Rangelands cover nearly 45% of the world’s land area (Squires et al., 2018). As a common resource, they are mainly used for livestock grazing supporting 50% of the world’s livestock and 78% of global grazing area (Asner et al., 2004; MEA, 2005; Creamer and Horback, 2021). Despite the vital role of rangelands in sustaining the livelihoods of rural people, they are subject to human and climate drivers that can result in reduced production (Jama and Zeila, 2005; Ouled Belgacem and Louhaichi, 2013). Rangelands are especially vulnerable as semi-arid ecosystems experience extreme stress associated with low rainfall (Gamoun, 2016), prolonged periods of drought (Köchy et al., 2008; Gamoun et al., 2011), poor soil fertility, mismanagement, and other human-induced activities (Hanafi and Jauffret, 2008; Vetter, 2009; Zhou et al., 2013). All these factors negatively impact rangeland plant communities (Ouled Belgacem et al., 2013; Belgacem et al., 2019) and lead to changes in soil-plant-water dynamics (Fay et al., 2008; Heisler-White et al., 2009), sparse vegetation, and increases in the spread of invasive species (McNeely, 2004; Wang et al., 2018).

Rangelands offer habitats for wildlife and provide multiple goods and services of economic value (Yu et al., 2010). However, as rangelands become degraded, their potential to provide these services diminishes (Favretto et al., 2016). Overgrazing remains the primary anthropogenic factor impacting arid and semi-arid vegetation (Smet and Ward, 2005; Gamoun, 2013; Louhaichi et al., 2019). Associated with overstocking and drought, overgrazing further contributes to degradation resulting in reduction in biodiversity and rangeland productivity (Harris, 2010; Squires, 2010; Teague et al., 2011; Gamoun et al., 2016).

The impact of grazing on rangelands depends mainly on its intensity and timing (Holechek et al., 1998; Henkin et al., 2007). For example, light to moderate grazing may not affect productivity or species richness while heavy grazing often reduces vegetation by preferential removal of the more palatable species preferred by grazing animals (Louhaichi et al., 2009; Schönbach et al., 2009; Gamoun, 2014). Under heavy grazing, shrubs develop very dense small branches that protect their leaves and allow continued plant growth (van Duivenbooden, 1993).

In the late 1960s, the concept of high-stocking-density grazing for short periods was first introduced in North America by Goodloe (1969) and further developed by Savory in the 1980s (Savory, 1978). It quickly became a widely popular but controversial tool for grazing management. In this grazing scheme, a rangeland is divided into several paddocks grazed one at a time, allowing plants enough time to recover (Goodloe, 1969; Savory, 1978; Joseph et al., 2002). Another widespread grazing strategy is herd mobility. Livestock mobility is based on a deep knowledge of rangeland vegetation and is referred to as “opportunistic grazing” (Behnke et al., 1993; Scoones, 1995). This type of grazing management is often independent of stocking density and is guided more by inter-annual rainfall variation. Through their pastoral networks, herders know where the best rangelands are and when to use them (Bassett and Koné, 2006). Eventually, opportunistic grazing formalizes optimal relationships between livestock and the environment (McCabe, 2004) and has proven to be effective in terms of enhancing livestock performance and vegetation productivity (Suttie et al., 2005).

Rangelands in some areas of Tunisia continue to degrade with no restrictions on stocking rate (Belgacem et al., 2019). Their future sustainability will depend on identifying and promoting sustainable rangeland management practices that are environmentally sustainable and socially acceptable to local pastoral communities. Toward this end, the Government of Tunisia launched a national strategy for rangeland improvement in 1990. Since then, thousands of hectares covering natural rangelands, including private and collective lands, have been managed by simply excluding livestock grazing for 3 years. The program has played a paramount role in alleviating pressure on already fragile degraded arid rangelands, especially during dry years. Nevertheless, during years with sufficient rainfall, vegetation response to the wet season is phenomenal, even after only a few months of protection (Sullivan and Rohde, 2002).

Unfortunately, banning livestock grazing for three consecutive years has created conflict between administrations in charge of implementing the strategy and pastoral communities, especially when local rainfall conditions produce a considerable quantity of green biomass suitable for opportunistic livestock grazing.

To improve the current policy and procedures and to allow more flexibility in grazing practices when certain conditions are met, this study was undertaken to assess the effect of short-duration, high-stocking-rate opportunistic grazing on the arid rangelands of southern Tunisia. The findings of this study may prove useful to policymakers who make recommendations to national and international development agencies to enhance livestock production while conserving the natural resource base.

Rangeland management strategies can be used as a tool to improve sustainability (Louhaichi et al., 2019, 2021a). A growing number of studies have shown the positive contributions of grazing and how it can be a cost-effective practice for enhancing productivity, species diversity, and ecosystem health (Hodgson et al., 2005; Dorrough et al., 2007; Kohyani et al., 2008). This study highlighted the effects of a short period of high-density grazing on vegetation cover, rangeland productivity, plant density, and species richness. As found in previous studies, these results showed that continuous grazing was linked with poor rangeland conditions, scattered vegetation, low forage productivity, and a low level of diversity.

Grazing livestock at a high density for a short period provides different results in late spring. Under intensive short-duration grazing, there were no effects on perennial shrub species but a high reduction in annual species. The abundance of annuals increased rapidly during spring in the rested (protected) areas. During late spiring period, grazing animals focus mainly on annuals and rarely select woody species, particularly if they are less palatable. Allowing animals to browse the leaves of perennial species does not retard plant growth because they retain the capacity to provide enough energy for further growth and strengthening their root system reserves (Le Floc’h, 2001).

In general, green forage in late spring is high quality, particularly for annual plants. As summer progresses and temperatures increases, herbaceous plants begin to dry out and lose nutritional value. As plant growth progresses, high forage-quality indicators such as protein, energy, vitamins, and minerals decline. As forage plants mature, indicators of low quality or feed value such as fiber and lignin increase (George et al., 2001). The digestibility of annual plants declines with progression through flowering to seed-set and senescence (Kemp and Michalk, 1993), although Louhaichi et al. (2021b) found that the indigenous Tunisian range species contain high nutritional value due to moderate to high protein, low fiber, and high digestibility content and can be used as feed for livestock to enhance local livestock production and contribute to economic development.

For rangelands rested for 2 years, late spring grazing at high-density stocking rates for a short period had no effect on cover, density, and richness of perennial species. Delayed grazing after maturation of forage species and seed dispersal in late spring provides an opportunity for flash-grazing annual species. Skipping woody and perennial species provides an opportunity for selective grazing of annual species. It is well known that sheep are more selective of annual and herbaceous species in their diet than goats for example, which are more likely to browse perennial species (Yiakoulaki and Papanastasis, 2005).

The grazing regimes in this experiment were not detrimental to rangeland productivity because they reduced selectivity, which encouraged the growth of palatable species and enhanced rangeland diversity. Martin (1975) also reported that heavy grazing for a short period results in a more even use of forage, both from place to place and among different species. The grazing and trampling resulting from high-density grazing for a short period did not favor perennial over annual species. This is important because long-term sustained rangeland productivity is strongly dependent on conserving key perennial vegetation (Curry and Hacker, 1990). Grazing and trampling can improve rangeland conditions and plants may stay upright for a long time by removing accumulated dead forage due to senescence or disturbances such as drought and heavy grazing (Heukes and Cowling, 2000). A few months of rest immediately after each period of late spring-early summer grazing can be expected to reduce the effect of intensity of grazing and regrazing on favored plants in the spring.

The critical timing for high-intensity, short-duration grazing may vary from year to year and is influenced by multiple factors, including precipitation, temperature, and vegetation type. Therefore, it is important to base grazing plans on the state of the vegetation cover rather than simply on the length of resting times. This result supports findings highlighting the need for flexible grazing management depending on weather and climate variability (Louhaichi et al., 2021a) and offers an opportunity to develop grazing strategies that exploit these results.

The current national rangeland improvement programs simply ban livestock grazing for a minimum duration of 3 years at a time when sources of supplementary feed to fill feed-gap periods are expensive and where animal demand exceeds rangelands supply. During rainy years, the vegetation response is impressive. Such positive responses do not occur every year as the most common scenario under arid conditions is recurrent drought. Therefore, it would be a lost opportunity for pastoral communities if they are not allowed to use this abundant and rich biomass. From this perspective, development agencies have been keen to revise and update projects and programs for a more flexible approach linking administration with end-user needs based on scientific evidence. The suggested grazing scheme in this study produced satisfactory results compared to protected sites (livestock exclusion) or continuous grazing (control). These findings have implications for the health of the arid rangelands of Tunisia and the livelihoods of pastoral communities. Properly managed, arid rangelands can provide sustainable forage resources that reduce feeding costs and enhance livestock productivity. The findings of this pilot study may offer evidence for designing approaches that could be scaled out to other regions, such as the Middle East and North Africa.

The data analyzed in this study are subject to the following licenses/restrictions: Data are restricted for 5 years. Requests to access these datasets should be directed to ML, m.louhaichi@cgiar.org.

ML and MG conceptualized the study, did a general literature review, led the formal analysis, and contributed to writing manuscript drafts and revisions. MG and FG collected the data. ML acquired research funding. All authors have read and agreed to the published version of the manuscript.

The views expressed in this article are those of the authors and not necessarily reflect those of ICARDA or the CGIAR.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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