5. CONCLUSIONS
The
present study revealed that soil bacteria, fungi, protists, and the food
webs they form respond differently to vegetation type depending on the
ambient temperature. We demonstrated that bacterial, fungal, and protist
diversity and community composition differed under vegetation
restoration and cropland. However, bacterial, fungal, and protist
diversity and community composition were similar under plantation forest
and shrubland because the soils under these vegetation types had similar
nutrient profiles. There were significant differences in bacterial,
fungal, and protist community composition between Guizhou (MAT, 14.6 °C)
and Guangxi (MAT, 20.9 °C) because of the substantial temperature
difference between these regions. The low temperature at Guizhou
strengthened interspecific interactions among bacterial, fungal, and
protist taxa. There might have been relatively greater bacterial
diversity at Guizhou than at Guangxi. Similarly, high bacterial
diversity in cropland soil caused to stronger interactions in the
microbiome network under cropland than under plantation forest or
shrubland. Hence, it is primarily bacteria that shape the co-occurrence
networks among microbial taxa. The protist phyla Cercozoa and Lobosa
prey upon the bacterial phyla Acidobacteria and Proteobacteria, and the
fungal phylum Ascomycota. Proteobacteria, Acidobacteria, Ascomycota, and
Cercozoa predominated in the karst and regulated the variations in the
C, N, and P nutrient levels in the soils there. Bacterial and fungal
community compositions were strongly affected by changing temperature
and vegetation type whereas protist community composition was influenced
mainly by vegetation type and soil properties. Taken together, these
findings underscore the importance of evaluating the relationships among
bacterial, fungal, and protist taxa during vegetation restoration. They
also suggest that temperature must be considered in during soil nutrient
cycling as microbial interactions are strongly influenced by it. Fungi
were comparatively more dependent than bacteria on plant community.
Nevertheless, in the present study, we did not compare plant diversity
between plantation forest and shrubland. Future studies should integrate
plant characteristics and examine the complex relationships among
microorganisms and vegetation.