How are fungi related to butterflies? Certain species of fungi help wildflowers survive and butterflies need wildflowers for food and shelter. Recent findings by Sasha Porter (Master’s of Environmental Studies, The Evergreen State College), and Sarah Hamman (Center for Natural Lands Management) have shown that introducing mycorrhizal fungi to roots of native prairie plants can increase the survival and number of flowers produced. Thus, this kind of fungi could improve our ability to establish plants in the prairies and help the survival of important animals, such as butterflies, that depend of these plants.
Mycorrhizal fungi are organisms that live in the soil and form symbiotic (mutually beneficial) associations with the roots of over 80% of all terrestrial plant species. These fungi are not photosynthetic and cannot fix carbon like plants do. They acquire carbon compounds (photosynthetically-derived sugars) from plant roots, and in exchange, they provide additional nitrogen, phosphorus and water from the soil through microscopic root-like structures called ‘hyphae’. Hyphae act as extensions of the plant’s root system, increasing the surface area in contact with the soil, giving the plant greater access to soil resources. This symbiosis can be extremely beneficial to plants growing in harsh environmental conditions.
In addition to improving plant nutrition, mycorrhizal fungi provide pathogen resistance to their host plants. This resistance can arise from mycorrhizal fungi out-competing pathogenic fungi or by activating the plant’s defense mechanisms Mycorrhizal fungi can also affect the structure and composition of the rhizosphere (the root system and microbes found in the surrounding soil) in ways that increase the plant’s resistance to disease.
Not all mycorrhizal fungi are equal. The composition of the fungal community influences if and how benefits are bestowed to the host plant. Most mycorrhizal fungi can colonize the roots of any plant species. However, researchers have found that different fungal species/communities affect host plants differently. So, it’s important to make sure the mycorrhizal treatment used in any restoration project is beneficial to the target plant species.
As part of her master’s thesis and working with CNLM on a project supported by the Washington State Department of Agriculture’s Nursery Research Program, Sasha studied how treating the soil with two different sources of arbuscular mycorrhizal fungi (AMF), a type of fungus that colonizes roots of herbaceous plant species, affected native plant growth and field establishment. Using a previously cultivated ‘native’ AMF mix (grown from roots harvested from native plants at Joint Base Lewis-McChord), a horticulturally-sourced ‘generic’ AMF mix, and an untreated ‘control’, she grew replicates of nine prairie plant species in the greenhouse for nine months before transplanting them into prairie sites in fall 2014. Of the nine species, five did not have enough surviving plants in any treatment to conduct analysis. For the remaining species (Dodecatheon pulchellum, Festuca roemeri, Micranthes integrifolia, Silene douglasii), she measured survival, growth and number of flowers of the outplanted seedlings with a CNLM monitoring crew in spring 2015.
Overall, Sasha found positive impacts of AMF inoculation on all measured variables for wholeleaf saxifrage (Micranthes integrifolia). This important nectar-producing plant highly benefited from the fungi: 80% of the treated plants survived, vs. only 40% of untreated plants. Also, surviving treated plants were three times more likely to flower than the untreated plants. Finally, interestingly, the ‘generic’ treatment generated more flowers than the ‘native’ treatment for wholeleaf saxifrage. For the other three species, adding AMF to the soil did not impact survival or flowering. However, previous research has shown that the benefits of AMF may not be immediately apparent; sometimes the fungi act as a sort of ‘insurance’, providing resources to the plant when it is under stress.
Restoration efforts are dependent on plants surviving in the wild to improve habitat. Mycorrhizal treatments might be able to increase the survival of the transplanted prairie plants, as well as support the recovery of rare fauna, such as the Taylor’s checkerspot, by providing more nectar-producing flowers. Future studies will analyze the effects of mycorrhizal treatments on other hard-to-grow native plants to define if these treatments can be implemented on a broad scale to facilitate prairie restoration.