Recently, Dr. Qing Liu, a researcher from the Forest Ecology and Regulation Project Group at the Chengdu Institute of Biology, Chinese Academy of Sciences, collected root exudates from dominant plant species in different successional stages (grassland-shrubland-forest) of high-altitude forests in Southwest China. They conducted greenhouse pot experiments to explore the effects of root exudate addition on seed germination and seedling growth of dominant tree species (spruce, birch, and aspen) in subalpine forests, as well as the potential mechanisms involved. The related findings were published online in the "International Journal of Soil Science".
Root exudates refer to various organic compounds and inorganic ions released by active plant roots into the rhizosphere, mainly including abundant low-molecular-weight organic compounds and high-molecular-weight biopolymers. Plants can regulate soil ecosystems through root exudates.
In recent years, the important role of root exudates in regulating soil biogeochemical cycles and the interaction between roots, soil, and microorganisms has been widely recognized. However, previous studies have mainly focused on the underground ecological effects of root exudates, neglecting the feedback of root exudates on aboveground vegetation dynamics. Currently, research on the regulatory role of root exudates in vegetation regeneration is still scarce, greatly limiting researchers' further understanding of the potential regulatory mechanisms of rhizospheric ecology in plant community succession.
The study found that root exudates had significant and differentiated effects on seed germination and seedling growth of dominant tree species at different successional stages. For example, root exudates from herbaceous plants promoted spruce seed germination and seedling growth but inhibited birch and aspen seed germination and seedling growth.
Moreover, compared to soil properties and fungal communities, soil bacterial communities made a greater contribution to the growth of seedlings of dominant tree species in subalpine forests, and the effects of root exudates on seedling growth of dominant tree species were mainly mediated by soil bacterial communities.
These results, by integrating and evaluating this underestimated underground parameter of root exudates, further advance the previous research on forest succession mechanisms, emphasizing the important role of root exudates in the process of forest succession.
The first author of the paper is Dr. Jia Liu, Assistant Researcher at the Chengdu Institute of Biology, Chinese Academy of Sciences, and the corresponding author is Dr. Qing Liu.
Related Paper Information: https://doi.org/10.1016/j.geoderma.2024.116833
