红砂对大气CO_2浓度升高及降水变化的生长响应

以荒漠植物红砂(Reamuria soongorica)为试材,采用开顶式CO_2控制气室模拟CO_2浓度变化(350,550和700μmol·mol–1),研究了降水变化(-30%,-15%,0,+15%,+30%)及其与CO_2的协同作用对红砂生长特性的影响。结果表明:在6、7、8月份,CO_2浓度增加对5种降水下红砂的株高、地上生物量、根生物量和总生物量均有增肥效应,且降水增加时的增肥效应大于降水减少时的。6、7月份,红砂的根质量分数和根冠比在5种降水下均随CO_2浓度的升高而降低;而在8月份仅降水为-15%时,CO_2浓度增加可促进红砂的根质量分数和根冠比。综上所述,未来降水增多时,CO_2浓度升高可促进红砂地上生物量积累来获取更多资源;降水减少,CO_2浓度增加可促进地下生物量的分配来适应干旱环境,但这种调节作用与降水的多少及处理时间长短有关。

Growth Responses of Reaumuria soongorica to Elevated CO2 Concentration and Precipitation Changing

Pot experiments were conducted to study the co-effects of elevated CO2 concentration and changing precipitation on growth characters of Reaumuria soongorica, a dominant of desert steppe in the arid region of China, in order to assess the possible effect of global climate change on desert ecosystem.The main plot contained three CO2 concentrations (350,500 and 700μmol · mol-1) and five precipitation levels [natural precipitation as control (0), precipitation minus 30％ (-30％), precipitation minus 15％ (-15％), precipitation plus 15％ (+15％), precipitation plus 30％ (+30％)].The results showed that in June, July and August, elevated CO2 promoted the increase of plant height, aboveground biomass, root biomass and total biomass of R.soongorica under five precipitation conditions, and CO2 fattening effect on the growth in increased precipitation was bigger than that of in decreased precipitation.In June and July,root mass fraction and root/shoot ratio were decreased with elevated CO2 concentration under five precipitation conditions, and only in August, root mass fraction and root/shoot ratio of R.soongorica were enhanced by elevated CO2 under-15％ precipitation.In conclusion, elevated CO2 concentration would promote R.soongorica to accumulate more aboveground biomass to abtain more resources when precipitation is increased in the future;elevated CO2 concentration would stimulate this plant distribute more belowground biomass to adapt drought environment when precipitation is decreased in the future, but the effect was limited by the amount of precipitation and processing time.