Radiative Transfer In The Subalpine Forest Ecosystems Of Western Sichuan

Radiative transfer plays a key role in forest ecosystems. Solar radiation provides energy for photosynthesis, appropriate ambient temperature and development information for plants. However, quality and quantity of radiation reaching land surface are affected by weather and subsequently influence the growth and development of plants, which in turn changes the budget of radiation in forest. Soil temperature changes with the variation of radiation under forest canopy and influences the activity of roots and rate of nutrient turnover. Thus, any changes of radiation will induce chain reactions in the entire ecosystem and display in the value of net primary productivity which will possibly shift the relationship between carbon source and sink at local or regional scale and feed back to the global climate system. On the other hand, as a component of ecosystems, human beings of course need to demand more materials and better service from ecosystems. For these purpose, man must adapt their pattern and frequency of interference to ecosystems. This paper aims to research on the canopy structure, the radiation distribution and their influence on soil temperature from the process of radiative transfer in subalpine forest ecosystem of western Sichuan. The main results are:1 Present a new photogrammetric method for leaf area. The main idea is to convert non-vertically taken images of planar leaves to orthoimages through projective transformation. The resultant images are used to get leaf morphological parameters through image processing. This method enables users to take photos at almost any orientation and distance if only the leaves are placed on same plane, and to process...