| Threats such as climate change, toxin and nutrient loading, and the spread of invasive species are among the greatest threats to biodiversity worldwide. Yet, only recently have we begun to investigate how these disturbances affect the microbial community. However, it is vital to consider the roles that microorganisms play in our ecosystems, as well as the feedbacks and drivers that shift their functioning if we wish to conserve, restore and manage our environment. The single-carbon (C1)-cycling microorganisms have received considerable attention due to their importance to global carbon cycling. This dissertation focuses on the role of C1-cyclers in two imperiled habitats, coastal sage scrub and coastal salt marshes. The aim of this suite of studies was to provide useful information to allow for better management decisions and potential mitigations to protect these ecologically important habitats. A combination of field and laboratory experiments in each habitat examined ( a) the abundance of phytosymbiotic pink-pigmented facultative methylotrophic bacteria (PPFMs) in the root zones of native and invasive plant species in invaded coastal sage scrub habitat, (b) the relationships among methylobacteria, a common herbicide (glyphosate, RoundUpRTM), native versus invasive plant species, and the implications for restoration and, ( c) biological methane cycling and the controls on methane flux in eutrophied California salt marshes.;I found that PPFMs varied significantly between plant species and that plant life history appears to be driving that pattern. PPFMs and methanol (a PPFM substrate) were beneficial to native plants in mitigating the use of glyphosate in a restoration. Finally, methane emission in three salt marshes appears to be influenced by nitrogen and carbon limitation in methane-producers, whereas carbon limitation affected methane-consumers. Overall, these studies found that C1-cyclers in these systems are vulnerable to various perturbations such as herbicide and nitrogen addition. However, there are feasible mitigations available to reduce the effects on these ecosystems. While more work is needed to broaden our knowledge of other systems, these findings suggest that land management planning is incomplete without considering microorganisms. |
