The Future of Mycorrhizae

Mycorrhizal fungi filaments and bound soil particles on the root tip of a garlic plant. (Photos by Faith Forry)

To wrap up our discussion of mycorrhizal fungi, I wanted to briefly touch on the uncertainties regarding the future of this ecologically essential fungus. As described last time, approximately 90% of all vascular plants on land share some connection with mycorrhizae. Underground and soil-shrouded, the presence of mycorrhizae quite literally connects our terrestrial environments and allows life to continue as we know it. It is important then that mycorrhizae can adapt to ever-changing environmental conditions due to global and human activities. Specifically, global warming, deforestation, land development, loss of biodiversity and host species, increasing non-native and invasive species, and chemical pollution are all factors which can negatively impact mycorrhizal fungi.

The rampant burning of fossil fuels since the Industrial Revolution has increased levels of nitrogen in our smog-laden air. This excess nitrogen is deposited into the ground, acidifying our soils; not only does this damage plant and fungal tissues, but over time it also removes essential nutrients like calcium and potassium from the soil, effectively decreasing its fertility. This process of nitrogen deposition can have a deeply negative effect on plants and mycorrhizae, especially ectomycorrhizae.

While much more research is still to be done, early studies have found that increased nitrogen deposition decreases the rate at which ectomycorrhizae colonizes plant roots-- as well as decreasing the overall biodiversity of ectomycorrhizae. With mycorrhizal biodiversity and colonization rates decreasing, the host plants will lose their adaptive advantage over non-host neighbors. More individuals and species are likely to lose access to improved water and nutrient resources and become vulnerable to drought. Further, the loss of mycorrhizae and well-nourished plants could lead to the degradation or even loss of some habitats, such as oak forests, while it could cause other environments, like grasslands (which do not rely on mycorrhizae), to thrive. With continuing research, the impact of such exacerbating factors on the direct functioning of mycorrhizal fungi will be better understood.

Next time I’d like to tell you about a peculiar plant which can be found in our forests-- the ghostly mycotrophic wildflower Monotropa uniflora. To read more about mycorrhizal fungi, visit https://sciweb.nybg.org/science2/hcol/mycorrhizae6.asp.html.

Written by Faith Forry — July 21, 2021