| Popis: |
In this study,we evaluateed the spectral response characteristics of 6 typical tree seedlings in subtropical areas under acid rain in different simulative levels.The experiment shows that there are conspicuous differences between the coniferous and broadleaf in terms of their sensitivities to the acid rain.3 conifers,i.e.Pinus massoniana,Cunninghamia lanceolata and Torreya grandis are evidently more sensitive to the acid rain than Machilus pauhoi,Cinnamomum camphora and Myrica rubra,3 kinds of broad-leaved trees.For conifer,the chlorophyll content of Pinus massoniana and Cunninghamia lanceolata was greatly higher than that of Torreya grandis.For the species of broad-leaved trees,however,there was no significant difference among the Machilus pauhoi,Cinnamomum camphora and Myrica rubra.Since Pinus massoniana,Cinnamomum camphora and Torreya grandis cannot stand the high level of acid rain,their chlorophyll content at first increaseed and later declineed,which was contrary to that of Cunninghamia lanceolata.While Myrica rubra could withstand long-term acid rain of high level,its chlorophyll content under pH2.5 was higher than that under pH5.6.As for the Machilus pauhoi,there was no evident law in the changes of chlorophyll content of Machilus pauhoi during the 4 experimental phases.What′s more,the red-edged spectral reflectance positions of the testing plants were substantially consistent with the changing rules of the chlorophyll content.To be more exact,Pinus massoniana and Torreya grandis which belong to the species of coniferous tree mainly showed a "blue shift",while Cunninghamia lanceolata showed "blue shift" first and "red shift" later,which reflected the long-term resistance to the acid rain of high level.Cinnamomum camphora,a type of the broad-leaved tree showed"red shift" first and "blue shift" later,which was the acceleration and then the resistance to the simulated acid rain of high level.The first derivative curve of Myrica rubra spectral reflectance was relatively flat,and there was no obvious phenomenon related to the "red shift" and "blue shift".Machilus pauhoi showed "red shift" and "blue shift" alternatively,which corresponded to the changes of chlorophyll content and revealsed its inconspicuous sensitivity to the acid rain. |
