冰雪灾害后木荷倒木萌枝光合特性研究

采用Li-6400型便携式光合测定仪,对冰雪灾害后夏季木荷倒木萌枝和未受损木荷枝条的叶片进行光合特性研究。结果表明:倒木萌枝和未受损木荷枝条的Pn、Tr和Gs日变化均呈双峰曲线,具有典型的光合"午休"现象,中午Pn降低均为气孔限制;未受损木荷Pn中午午休时间(10:00～15:00)长于倒木的午休时间(11:00～15:00),其自我保护能力强于倒木,且对光适应的生态辐较宽;环境因子对Pn的直接作用由大到小为倒木:PAR>Ca>Ta>RH,未受损木荷:Ta>PAR>Ca>RH。倒木和未受损木荷的RH与Pn分别呈极显著(P<0.01)和显著(P<0.05)负相关,高温高湿、高湿分别是制约倒木、未受损木荷Pn进一步升高的主要环境因子。

Photosynthetic characteristics of resprouts on uprooted Schima superba after great ice storm

The photosynthetic characteristics of uprooted and undamaged trees on Schima superba were measured in summer by Li-6400 portable photosynthesis system,and the data were analyzed to explore the diurnal variation of photosynthesis and its relationship with environmental factors.The results indicated that the diurnal variation of Pn,Tr and Gs showed a typical double-peak curve with a midday depression of photosythesis,and the Pn reduction at noon originated from the co-effects of stomata factor.The time of valley for undamaged trees(10:00-15:00) was longer than that of uprooted trees(11:00-15:00) .The capacity ability of self-protection and the ecological amplitude to light adaptation for uadamaged trees were higher and broader than those of uprooted trees.The direct impact of enviromental factors to Pn was the order of PAR>Ca>Ta>RH for uprooted trees,Ta>PAR>Ca>RH for undamaged trees.There was a significant negative relationship between RH and Pn on uprooted trees(P<0.01) and undamaged trees(P<0.05) .High temperature and humidity were the most sensitive environmental factor effecting on the Pn of the uprooted trees.High humidity was the most important environmental factor influencing the Pn of the undamaged trees.