亚热带典型树种对模拟酸雨胁迫的高光谱响应

对亚热带地区6种典型树种幼苗在不同模拟酸雨梯度下的光谱响应特征进行了研究。结果表明,针叶树种和阔叶树种对酸雨敏感性具有明显差异。针叶树种马尾松、杉木和香榧对酸雨敏感性高于阔叶树种刨花楠、香樟和杨梅。针叶树种内部,马尾松和杉木叶绿素含量随酸雨浓度变化的幅度明显高于香榧;而阔叶树种内部,刨花楠、香樟和杨梅三者之间无显著差别。马尾松、香樟和香榧不能承受长时间高浓度酸雨胁迫,叶绿素含量呈先增加后减少趋势,杉木则先减少后增加,杨梅能承受长时间高浓度酸雨胁迫,pH值2.5处理下叶绿素含量高于pH值5.6处理。刨花楠4期试验中叶绿素含量变化无明显规律。各受试植物光谱反射率红边位置与其叶绿素含量变化规律基本一致。针叶树种马尾松和香榧主要表现为"蓝移",杉木则先"蓝移"后"红移",表现出对高浓度酸雨长时间的抗性;阔叶树种香樟先"红移"后"蓝移",对高浓度模拟酸雨表现出先促进后抑制现象,杨梅光谱反射率一阶导数曲线比较平缓,无明显"红移"和"蓝移"现象,刨花楠则"红移"和"蓝移"交替出现,与其叶绿素含量变化相一致,对酸雨敏感性不明显。

Hyperspectral characteristics of typical subtopical trees at different levels of simulated acid rain

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.