Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

A low organic matter soil does not maintain a native grassland restoration in the Colorado front range.

Abstract

A study was conducted to reevaluate the grassland restoration previously surveyed back in 2004 at the University of Colorado's south Boulder campus property. Point-intercept methods were used to quantify plant cover in 2004 as well as 2016, resulting in 36 quadrats in 2004 and 76 quadrats in 2016. 79[%] of the dominant plant cover in 2004 were composed of Sporobolus airoides, Agropyron smithii, and Bouteloua gracilis, while in 2016, Bromus tectorum (cheatgrass) and Bromus arvenisis joined S. airoides to account for the 75[%] of the vegetation cover. S. airoides remained dominant while the other natives diminished, once rare invasive B. tectorum become the second most abundant, and introduced B. arvenisis became the third most common plant. The relative cover of introduced species increased from 8-10[%] in 2004 to 55[%] of cover in 2016. Having a drier climate, point-intercept "hits" dropped from 112 hits per 100 points in 2004 to 83 hits per 100 points in 2016, resulting in more bare ground. In addition, observed dried stems of numerous species that flowered in 2015 have senesced in 2016, thus pointing that the drier climate affected the subsequent survey. In 2004, carbon averaged 1.25[%] and nitrogen averaged 0.10[%] from 80 samples measured, while in summer 2016, carbon averaged 1.44[%] and nitrogen averaged 0.11[%] from 10 samples measured. However, additional nitrogen inputs coming from N fixation, atmospheric N deposition, and proximity to a major freeway may be influencing vegetation change. Through these criteria, previous grassland restoration cannot be deemed successful. The use of seed mix made the site vulnerable to invasive species, and a low carbon, low nitrogen soil cannot guarantee preventing invasions in restored grasslands.