The Thermophysical Properties And Energy Distribution In The Leaves Of Populus Tomentosa Carr.

Populus tomentosa Carr. is main afforestation species in the north China, playing an important role in greening and ecological protective forest and having wide use in wood processing and paper industry. Leaf tissue is one of the vital organs in plant and is the main occasion of photosynthesis. We can know the energy exchanges between leaves of P. tomentosa and environments through studying the thermophysical properties.This paper mainly study the thermal conduction functions and energy distribution of P.tomentosa's leaf. Firstly, analyzing and constructing the model of energy distribution of the leaf of P.tomentosa and then studying their thermal conductivities,tissue structures,temperature and physiological parameters, exploring the temperature response, the relationship between tissues and thermal conductivities, and the energy distribution in leaves of different years and kinds of P.tomentosa.The results show that the temperature on leaf surface is almost the same, the relationship between leaf heat conductivity and temperature is positively correlated. The quadratic function formula between heat conductivity and temperature of 3 years is y = ?0 .0009 x 2+ 0.037 x? 0.1215, and the 30 years is y = ?0 .0007 x 2+ 0.0273 x? 0.067. The total and each widths of 30 years'leaf tissue are bigger than that of 3 years, and the interspaces of the former is smaller than the latter, which is not good for heat transfer, so the leaf heat conductivity of 3 years is bigger than that of 30 year. At last, we validate the model by analyzing 6 different kinds of P. tomentosa through experiments. The result shows that the radiation from sun is the main energy input, and the dominating ways of thermal diffusion are the heat transfer between upper and lower leaf and the evaporation from leaf surface. And the difference in temperature deduced by the model is not very different from the real survey datas.