鲁东南杨树人工林根际微生物数量时空动态

为了探讨杨树人工林根际微生物对环境变化的响应，对鲁东南杨树人工林根际微生物数量时空变化、根际效应及其与土壤养分的相关性进行了研究。结果表明：根际细菌、真菌、放线菌数量和微生物总数均呈“增—减—增—减”的季节变化模式，即春秋高，夏冬低。根际微生物数量以细菌最多，放线菌次之，真菌最少。细菌、放线菌数量和微生物总数随林龄的增加而增加，真菌数量随林龄的增加而减少。除0~10 cm外，根际微生物数量的垂直分布总体上表现为随土层加深而逐渐减少。杨树人工林细菌、真菌、放线菌数量和微生物总数存在明显的根际效应，根际效应均呈显著的单峰季节变化，8月达到峰值。根际细菌、真菌、放线菌和微生物总数与根际土壤水解N、速效P均呈正相关，与土壤有机质呈反相关关系。

Spatio-temporal Dynamics of Rhizosphere Microbes in Populus tremula Plantations in Southeast Shandong Province

To explore how rhizosphere microbes responded to environmental change in Populus tremula plantations in southeast Shandong Province. Seasonal dynamics and vertical distribution of rhizosphere microbe number and rhizosphere effect were investigated and compared it to the bulk soil by using plate count and conventional chemical methods, respectively. Additionally, the correlation between rhizosphere microorganism number and soil available nutrients were also studied. The results obtained were as follows： the seasonal dynamic patterns of bacteria, fungi, actinomycete and total microorganism were increase-decrease- increase- decrease, that was spring and autumn were higher than summer and winter. Bacteria, fungi, actinomycete and total microorganism reached the highest value in the middle of April, and the second peak appeared in October and minimum value occurred in December. The number of rhizosphere microbe was shown as bacteria〉actinomycetes〉fungi. The number of bacteria, actinomycetes and total microbe in rhizosphere increased with age, but the number of fungi decreased. In general, vertical distributions of bacteria, fungi, actinomycete and total microorganism reduced as the soil depth increased, except 0-10 cm. The rhizosphere effect （R/S） of bacteria, fungi, actinomycete and total microorganism was distinct. Furthermore, the rhizosphere effect showed unimodal peak with maximum value in August. The correlation between number of rhizosphere bacteria, fungi, actinomycete, total microorganism and soil hydrolyzable nitrogen, soil rapid available phosphorus were positive, respectively, and the correlation between number of rhizosphere microbes and soil organic matter were negative.