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To investigate the impact of removing a plant species on C- and N-mineralization, we sampled four existing, independent plant removal experiments located at four locations along an elevational gradient near the Rocky Mountain Biological Laboratory, Gothic, Colorado, USA. Each of the four experiments removed different focal plant species, and the experiments have been running from five to seventeen years. A dominant plant species was removed at each site along the elevational gradient, but because there is nearly complete turnover of the plant community across the elevational gradient, the identity of the removed species was different at each elevation, confounding the functional type of the removed species as well as environmental conditions across the elevational gradient. At the low elevation site, located at 2740 m asl (38.71 N, -106.82 W), we removed the dominant plant species Wyethia x magna (Asteraceae), a perennial forb that is a stable hybrid of Wyethia amplexicaulis and W. arizonica (Weaver, 1915), by clipping aboveground biomass to the soil surface annually for five years prior to sampling. Plots at this site were 2.0 m × 2.0 m in area (n = 8). Soils at the low elevation site were classified as Mayoworth loam. At the mid-low elevation site, located at 2890 m asl (38.95 N, -106.98 W), we maintained a seventeen-year removal of Linaria vulgaris (Plantaginaceae), a perennial, invasive forb with an extensive horizontal root system, in 2.0 m × 2.0 m (n = 6) (Wilke and Irwin, 2010). Plants were removed from the mid-low elevation site by gently pulling on the base of the plant to remove the plant and a small portion of the L. vulgaris root mat. Soils at the mid-low elevation site were classified as Tine sandy loam and Bassel sandy loam, depending on the slope of each plot. At the mid-high elevation site, we removed Festuca thurberi (Poaceae), a perennial grass that forms shallow but dense root systems, by clipping to the soil surface annually for seven years prior to sampling. Removal treatments at the mid-high elevation site (2904 m asl, 38.94 N, -106.99 W) were applied in 1.5 m × 1.5 m (n = 4) (Read et al., 2018, Henning et al., 2019), with soils at this site classified as Leaps silty clay loam. In the W. magna and F. thurberi removals at the mid-high and low elevation sites, a small amount of glyphosate herbicide was applied to the remaining base of the stems after the aboveground biomass was removed to attempt to kill belowground biomass. Herbicide was only applied to stem bases at these sites for the first two years of the removal treatments, and because of the meticulous way in which it was applied to the base of the remaining stems following removal using a paintbrush, we are confident that herbicide application had negligible effects on the fitness of the other plant species. At the high elevation site (3460 m asl, 38.99 N, -107.06 W), we removed the dominant species Juncus drummondii (Juncaceae), a perennial rush that grows in thick bunches, by clipping aboveground biomass to the soil surface annually for five years before sampling. Plots at this site covered an area of 2.0 m × 2.0 m (n = 8). Soils at the high elevation site were classified as Moran-Rubble land complex, characterized by extremely gravelly loam/sandy loam. Roots of the removed plants species were left intact at all sites that used clipping to removed aboveground biomass in removal treatments (low, mid-high, and high elevation sites) in order to minimize disturbance caused by the removal treatment for the remaining plant species and the soil community. While L. vulgaris individuals were removed by tugging gently on the base of the stem, removing some root biomass in the process, the majority of the root runners that extend horizontally just beneath the soil surface remained behind in the soil. In addition to the control (i.e., no plant biomass removed from plots with the focal species naturally present) and individual species removal treatments present at all sites, the mid-low and mid-high elevation sites had an additional random biomass removal treatment where biomass from random plant species was removed to reflect the amount of biomass that was removed annually from the treatments in which a specific plant species was removed. This treatment was intended to isolate the disturbance effect that plant removal has on the remaining plant community through loss of aboveground biomass. Finally, a natural control treatment, i.e. plots where the focal plant species was naturally absent, existed at the mid-low elevation site. During the peak of the 2018 growing season, when aboveground biomass was greatest at each site, we conducted plant community surveys by visually assessing the percentage of the plot area covered by each plant species. Rare species were recorded as covering < 1 %. At the low, mid-high, and high elevation sites, data were collected annually on the amount of plant biomass removed from each plot that received a removal treatment by collecting removed biomass in paper bags and drying the plant biomass for 48 h at 60 °C. We calculated the average amount of biomass removed annually from each plot by pooling the total amount of biomass removed over the entire length of the experiment at each site, and dividing this cumulative number by the length of each experiment in years. On July 23rd-25th, 2018, we took two separate soil cores (< 15 cm deep), one for the potential mineralization incubation and one for extracellular enzyme assays, from random locations within each plot. Soil samples were refrigerated and transported to the University of Vermont, Burlington, VT USA for processing. We sieved each sample to remove rocks and large plant material (> 2 mm) and measured gravimetric water content (g H2O g-1 dry soil) by drying 10 g of field-moist soil in an oven at 105 °C for 48 hours (Robertson et al., 1999). We measured soil organic matter content using the loss on ignition method (SOM-LOI) by combusting oven-dried soil samples (105 °C) at 550 °C for six hours, and then measuring SOM-LOI (g C kg-1 dry soil) by quantifying the mass difference between oven-dried and combusted soil samples (Hoogsteen et al., 2015). To measure the effect of plant removal on potential C- and N- mineralization in soils under standardized environmental conditions, we conducted a 30-day laboratory incubation of soils exposed to ideal moisture and temperature conditions (30% volumetric water content, 20 °C) (Robertson et al., 1999). 30% volumetric water content was the maximum soil moisture content recorded during the growing season at these four sites in the two years preceding this study, so this moisture threshold was chosen to represent ‘ideal’ but realistic conditions under which we could investigate the full capacity of the microbial community in sampled soils to mineralize C and N. We divided field-moist soil samples from each plot into paired 10 g subsamples. One subsample was extracted immediately using a 2.0 M KCl solution to measure extractable NH4+ and NO3-. We incubated the second subsample in the dark for 30 days in 1 L clear, glass jars fitted with rubber septa in the metal lid. We measured the CO2 evolved in the headspace of the jars via direct injection by using a syringe to sample the air in each sealed jar and injecting 7 mL of air into a LI-COR 7810 trace gas analyzer (LI-COR Instruments, USA) at six time points (days 1, 2, 4, 8, 16, and 30 of the incubation) to track potential C-mineralization (µg C g-1 dry soil day-1). At the completion of the incubation, we extracted the incubated soil subsample with 2 M KCl to again measure extractable NO3- and NH4+ concentration. We measured the concentration of NO3- and NH4+ in the extractions colorimetrically (Doane and Horwath, 2003) using a Synergy HT microplate fluorimeter/spectrophotometer (Synergy HT, Biotek Inc., Winooski, VT, USA). We then calculated total N-mineralization rates by subtracting the sum of NO3- and NH4+ (i.e., inorganic N) in the initial subsample from the sum of extractable inorganic N in the final subsample and dividing the amount of inorganic N produced during the reaction by the length of the incubation in days (mg N kg-1 dry soil day-1). In addition to a laboratory incubation of soils to measure N- and C-mineralization rates, we measured the activities of six different soil extracellular enzymes to understand how plant removal impacts potential microbial activity. Using the protocol established by Saiya-Cork et al. (2002), we assayed the carbon degrading enzymes α-glucosidase (AG), β-glucosidase (BG), Cellobiohydrolase (CBH), and β-Xylosidase (XYL), nitrogen acquiring enzyme β-N-acetylglucosaminidase (NAG), and phosphorus acquiring enzyme Acid phosphatase (PHOS). All assays were performed by incubating enzymes in a soil slurry prepared with a buffered solution (pH 5.0 sodium acetate buffer) at an ideal temperature (20.0 °C) with non-limiting amounts of substrate. Following incubation, potential enzyme activities were quantified using a Synergy HT microplate spectrophotometer (Biotek Inc., USA). References Doane TA, Horwáth WR. 2003. Spectrophotometric Determination of Nitrate with a Single Reagent. Analytical Letters 36: 2713–2722. Henning JA, Read QD, Sanders NJ, Classen AT. 2019. Fungal colonization of plant roots is resistant to nitrogen addition and resilient to dominant species losses. Ecosphere 10: e02640. Hoogsteen MJJ, Lantinga EA, Bakker EJ, Groot JCJ, Tittonell PA. 2015. Estimating soil organic carbon through loss on ignition: effects of ignition conditions and structural water loss. European Journal of Soil Science 66:320–328. Read QD, Henning JA, Classen AT, Sanders NJ. 2018. Aboveground resilience to species loss but belowground resistance to nitrogen addition in a montane plant community. Journal of Plant Ecology 11: 351–363. Robertson GP, Coleman DC, Bledsoe CS, Sollins P. 1999. Standard Soil Methods for Long-Term Ecological Research. Oxford, New York: Oxford University Press. Saiya-Cork KR, Sinsabaugh RL, Zak DR. 2002. The effects of long term nitrogen deposition on extracellular enzyme activity in an Acer saccharum forest soil. Soil Biology and Biochemistry 34: 1309–1315. Weaver JE. 1915. A study of the root-systems of prairie plants of Southeastern Washington. The Plant World 18: 227–248. Wilke BJ, Irwin RE. 2010. Variation in the phenology and abundance of flowering by native and exotic plants in subalpine meadows. 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