Clipping and irrigation enhance grass biomass and nutrients: Implications for rangeland management Samuel Tuffa a, b, * , Dana Hoag c , Anna C. Treydte b, d a Yabello Pastoral and Dryland Agriculture Research Centre, P. O. Box 85, Yabello, Ethiopia b Department of Agroecology in the Tropics and Subtropics, University of Hohenheim, Garbenstr. 13, University of Hohenheim, 70599 Stuttgart, Germany c Department of Agricultural and Resource Economics in the College of Agricultural Sciences, Colorado State University, USA d Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania article info Article history: Received 26 September 2016 Received in revised form 4 April 2017 Accepted 3 May 2017 Keywords: Borana rangelands Crude protein Ethiopia Herbivory Semiarid abstract Increasing frequency of drought and high herbivore pressure significantly affect individual grass func- tions in semiarid regions. Reseeding of degraded rangelands by native grass species has been recom- mended as a tool for restoration semiarid rangelands. However, how grass species used for reseeding respond to stressors has not been fully explored. We examined biomass allocation and nutrient contents of Cenchrus ciliaris and Chloris gayana in the semiarid Borana rangelands, Ethiopia. We tested clipped mature tufts of the same species for biomass allocation and nutritive values. Further, shifts in rainfall and herbivory were simulated by three irrigation and four clipping treatments, respectively, for newly established grasses in pot and field plot experiments. Aboveground biomass (AG B ) significantly declined by up to 75% under increased clipping in mature tufts. In contrast, clipping significantly stimulated up to 152% higher AG B of newly established grasses. Lower irrigation reduced the AG B by 24 and 42% in C. ciliaris and in C. gayana, respectively. Clipping, further, significantly enhanced grass nutrients in grass tufts by up to 82 and 105% in C. ciliaris and C. gayana, respectively. Hence, management should focus on balancing this trade-off in mature grasses for nutritious rangeland production by clipping and storing for later supplemental feeding when grass nutrients drop. Further, young pastures should be moderately clipped/grazed for better establishment and biomass allocation. Additionally, our experiments estab- lished the first interactive effect of clipping and irrigation frequencies on the biomass allocation of native grasses in the semiarid Borana rangelands, Ethiopia. Knowledge of these interacting factors is deemed essential for policy makers to enhance productivity of degraded rangelands such as the Borana rangelands. © 2017 Elsevier Masson SAS. All rights reserved. 1. Introduction Maintaining productivity of rangelands requires extensive knowledge on how vegetation responds to the dominant environ- mental factors such as grazing and climate variability. Rangelands across the world are facing increasing pressure due to overgrazing and climate change (Chimner and Welker, 2011); drought and herbivory are the primary savanna stressors (Baruch and Jackson, 2005). Particularly in eastern Africa, drought and overgrazing have led to deteriorated rangelands and a subsequent die-off of livestock populations after severe droughts (Catley et al., 2014). Generally, climatic stresses account for about 63% of all stressors on land degradation in Africa (Porto, 2014) while overgrazing causes 49% of soil degradation, mainly in semiarid and arid regions of Africa (WRI et al., 1992). Hence, sound management of rangelands including reducing livestock numbers (Abusuwar and Yahia, 2010; Zhang et al., 2015), letting the pasture vegetation recover (Angassa and Oba, 2010), and reseeding with perennial grasses (Mganga et al., 2011; Tebeje et al., 2014) is required. However, often, inten- sive management activities have been neglected as little is known on the resilience of the existing grass species and which grass species would be most suitable for reseeding (Mganga et al., 2013). The effects of herbivory on biomass production have been controversial. Many findings indicated that herbage dry matter yield decreases with increasing herbivory (Kramberger et al., 2014; Yan et al., 2012) but Martin and Chambers (2001) claimed that * Corresponding author. E-mail addresses: satukada@gmail.com (S. Tuffa), Dana.Hoag@colostate.edu (D. Hoag), anna@treydte.com (A.C. Treydte). Contents lists available at ScienceDirect Acta Oecologica journal homepage: www.elsevier.com/locate/actoec http://dx.doi.org/10.1016/j.actao.2017.05.001 1146-609X/© 2017 Elsevier Masson SAS. All rights reserved. Acta Oecologica 81 (2017) 32e39