Woody Vegetation Removal Benefits Grassland Birds on Reclaimed Surface Mines

Abstract

Grassland birds have declined throughout North America. In the midwestern United States, reclaimed surface mines often provide expanses of contiguous grassland that support grassland birds. However, some reclaimed surface mines often experience severe woody vegetation encroachment, typically by invasive trees and shrubs, including black locust Robinia pseudoacacia, autumn olive Elaeagnus umbellata, and bush honeysuckle Lonicera spp. We conducted point-count surveys to investigate the effects of woody canopy cover and response to treatments of woody vegetation on the abundance of birds. Our treatments were a control, an herbicide application, and an herbicide application followed by cutting and shredding of standing dead woody vegetation. Estimated density of eastern meadowlark Sturnella magna, grasshopper sparrow Ammodramus savannarum, and Henslow's sparrow Centronyx henslowii was 670%, 958%, and 200%, respectively, greater on areas treated with herbicide and shredding and 279%, 666%, and 155%, respectively, greater on areas treated with herbicide-only when compared with control sites. When woody canopy cover increased from 0% to 20%, densities of eastern meadowlark, grasshopper sparrow, and Henslow's sparrow decreased by 83.9%, 74.9%, and 50.7%, respectively. Conversely, densities of eastern towhee Pipilo erythrophthalmus, prairie warbler Setophaga discolor, yellow-breasted chat Icteria virens, and yellow warbler Setophaga petechia increased 67.4%, 57.0%, 34.6%, and 117.7%, respectively, as estimated woody canopy coverage increased from 20% to 60%. Our results showed treating encroaching woody vegetation on reclaimed surface mines with herbicide and shredding increases available habitat used by grassland birds. Maintaining grasslands on reclaimed surface mines at ≤10% woody canopy coverage would be most beneficial to eastern meadowlarks, grasshopper sparrows, and Henslow's sparrows.

Trimming the hedges in a hurricane: Endangered Species lack research on the outcomes of conservation action

“…Surprisingly, the effect of invasive species removal on endangered species was not well studied, and in some contexts we found this action had a negative impact on the target species. For example, the removal of woody vegetation at reclaimed mine sites resulted in lower densities of Yellow-breasted Chat (Icteria virens; Lautenbach et al, 2019), and a herbicide used to reduce the growth of leafy spurge (Euphorbia Esula) had negative effects on growth and reproduction in Western Prairie Fringed Orchid (Platanthera praeclara; Erickson et al, 2006). The unintended negative consequences of these actions on Endangered species reinforce the need to assess the outcomes of conservation actions that have been implemented.…”

The main factors and prospects for the restoration of biodiversity in technogenic territories (on the example of the Poltava Mining and Processing Plant)

“…Most birds feed on widespread insect species, which allows them to quickly colonize new technogenic territories (Devictor et al, 2008). On the contrary, some experts suggest regularly removing woody vegetation in quarries, thus forming a prototype of natural steppe biotopes that are usually ploughed up, which will contribute to the conservation of birds in an open complex (Lautenbach et al, 2019;Koshelev & Pakhomov 2020;Koshelev et al, 2020b).…”

The long shadow of woody encroachment: An integrated approach to modeling grassland songbird habitat

“…While grassland birds exhibit species‐specific responses to herbaceous vegetation, responses to woody vegetation tend to be negative across grassland bird communities (Bakker, 2003). Trees and shrubs are expanding in many grasslands, and woody plant encroachment has been implicated in the decline of grassland‐dependent birds (Coppedge et al, 2001; Lautenbach et al, 2020). Woody vegetation in grasslands is associated with lower occurrence, abundance, nest densities, and nest survival (Bakker, 2003; Coppedge et al, 2001; Ellison et al, 2013; Graves et al, 2010; Lautenbach et al, 2020).…”

“…Trees and shrubs are expanding in many grasslands, and woody plant encroachment has been implicated in the decline of grassland‐dependent birds (Coppedge et al, 2001; Lautenbach et al, 2020). Woody vegetation in grasslands is associated with lower occurrence, abundance, nest densities, and nest survival (Bakker, 2003; Coppedge et al, 2001; Ellison et al, 2013; Graves et al, 2010; Lautenbach et al, 2020). Territory selection may also relate to topography, although few studies have analyzed this relationship (see Renfrew & Ribic, 2002).…”