Can a Mesic Grassland Mosaic Recover from Thicketization? Insights from Seven Years Monitoring Species Abundance

Abstract

This study examines a 65-ha botanically rich grassland mosaic with extensive woody encroachment to determine whether prairie habitat can be restored over a six-year period post treatment. A stratified sample design was utilized for vegetation monitoring. Two vegetation types, Prairie and Old Field, were identified from baseline differences in species composition. Additional plots also were established in relatively undegraded prairie habitat. This Reference Prairie provided a restoration benchmark for Transect Prairie and Old Field on transects. Management efforts resulted in a 95% reduction of woody stems, which were cut, piled, and burned on site. Cut stems were removed by hand in Reference Prairie; however, a compact track loader was used in remaining zones. Vegetation parameters of conservation interest based on species composition and diversity were utilized as predictor variables. We establish testable hypotheses and a statistical framework for evaluating mean differences and patterns of change among vegetation types.

Reference Prairie retained baseline levels of floristic diversity and species integrity. However, it took six years for Transect Prairie to recover to baseline conditions. Old Field increased in native and non-native species richness leading to a floristic merger with recovering Transect Prairie; however, restoration goals fell short as Reference Prairie remained distinct in habitat quality from both successional community types. Our data suggest that population declines among resident species in Transect Prairie were a response to the more invasive management techniques. We recommend more gradual management practices to minimize the impacts of heavy equipment utilized for rapid and efficient treatment.