Physiological And Ecological Effects Of Ginkgo-tea Agroforestry Systems

To explore the physiological and ecological effects of ginkgo(Ginkgo bilobaL.)-tea[Camellia sinensis (L.)O.Kuntze] intercropping systems, micro-climate characters,photosynthetic characteristics, soil nutrients, soil enzyme activities, soil microbial biomass, soilmicrobial diversities and soil carbon mineralizations were inverstigated in Yushan Farm inChangshu, Jiangsu Province. The main results were as follows:1. There were no significant differences in photosynthetic available radiation(PAR), airtemperature(T) and relative humidity(RH) in ginkgo-tea intercropping plantations and pure teaplantation in winter and spring. However PAR and T in summer and autumn were significantlylower and RH was significantly higher in intercropping plantations than those in pure teaplantation. Diurnal variation of net photosynthetic rate of tea in different plantations displayed asingle peak curve in spring, autumn and winter. Diurnal variation of net photosynthetic rate ofpure tea plantation in summer displayed a double peaks curve, with midday depression ofphotosynthesis. Tea polyphenol was significantly lower and amino acid and caffeine of tea weresignificantly higher in intercropping plantations than those in pure tea plantation.2. The content of soil total organic carbon, total nitrogen, hydrolyze nitrogen, totalphosphorus, available phosphorus, total kalium and available nutrients declined with soil depth.The content of soil total phosphorus, soil total kalium and soil available nutrients in ginkgo-teaintercropping plantations was significantly higher than those in pure tea plantation.3. The activities of soil catalase, polyphenol oxidase, dehydrogenase, urease, proteinase andsucrase declined with soil depth. Seasonal dynamics of soil enzyme activities were significantly.The activities of soil catalase, dehydrogenase, urease, proteinase and sucrase were lowest inwinter and highest in summer, but the activities of polyphenol oxidase was highest in spring. Soilenzyme activities were significantly higher in ginkgo-tea intercropping plantations than in puretea plantation. Correlation analysis of soil enzymes and soil nutrients showed that soil enzymeactivities were positively correlated with soil nutrients, except polyphenol oxidase.4. Seasonal dynamics of soil microbial biomass were significantly. Soil microbial biomassin summer and autumn was higher than that in winter and spring. Soil microbial biomassdeclined with soil depth. Soil microbial biomass was significantly higher in ginkgo-teaintercropping plantations than in pure tea plantation at0~10cm depth. Soil basic respiration wassignificantly higher in ginkgo-tea intercropping plantations than in pure tea plantation in differentsoil depths. Soil microbial metabolic quotient increased with increasing depths.5. Genotypic richness and diversity index of soil bacteria and fungi communities in summerand autumn were higher than that in winter and spring. Soil bacteria communities similaritycoefficients in different months in ginkgo-tea intercropping plantations were higher than those in pure tea plantation, while soil fungi communities similarity coefficients in different months ofeach system were relatively lower. Diversity indexes of soil bacteria and fungi communities werepositively correlated with soil total organic carbon, total nitrogen, microbial biomass, catalase,proteinase and sucrase activities.6. Soil organic carbon mineralization rates of different plantations were higher at theprophase of incubation, declined later and then tended to stable. Soil organic carbonmineralization rates of different soil depths could be described with logarithm equation duringincubation, and organic carbon cumulated mineralizations could be described with linearequation. Soil organic carbon mineralization rates and cumulated mineralizations declined withincreasing depths. Soil organic carbon mineralization rates were significantly higher inginkgo-tea intercropping plantations than in pure tea plantation at0~20cm depth.7. Soil fertility quality indexes of different plantations were evaluated through theprocedures of improved analytic hierarchy process, the sequence was intercropping plantationwith high ginkgo density>intercropping plantation with low ginkgo density>pure tea plantation.The pure tea plantation showed the lowest soil fertility index.