海南热带山地雨林幼苗幼树的光合能力与水分利用效率

Photosynthetic capacity and water use efficiency of tropical montane rainforest seedlings or saplings in Hainan Island

应用Li-6400光合测定系统研究了海南岛热带山地雨林林内幼苗、幼树的最大光合能力及其水分利用效率.结果表明:150个树种中,大戟科中平树的最大光合速率(Pmax)和山毛榉科竹叶栎的水分利用效率(WUE)最高,分别为13.27μmol.m-2.s-1和5.99mmol.mol-1;桃金娘科柬埔寨子楝树的Pmax和大戟科山乌桕的WUE最低,分别为1.35μmol.m-2.s-1和2.4mmol.mol-1.其中,Pmax以桑科的平均值最高,桃金娘科最低;WUE以山矾科的平均值最高,桑科最低;但各科间的差异均不显著(P>0.05).乔木和灌木之间的Pmax和WUE也无显著差异(P>0.05).Pmax随着科分布区的扩大而增大,为宽分布科>中分布科>窄分布科,且差异显著(P<0.05);WUE无显著差异.在种的层次上,随着物种分布区的扩大,植物Pmax逐渐增大,为热带亚热带温带种>热带亚热带种>热带种>海南特有种.而WUE则相反,为海南特有种>热带亚热带种>热带种>热带亚热带温带种.

By using a Li-6400 portable photosynthesis system, this paper measured the maximal photosynthetic capacity （Pmax） and water use efficiency （WUE） of the seedlings or saplings of 150 species of tropical montane rainforest in Hainan Island. The results showed that among the test 150 species, Quercus bambusifolia （Fagaceae） had the highest Pmax （ 13.27 μmol · m^-2 · s^-1 ） and Macaranga denticulate （Euphorbiaceae） had the highest WUE （ 5.99 mmol · mol ^-1 ）, while Decaspermum cambodianum （Myrtaceae） had the lowest Pmax （1.35 μmol · m^-2 · s^-1） and Sapium discolor （Euphorbiaceae） had the lowest WUE （2.4 mmol · mol^-1）. The average Pmax was the highest in Moraceae but the lowest in Myrtaceae, and the average WUE was the highest in Symplocaceae but the lowest in Moraceae. However, there were no significant differences （P 〉 0. 05 ） among the families. No significant differences （ P 〉 0. 05 ） in Pmax and WUE were also observed a- mong arbors and shrubs. The P value increased significantly （P 〈 0.05 ） with the widening of families＇ geographical distribution range, in the order of narrow distribution families 〈 medium dis- tribution families 〈 wide distribution families, while no significant differences were existed among their WUE （P 〉0. 05）. The Pmax value also increased with the widening of species＇ geographical distribution range, in the order of endemic species in Hainan Island 〈 tropical species 〈 tropical-subtropical species 〈 tropical-subtropical-temperate species, but WUE was opposite to Pmax, namely,in the order of endemic species in Hainan Island 〉 tropical-subtropical species 〉 tropical species 〉 tropical-subtropical-temperate species.