Ecology and eco-physiology of mycorrhizal symbioses in arid riparian areas

Markovchick, Lisa Mira (2022) Ecology and eco-physiology of mycorrhizal symbioses in arid riparian areas. Doctoral thesis, Northern Arizona University.

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Abstract

My dissertation consists of three related research topics focused on translating previous research on mycorrhizal fungi into best practices for natural regeneration, replanting and habitat restoration. In the first chapter, I highlight the ecosystem services known to be provided by mycorrhizal fungi (symbiotic with plant roots), and examine whether utilization of diverse mixes of native mycorrhizal fungi, a potentially crucial tool in land managers’ toolboxes to alleviate restoration challenges, has made the translation from academia to restoration practice. In the second chapter, I examine crucial questions surrounding the need for restoring diverse mixes of native mycorrhizal fungi alongside plant communities, and the implications of research on the co-adaptation of mycorrhizal fungi with their symbiont plant hosts for assisted migration. In the final chapter, I investigate whether mycorrhizal restoration and assisted migration can be conducted successfully in tandem with mycorrhizal restoration under by conducting a common garden experiment with reciprocal plantings of local and migrant plant provenances and a migrant mycorrhizal inoculum treatment under harsh, post-Tamarix spp. (tamarisk) invasion and drought conditions. In combination, these three chapters have built on previous research and advanced knowledge of the following. 1) Although the separate, intentional step of mycorrhizal restoration has been shown to have clear benefits if conducted appropriately, and mycorrhizae clearly support many ecosystem services that are often part of the goals of land management plans, they are still overwhelmingly left out of management planning. 2) Even under ideal circumstances with adjacent natural sources, natural regeneration two-years post planting fails to achieve ectomycorrhizal colonization rates similar to that in natural tree source populations after agricultural disturbance. 3) Natural regeneration of local mycorrhizal colonization is poorer in assisted migrant plant provenances, and concurrent with trends in other ecotype differences such as survival and growth. 4) Under multiple stressors in the field, assisted migrant plant provenances given an appropriate mycorrhizal inoculum can survive at higher rates than local plant provenances. 5) Inoculation with a contrasting ecotype’s live mycorrhizae can have neutral to negative effects that interact with site conditions. 6) The afterlife of an invasive species in the soil once the invasive plants have been removed can have dire consequences for native plants after restoration. Below is a summary of each of the three chapters. Chapter 1: During the coming decade, planting material shortages are expected to constrain restoration. Climate change will reduce recruitment and exacerbate the need for restoration and natural regeneration. Concurrently, research shows that native mycorrhizal fungi optimized to plant provenance and site conditions significantly and meaningfully accelerate restoration, support crucial ecosystem services, and provide natural climate solutions (sequestering carbon), and nature-based solutions for climate change (providing climate adaptation). We reviewed 130 systematically available management plans for natural areas in the United States to evaluate whether the science-based innovation of restoring native mycorrhizal communities has translated into implementation. Results are notable: management plans frequently discussed the ecosystem services mycorrhizal fungi provide, but nearly one half (46%) viewed fungi solely as pathogens or ignored them altogether. Only 8% of plans mentioned mycorrhizae. Only one plan mentioned that mycorrhizae were potentially helpful to natural regeneration, and one mentioned utilizing soil as a restoration tool. Our examination of publicly available data and case studies suggests that relatively meager protections and research funding, research difficulty and data paucity, and limited access to mycology experts and training characterize this gap between science and implementation. A database of literature showcasing mycorrhizal ecosystem services and benefits is provided to highlight when and why mycorrhizae should be considered in management, regeneration, and restoration. Three action items are recommended to safeguard native mycorrhizal communities and accelerate restoration and regeneration. Ten implementation tips based on scientific literature are provided to clarify the need and methods for mycorrhizal restoration. Chapter 2: Many factors deplete and shift the mycorrhizal fungal communities upon which native plants depend, and consequently their often sizable and meaningful benefits to plant survival and growth, and a variety of ecosystem services. Yet, as the UN Decade on Ecosystem Restoration begins, active restoration of native mycorrhizal fungal communities is often overlooked as a strategy to enhance and sustain ecosystem restoration. Few studies focus specifically on implementation questions, such as the success and timeliness of natural mycorrhizal regeneration in disturbed soils and its effect on replanting success. Simultaneously, assisted migration of plant species or provenances has been suggested to hasten ecosystem climate change adaptations, but the consequences of assisted migration for mycorrhizal regeneration and associations remain poorly described. To determine the success of natural mycorrhizal regeneration, its interaction with plant provenance, and the consequences for restoration success, we evaluated naturally regenerating mycorrhizal colonization of Populus fremontii (Fremont cottonwood), a foundation riparian tree, in trees from one local and two assisted migrant source populations two years after planting. Three main lessons emerged. 1) Ectomycorrhizal colonization rates two years post-planting were considerably lower than those found in source populations, even under ideal conditions with an adjacent source of mycorrhizal host trees. 2) Within the planting site, proportions of dedicated exchange sites between plants and mycorrhizal fungi closely followed plant provenance, with trees from greater distances demonstrating fewer EMF root tips and AMF arbuscules. 3) For the plant provenance struggling the most, a close association between tree survival rates and mycorrhizal colonization was found. Results suggest that active mycorrhizal restoration and optimizations of pairings between fungal, plant, and site provenances could maximize investments in restoration and natural area management, and help offset challenges posed by shortages in planting material and climate change. Chapter 3: Under climate change, the need for and importance of natural regeneration, replanting, and restoration is expected to grow while planting and recruitment success decrease, and planting material shortages continue to constrain replanting efforts. Thus, strategies to optimize restoration effectiveness seem increasingly important. Assisted migration and the restoration of native mycorrhizal communities appear promising. However, intraspecies assisted migrations often still show reduced survival compared to local provenances, and mycorrhizal inoculation, effective if well-matched to plants and site conditions, can have neutral to negative results with poor pairings. Few studies examine the interaction between these two strategies and invasive species soil legacies, particularly under drought conditions exacerbated by a warming, drying climate. To evaluate these interactions, we planted Populus fremontii (Fremont cottonwoods) from two ecoregions (local and warmer) in soils with and without legacies of invasion by Tamarix spp. (tamarisk), and with and without restoration of native mycorrhizal fungi. Four main lessons emerged. 1) The soil legacies left behind after tamarisk invasion reduced survival by 85%. 2) Actively restoring a diverse, native community of mycorrhizal fungi after tamarisk invasion doubled and then tripled survival during the first and second field seasons, respectively. 3) Inoculation sometimes had neutral and even negative effects, interacting with timing, pairing between tree and inoculum sources, and site conditions. 4) During the second field season, assisted migrants survived at twice the rate of trees from the local ecoregion, if inoculated with an appropriate and diverse native mix of mycorrhizal fungi. Results emphasize the detrimental effects of soil legacies left behind after tamarisk invasion, the beneficial effects of appropriate mycorrhizal restoration, and the need to thoughtfully optimize pairings between plants, fungi, and site conditions.

Item Type:	Thesis (Doctoral)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	assisted migration; ecosystem restoration; fungi; invasive species; mycorrhiza; regeneration
Subjects:	Q Science > QH Natural history Q Science > QH Natural history > QH301 Biology
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > Biological Sciences
Date Deposited:	22 May 2023 22:15
Last Modified:	25 May 2024 08:30
URI:	https://openknowledge.nau.edu/id/eprint/5899

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