The Hyperspectral Response Of Typical Subtopical Trees Under Radiation Forcing

The phenomenon that global climate become more and more cold ,which caused by human and natural driving factors called Radiation forcing. As the rapid development of industry and burning of fossil fuels, it released CO2 and a large number of smokes. The smoke made the increase of atmospheric turbidity which turned back the radiation from the sun to ground. So it caused the decline of ground temperature. The process called"Umbrella effect". The umbrella effect which caused by human activity have already reached the 45±20% of radiation sources.In this study, seven tree species of subtropical evergreen broad-leaved forest was chose as the experimental materials, use sunshade net to simulate different kind of radioactive forcing. This paper analyzes the growth index such as the height and the ground diameter and physiological index such as the chlorophyll content as well as the characteristics and patterns of changing in spectral reflectance of plant leaves of 7 kinds of tested plant under different treatment, getting the following conclusions:The results reveal that tested plants show adaptability to radiation forcing. And the concrete manifestation is that for evergreen broad-leaved trees ,the chlorophyll content which are under strong radioactive forcing are generally higher than the control group; compared with control group, each species reduces generally in the spectral reflectance and first derivative spectrum reflectance in visible light area .Combine with the data of chlorophyll content, we can conclude that there is negative correlation relationship exist between the chlorophyll content and spectrum reflectance; the analysis to first derivative spectrum reflectance can also indicate that as the increase of radioactive focing,each species all show"red-shift"in different content; From the multiple Comparisons results, the author draw a conclusion that the differences in the visible spectral reflectance mainly focus on green light relaxation peak and nearby red edge under the effect of radioactive forcing. Meanwhile, the IG model demonstrates further that as the increase of radioactive forcing, each species shows"red-shift"phenomenon. The results for the features waveband show that differences in the reflectance of plant leaves which result from different treatment of radioactive forcing can be distinguished effectively through the average spectral reflectance within a quite narrow range of wavelength. Besides, according to the interaction analysis of different treatment groups of radioactive forcing and month of experiment, there are obvious differences in the selected features waveband within different months and most different treatment.