Introduction

Rangelands are crucial part of the global ecosystem, covering an estimated at 54% of the world’s terrestrial area (Teillard et al. , 2016). They are home to a wide variety of plants, animals, and microbes that are of ecological, economic, and cultural significance (Seid, Kuhn and Fikre, 2016). Rangeland also provides about 70% of the global forage for both domestic and wild ungulates through grazing and browsing (Derner et al., 2006). In Africa, rangeland coverage is estimated about at 43% of the total land area, and at 62% of Ethiopia’s total landmass, making them a primary source of feed for ruminants, and an important habitat for dry-land biodiversity. However, the arid and semi-arid rangeland ecosystems face degradation from poor management, population growth, deforestation, continuous overgrazing, as well as land use and climate changes (Oba and Kotile, 2001; Maitimaet al. , 2004; Miehe et al. , 2010). The loss of traditional indigenous knowledge and the decline in participation of the elders in rangeland management are the leading causes of this degradation (Oba, 2012; CARE, 2015), resulting in the decline of rangeland resources and biodiversity, negatively impacting forage production and conservation efforts.
Pastoralism, with its inherent traditional rangeland management practices, has shaped rangeland environments for thousands of years. Traditional grazing management practices have a significant impacts on the vegetation attributes of rangelands, such as composition, diversity, and biomass yield (Abate et al., 2010; Angassa et al., 2010; Angassa & Beyene, 2003; Briske et al., 2008; Gordon & Iii, 2017). For example, the pastoralists in east Africa have been using enclosures to enhance plant productivity and establish mixed forage more effectively (Angassa and Oba, 2010a, 2010b; Haftayet al. , 2013; Wairore et al. , 2016). Several studies ( e.g. Teshome Abate et al., 2009; Abule et al., 2007; Beyene & Kenee, 2008; FAO, 2017; Terefe et al., 2010) show that a livestock mobility grazing strategy favors biodiversity conservation and sustainable rangeland management. Conversely, areas with limited mobility may experience overgrazing, which endangers biodiversity conservation and reduces biomass yield. Excessive grazing can also decrease the fuel load, resulting in less intense fires and less damage to trees, leading to an increase in woody vegetation (McGinty, Baldwin and Banner, 2009; Bikila, Tessema and Abule, 2016; Mekuriaw, Mengistu and Tegegne, 2019). Thus, balancing traditional indigenous knowledge and involving elders in rangeland management is essential for ensuring the sustainability of rangelands and positively impacting rangeland ecosystems, livestock production, and the livelihoods of the pastoral communities.
The Somali Regional State in Ethiopia is predominantly a pastoral ecosystem with 90% of its area being rangeland (Gezahegn, 2006). In this region, there are around 800 endemic plant species out of the total 1600 found in the country, which makes up a quarter of Ethiopia’s flora (Barkhadle, Ongaro and Pignatti, 1994). Pastoralists in this area use various traditional rangeland resource management strategies such as enclosures and splitting of herds. Enclosures are one of the various management and rehabilitation strategies that are used to improve species diversity, cope with drought and ecosystem productivity. They also split their herds based on patchy resource distribution to ensure optimum resource utilization, as different domestic animals have different feed preferences. For example, the dominant animals in browsing complex areas are goats and camels, while cattle and sheep are raised in grazing complex areas. However, the potential benefits of these alternative management practices have often been overlooked by extension and research services, and little is known about changes in vegetation attributes resulting from these grazing practices. Therefore, this study investigates the effects of three grazing management practices (enclosure, open grazing, and browsing lands) on herbaceous and wood species composition, richness, diversity, biomass yield, and wood density and canopy cover.