Vegetation Change in a Sand Prairie over Ten Years Following a Gas Pipeline Installation

Sand prairies experience relatively high rates of small-scale disturbance, feature a high complement of annual plant species, and are fairly dynamic in terms of year-to-year micro-scale species composition. In summer 2011, an underground natural gas pipeline was installed across Sand Prairie Natural History Reservation 19 km west of North Newton, KS. The resulting excavation left a strip 560 m long and 24 m wide devoid of aboveground vegetation. From August 2012 to 2021, I monitored vegetation composition in 60 0.75 × 0.75 m2 quadrats along six parallel transect lines: three lines along the center of the excavated area and three placed 20 m away in prairie unaffected by earth-moving vehicles. Quadrat species richness was higher in the undisturbed reference area in the first year, but higher in the pipeline area in four later years. There were no consistent area differences in species evenness. Annual species richness was higher within the pipeline area every year. In contrast, perennial species richness was higher in the reference area during the first seven years. Coverage by annuals was higher every year within the pipeline area, whereas coverage by perennials was consistently higher in the reference area. Bray-Curtis Similarity for the two areas ranged from 29.2 to 55.8% across years, but was not trending upward with time. Twenty-one species were restricted to the pipeline area; several other species were beginning to move from the reference area to the pipeline area. Both Floristic Quality Index and modified FQI were consistently higher for the reference area than for the pipeline area. It is too early to project the time frame for the pipeline area to recover a species composition indistinguishable from the undisturbed reference site, but clearly a period longer than ten years will be required.