Interactions between plants and mycorrhizal fungi in mountainous pasture ecosystems subjected to future climate conditions concerning their productivity and species composition
State of the art
Pastoral ecosystems contribute a crucial part to alpine ecology, the attractiveness of mountain landscape and above all to the agricultural production in the Alps. Their productivity depends on the management and intensity of agricultural use as well as on the climate. However, it is expected that climate change with its predicted rise in temperature and decreasing precipitation will have an impact on the Alps and their ecosystems.
Mycorrhizal fungi associated with plant roots can affect the productivity of plants either in a positive or negative way. Plants benefit for example from the mycorrhiza’s ability to increase the absorbing tissue of their roots. On the other hand, the fungi’s carbon requirements might cause a decrease in plant productivity. At present, work studying the role of mycorrhiza in alpine meadows focusing on their productivity and composition are few and most of them approach the subject in a more general manner.
PROMYCO aims to contribute to a better understanding of interactions between mycorrhizal fungi and plants in mountain ecosystems, especially in the context of climate change. Drought and increased temperature are taken into consideration as main aspects of climate change. We focus our investigation on the type of the symbiotic relationship between plants and mycorrhiza.
In an in situ experiment, along an altitudinal gradient in the Central French Alps (Oisans mountain massif), we do basic research by studying the changes in the rate of mycorrhizal colonisation, their relationship with plants, plant productivity and composition. In addition, we observe separately the influence of increased temperature and reduced precipitation in a growth chamber experiment under controlled conditions. The separated analysis of these two consequences of climate change permits to distinguish their different effects on plants and mycorrhiza.
Samples of other experiments studying different effects of climate change on mountain ecosystems in Switzerland and Italy, are also analysed concerning their mycorrhizal colonisation rate. These additional data are used to be compared to our results from the growth chamber experimentation and ideally support its validity.
In the context of water or heat stress, interactions between plants and mycorrhizal fungi are generally mutualistic, while under more favourable conditions, mycorrhizal fungi behave more like parasites. An increase in temperature caused by climate change could lead to more favourable conditions for plants and shift the plant–fungus relationship towards the parasitic end of the mutualism-parasitism-continuum. In contrast, a reduction in precipitation during the spring and early summer periods could be manifested by an increase in drought. This would have the effect of reducing the amount of available minerals. However, this could potentially shift the interactions between mycorrhizal fungi and vegetation from a parasitic to a more mutualistic type. There is a trade-off between positive effects (increased temperature causes an increase in the length of mycorrhizal hyphae and thus the volume explored by mycorrhizal fungi) and negative (increased drought reduced the rate of colonization roots by mycorrhizal fungi) of climate change. We hypothesise however, that negative effects might predominate and interactions between plants and mycorrhiza could shift the symbiosis to the parasitic side of the parasitism-mutualism continuum. Herbaceous productivity of alpine meadows would be reduced accordingly.
Duration of the project