The importance of soil bacteria related to N cycle in eucalyptus plantations under the near-natural management model

Zhao-lei Qu, Bing Liu, Yue-mei Zhang, Lin Huang, An-gang Ming, Hui Sun

This is a plain language summary of a Functional Ecology research article that can be found here.

Eucalyptus, due to its fast growth and high yield of commercial timber, is widely planted in China, especially in Guangxi province, a mountainous region in the far south of China. However, inappropriate plantation management strategies (e.g., crop rotation, planting density, monoculture, etc.) have caused severe soil erosion and water deficiency as well as other ecological issues. Near-natural management is an emerging management model that transforms plantations into near-natural forests to achieve the management objectives with the minimum necessary human intervention.

The eucalyptus plantation mixing with a nitrogen-fixing tree—Chinese Rosewood (Dalbergia odorifera T. Chen)—in Guangxi, China (credit: Zhao-lei Q)

The management model has mainly been implemented through the introduction of other species, promotion of natural regeneration, understory protection and structural adjustments. In this study, we selected two management systems, rotation and introduction of mixed nitrogen-fixing tree species, in eucalyptus plantations in Guangxi, to investigate the response of the soil bacteria community to the managements and highlight the importance of the nitrogen-fixing bacteria. Both the managements significantly increased bacterial species richness and diversity. The plantations with different management histories formed different bacterial communities and potential functional structures. The eucalyptus mixed with nitrogen-fixing trees significantly affected the bacterial genes involved in the nitrification and denitrification processes, which improved the efficiency of nitrogen fixation in the soil. Soil environment conditions, such as pH and soil moisture in the eucalyptus plantation, can have strong effects on the bacteria community. Our results highlight the importance to the microbes of near-natural management in eucalyptus plantations and provide useful information on the management of eucalyptus plantations in the future.


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