Ecological Basis And Benefit Of The Intercropping System Of Chestnut And Tea

On the basis of the analysis of present domestic and foreign agroforestry research, especially the actual situation of the management construction of the intercropping tea of chestnut in Qianshan County,the ecological and economic benefit of the interplanting systems of chestnut and tea under different levels of shade, unshaded tea plantation and chestnut plantation was analyzed qualitatively and quantitatively, and the comprehensive benefit of the those was evaluated with Analysis Hierarchy Process. Results are as follows:(1) In spring ,the light compensate and saturated point of tea were 8.2μmol·m^-2·s^-1 and 800μmol·m^-2·s^-1,respectively;the apparent quantum efficiency was 0.039,which showed apparent quantum requirement was 26.And in summer the light compensate and saturatedpoints of tea were 9.0μmol·m^-2·s^-1 and 97μmol·m^-2·s^-1 ,respectively;the apparent quantum efficiency was 0.053,which showed apparent quantum requirement was 19. The experiment had indicated that the tea tree had obvious characteristic of shade plant, is suitable transplants under the weak light condition. The apparent quantum requirement in summer is much smaller than that in spring, possibly because of the ecology compensation caused by other ecological factors(temperature, humidity and so on); and it also indicated many other ecological factors played more important influence to net photosynthesis besides the light intensity in summer.(2)The microclimate was obviously improved in the intercropping systems of chestnut and tea, and the improvement was gradually increased as the shade intensity was increased. In the intercropping plantations of the shading of 20% to 30% , 30% to 40%,40% to 50% the mean atmosphere impedance coefficient of four months increased by 32.50%,46.93% and 66.94% respectively;so as 5.42%,7.98%,9.79% for the mean relative humidity of a day in spring and 13.47%,16.76%,20.94% for in summer;while turbulent exchange decreased by 21.43%,30.00% and 40.00% respectively.Meanwhile the temperature of air and soil had characteristic of droping in spring and summer, especially the time for which high temperature lasted decreased remarkably.(3)The soil physical and chemical characteristics got significantly improved in the intercropping systems.The bulk density of soil in all intercropping gardens decreased about 3.79 %- 13.61%,while the total soil porosity, percentage of no-capillary tube porosity respectively increased by 5.98 %- 29.23 % and 25.64 %- 230.61 % .The water-holding capacity of no-capillary tube porosity in different systems increased by 47.46% - 69.92%.The even content of organic matter, total nitrogen, hydrolyzable nitrogen of all soil layers were increased by 40.35%-56.14%,22.95%-40.98%,1.52%-17.27% in the intercropping than in unshaded tea plantation,while the readily available phosphorus decreased by 6.78% - 30.51 % .The even readily available potassium of all soil layers increased by 8.23% and 2.43% in the intercropping plantions with shading of 20% to 30% and 30%-40%,while decreased by 8.35% in in the intercropping plantions with shading of 40% to 40%.In the interplanting systems the content of soil moisture was increased by 8.75%-18.58% in the 0-20cm depth of the soil ,but decreased little in the 20-80cm depth of the soil. The even content of soil moisture in 0-80cm depth of soil decreased by 1.34%,0.73% and 7.12% in the intercropping systems with shading of 20%-30%, 30%-40%,40%-50%.In the 20-40 cm depth of the soil of the intercropping systems with shading of 20%-30%,30%-40%,40%-50%,the hydrolysable nitrogen and readily available potassium was lower 10.90% and 7.22%,13.49% and 10.74%,18.52% and 15.70% than those in the corresponding pure tea plantation,which suggested some competion for hydrolysable nitrogen and readily available potassium between chestnut and tea, resulting in the reducing of them in this layer.(4)Regress analysis showed in spring the most most influential factors on the photosynthesis was atmosphere relative humidity,the secondly was intercellular CO₂ concentration (Ci),and followed by photosynthetic available radiation;in summer the most most significant factors affecting the photosynthesis was intercellular CO₂ concentration (Ci), the following was temperature,the last was was transpiration.(5)The light intensity displayed significant reduction in the intercropping systems compared to the pure tea plantation.In spring the time that the light intensity exceeded light saturated point was 6h in the pure tea plantation,which reduced to be 4h or 3h in the intercropping systems with shading of 20%-30% and 30%-40%.And the light intensity did not preponderate over light saturated point all the day in the intercropping system under 40%-50% shade. In summer the time that the light intensity exceeded light saturated point was 7h in the pure tea plantation,which reduced to be 5h or 3h in the intercropping systems with shading of 20%-30% and 30%-40%.And the light intensity preponderated over light saturated point only atl2:00 in the intercropping system under 40%-50% shade.(6)In spring or summer,the midday depression of photosynthesis of tea decreased less in the intercropping systems of shading of 20%-30% and 30%-40% than that in the pure tea plantion,and the diurnal variation of net photosynthetis rate almost presented a single-peak curve in the intercropping plantion of shading of 40%-50%.Compared with the pure tea garden, the averaged value of diurnal net photosynthesis was 5.92%,8.58%,2.07% higher respectively in the intercropping gardens of shading of 20%-30% , 30%-40% and 40%-50% in spring ,and it was 8.04%,10.27%,7.59% higher respectively in summer. Therefore it showed the intercropping garden of shading of 30%-40% in this region had the highest net photosynthetis rate.(7) The absorbing root of tea tree mostly distributed in the layers in the 0- 40 cm deph of the soil;while that of chestnut mainly lived in the layers in the 20- 60 cm deph of the soil.The two plants counld grow harmoniously in a systems with their niches overlapping and separate partly.The total absorbing roots of tea in the intercropping under 30%-40% shade was more than that in correspounding pure tea garden.(8) Of various systems,the pure tea garden had the largest output of tea,and so it was with the pure chestnut garden,the intercropping garden under 30% -40% shade obtained the most net income.(9)The intercropping systems of shading of 40%-50% had largest ecological and societal benefit, the intercropping systems of shading of 30%-40% had largest economic and comprehensive benefit .Therefore in this area,the intercropping tea of chestnut under 30%-40% shade could acquire the most comprehensive benefit.(10)The comprehensive evaluation model is established according to the characteristics of the chestnut-tea interplanting systems in Qianshan region and evaluation criteria of other aroforestry systems.It can reflect the actual benefits of the systems and can be applied to guide and play an important role in the mamagement of the chestnut-tea systems in Qianshan region.