The Microclimate Effects Of Agroforestry System In XU HUAI Plain Areas

The paper has analysed microclimate changes in different phonological periods and its effect on physiology,output and quality of crops by fixe-dfield observation in poplar-crop intercropping and shelterbelt in XU HUAI plain agroforestry.The main conclusions can be drawn as follows:(1)In dif-ferent phonological periods of wheat and poplar,compared to the CK,the light intensity is much lower in agroforestry system.From Leaf-expansion period, omnileaf period to Leaf-flourishing period, the ratio of the light intensity in agroforestry gradually decreased.Closer from tree row,lower the light intensity was,which decreased with tree spacing diminishing.the length of tree shade and illumating hours had close relation with the solar altitudinal angle,tree height and tree spacing.And the equation between the tree shadow length and time was established.(2)The average wind,air temperature,soil temperature in agroforestry system was smaller than the Ck.The average proctection effect was 35.7%～57.9% in poplar-crop intercropping,and was 21.4%～43.8% in shelterbelt. At internode pulling stage of wheat,the average air temperature was decreased by 0.5 in poplar-crop intercropping,and by 1.3 in shelterbelt.During wheat seedfilling and soybean flowering, the average air temperature was decreased by 1.7 in poplar-crop intercropping,and by 1.3 in shelterbelt.The lowest soil temperature was higher than the CK.In different phonological periods,the relative humidity in poplar-crop intercropping was increased by 3.8%～6.5%,and by 5%～5.7% in shelterbelt.The soil moisture was different apparently in different phonological periods, which had a relation with rainfall.(3) The light intensity,air temperature,soil temperature,wind,relative humidity,soil moisture were mainly ecological factors in agroforestry by principal component analysis.Double factors analysis of variance of the microclimate factors showed the poplar's phonological and tree spacing had obvious effect on the microclimate.(4) The agroforestry system had effect on the plant height,panicle length,output and quality of wheat,soybean and rice.Where tree spacing was smaller and closer to forest belts,the effect was greater and effect on soybean and rice was more obvious.(5) In the agroforestry system, the relationship between Photosynthesis and micro-climate are great, the change of photosynthetic rate are smooth,and the peak of photosynthetic rate turned up later than the CK.Where it was closer to forest belts the influences on photosynthetic rate were greater.Tree spacings and locations had influences on photosynthetic rate.