Manipulation of vegetation with activated carbon reveals the role of root exudates in shaping native grassland communities

Abstract

Question Plant community assembly has traditionally been viewed from the perspective of plant resource niches and competition and, more recently, facilitation in stressful environments. However, plants also engage in biotic interactions with neighbours and soil microbiome by producing chemically diverse root exudates. Root exudates have the potential to affect plant community productivity and composition by mediating plant interactions, fostering beneficial microbial interactions and affecting nutrient cycling. However, empirical evidence for the role of root exudates in plant community dynamics is still lacking, particularly under field conditions. Location Two calcareous grasslands in Western Estonia, Europe. Methods We tested the role of root exudates in shaping plant community productivity and composition by applying activated carbon powder, known to adsorb root exudates from soil solution, to two intact species‐rich grasslands. The experiment continued for four years and was combined with fertiliser application. Results We found that the application of activated carbon triggered significant changes in root morphology, plant productivity and growth form composition that were distinct from the effects of fertilisation. Community responses were site‐specific and varied with the duration of activated carbon application. Activated carbon addition increased the production of finer roots in a community with shallow soil in the first year of the experiment and significantly reduced above‐ground productivity at both sites by the end of the fourth growth season. The application of activated carbon promoted legume abundance at both sites and suppressed forb dominance at the site with shallow soil. Conclusion Our findings suggest that chemical interactions in the plant rhizosphere may play an important role in shaping grassland productivity and plant community composition. We also show that activated carbon can be used as an effective tool for manipulating plant interactions in intact grasslands occupied by long‐lived individuals.

Spatial mapping of root systems reveals diverse strategies of soil exploration and resource contest in grassland plants

“…were collected in 2008 from a semi‐natural, calcareous (alvar) grassland in Estonia (58°38′31″N, 23°30′55″E). The site is characterised by high species richness and rendzic leptosol soil type, with an average of 18 cm of humus layer over limestone shingle parent material (Nettan et al., 2019; Pärtel et al., 1999). The seeds were air‐dried and stored at 4°C.…”

Effects of animal grazing on vegetation biomass and soil moisture on a typical steppe in Inner Mongolia, China

“…In arid or semi‐arid grasslands, changes in soil moisture play an important role in plant growth and productivity (Nettan et al, 2019) and are a limiting factor for plant communities and thus have a decisive influence on grassland community composition (Cleland et al, 2013; Sazib et al, 2020; Tian et al, 2018). The growth of vegetation is mainly controlled by climatic factors, with moisture being the dominant factor limiting the yield of natural grassland communities, while the soil moisture status during the growing season determines the yield of forage grasses (Poděbradská et al, 2019).…”

If you can’t beat them, join them: using invasive plants to understand rhizodeposits as drivers of plant-soil feedbacks

“…Exudates can directly affect neighboring plants, thereby influencing plant competition and the composition of plant communities (Nettan et al, 2019;Semchenko et al, 2019). Initial interest in plant-soil feedbacks was largely driven by the realization that living or decomposing plant tissues can release allelopathic compounds into the soil that inhibit plant germination or growth (Callaway and Ridenour, 2004).…”