濒危孑遗植物珙桐在不同水分条件下对增温和CO_(2)浓度升高的响应

The Responses of Davidia involucrate to the Elevated Temperature and CO_(2) Concentration under Drought Environment

全球气候变化以及由此引发的极端气候会对物种分布和生存产生影响,目前有关濒危孑遗物种应对气候变化能力的研究还较少.本研究采用人工气候室模拟增温和CO_(2)浓度加倍,分析珙桐幼苗的生长和光合作用在水分充足和干旱条件下对增温、CO_(2)升高以及两因子共同作用下的响应.结果表明:两种水分条件下增温对珙桐幼苗的生长和干物质积累的影响都不明显;CO_(2)升高在水分充足时能增加根系干物质积累和总生物量,在增温和CO_(2)升高共同作用下除了促进根重和总生物量还能促进基径增长,且促进作用比在单独CO_(2)升高作用下更强;干旱条件下CO_(2)升高和与增温的共同作用对生长和物质积累的促进程度会降低;光合参数在正常水分状况下受几种气候因子的影响较显著,但干旱条件下影响会减弱;从干旱在各气候因子作用下对珙桐生长和光合的影响来看,在增温和CO_(2)升高的交互效应下,与正常水分条件相比,根、叶、总生物量及基径生长与干旱下差异显著.结论:与正常水分条件相比,干旱条件下气候因子对珙桐生长和光合的促进作用会减小;此外,在增温和CO_(2)升高的交互效应下干旱与非干旱间珙桐干物质积累和生长的差异较大.

Global change and the resulting extreme climate have an impact on the distribution and survival of species.At present,few studies were found on the responses of endangered and relict species with climate changes.In this study,the growth chamber to simulate the elevated temperature and doubling CO_(2) concentration were used to test the changes on growth and photosynthesis of Davidia involucrate Bail,under warming,elevated CO_(2) temperature and the interaction of two factors.The results showed that,there were no significant effects on growth and photosynthesis resulted by warming.Elevated CO_(2) concentration stimulated the accumulation of root dry matter and total dry matter under normal water condition,while the root dry matter,total dry matter and base diameter width significantly increased resulted by the interaction of warming and elevated CO_(2) concentration.Moreover,the positive effects resulted by the interaction were stronger than elevated CO_(2).On the other hand,under drought condition,the effects of the interaction on growth and photosynthesis decreased.In addition,under the two climate factors and the interaction treatments,there were significant differences on root dry weight,leaf dry weight,total dry weight and base diameter width between normal water condition and drought condition.Therefore,compared with the normal water condition,the positive effects of climate factors on the growth and photosynthesis of Davidia involucrate under drought will be reduced.In addition,the dry matter accumulations and photosynthesis under the interaction effects of warming and elevated CO_(2) were significantly different between drought and normal water condition.