No abstract

Wild pollinator bees play an important role in ecosystem function and food security. In recent years, natural forests have been lost, while afforestation programs are primarily monoculture plantation, whether commercial or restorative. The net effect for bees has been fragmentation and sometime wholesale loss of habitats. For instance, diversity of wild bees in pure forest, Camellia oleifera and rubber (Hevea brasiliensis) plantation was found to be unexpectedly low. The rampant use of neonicotinoid pesticides and herbicide is known to negatively impact development and behavior of bees. Urbanization has dramatically impacted bee communities, with significant changes in species richness between suburban and central business areas. These are likely tied to the effect of effluent, exhaust gas and dust on foraging, growth and development. Climate change from greenhouse gas emissions can disrupt the mutualistic relationship between pollinating bees and plants via rapid phenological shifts. The above environmental changes occurring in China are likely cause wide declines in diversity and decreases in populations. Although China has rich natural heritage for bees, there is a lack of long term monitoring programs for species of pollinator bees and a dearth of data on distributions of bee species. As a result, the drivers of bee community composition and population decline are poorly understood. We emphasize the need to prioritize surveys of pollinating bees, continue ongoing monitoring programs and build wider research networks for the study of wild pollinator bees. These steps will ensure that sufficient data can accumulate for developing a prediction and risk assessment framework to help manage the declines in pollinating bee populations and mitigate the attendant economic and non-economic impacts.

Despite our extensive knowledge on the effects of long-term straw returning on soil, little is known about the effects of short-term straw returning. We identified three study sites and evaluated their soil organic matter (OM), pH, and enzyme activity after two years of straw returning treatment. Bacterial diversity and community were determined by 16s RNA sequencing. We observed elevated OM content and pH after short-term straw returning treatment. The bacterial phyla Proteobacteria and Bacteroidetes exhibited similar dynamics on straw application. We observed reduced levels of Actinobacteria and Chloroflexi bacterial phyla after straw returning. Reduced Actinobacteria and Chloroflexi may be due to competition from dominant bacteria. In general, OM content and enzyme activity had the same trend that closely correlated with the amount and community of microorganisms in the soil. Proteobacteria and Bacteroidetes were the critical phyla in straw degradation and might improve soil OM content. Proteobacteria and Actinobacteria were identified as copiotrophic taxa. In summary, straw returning treatment might maintain soil stability and bacterial diversity better. The bacterial phyla Proteobacteria and Bacteroidetes were dominant over other microbial fractions during straw decomposition. The survival competition might be one of the main reasons for the decrease of Actinobacteria and Chloroflexi. Short-term straw returning to the field can markedly improve soil quality. However, soils in different locations respond differently to straw return practices and their responses are influenced by the soil's basic parameters and climate.