University of Guelph

About: University of Guelph is a education organization based out in Guelph, Ontario, Canada. It is known for research contribution in the topics: Population & Gene. The organization has 26542 authors who have published 50553 publications receiving 1715255 citations. The organization is also known as: U of G & Guelph University.

Plant coexistence mediated by arbuscular mycorrhizal fungi

Abstract: Recent research has indicated the importance of arbuscular mycorrhizal fungi (AMF) in mediating plant coexistence. Coarse-scale studies compare the effects of the presence versus absence of AMF on plant coexistence, a phenomenon that is most relevant in early successional ecosystems where AMF are patchily distributed. By contrast, fine-scale studies investigate interactions that might occur once AMF have developed more fully within ecosystems, and most plants come into contact with AMF. Whereas coarse-scale effects are well understood, our understanding of fine-scale factors is just developing, as a result of investigations into AMF‐ plant specificity, AMF species richness, shared mycelial networks, and plant‐AMF feedback effects. Further research into these areas will provide a better understanding of factors that mediate plant species co-existence and, ultimately, the maintenance of biodiversity within plant communities. The term ‘coexistence’ has been used by ecologists to describe a balanced mixture of species in a biotic community. Such coexistence is a biological riddle, because the tendency towards competitive exclusion should favour a monoculture. Theories attempting to explain plant coexistence have focused on either interactions among species, such as competitive balance [1–3], or the avoidance of interaction among species [4,5]. Non-interaction theories have traditionally examined the role of spatial segregation and disturbance in promoting or suppressing plant coexistence. Agent-mediated coexistence is a non-interaction theory proposed as a mechanism for maintaining multi-species assemblages in plant communities [6,7]. When the ‘agent’ is a pathogen or a predator, it can reduce the ability of a plant to compete for resources if the tissues affected are involved in resource gathering (root or leaf). Often, the effects of pathogens and predators can be density dependent, in that the most abundant host plant species loses more tissue than do less abundant plant species. As a result, less abundant plant species experience reduced competition, lessening their chance of competitive exclusion, and thus promoting species coexistence within plant communities.

Increasing Crop Diversity Mitigates Weather Variations and Improves Yield Stability

Abstract: Cropping sequence diversification provides a systems approach to reduce yield variations and improve resilience to multiple environmental stresses. Yield advantages of more diverse crop rotations and their synergistic effects with reduced tillage are well documented, but few studies have quantified the impact of these management practices on yields and their stability when soil moisture is limiting or in excess. Using yield and weather data obtained from a 31-year long term rotation and tillage trial in Ontario, we tested whether crop rotation diversity is associated with greater yield stability when abnormal weather conditions occur. We used parametric and non-parametric approaches to quantify the impact of rotation diversity (monocrop, 2-crops, 3-crops without or with one or two legume cover crops) and tillage (conventional or reduced tillage) on yield probabilities and the benefits of crop diversity under different soil moisture and temperature scenarios. Although the magnitude of rotation benefits varied with crops, weather patterns and tillage, yield stability significantly increased when corn and soybean were integrated into more diverse rotations. Introducing small grains into short corn-soybean rotation was enough to provide substantial benefits on long-term soybean yields and their stability while the effects on corn were mostly associated with the temporal niche provided by small grains for underseeded red clover or alfalfa. Crop diversification strategies increased the probability of harnessing favorable growing conditions while decreasing the risk of crop failure. In hot and dry years, diversification of corn-soybean rotations and reduced tillage increased yield by 7% and 22% for corn and soybean respectively. Given the additional advantages associated with cropping system diversification, such a strategy provides a more comprehensive approach to lowering yield variability and improving the resilience of cropping systems to multiple environmental stresses. This could help to sustain future yield levels in challenging production environments.