Does Conservation Practice and Site Age Influence Vegetation Structure and Avian Abundance in Restored Fields?

Abstract

ABSTRACTFarmland set‐aside programs provide important habitat for many wildlife species, yet little information exists regarding how vegetation structure and species respond to conservation practice and site age. This information could provide managers with a guide for how to implement, enhance, and maintain wildlife benefits of conservation programs. We describe how vegetation structure and avian species respond to conservation practice and time since restoration at 172 sites enrolled in the Conservation Reserve Enhancement Program (CREP) in Illinois, USA. We surveyed 172 sites enrolled in 4 different conservation practices (CP) within CREP during the breeding seasons of 2012–2015 using avian point counts and vegetation surveys. Vegetation structure and composition varied among CPs, with hardwood tree plantings (CP3A) having the greatest amount of understory vegetation and tree cover. Conversely, permanent wildlife habitat (CP4D) had the greatest grass cover and least tree cover. Many bird species were found in similar numbers across CP types; however, only dickcissel (Spiza americana) density was greater in sites enrolled as permanent wildlife habitat. Bell's vireo (Vireo bellii) and yellow‐billed cuckoo (Coccyzus americanus) were more numerous in hardwood tree plantings. Dickcissel density decreased and field sparrow (Spizella pusilla) density increased as fields aged, but the relationships were not consistent among CP types. Differences among CPs largely resulted from differences in dominance in woody vegetation due to initial habitat management and differential succession rates. Interestingly, many of our focal species had wider successional tolerances than previously suggested. Overall, our results demonstrate that conservation benefits change over time depending on the starting CP, that there can be considerable similarity in vegetation structure and bird communities among what appear to be very different conservation practices. This information can be used to target conservation benefits toward conservation priority species. © 2020 The Wildlife Society.