Agroforestry systems (AFSs), in which at least one woody perennial species is grown alongside crops in order to increase diversity and productivity, are increasingly being recognized as a sustainable form of land use. However, their impact on soil microbial biodiversity remains poorly understood. No study has attempted to determine the temporal response of bacterial communities to rubber-based AFSs. 

Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study to explore the seasonal dynamics of bacterial communities in rubber-based AFSs in tropical Yunnan. The two AFSs are under different management types (monocropping and intercropping) and two different stand ages (10 and 22 years old, representing young and mature stands, respectively). 

They got their research findings published in Agriculture, Ecosystems & Environment. 

The researchers examined bacterial communities and the relevant plant and soil physicochemical properties at three depths depending on the vertical distribution of fine roots. 

They found that stand age exerted a stronger influence on bacterial communities than management type or season, which was controlled by obvious changes in edaphic factors. 

Compared to their monocultures, young rubber-based AFS maintained bacterial diversity but decreased the abundance. Mature rubber-based AFS supported higher bacterial diversity with a constant abundance. 

Bacterial communities in AFSs exhibited obvious horizon-specific seasonal variations, which were associated with spatial heterogeneity in soil nutrients, with the surface layer being more nutrient-rich than the intermediate and deep horizons. 

Furthermore, they found that soil pH, available phosphorus and dissolved organic nitrogen emerged as the major drivers of bacterial community characteristics in tropical agroforesty systems. 

“Our findings imply that the establishment of rubber-based AFSs with less-intensive disturbances, particularly in mature stands, could be a good approach for overcoming the detrimental effects of chemical fertilization on bacterial diversity due to the dynamic decomposition of litter and fine roots”, said Dr. LIU Chenggang, the first author of the study. 

Contact 

LIU Chenggang Ph.D 

Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China
E-mail:  liuchenggang@xtbg.ac.cn