Abstract:

Incubation experiment and field investigation on soil microbial biomass dynamics in agroforestry system in coastal saline soil, which impacted by litter decomposition process of Populus and Metasequoia glyptostroboides, were carried out in this study. It was showed that the litter of Populus was more favorable to soil microbial biomass increase, whereas litter of M. glyptostroboides was less favorable to soil microbial biomass increase, but the microbial biomass N content associated with litter decomposition of M. glyptostroboides was higher than that of Populus, and litter of M. glyptostroboides was easier to be accumulated in the soil. There was a positive interaction for microbial biomass increase when M. glyptostroboides leaves mixed with Populus leaves during decomposition. According to soil microbial parameters, such as ratio of microbial biomass N and total N, metabolic quotient (qCO₂) from field investigation, it was also proved that although the soil organic content under forest increased, the soil salinity content had not decreased significantly, and the qCO₂ was still high. This may suggest that the increase of organic matter through agroforesty practice did not efficiently mitigate the environmental stress for soil microbes. Therefore, in the study soil, it is still necessary to adopt other measures to improve site conditions.

Key words: Agroforestry, Soil, Litter, Microbial biomass, Impact