Experimental tree removal in tallgrass prairie: variable responses of flora and fauna along a woody cover gradient

Abstract

Abstract. Woody plant encroachment is a worldwide phenomenon in grassland and savanna systems whose consequence is often the development of an alternate woodland state. Theoretically, an alternate state may be associated with changes in system state variables (e.g., species composition) or abiotic parameter shifts (e.g., nutrient availability). When statevariable changes are cumulative, such as in woody plant encroachment, the probability of parameter shifts increases as system feedbacks intensify over time. Using a Before-After Control-Impact (BACI) design, we studied eight pairs of grassland sites undergoing various levels of eastern redcedar (Juniperus virginiana) encroachment to determine whether responses of flora and fauna to experimental redcedar removal differed according to the level of pretreatment redcedar cover. In the first year after removal, herbaceous plant species diversity and evenness, woody plant evenness, and invertebrate family richness increased linearly with pretreatment redcedar cover, whereas increases in small-mammal diversity and evenness were described by logarithmic trends. In contrast, increases in woody plant diversity and total biomass of terrestrial invertebrates were accentuated at levels of higher pretreatment cover. Tree removal also shifted small-mammal species composition toward a more grasslandassociated assemblage. During the second year postremoval, increases in herbaceous plant diversity followed a polynomial trend, but increases in most other metrics did not vary along the pretreatment cover gradient. These changes were accompanied by extremely high growingseason precipitation, which may have homogenized floral and faunal responses to removal. Our results demonstrate that tree removal increases important community metrics among grassland flora and fauna within two years, with some responses to removal being strongly influenced by the stage of initial encroachment and modulated by climatic variability. Our results underscore the importance of decisive management for reversing the effects of woody plant encroachment in imperiled grassland ecosystems.

Past, present, and future distribution of Afromontane rodents (Muridae: Otomys) reflect climate-change predicted biome changes

“…Bush encroachment of savanna and grasslands has implications for biome-specific floral and faunal assemblages with avian studies, for example, showing a rapid turnover in species composition and negative effects on diversity (Hahn 2006, Sirami and. Conversely, experimental tree removal in grasslands being encroached has been shown to rapidly increase important native floral and faunal community metrics (Alford et al 2012). Our study shows a historical shift in species composition in a bush encroached landscape further at risk from climate change, underscoring the need for historical perspective in modeling future changes.…”

A dryland re‐vegetation in northern China: Success or failure? Quick transitions or long lags?

“…Yet, data from restorations are often sparse to judge long‐term trajectories or lack the temporal resolution to measure time lags (Suding , Alford et al. , Halpern et al. , Korb et al.…”

Landowners' perceptions of risk in grassland management: woody plant encroachment and prescribed fire

“…In more recent times, eastern redcedar expansion has converted vast expanses of Oklahoma and Kansas from open prairie rangelands to closed canopy woodlands (Briggs et al 2002a, Engle et al 2008. The ecological consequences of this conversion can be profound, including radical changes in grassland bird and small mammal communities and altered soil chemical and hydrologic properties (Chapman et al 2004, Coppedge et al 2004, Pierce and Reich 2010, Alford et al 2012. Furthermore, economic loss to agricultural producers is manifested in substantially reduced forage production (Ortman et al 1998).…”