Zane Ashford - June 2018

It has been a busy past few weeks, both in the field and in the lab. During the last week of May, Dr. Catherine Zabinski, Kristi D’Agati, and I went to the MPG Ranch in the Bitterroot Valley, Montana to collect my soil core samples. And as the name of the game goes with research, our intended sampling plots, consisting of native and invasive forbs, weren’t growing well this year. In order to assess how belowground root traits affect soil quality, it is imperative that we have healthy roots to sample. We made the quick decision to sample another set of plots that have been established since 2011. The study design for these plots consisted of five replications of five plots, four of which were composed of monocultures of invasive weeds – cheatgrass (Bromus tectorum), knapweed (Centaurea stoebe), leafy spurge (Euphorbia esula), and sulphur cinquefoil (Potentilla recta) – and the last plot was a mixed native plant community composed of yarrow (Achillea millefolium), bluebunch wheatgrass (Pseudoroegneria spicate), bottlebrush squirrel-tail (Elymus elymoides), blue flax (Linum lewisii), prairie junegrass (Kolaria macrantha), blue grama (Bouteloua gracilis), beard tongue (Penstemon strictus), aspen fleabane (Erigeron speciosus), and blanketflower (Gaillardia aristate).These plots of native and invasive forbs and weeds will help in addressing my original research questions surrounding how monocultures of different species, both native and invasive, with varying root traits, architecture, and aboveground biomass inputs, affect soil parameters.

Image 1: Cathy and Kristi at our field site on the MPG ranch near Florence, Montana

During my fieldwork, we took two 8-cm cores 15-cm deep within each plot in order to get a representative sample; this provided us with fifty cores for analysis in the laboratory, ten of each species (or group of species).

Image 2: Monoculture of non-native sulphur cinquefoil containing dead biomass from past years along with new growth

Image 3: An 8-cm soil core, taken with a root auger to preserve root structure

Image 4: An entire core extruded from the auger fully intact

Images 5 and 6: Monocultures of non-native leafy spurge

Image 7: Kristi taking a soil core from a knapweed plot

Image 8: Mixed native community

Image 9: Non-native cheatgrass monoculture

After collecting all of our samples on the MPG Ranch, we brought them back to the Zabinski Laboratory to begin analyzing the soil for parameters indicative of soil quality. Firstly, we are extracting the potentially mineralizable nitrogen (PMN) from the soil in order to see how much nitrogen is available to plants within a growing season. This analysis is performed in triplicates in order to get a representative understanding of plant available nitrogen and to account for variability in the soil. Currently, half of our extractions are incubating for the next two weeks to represent nitrogen levels at the end of a growing season, while the other half are in the freezer to estimate nitrogen levels at the beginning of the growing season.

Image 10: Filtering out the soil from the PMN extraction

Additionally, we are extracting enzymes from the soil to understand the potential for nutrient cycling. We are measuring enzymes such as β-glucosidase, β-glucosaminidase, and acid/alkaline phosphatases in order to assess carbon, nitrogen, and phosphorus cycling, respectively. The color of the extractions is then measured to estimate nutrient cycling potential.

Our next step in the lab is to separate roots from the soil to get an understanding of the belowground biomass typical of each species. Hopefully, this will give us a better understanding of how different root traits are affecting soil quality parameters such as plant available nitrogen and nutrient cycling potential.

I have had an incredible experience this summer collecting my own samples and having the opportunity to analyze them myself in the lab. Being able to follow the process from start to finish has been fundamental in my understanding of how much hard work goes into research; however, it just makes the experience that much more exciting and rewarding.


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