CLIMATE AND ENVIRONMENTAL CHANGE IMPACTS ON THE ASSEMBLY, DIVERSITY, AND FUNCTIONS OF SOIL AND OTHER MICROBIAL COMMUNITIES

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1005159
• Project Start Date: Oct 23, 2014
• Project End Date: Aug 21, 2019
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF CALIFORNIA, RIVERSIDE
(N/A)
RIVERSIDE,CA 92521

Performing Department
Plant Pathology, Riverside

Non Technical Summary
The Earth is experiencing unprecedented climatic and environmental changes which are impacting the natural and managed ecosystems around us. In Southern California, the changes in precipitation frequency and intensity, due to overall shifts in climate, are having far-reaching and unknown impacts. In addition, the high rates of agriculture and industry in this region are causing increased N deposition, with unknown impacts alone and in combination with climatic changes. This project experimentally investigates the impacts of these drivers on soil microbial communities, and their ecosystem functions, in dryland locations. This project also evaluates several potential vectors of soil microbial dispersal to new locations, which are all hypothesized to contribute some amount to soil microbial community assembly. The vectors to be investigated are wind and invasive plants and animals. My research program includes varied investigations, however all of them make good use of the state of the art technology to sequence microbial communities.The impact of this project on natural resources and agriculture will be to expand our understanding of soil microbial dispersal, transport, and community assembly. This project will help us to comprehend the role of microorganisms in ecosystem functions. Further, this project will increase understanding of the impacts of climate and environmental changes, such as increased prevalence of drought and N deposition on natural and agricultural areas, on soil microbial communities and their functions. Finally, this project will evaluate the roles of various vectors of dispersal on the composition of microbial communities in soils and associated with plants and animals. This investigation may help to identify potential biocontrol for invasive plants and animals may prevent the loss of native ecosystems.

Animal Health Component

40%

Research Effort Categories

Basic

60%

Applied

40%

Developmental

0%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
132	0730	1070	20%
213	4010	1070	20%
205	4010	1070	20%
215	3130	1100	20%
102	0710	1070	20%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 215 - Biological Control of Pests Affecting Plants; 205 - Plant Management Systems; 132 - Weather and Climate; 213 - Weeds Affecting Plants;

Subject Of Investigation
0730 - Mountain grasslands, meadow, and alpine; 3130 - Nematodes; 4010 - Bacteria; 0710 - Desert and semidesert shrub land and shinnery;

Field Of Science
1070 - Ecology; 1100 - Bacteriology;

Keywords

climate

environment

microbial community

community assembly

microbial diversity

microbial functions

soil

soil microorganisms

invasion

greenhouse gases

Goals / Objectives
The major goal of this project in the Aronson lab is to understand what determines the assembly, diversity, and functions of microbial communities, and how these properties respond to climate and environmental change. My lab approaches this goal using both basic and applied science techniques. This project aims to understand how environmentally-induced shifts in soil microbial communities, and their related functions, in turn impact the climate and environment. The primary focus is on prokaryotic microbes, including bacteria and archaea, but micro-eukaryotes, such as mycorrhizae and endophytes, are being investigated as well. In order to achieve this goal, there are several objectives my lab will achieve over the next five years of this project:Aeolian Transport: We will determine to what extent wind and aeolian particles act as vectors for dispersal for microorganisms and nutrients along an elevational gradient in the UC Merced Sierra Nevada Research Institute and Southern Sierra Critical Zone Observatory.Invasive Plants: We will elucidate whether invasive plants can act as carriers for potentially invasive microbes. We will use the model cereal grass plant Brachypodium distachyon and its close relative that is invasive in California, B. hybridum. To begin this study, we will compare the root endophytes and rhizosphere microbial communities of these grasses in their native Spain and invaded lands in Southern California, including in Irvine Ranch Conservancy Land and other managed lands in San Diego counties. Over the long term, we intend to develop biocontrol for the incipient invasive grass, alternately named Purple False Brome, Brachypodium distachyon, or B. hybridum, develop strategies of pest management for B. distachyon.Restoration Impacts: We will generate a better understanding of how post-plant invasion legacy effects and restoration activities impact soil microbial communities and their functions. In particular, we will quantify and qualify how invasive plants create legacy effects by changing rhizosphere microbial communities, either by introducing new microorganisms, or selecting for or against existing microbes. We will explore whether native rhizosphere pathogenic microorganisms of invasive plants be used to control invasive plants in their non-native range. We will further investigate the impacts of management, such as herbicide, clipping, and native re-vegetation activities on soil microbial communion. This will be investigated in existing restoration projects in San Diego and Los Angeles counties.Gastropod Microbiomes: We will investigate whether invasive terrestrial gastropods, in plant nurseries in the San Diego and Riverside counties, carry their own endemic bacterial pests. Further, we will test whether those bacterial pests are associated with specific nematodes. We will then attempt to use the bacteria or nematode-bacterial combination to control the invasive gastropods.Desert Drought: We will also ascertain how desert soil microbial communities respond to increased drought and fewer, more severe storms. We will establish whether desert soils in the low N deposition site Boyd Deep Canyon UC Reserve and high N site Oasis de los Osos in Palm Springs, CA, are suffering from sequential multiple limitation of not just water, but nutrients as well. We will measure the microbial community functional response, in terms of the fluxes of the greenhouse gases (GHGs) methane, carbon dioxide and nitrous oxide. We will then generate a model of the response to wet-up after prolonged drought, by modeling the data we collect the microbial community functional gene-transcript-product system.

Project Methods
The methods for each objective are given in the same order as the objectives:Aeolian Transport:In order to determine to what extent wind and aeolian particles act as vectors for microbial dispersal, Dr. Aronson, postdoc Dr. Chelsea Carey, and collaborators, are collecting samples along an elevational gradient in the UC Merced Sierra Nevada Research Institute and Southern Sierra Critical Zone Observatory (SSCZO). We will study dust fluxes at four sites along the SSCZO altitude transect. Data collected from this transect over the project period will be used to quantify: i) the relative flux of aeolian inputs during a mega drought (i.e., in 2014), which we will seek further funding to compare to the wetter years that will likely follow; and ii) the relative importance of local (e.g., Central Valley) versus distant (e.g., China) sources on the biogeochemistry and microbial makeup of soils and ecosystems in the Sierra Nevada foothills. In addition, we will to compare data from the various sites to identify the relative importance of local and distant dust sources changes with elevation and distance from the Central Valley.This project uses dust collectors of the type successfully used for many years by researchers at the USGS and their affiliates. My collaborators and I have based our design on the passive collector template pioneered by Marith Reheis. To supplement passive sample collection, the active CO2 samplers already installed on the towers will have their 1 um filters changed when passive dust are collected, which will be analyzed for microbial composition attached to dust particles on the filters. In addition, 5-10 soil samples, 2.5 cm diameter and 10 cm depth, are being collected at each of the sites within the footprint of the towers coincident with passive sampler dust collection. Dust samples are being divided into aliquots for isotope, nutrient and microbial analysis. Dust samples will be analyzed for C, N, P and other nutrients, as well as Sr and Nd quantity and isotopic compositions. Dust, soil and filter samples are being on dry ice to the Aronson lab where they will be analyzed for bacterial, archaeal and fungal community composition. Additional analyses will be performed using SourceTracker (Knights et al., 2011) to predict the origin of microbial communities in the soil.Invasive Plants:The Aronson lab will compare the root endophytes and rhizosphere microbial communities of these grasses in their native Spain, near Zaragoza University in Central Spain, where they co-occur, with the assistance of Collaborator Dr. Pilar Catalán. In addition, we will collect B. distachyon in invaded lands in Southern California, including in Irvine Ranch Conservancy Land and other managed lands in San Diego counties. The rhizosphere microbial communities of the Brachypodium species will then be compared to the co-occurring rhizosphere microbial communities of non-Brachypodium, native grasses in both locations. Putative invasive microorganisms will be identified as those in the Brachypodium rhizospheres in both locations which are missing from the other native rhizospheres and bulk soil in California, but present in the other native Spanish rhizospheres. Both B. distachyon and B. hybridum, annual grasses, flower between April and June, depending on location (Dickens et al. 2013). In April - June 2014, Dr. Aronson collected samples of B. hybridum in Orange and San Diego counties of CA, US, and B. distachyon and B. hybridum in the Zaragoza region in Spain, along with co-occuring native grasses. We will use the tested DNA barcoding technique to identify the Brachypodium to species (Lopez-Alvarez et al. 2012), and sequence the 16S (bacterial/archaeal) and ITS (fungal) communities for statistical comparisons.Restoration Impacts:We are investigating the impacts of invasive plant legacy effects and restoration on soil microbial communities in two main projects. In the primary project, graduate student Brooke Pickett is leading an investigation into the legacy effects of invasive grasses on native coastal sage scrub (CSS) in the LA region. At Satwiwa cultural center, in the foothills of the Santa Monica Mountains, Phalaris aquatica is an invasive perennial bunchgrass that was removed in patches from approximately 2006-2013. Native species recruitment into the bare ground where invasive P. aquatica had previously grown was minimal, despite intact CSS bordering the treatment areas, suggesting soil legacy effects of P. aquatica. We are currently analyzing the microbial communities in both soil types (invaded and native). Further, we are testing whether we can improve native plant establishment through inoculation of native seedlings with CSS soil before planting into the post-P. aquatica soil. In the secondary restoration project, the Aronson lab is working with the Irvine Ranch Conservancy and with Dr. Erin Conlisk, of UC Berkeley, in San Diego County reserve lands. In both projects, the Aronson lab is investigating the long-term impacts of invasive plant remediation strategies, including herbicide application, clipping and re-vegetation efforts.Gastropod Microbiomes:To identify microbial taxa that are likely biocontrol agents for invasive gastropods, we will investigate the bacterial microbiome of the land gastropods and their associated nematodes. Gastropods will be collected from multiple plant nurseries in San Diego County, and grown in a vivarium. Using 16S sequencing e will compare the microbiomes of those gastropods that die prematurely to those that live for at least 2 months in the vivarium, and both microbiomes will be compared to that of gastropods that are sacrificed immediately upon collection. Candidate biocontrol agents will be selected from those bacteria that inhabit the dead gastropods, and were also present on those immediately sacrificed, but not on those which live for 2 months in the vivarium.Desert Drought:In order to measure the microbial response of desert soils to water and nutrients in two sites, a low N deposition site Boyd Deep Canyon UC Reserve and a high N site Oasis de los Osos in Palm Springs, Ca. In the summer months, after prolonged drought, will experimentally add water or water plus N to soil under shrubs and in the interspaces. We will then investigate the soil microbial community composition, as well as the functional diversity, via sequencing, and abundance of key trace gas function genes using qPCR.Microbial Community Analysis Across All Projects:In all projects the Aronson lab will use Illumina MiSeq sequencing to determine the phylogenetic and/or functional composition of the microbial community. We will extract DNA using the MoBio, Inc. kits, including the Ultraclean Tissue and Cell DNA Isolation Kit for gastropods, the PowerLyzer PowerSoil DNA Isolation Kit for soils, the PowerPlant Pro DNA Isolation Kit for plants, and the PowerWater DNA Isolation Kit for filtered water-suspended dust samples and air filter samples. Microbial community composition will be determined by amplifying the bacterial/archaeal 16S small subunit (SSU) ribosomal RNA gene using universal primers, and in some cases the internal transcribed spacer (ITS) gene for fungal diversity. Universal primers will allow us to determine the relative abundances of bacteria in a single reaction. When necessary, we will also determine the functional diversity by amplifying and sequencing methane production and consumption genes, mcrA and pmoA, respectively, as well as various N-cycling genes, including amoA, nifA, nirK, nirS and nosZ. For sequence preparation, will use 96-well amplification/purification formats and Illumina barcodes to allow post-sequencing sample separation. Sequence data will be analyzed using tools currently available from the DOE Argonne National Lab including MG-RAST (the Meta-genomics Rast) and K-Base, and the open-source platform QIIME. Data will be further analyzed using a combination of JMP (SAS, Inc.) and R.

Progress 10/23/14 to 08/21/19

Outputs
Target Audience:The primary target audience reached during this research period continued to be the scientific community, ranging from microbiologists and ecologists to atmospheric chemists and earth system scientists. Outreach efforts in the scientific community were in the form of conference presentations, including one at the Soil Ecology Society meeting, one at the American Geophysical Union Annual Meeting, one at the Mycological Society of America Meeting. In addition, there were two presentations from personnel on this project at the UCR Microbiome Initiative Annual Meeting. In addition we have published one peer-reviewed book chapter, six articles published, and six articles in press, in addition to one in review, enumerated under "Products." In addition, Dr. Aronson hosted a workshop at UCR, for both geoscience computer scientists and early career scientists involved in Critical Zone research from around the country, and was invited once again as the international leader in Critical Zone Microbiology to lead this section of a 10-day international graduate field course on Critical Zone Science. The secondary target audience for this study has been land managers working to eradicate invasive plant species from managed lands. In particular, we worked to remediate legacy effects with targeted restoration activities in association with Los Angeles county and Bay Area land managers to collect samples of invasive plants, including Brachypodium and Phlaris spp. Further, we are working with these land managers to devise microbe-based biocontrol for invasive plants, and treatments for legacy effects, and have communicated new results to this community through informal meetings and field trips. The tertiary audience during this time period has been the entire NSF-funded Geoscience community, as well as relevant data scientists. I was recently elected the Chair of the NSF EarthCube Science Committee during this funding period, and in that capacity, spoke at scientific sessions at the All Hands Meeting and the Annual Meeting of the American Geophysical Union, and continue to guide the development of cyberinfrastructure for geoscientists around the country. The final target audience for this study has been plant nursery owners, who are battling invasive gastropods on a regular basis. We continue to work with them to collect invasive slugs, which are eating nursery plants, and are investigating their microbiomes for potential biocontrol. We are building connections with these nursery owners to work towards testing potential biocontrol strategies at the nurseries, in association with these nursery personnel. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has assisted in the training of a postdoctoral researcher in the pursuit of multiple objectives. In addition, this project has supported the training of four graduate students. There have also been several undergraduate students from UC Riverside and other undergraduate programs trained in this work. Training has taken place in the field sites in California, at a field school in Ceresole Reale, Italy, as well as in my laboratory at UC Riverside. All graduate students and postdoctoral researchers, and Dr. Aronson, have participated in multiple conferences and workshops, including the California Inasive Plant Council and Ecological Society of America Annual Meetings, and a workshop organized on the UCR campus. One graduate student has also received special methods training at Northern Arizona University in mycorrhizal sequencing and DNA Stable Isotope Program. How have the results been disseminated to communities of interest?Findings have again been disseminated via informal meetings and field trips by project personnel with land managers in Southern California regions impacted by Phlaris aquatica or Brachypodium distachyon and/or hybridum invasion, as well as nursery owners. I hosted a workshop at UCR of data scientists and early career geoscientists involved in Critical Zone research from around the country. In addition, project results continue to be disseminated to middle school female students through UCR's SISTERS program, as well as to 35 UCR undergraduate and 10 graduate students through my lectures in the courses Environmental Microbiology and Microbial Ecology. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The overall impact of this project is an increase in knowledge about how microorganisms disperse around the globe, and their ecosystem-scale effects in soil communities. In terms of the aeolian dispersal of bacteria, we found that drying of the Salton Sea is contributing to dust across the Coachella Valley, bringing potentially harmful bacteria with it. In terms of invasive plants and restoration, we have made great strides in identifying microorganisms associated with invasive and native plant soils. Further, we found that invasive grass legacy effects preventing the restoration of native shrubs is due to fungal differences in the soil community between invaded and native soils, and we communicating methods to counteract these effects. In terms of invasive gastropods, we have confirmed that the slug microbiome can be changed through changes in their environment, and that slugs can transport bacteria from one soil to another. 1. Aeolian Transport: Activities performed included analysis of bimonthly samples of dust and soil in the area of the Sierra Nevada and the Salton Sea for microbial composition. We analyzed data from a second drought year in the Sierras, and made progress writing up the data showing that the dust inputs were greater from Asia, where there was also a worsening drought. We have confirmed that microbial communities found to be co-deposited with the dust differed from the soils at all locations and timepoints, and are drafting a paper describing these data. These microbial communities were found also to differ with elevation, however the microbial communities at a lower elevation were often found to be similar to the community at the next-highest elevation during the following month of sampling throughout the summer. We are writing up data showing that dust at all elevations in the Sierra Nevada was found to contain fungal plant pathogens, with greater pathogen concentrations at the lower elevations. We also found that fungi in dust cluster into several distinct groups. 2. Invasive Plants: Activities performed included the completion of the analysis of samples collected in 2016 and 2015 of Brachypodium species and nearby grasses and soils in both Spain and California. The full data set shows that the microbial communities of the roots, rhizosphere, and bulk soils, are distinct. Finally, we found that within Spain root microbiomes differed between B. distachyon and its close relative B. hybridum. We are finishing all bioinformatics and data analysis in the coming months, as we write up these data. 3. Restoration Impacts: We completed all sequencing and data analysis for the project involving native plant restoration in the coastal sage scrub ecosystem in the Santa Monica Mountains in California, where we found that native soil microbes were beneficial to native plant growth. In this project post-invasive removal, native plants were planted with of either sterilized or unsterilized native soil inoculum. We sampled the soil surrounding the plants every few months, and then destructively sampled the roots and rhizosphere of 10% of the plants after 7 months. We found that the periodic soil samples of the sterilized and unsterilized native soil-inoculated restored plants had the same microbial communities. On the other hand, after destructive sampling, these soil fungal, bacterial, and archaeal communities had diverged in the rhizosphere. We completed fungal sequencing for ITS and mycorrhizal-specific genes, analyzed all data, and have published this research as both a book chapter and a journal article. 4. Gastropod Microbiomes: Our work on the gastropod microbiome has shifted away from investigating biocontrol, as those experiments require a better understanding of the slug microbiome. We have continued working with local plant nurseries to collect slugs and then introducing a subset of these slugs into sterile microcosms to test for bacterial transfer. Our continuing experiments have shown that slugs do not have a stable microbiome, but are rather influenced by the microbiome of their environment and food. Further, we have found that slugs can transport bacteria from one soil to another. 5. Desert Drought: In the past year, we collected new 15N2O and NOx measurement data that confirms the large NOx and N2O fluxes out of the desert soils in response to a 15N addition with a water pulse that we had previously observed. We also performed several rounds of DNA quantitative stable isotope probing (qSIP) experiments with samples from Boyd Deep Canyon, of the UC Natural Reserve System, using water labeled with 18O. We continue to work to sequence the soil microbial communities associated with these observed fluxes at multiple sites. Additionally, we will be repeating the experiment in the winter months. We will perform high-throughput shotgun metagenomics on the qSIP DNA to better understand which soil microorganisms are responding to the added N and water over time.

Publications

• Type: Journal Articles Status: Published Year Published: 2019 Citation: Peng, X, M Maltz, JK Botthoff, EL Aronson, T Nordgren, D Lo, and D Cocker. 2019. Establishment and Characterization of a Multi-Purpose Large Animal Exposure Chamber for Investigating Health Effects. Review of Scientific Instruments. doi: 10.1063/1.5042097.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Swanson, A, L Schwendenmann, M Allen, EL Aronson, A-L Allan, D Dierick, A Fernandez-Bou, T Harmon, C Murillo-Cruz, A Pinto-Tom�s, P Rundel, and T Zelikova. 2019. Welcome to the Atta world: A framework for understanding the effects of leaf cutter ants on ecosystem functions. Functional Ecology. doi: 10.1111/1365-2435.13319
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Aronson, EL, D Dierick, JK Botthoff, RF Johnson, AC Swanson, A Pinto-Tom�s, A Artavia-Le�n, B Matarrita-Carranza, and MF Allen. 2019b. ENSO-influenced soil moisture and drought drive methane flux dynamics in a Costa Rican rainforest soil. In Press at Journal of Geophysical Research  Biogeochemistry.
• Type: Book Chapters Status: Published Year Published: 2019 Citation: Pickett, B, M Maltz, and EL Aronson. 2019b. Impacts of Invasive Plants on Soil Fungi and Implications for Restoration. in Invasive Plants. London: IntechOpen. doi: 10.5772/intechopen.82108.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Maltz, MR, Z Chen, J Cai, K Arogyaswamy, H Shulman, and EL Aronson. 2019. Inoculation with Pisolithus tinctorius may ameliorate acid rain impacts on soil microbial communities associated with Pinus massoniana seedlings. Fungal Ecology. doi: 10.1016/j.funeco.2018.11.011.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Phillips, M, SE Weber, LV Andrews, MF Allen, EL Aronson, and EB Allen. 2019. Multiple environmental factors structure symbiotic and non-symbiotic soil fungal communities under invasion. Fungal Ecology. doi: 10.1016/j.funeco.2019.01.002
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Weber, SE, JM Diez, L Andrews, ML Goulden, EL Aronson, and MF Allen. 2019. Responses of arbuscular mycorrhizal fungi to multiple coinciding global change drivers. Fungal Ecology. doi: 10.1016/jfuneco.2018.11.008.
• Type: Journal Articles Status: Published Year Published: 2019 Citation: Aronson, EL, ML Goulden, and SD Allison. 2019. Greenhouse gas fluxes under drought and nitrogen addition in a Southern California grassland. Soil Biology and Biochemistry. 131, 19-27.
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Brewer, TE, EL Aronson, K Arogyaswamy, SA Billings, JK Botthoff, AN Campbell, NC Dove, D Fairbanks, RE Gallery, SC Hart, J Kaye, G King, KA Lohse, E Mayorga, F Meyer, C ONeill, SM Owens, A Packman, J Pett-Ridge, AF Plante, DD Richter, WL Silver, WH Yang, and N Fierer. 2019. Ecological and genomic attributes of novel bacterial taxa that thrive in subsurface soil horizons. In Press at mBio. (note, this is a co-first author paper).
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Chen, Z, MR Maltz, J Cao, H Yu, H Shang, and EL Aronson. 2019. Elevated O3 alters soil bacterial and fungal communities and the dynamics of carbon and nitrogen. In Press at Science of the Total Environment. doi: 10.1016/j.scitotenv.2019.04.310.
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Frie, A, A Garrison, M Schaefer, S Bates, J Botthoff, M Maltz, S Ying, T Lyons, EL Aronson, R Bahreini. 2019. "Dust Sources in the Salton Sea Basin: A Clear Case of an Anthropogenically Impacted Dust Budget." In Press at Environmental Science & Technology.
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Meyer, RS, E Curd, T Schweizer, Z Gold, D Ruiz, S Shirazi, G Kandlikar, W-Y Kwan, M Lin, A Freise, J Moberg-Parker, MM Ramos, B Shapiro, M Dawson, J Sexton, L Pipes, AG Vedrenne, M Palacios, EL Aronson, T Moore, R Nielsen, H Lewin, P Barber, J Wall, N Kraft, and RK Wayne. 2019. The California eDNA "CALeDNA" Program. In Press at California Agriculture.
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Pickett, B, I Irvine, E Bullock, K Arogyaswamy, and EL Aronson. 2019. Legacy Effects of Invasive Grass Impact Soil Bacteria and Native Shrub Growth In Press at Invasive Plant Science and Management.

Progress 10/01/17 to 09/30/18

Outputs
Target Audience:The primary target audience reached during this research period continued to be the scientific community, ranging from microbiologists and ecologists to atmospheric chemists and earth system scientists. Outreach efforts in the scientific community were in the form of conference presentations, including several at the Ecological Society of America Annual Meeting, one at the American Geophysical Union Annual Meeting, and two at the UCR Microbiome Initiative Annual Meeting, and a peer-reviewed book chapter, and two articles in review, enumerated under "Products." In addition, Dr. Aronson hosted a workshop in at UCR, for scientists involved in Critical Zone research from around the country, and was invited as the international leader in Critical Zone Microbiology to lead this section of a 10-day international graduate field course on Critical Zone Science. The secondary target audience for this study has been land managers working to eradicate invasive plant species from managed lands. In particular, we worked to remediate legacy effects with targeted restoration activities in association with Los Angeles county and Bay Area land managers to collect samples of invasive plants, including Brachypodium and Phlaris spp. Further, we are working with these land managers to devise microbe-based biocontrol for invasive plants, and treatments for legacy effects, and have communicated new results to this community through informal meetings and field trips. The tertiary audience during this time period has been the entire NSF-funded Geoscience community, as well as relevant data scientists. I was recently elected the Chair of the NSF EarthCube Science Committee during this funding period, and in that capacity, I have organized scientific sessions at the All Hands Meeting and the Annual Meeting of the American Geophysical Union, and continue to guide the development of cyberinfrastructure for geoscientists around the country. The final target audience for this study has been plant nursery owners, who are battling invasive gastropods on a regular basis. We continue to work with them to collect invasive slugs, which are eating nursery plants, and are investigating their microbiomes for potential biocontrol. We are building connections with these nursery owners to work towards testing potential biocontrol strategies at the nurseries, in association with these nursery personnel. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has assisted in the training of a postdoctoral researcher in the pursuit of multiple objectives. In addition, this project has supported the training of four graduate students. There have also been several undergraduate students from UC Riverside and other undergraduate programs trained in this work. Training has taken place in the field sites in California, at a field school in Ceresole Reale, Italy, as well as in my laboratory at UC Riverside. All graduate students and postdoctoral researchers, and Dr. Aronson, have participated in multiple conferences and workshops, including the California Inasive Plant Council and Ecological Society of America Annual Meetings, and a workshop organized on the UCR campus. One graduate student has also received special methods training at Northern Arizona University in mycorrhizal sequencing and DNA Stable Isotope Program. How have the results been disseminated to communities of interest?Findings have again been disseminated via informal meetings and field trips by project personnel with land managers in Southern California regions impacted by Phlaris aquatica or Brachypodium distachyon and/or hybridum invasion, as well as nursery owners. I hosted a workshop at the UCR Botanic Gardens, of data scientists involved in Critical Zone research from around the country. In addition, project results continue to be disseminated to middle school female students through UCR's SISTERS program, as well as to 35 UCR undergraduate and 10 graduate students through my lectures in the courses Environmental Microbiology and Microbial Ecology. What do you plan to do during the next reporting period to accomplish the goals?Research will continue in all areas, we will continue to publish the results, including a paper that is currently in review. Several more papers will be submitted for publication this year. In addition, I will host more and more varied workshops to highlight the issues and results of this project and other compatible research. Desert field work in particular will be a primary activity as well as laboratory, bioinformatics and statistical analysis associated with that research.

Impacts
What was accomplished under these goals? Our work on the gastropod microbiome has shifted away from investigating biocontrol, as those experiments require a better understanding of the slug microbiome. We have continued working with local plant nurseries to collect slugs and then introducing a subset of these slugs into sterile microcosms to test for bacterial transfer. Our continuing experiments have shown that slugs do not have a stable microbiome, but are rather influenced by the microbiome of their environment and food.In the past year, we collected 15N2O and NOx measurement data that confirms the large NOx and N2O fluxes out of the desert soils in response to a 15N addition with a water pulse that we had previously observed. We also performed a DNA stable isotope probing experiment with samples from Boyd Deep Canyon, of the UC Natural Reserve System, using water labeled with 18O. We continue to work to sequence the soil microbial communities associated with these observed fluxes at multiple sites. Additionally, we will be repeating the experiment in the winter months.

Publications

• Type: Book Chapters Status: Accepted Year Published: 2019 Citation: Pickett, B, M Maltz, and EL Aronson. 2019. Impacts of Invasive Plants on Soil Fungi and Implications for Restoration. In Press, invited as part of the book Invasive Plants. London: IntechOpen.
• Type: Journal Articles Status: Accepted Year Published: 2019 Citation: Pickett, B, I Irvine, E Bullock, K Arogyaswamy, and EL Aronson. 2019. Legacy Effects of Invasive Grass Impact Soil Bacteria and Native Shrub Growth In Press at Invasive Plant Science and Management.
• Type: Journal Articles Status: Submitted Year Published: 2019 Citation: Eberwein, J, P Homyak, C Carey, EL Aronson, and G Jenerette. 2019. Large Nitrogen Emissions and Microbial Community Changes in Desert Soils Following Wetting" In Revision at Global Change Biology.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The primary target audience reached during this research period continued to be the scientific community, ranging from microbiologists and ecologists to atmospheric chemists and earth system scientists. Outreach efforts in the scientific community were in the form of conference presentations, including several at the Ecological Society of America Annual Meeting, and a peer-reviewed article, enumerated under "Products." In addition, Dr. Aronson hosted workshop in Portland, OR, for scientists involved in Critical Zone research from around the country, as well as the NEON microbial community science advisors. In addition, my lab group has participated in research trips to Mexico, which included scientific exchanges with natural system and agricultural researchers. The secondary target audience for this study has been land managers working to eradicate invasive plant species from managed lands. In particular, we worked to remediate legacy effects with targeted restoration activities in association with Los Angeles county and Bay Area land managers to collect samples of invasive plants, including Brachypodium and Phlaris spp. Further, we are working with these land managers to devise microbe-based biocontrol for invasive plants, and treatments for legacy effects. These data were presented to a large group of land managers by Dr. Aronson and Graduate Student Brooke Pickett at the 2017 Cal-IPC meeting, and updated by Ms. Pickett at the 2018 meeting. The tertiary audience during this time period has been the entire NSF-funded Geoscience community, as well as relevant data scientists. I was re-elected the Co-Chair of the NSF EarthCube initiative Science Committee during this funding period, and in that capacity, I have organized scientific sessions at the All Hands Meeting, and continue to guide the development of cyberinfrastructure for geoscientists around the country. The final target audience for this study has been plant nursery owners, who are battling invasive gastropods on a regular basis. We continue to work with them to collect invasive slugs, which are eating nursery plants, and are investigating their microbiomes for potential biocontrol. We are building connections with these nursery owners to work towards testing potential biocontrol strategies at the nurseries, in association with these nursery personnel. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has assisted in the training of two postdoctoral researchers in the pursuit of multiple objectives. In addition, this project has supported the training of four graduate students and a visiting graduate student from the Universidad Autonomia de Yucatan in the past year. There have also been several undergraduate students from UC Riverside and other undergraduate programs trained in this work. Training has taken place in the field sites in Mexico and California, as well as in my laboratory at UC Riverside. All graduate students and postdoctoral researchers, and Dr. Aronson, have participated in multiple conferences and workshops, including Ecological Society of America in Portland, OR, and a workshop organized in Portland by Dr. Aronson, and another organized on the UCR campus. Further, related research funding has supported one graduate student from the University of Wyoming and one postdoc from the University of California, Irvine, to receive training for complex, small-sample isotope methods. Finally, during this grant period one of my postdocs was hired into a permanent position at a land management nonprofit, a job directly related to the professional development she received while on this project. How have the results been disseminated to communities of interest?Findings have again been disseminated via informal meetings and field trips by project personnel with land managers in Southern California regions impacted by Phlaris aquatica or Brachypodium distachyon and/or hybridum invasion, as well as nursery owners. I hosted a workshop in Portland, OR, of scientists involved in Critical Zone research from around the country, as well as the advisors of NEON microbial community data, and an EarthCube project meeting at UCR. In addition, I have participated in research trips and presented data at an international conference in Merida, Mexico. My work in Mexico included scientific exchanges with natural system researchers from all over the world. In addition, project results have been disseminated to middle school female students through UCR's SISTERS program, as well as to 130 UCR undergraduate and 10 graduate students through lectures in the courses Introductory Microbiology, Environmental Microbiology and Microbial Ecology. What do you plan to do during the next reporting period to accomplish the goals?Research will continue in all areas, we will continue to publish the results. In fact, there are 3 related articles in review right now, and several more will be submitted for publication this year. In addition, I will host more and more varied workshops to highlight the issues and results of this project and other compatible research. Field work is tapering off, while lab analysis is in full swing and data analysis and writing are primary concerns.

Impacts
What was accomplished under these goals? The overall impact of this project continues to be a set of changes in knowledge about how microorganisms disperse around the globe, and their ecosystem-scale effects in soil communities. In terms of aeolian dispersal of bacteria, we have collected dust samples for sequencing from the Sierras in a rare wet year, as well as monthly for a year surrounding the Salton Sea. In terms of invasive plants and restoration, we have made great strides in identifying microorganisms associated with invasive and native plant soils. Further, we found that invasive grass legacy effects preventing the restoration of native shrubs may be through the manipulation of the soil microbial community, and we are developing methods to counteract these effects. In terms of invasive gastropods, we have initial findings that slugs can transport bacteria to sterile microcosms, and that the slug microbiome can be changed through changes in their environment. 1) Aeolian Transport: Activities performed included monthly monitoring of the aeolian transport of dust and soil in the area of the Salton Sea, and analysis of these samples for microbial composition. In addition, we published on our initial data on dust inputs to the Sierra Nevada Mountains of California, and collected another round of summer samples. We had found that dust inputs are coming from as far away as the Gobi Desert of China. Dust inputs to lower elevations were more likely to be from regional sources in the Central Valley, CA, while the higher elevations were more likely to receive dust inputs from farther away. In 2014, in the spring to summer months, as time progressed so did the drought, which we had predicted would bring regional Central Valley inputs to ever higher elevations. However, we have now analyzed 2015 samples and found that the increasing Asian drought in the summer led to greater Gobi dust deposition in the summer months. We also found that microbial communities found to be co-deposited with the dust differed from the soils at all locations and timepoints. These microbial communities were found also to differ with elevation, however the microbial communities at a lower elevation were often found to be similar to the community at the next-highest elevation during the following month of sampling throughout the summer. Finally, the dust at all elevations was found to contain fungal plant pathogens 2) Invasive Plants: Activities performed have included the analysis of samples collected in 2016 and 2015 of Brachypodium species and nearby grasses and soils in both Spain and California, and we are continuing analysis of these samples for microbial composition. Last year, we found that the microbial communities of the roots, rhizosphere, and bulk soils, are distinct. We are finishin all sequencing of samples in the coming months. 3) Restoration Impacts: Work continues on the project involving native plant restoration in the coastal sage scrub ecosystem in the Santa Monica Mountains in California, where we found that native soil microbes were beneficial to native plant growth. Post-invasive removal, native plants were planted with of either sterilized or unsterilized native soil inoculum. We sampled the soil surrounding the plants every few months, and then destructively sampled the roots and rhizosphere of 10% of the plants after 7 months. We have found that the periodic soil samples of the sterilized and unsterilized native soil-inoculated restored plants had the same microbial communities. On the other hand, after destructive sampling, these soil bacterial and archaeal communities had diverged in the rhizosphere. Fungal sequencing for ITS and mycorrhizal-specific genes is ongoing. 4) Gastropod Microbiomes: Our work on the gastropod microbiome has shifted away from investigating biocontrol, as those experiments require a better understanding of the slug microbiome. We have continued working with local plant nurseries to collect slugs and then introducing a subset of these slugs into sterile microcosms to test for bacterial transfer. Our first round of experiments have shown that slugs do not have a stable microbiome, but are rather influenced by the microbiome of their environment and food. 5) Desert Drought: Last year we found large NOx and N2O fluxes out of desert soils in response to N addition with a water pulse. However, we found these fluxes to be greater in a high N deposition site than in a low N deposition site. We continue to work to sequence the soil microbial communities associated with these observed fluxes at the two sites. Additionally, repeating the experiment in the winter months after a month-long drought showed N2O uptake into the soil, which we have yet to explain.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Aciego, SM, CS Riebe, S Hart, MA Blakowski, C Carey, SM Aarons, N Dove, JK Botthoff, KWW Sims, and E Aronson. 2017. Dust outpaces bedrock in nutrient supply to montane forest ecosystems. Nature Communications. 10.1038/ncomms14800.
• Type: Journal Articles Status: Submitted Year Published: 2018 Citation: Aronson, EL, D Dierick, JK Botthoff, RF Johnson, AC Swanson, and MF Allen. 2018. ENSO Drives Tropical Soil Methane Fluxes and Atmospheric Column Concentrations. In Review at Nature Communications.
• Type: Journal Articles Status: Submitted Year Published: 2018 Citation: Maltz, MR, Z Chen, J Cai, K Arogyaswamy, and EL Aronson. 2018. Ectomycorrhizal inoculation may ameliorate acid rain impacts on soil microbial communities associated with Pinus massoniana seedlings. In Review, invited as part of a Special Issue of Fungal Ecology.
• Type: Journal Articles Status: Submitted Year Published: 2018 Citation: Phillips, M, SE Weber, LV Andrews, MF Allen, and EB Allen. 2017. Multiple environmental factors structure symbiotic and non-symbiotic soil fungal communities under invasion. In Review, invited as part of a Special Issue of Fungal Ecology.
• Type: Journal Articles Status: Submitted Year Published: 2018 Citation: Weber, SE, JM Diez, L Andrews, ML Goulden, EL Aronson, and MF Allen. 2017. Responses of arbuscular mycorrhizal fungi to multiple coinciding global change drivers. In Review, invited as part of a Special Issue of Fungal Ecology.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Jackson, D., Aronson, E.L. 2017. Soil Microbial dispersal by way of terrestrial slugs. Soil Ecology Society Bi-annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Aronson, E.L., Dierick, D., Botthoff, J.K., Swanson, A., Allen, M. 2017. Tropical rainforest methane consumption by leaf cutter ant nests and soils under variable moisture. Association for Tropical Biology and Conservation Bi-annual Meeting
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Jackson, D., Aronson, E.L. 2017. Bacterial dispersal by way of terrestrial slugs: A microbiome and microcosm experiment. Ecological Society of America Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Costa, M., Aburto-Oropeza, O., Aronson, E.L., Botthoff, J.K., Ezcurra, E. 2017. Deep peat deposits in Baja California Sur mangroves record slow rate of organic matter decomposition. Ecological Society of America.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Pickett, B., Irvine, I., Aronson, E.L. 2017. Identifying and remediating the microbial legacy effects of invasive grasses for restoration. Ecological Society of America Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Pickett, B, I Irvine, and EL Aronson. 2016. Remediating the microbial legacy effects of invasive grass for restoration. Cal-IPC annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Aronson, EL, JK Botthoff, C Carey, B Pickett, and P Catalan. 2016. Brachypodium invasion in California is facilitated by rhizosphere microbes. Cal-IPC annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Maltz, M., Mitrovich, M., Kimball, S., Lulow, M., Burger, J.C., Pratt, R.T., Nerhus , B., Balazs, K., Weber, S., Allen, M., Allen, E., Aronson, E.L. 2017. Restoration methods alter AM fungal abundance and community composition. Ecological Society of America Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Dove, N., Arogyaswamy, K., Carey, C.J., Packman, A., Hart, S. 2017. Over half of potential soil extracellular enzyme activity occurs below 20 cm. Ecological Society of America Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Aronson, E.L., Costa, M., Botthoff, J.K., Maltz, M., Aburto-Oropeza, O., Ezcurra, E. 2017. Mangrove peat and sediment microbial communities. Ecological Society of America Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Arogyaswamy, K., Aronson, E.L. 2017. Copper addition induces soil microbial community shifts and changes in biogeochemical cycling. Ecological Society of America Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Jenerette, D., Wang, J., Sickman, J., Aronson, E.L., Fenn, M., Ge, C. 2017. Pulses of biogenic nitrogen cycling lead to atmospheric-based nutrient spiraling in southern California. Ecological Society of America Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: ronson, E.L.., Dierick, D., Botthoff, J.K., Swanson, A., Allen, M. 2016. Tropical rainforest methane consumption during the El Nino of 2015-16. American Geophysical Union Annual Meeting.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Eberwein, J., Carey, C.J., Aronson, E.L., Jenerette, D. 2016. Investigating the microbial community responsible for unusually high soil N2O and NOx emissions in the Colorado Desert. American Geophysical Union Annual Meeting.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:The primary target audience reached during this research period was the scientific community, ranging from microbiologists and ecologists to atmospheric chemists and earth system scientists. Outreach efforts in the scientific community were in the form of conference presentations and peer-reviewed articles, enumerated under "Products." In addition, Dr. Aronson hosted workshop in Montreal, Canada, of scientists involved in Critical Zone research from around the country, as well as the advisors of NEON microbial community data. In addition, I have participated in research trips to Costa Rica and Mexico, which included scientific exchanges with natural system researchers from all over the world. The secondary target audience for this study has been land managers working to eradicate invasive plant species from managed lands. In particular, we worked directly with Los Angeles county and Bay Area land managers to collect samples of invasive plants, including Brachypodium and Phlaris spp., and remediate legacy effects with targeted restoration activities. Further, we are working with these land managers to devise microbe-based biocontrol for invasive plants, and treatments for legacy effects. The tertiary target audience for this study has been plant nursery owners, who are battling invasive gastropods on a regular basis. We continue to with them to collect invasive slugs, which are eating nursery plants, and are investigating their microbiomes for potential biocontrol. We are building connections with these nursery owners to test potential biocontrol strategies at the nurseries, in association with these nursery personnel. The final audience during this time period has been the entire NSF-funded Geoscience community, as well as relevant data scientists. I have been elected the Co-Chair of the NSF EarthCube initiative Science Committee, and in that capacity have organized scientific sessions at the All Hands Meeting, and am helping to guide the development of cyberinfrastructure for geoscientists around the country. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has assisted in the training of two postdoctoral researchers in the pursuit of multiple objectives. In addition, this project has supported the training of four graduate students and a visiting graduate student from the Universidad de Costa Rica. There have also been several undergraduate students from UC Riverside and other undergraduate programs involved in this work. Training has taken place in the field sites in Spain and California, as well as in the laboratory at UC Riverside and at the Universidad de Zaragoza in Huesca, Spain. All graduate students and postdoctoral researchers, and Dr. Aronson, have participated in multiple conferences and workshops, including the International Society of Microbial Ecology and a workshop organized in Montreal by Dr. Aronson. How have the results been disseminated to communities of interest?Findings have again been disseminated via informal meetings and field trips by project personnel with land managers in Southern California regions impacted by Phlaris aquatic or Brachypodium distachyon and/or hybridum invasion, as well as nursery owners. I hosted a workshop, workshop in Montreal, Canada, of scientists involved in Critical Zone research from around the country, as well as the advisors of NEON microbial community data. In addition, I have participated in research trips to Costa Rica and Mexico, which included scientific exchanges with natural system researchers from all over the world. In addition, project results have been disseminated to middle school female students through UCR's SISTERS program, as well as to 130 UCR undergraduate and 10 graduate students through lectures in the courses Introductory Microbiology, Environmental Microbiology and Microbial Ecology. What do you plan to do during the next reporting period to accomplish the goals?Research will continue in all areas, we will continue to publish the results. In addition, I will host more and more varied workshops and conference symposia to highlight the issues and results of this project and other compatible research. Field work is continuing, while lab analysis and data analysis are increasing in depth and frequency. In the next reporting period publishing data and articles will proceed at a more rapid rate than before.

Impacts
What was accomplished under these goals? The overall impact of this project continues to be a set of changes in knowledge about how microorganisms disperse around the globe, and their ecosystem-scale effects in soil communities. In terms of aeolian dispersal of bacteria, we have discovered microbial communities influenced by the Salton Sea area in the local dust. In terms of invasive plants and restoration, we found from numerous sampling campaigns in California and Spain, that invasive grass roots vary by genus in their selectivity to root endophytic bacteria. Further, we found that invasive grass legacy effects preventing the restoration of native shrubs may be through the manipulation of the soil microbial community, and we propose methods to counteract these effects. In terms of invasive gastropods, we have initial findings that slugs can transport bacteria to sterile microcosms. 1. Aeolian Transport: Activities performed included monthly to bi-monthly monitoring of the aeolian transport of dust and soil in the area of the Salton Sea, and analysis of these samples for microbial composition. In addition, we are beginning to publish our data on dust inputs to the Sierra Nevada Mountains of California. We have found that dust inputs are coming from as far away as the Gobi Desert of China. Dust inputs to lower elevations were more likely to be from regional sources in the Central Valley, CA, while the higher elevations were more likely to receive dust inputs from farther away. Throughout the spring to summer months, as time progressed so did the drought, which we had predicted would bring regional Central Valley inputs to ever higher elevations. This was borne out in the data, which showed a regional source was increasingly prevalent in the samples at the middle to higher elevations over the course of the summer. We also found that microbial communities found to be co-deposited with the dust differed from the soils at all locations and timepoints. These microbial communities were found also to differ with elevation, however the microbial communities at a lower elevation were often found to be similar to the community at the next-highest elevation during the following month of sampling throughout the summer. This microbial community trend followed that of the dust provenance (location of origin). 2. Invasive Plants: Activities performed have included collections of Brachypodium species and nearby grasses and soils in both Spain and California in May 2016, and we are continuing analysis of these samples for microbial composition. Last year, we found that the microbial communities of the roots, rhizosphere, and bulk soils, are distinct. Currently the May 2016 samples have had DNA extracted and we are working to PCR these for the 16S rRNA gene, which we will sequence with the remaining 2015 samples in the coming months. 3. Restoration Impacts: Work continues on the project involving native plant restoration in the coastal sage scrub ecosystem in the Santa Monica Mountains in California, where we found that native soil microbes were beneficial to native plant growth than the same soil without these microbes. Post-invasive removal, native plants were planted with of either sterilized or unsterilized native soil inoculum. We sampled the soil surrounding the plants every few months, and then destructively sampled the roots and rhizosphere of 10% of the plants after 7 months. We have found that the periodic soil samples of the sterilized and unsterilized native soil-inoculated restored plants had the same microbial communities. On the other hand, after destructive sampling, these soil bacterial and archaeal communities had diverged in the rhizosphere. We will be sequencing the sampled roots over the next several months 4. Gastropod Microbiomes: Our work on the gastropod microbiome has shifted away from investigating biocontrol, as those experiments require a better understanding of the slug microbiome. We have begun testing the slug ability to pick up bacteria from the soil environment, and deposit those bacteria into a novel environment. We are working with local plant nurseries to collect slugs and then introducing a subset of these slugs into sterile microcosms to test for bacterial transfer. Initial experiments show that bacteria are transferred each way, and more extensive testing is ongoing. 5. Desert Drought: Last year we found large NOx and N2O fluxes out of desert soils in response to N addition with a water pulse. However, we found these fluxes to be greater in a high N deposition site than in a low N deposition site. We are currently working to sequence the soil microbial communities associated with these observed fluxes at the two sites.

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Carey, C.J., Dove, N., Bemen, J.M.., Hart, S., Aronson, E.L. 2016. Meta-analysis reveals ammonia-oxidizing bacteria respond more strongly to nitrogen addition than ammonia-oxidizing archaea. Soil Biology and Biochemistry. Vol. 99: p.158166.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Collins, C., Carey, C.J., Aronson, E.L., Kopp, C., Diez, J.M.. 2016. Direct and indirect effects of native range expansion on soil microbial community structure and function. Journal of Ecology. Vol. 104: p.12711283.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Carey, C.J., Hart, S., Aciego, S., Riebe, C., Blakowski, M., Aronson, E.L. Microbial community structure of subalpine snow in the Sierra Nevada, California. Arctic, Antarctic, and Alpine Research. Vol. 48: p.685701.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Aronson, E.L. Grassland N addition and rainfall drive variation in microbial community structure and function. Global Soil Biodiversity Conference, Dijon, France.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Aronson, E.L. NEON-CZO Microbial ecology and biogeochemistry data integration and cross-site comparison. ESA Annual Meeting, Fort Lauderdale, FL, USA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Aronson, E.L. Co-occurring grasses share similar rhizosphere microbial communities, but differ in root endophytes. ESA Annual Meeting, Fort Lauderdale, FL, USA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Aronson, E.L. Year to year variation dominates annual determines grass rhizosphere microbial communities. International Society of Microbial Ecology Biennial Meeting, Montreal, QC, Canada.

Progress 10/23/14 to 09/30/15

Outputs
Target Audience:The primary target audience reached during this research period was a wide swath of the scientific community, ranging from microbiologists and ecologists to atmospheric chemists and earth system scientists. Outreach efforts in the scientific community were in the form of conference presentations and peer-reviewed articles, enumerated under "Products." In addition, Dr. Aronson hosted two workshops, one at UC Riverside and the other at Argonne National Labs, of scientists involved in Critical Zone research from around the country. The findings of the Aeolian Transport project were disseminated to these groups. The secondary target audience was high school students near University of California (UC) at Riverside and Merced. In this period, we have had one Riverside, CA, high school student participate in the Restoration Impacts project as part of her science fair project. In addition, the postdoctoral researcher on this project gave a talk on our Aeolian Transport findings to a group of Middle School students in Merced, CA. Dr. Aronson also participated in Discover Day on UCR campus and discussed all aspects of this project with high school students who had been accepted for entry into UC Riverside. The tertiary target audience for this study has been land managers working to eradicate invasive plant species from managed lands. In particular, we worked directly with San Diego, Orange and Los Angeles county land managers to collect samples of invasive plants, including Brachypodium spp., and remediate legacy effects with targeted restoration activities. Further, we will work with these land managers to devise microbe-based biocontrol for invasive plants, and treatments for legacy effects. The final target audience for this study has been plant nursery owners, who are battling invasive gastropods on a regular basis. We have worked with them to collect invasive slugs, which are eating nursery plants, and are investigating their microbiomes for potential biocontrol. We are building connections with these nursery owners to test potential biocontrol strategies at the nurseries, in association with these nursery personnel. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has assisted in the training of one postdoctoral researcher in the pursuit of multiple objectives. In addition, this project has so far supported the training of three graduate students, and several undergraduate students from UC Riverside. This training took place in the field sites in Spain and California, as well as in the laboratory at UC Riverside and at the Universidad de Zaragoza in Huesca, Spain. All three graduate students, the postdoctoral researcher, and Dr. Aronson, participated in multiple conferences and workshops, including special Organized Oral Sessions at the Ecological Society of America Meeting, and the workshops organized by Dr. Aronson. How have the results been disseminated to communities of interest?Dr. Aronson gave departmental seminars at the University of California, Riverside, to the Departments of Plant Pathology and Microbiology, as well as the Department of Biology, which included early findings of this research project. Dr. Chelsea Carey, the postdoc supported by this grant, spoke to a classroom of 7th graders in Merced, CA, live via Skype, and told them about the research we have performed this year and initial outcomes. Dr. Aronson also participated in Discover Day on UCR campus and discussed all aspects of this project with high school students who had been accepted for entry into UC Riverside. Initial findings have been disseminated via informal meetings and field trips by project personnel with land managers in Southern California regions impacted by Brachypodium distachyon and/or hybridum invasion, as well as nursery owners. In addition, Dr. Aronson hosted two workshops, one at UC Riverside and the other at Argonne National Labs, of scientists involved in Critical Zone research from around the country, these workshops also involved the postdoc and one of the graduate students working on this project. What do you plan to do during the next reporting period to accomplish the goals?Research will continue in all areas, we will continue to publish the results, and we will host more and more varied workshops and conference symposia to highlight the issues and results of this project and other compatible research. Field work is increasing, lab analysis and data analysis are growing and we are publishing data at a more rapid rate than ever before.

Impacts
What was accomplished under these goals? The overall impact of this project has been a set of changes in knowledge about how microorganisms disperse around the globe, and their ecosystem-scale effects in soil communities. In terms of aeolian dispersal of bacteria, through repeated sampling of dry dust, rain-associated dust and snow in the Sierra Nevada mountain range, we have found that microorganisms in deposited dust differ by elevation, and may sometimes originate from across the globe. We also found that the microorganisms in snow differ from both the co-located dust and soil microbial communities, and may be dominated by cyanobacteria. In terms of invasive plants and restoration, we found from numerous sampling campaigns in California and Spain, that invasive grass roots vary by genus in their selectivity to root endophytic bacteria. Further, we found that invasive grass legacy effects preventing the restoration of native shrubs may be through the manipulation of the soil microbial community, and we propose methods to counteract these effects. In terms of invasive gastropods, we have sequenced the first set of slug microbiomes using next-gen sequencing. 1) Aeolian Transport: Activities performed included monthly to bi-monthly monitoring of the aeolian transport of dust and soil, and analysis of these samples for nutrient, microbial and isotopic composition. We found that dust inputs to the Sierra Nevada Mountains of California are coming from as far away as the Gobi Desert of China. Dust inputs to lower elevations were more likely to be from regional sources in the Central Valley, CA, while the higher elevations were more likely to receive dust inputs from farther away. Throughout the spring to summer months, as time progressed so did the drought, which we had predicted would bring regional Central Valley inputs to ever higher elevations. This was borne out in the data, which showed a regional source was increasingly prevalent in the samples at the middle to higher elevations over the course of the summer. We also found that microbial communities found to be co-deposited with the dust differed from the soils at all locations and timepoints. These microbial communities were found also to differ with elevation, however the microbial communities at a lower elevation were often found to be similar to the community at the next-highest elevation during the following month of sampling throughout the summer. This microbial community trend followed that of the dust provenance (location of origin). 2) Invasive Plants: Activities performed have included collections of Brachypodium species and nearby grasses and soils in both Spain and California in May of each year, and analysis of these samples for microbial composition. We found that the microbial communities of the roots, rhizosphere, and bulk soils, are distinct. Within each plant genus, these sample groups share between 3.1% and 14.8% of microbial taxa, with bulk and rhizosphere soils being more similar than either is to samples of only roots. Analysis also showed that most locations had distinct soil and root microbial communities. In addition, while root endophyte microbial communities were distinct between Brachypodium spp. and Bromus spp., the rhizosphere and bulk soil communities overlapped. Further, there were almost twice as many overlapping microbial species between the rhizosphere and root communities in the Brachypodium samples as there were in the Bromus samples. These findings lead to the initial conclusion that grass roots select from their surrounding rhizosphere communities, and that Brachypodium spp. roots may be less selective than Bromus spp. These findings also indicate that grass root endophyte communities are unique between plant genera, while nearby soil communities are not. 3) Restoration Impacts: Activities performed include soil and plant sample collections before, and during various stages of restoration, experimental soil manipulations in greenhouses, as well as analysis of these samples for microbial composition. For a project involving native plant restoration in the coastal sage scrub ecosystem in the Santa Monica Mountains in California, we found that native soil microbes were beneficial to native plant growth than the same soil without these microbes. This was determined in a greenhouse experiment, wherein, after 7 months of growth, the native plants showed better growth in unsterilized native soil than sterilized native soil. Artemesia californica, a local native shrub, had a 3:1 mortality ratio for plants grown in sterilized vs. unsterilized native soil, while S. leucophylla, another native plant, had a 2:1 mortality ratio for plants grown in sterilized vs. unsterilized native soil. 4) Gastropod Microbiomes: Activities included collections of invasive terrestrial gastropods from plant nurseries, growth of these gastropods in the vivarium, microbial DNA extraction from these samples, and analysis of these samples for microbial composition. We have currently identified 119 isolates representing 38 bacterial groups from the slug/nematode association from a total of 4 different invasive slug species- Deroceras, Milax, Limax and Arion. This bacterial isolates, from Phasmarhabditis spp., will therefore be the focus of the infectivity study. In addition, next-gen sequencing was used to sequence two individuals from different invasive slug species, and found that their microbiomes were quite different, and included soil microorganisms not known to be slug-associated. 5) Desert Drought: Activities included field experiments to wet and N-fertilize soil, soil greenhouse gas (GHG) flux measurement and analysis of these soil samples at multiple time-points post-treatment for microbial composition, including DNA. We have found large NOx and N2O fluxes out of desert soils in response to N addition with a water pulse. However, we found these fluxes to be greater in a high N deposition site than in a low N deposition site.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Arogyaswamy, K. and E. Aronson. Complex microbiome and methane flux changes in response to metals in transitional grassland soil. Proceedings of the Annual Meeting of the Ecological Society of America.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Carey, C. S. Hart, C. Riebe, S. Aciego, M. Blakowski, and E. Aronson. 2015. The role of elevation and time in structuring soil microbial communities in the Sierra Nevada Mountains, California. Proceedings of the Annual Meeting of the Ecological Society of America.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Pickett, B., I. Irvine, and E. Aronson. 2015. Remediating the Microbial Legacy Effects of Invasive Grasses for Restoration Purposes. Proceedings of the Annual Meeting of the Ecological Society of America.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Aronson, E., C. Carey, C. Riebe, S. Aciego, M. Blakowski, and S.C. Hart. 2015. Aeolian deposit microbial communities differ along an elevation gradient in the Southern Sierra CZO. Proceedings of the Annual Meeting of the Ecological Society of America.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Aronson, EL., and S. Allison. 2014. Drought and N addition control grassland soil GHG flux and microbial composition. Proceedings of the Annual Meeting of the Ecological Society of America.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Zimmerman N., J. Izard, C. Klatt, J. Zhou and E.L. Aronson. 2014. The Unseen World: Environmental Microbial Sequencing and Identification Methods for Ecologists. Frontiers in Ecology and the Environment 12(4), 22431.
• Type: Journal Articles Status: Under Review Year Published: 2016 Citation: Carey, C., N. Dove, M. Bemen, S. Hart, and E. Aronson. 2016. Meta-analysis reveals ammonia-oxidizing bacteria respond more strongly to nitrogen addition than ammonia-oxidizing archaea. Soil Biology and Biochemistry.
• Type: Journal Articles Status: Under Review Year Published: 2016 Citation: Carey, C.J., S.C. Hart, S. Aciego, C. Riebe, M. Blakowski, and E.L. Aronson. 2016. Microbial community structure of subalpine snow in the Sierra Nevada, California. Arctic, Antarctic and Alpine Research.
• Type: Journal Articles Status: Under Review Year Published: 2016 Citation: Collins, C., C. Carey, E. Aronson, C. Kopp, and J. Diez. 2016. Direct and indirect effects of native range expansion on soil microbial community structure and function. Journal of Ecology.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Aronson, E., E. Mayorga, F. Meyer, and A. Packman. 2015. Barriers and potential solutions for Critical Zone data integration between environmental genomics and the geosciences. Proceedings of the Annual Meeting of the American Geophysical Union.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Aronson, E.L., C.J. Carey, C. Riebe, S.M. Aciego, and S. Hart. 2014. Altitudinal Contrasts in Drought-Driven Aeolian Microbial Inputs to Montane Soil Ecology: Impacts of a 500-Year Drought in the Sierra Nevada, California. Proceedings of the Annual Meeting of the American Geophysical Union.
• Type: Conference Papers and Presentations Status: Under Review Year Published: 2016 Citation: Aronson, E.L. C. Carey, J. Botthoff, and P. Catalan. 2016. Co-occurring grasses share similar rhizosphere microbial communities, but differ in root endophytes. Proceedings of the Annual Meeting of the Ecological Society of America.
• Type: Conference Papers and Presentations Status: Under Review Year Published: 2016 Citation: Aronson, E.L., C. Carey, A. Packman, N. Lu, E. Mayorga, S. Owens, F. Meyer and L. Stanish. 2016. NEON-CZO Microbial ecology and biogeochemistry data integration and cross-site comparison. Proceedings of the Annual Meeting of the Ecological Society of America.