Non-native, invasive Bromus tectorum (cheatgrass) is pervasive in sagebrush ecosystems in the Great Basin ecoregion of the western U.S., competing with native plants and promoting more frequent fires. As a result, cheatgrass invasion likely alters carbon (C) storage in the region. Many studies have measured C pools in one or more common vegetation types: native sagebrush, invaded sagebrush, and cheatgrass-dominated (often burned) sites, but these results have yet to be synthesized.

We performed a literature review to identify studies assessing the consequences of invasion on C storage in aboveground biomass (AGB), belowground biomass (BGB), litter, organic soil, and total soil. We identified 41 articles containing 386 unique studies and estimated C storage across pools and vegetation types and used linear mixed models to identify the main predictors.

We found consistent declines in biomass C with invasion: AGB C was 55% lower in cheatgrass (40 ± 4 g C m-2) than in native sagebrush (89 ± 27 g C m-2) and BGB C was 62% lower in cheatgrass (90 ± 17 g C m-2) than native sagebrush (238 ± 60 g C m-2). In contrast, litter C was > 4x higher in cheatgrass (154 ± 12 g C m-2) compared to native sagebrush (32 ± 12 g C m-2). Soil organic C (SOC) in the top 10 cm was significantly higher in cheatgrass than in native or invaded sagebrush. SOC below 20 cm was significantly related to the time since most recent fire and losses were observed in deep SOC in cheatgrass systems > 5 years after a fire. There were no significant changes in total soil C across vegetation types.

Synthesis and Applications: Cheatgrass invasion decreases biodiversity and rangeland productivity and alters fire regimes. Our findings indicate cheatgrass invasion also results in persistent biomass C losses that occur with this state change. We estimate that conversion from native sagebrush to cheatgrass leads to a net reduction of C storage in biomass and litter of 76 g C m-2, or 16 Tg C across the Great Basin without management practices like native sagebrush restoration or cheatgrass removal.10-Sep-2020

These data were collected from published studies as either raw data obtained from the study authors or mean values extracted from the study. All data has been cleaned (i.e., homogenized, converted to the same units (g C m-2)) and combined for the five carbon pools in aboveground biomass, belowground biomass, litter, soil organic carbon and total soil carbon in three vegetation types (native sagebrush, invaded sagebrush, cheatgrass). The code for processing and analyzing these data can be found at: https://github.com/nagyrc/C_fire_invasives.

There is a ReadMe file (readme.txt) that contains information and metadata on the primary data file (siwf.csv). There is a list of all data files contained in this repository (list_of_data_files_for_Dryad.txt). Finally, there is a list of references for the original data sources (data_studies_refs.pdf).