Riparian Habitat & Wildlife: What’s Mycorrhizae Got To Do With It?
Lisa Markovchick*1, Catherine A. Gehring1, Jose Ignacio Querejeta2, Abril Belgara-Andrew1, James Tracey3 and Thomas G. Whitham1
1Department of Biological Sciences and Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ 86011, U.S.A. Lisa_Markovchick@nau.edu; Catherine.Gehring@nau.edu; Thomas.Whitham@nau.edu
2Soil and Water Conservation Research Group, Spanish National Research Council, CEBAS-CSIC, PO Box 164, 30100 Murcia, Spain. querejeta@cebas.csic.es
3Department of Entomology, Texas A&M University, College Station, TX, 77843, U.S.A. jamesltracy@tamu.edu
Mycorrhizal fungi inhabit plant roots, and are known to improve plant survival and resiliency in the face of diverse kinds of stressors from drought to pests. Yet, these fungi are often degraded by disturbance and not intentionally restored in tandem with native vegetation – a concerning gap given the increased need for plant resiliency under increasing extreme weather events. Using a foundational riparian tree, we investigate the consequences of degraded mycorrhizal communities on plant survival, growth and resilience. Using both a common garden field experiment and a greenhouse experiment, we tested the impacts of: 1) contrasting sources of native cottonwood trees (Populus fremontii) used in restoration, 2) mycorrhizal communities degraded by a history of tamarisk invasion (Tamarix spp.), 3) and restoration of native mycorrhizal communities concurrent with native plantings. We examine the impacts of these factors and their interactions on native tree survival, growth, photosynthesis, and water use. Critically, it appears that a legacy of tamarisk invasion decreases plant water use efficiency, an effect counteracted by the restoration of native mycorrhizal fungal communities. Additionally, these effects interact with the source of the native trees used in restoration. We discuss the implications for how unseen mycorrhizal communities are affecting plant survival, growth, and physiological strategies, impacting their ability to provide the necessary canopy cover, cooling, and other requirements for native wildlife such as the endangered southwestern willow flycatcher (Empidonax trailii extimus; SWFL).