer were significant. Root range reduced by 16%,7% and 30% in June,August and October respectively. Total root length in 5-15 cm layer and root growth angle in 0-10 cm layer decreased significantly (P<0.05). 3) The increase of fine root biomass in August was the largest under the interactions of elevated CO_2 concentration and temperature,by 237%,51%,107% in 0-5 cm,5-10 cm,10-15 cm soil layer respectively. Total root length was reduced,but root angles in 0-10 cm layer and root range were significantly increased. The paper suggests that elevated CO_2 concentration and temperature both alter the root structure of B. albo-sinensis seedlings,and it is an acclimation to climate changes. It indicates that elevated CO_2 concentration and temperature significantly affect the root system structure of B. albo-sinensis seedlings,especially in shallow soil layer,and the change of root system structure is an adaption to climate.