Abstract: We recorded climatic factors and physical and chemical characteristics of vegetation in 5 experimental shelter-belt forest plantations in Dongdai, Jiangsu province. The variables recorded were: solar radiation, ground temperature, ground relative humidity and daily variation in these across different growing seasons, and transpiration, nutrient value and biomass of herbage. The effects of forest canopy closure on solar radiation can be divided into 3 stages: under both high and low canopy closure variation in closure has little effect on variation in radiation while under medium canopy closure variation in closure has a large effect. At the peak of the growing season temperature in the experimental plots had a mean value of 23.1±5.9˚ which is 24.3% and 62.4% higher, respectively, than the beginning and end of growing season. Relative humidity also peaks, at 91.6% ± 1.6%, 24.4% and 32.9% higher than the beginning and the end of growing season, respectively. Transpiration of Sorghum sudanense at the climax of growing season was 3660±489 g·dm-2·h-1, just 1.7% higher than at the end of growing season. The metabolic energy and fodder unit of Arthraxon pricnodes per unit area reached a peak of 4.88×103 kJ·m-2 and 3891 FU ·hm-2, 77.5% and 80.8% higher than the lowest value. The effect of temperature on dry biomass of Setaria faberii and S. sudanense in each growing season was not significant, nor was relative humidity. On the other hand, the effect of solar radiation on the biomass of S. faberii was significant (Y= –724.19+0.063L) at the beginning of growing season, and on that of S. sudanense in the end of growing season (Y= –1093.30+0.11 L). For the native grass S. faberii all 3 enviromental factors had a significant impact on biomass at the beginning of growing season: Y= –3859.39+25.35T+23.03RH+0.11L; but only relative humidity and solar radiation had a significant effect on biomass at the climax of the growing season: Y=1205.16+0.05L–14.84RH; there were no significant factors at the end of growing season. For the introduced grass S. sudanense, temperature and relative humidity had a significant effect on biomass at the beginning of growing season: Y=6186.48–69.38T–62.64RH; all 3 factors had a significant effect on the biomass at the climax of growing season: Y= –3777.95+11.61 T+16.36RH+0.15L; and solar radiation and relative humidity have a significant impact at the end of growing season: Y= –779.92+0.116L–5.59RH.