Community diversity, functional traits and adaptation of Stipa tenacissima L. under different grazing regimes in a North African arid montane rangeland

Abstract

Rangelands represent about one-third of terrestrial ecosystems around the world (Ellis and Ramankutty 2008). They provide many ecosystem services, such as forage resources, water infiltration and storage, erosion control, wildlife habitat, biodiversity and carbon sequestration (Vecchio et al. 2019). Tunisia, along with other countries in northern Africa, is currently facing degradation and desertification of its most fragile ecosystems, including the arid rangelands. The natural vegetal cover in these ecosystems is subject to several constraints related to edapho-climatic conditions and human activities, which affect the biophysical environment. Human pressure causes various disturbances that considerably modify the structure and the functioning of these ecosystems. For example, overgrazing is leading to the rarefaction or disappearance of the most palatable plant species and the spread of unpalatable ones (Tarhouni et al. 2010; Ouled Belgacem and Louhaichi 2013; Louhaichi et al. 2019). These degraded rangelands could be remediated by the application of appropriate management techniques, such as restoration and rehabilitation that provide sufficient capacity to these disturbed ecosystems to allow them to regenerate (Ouled Belgacem et al. 2008). The dominant perennial Poaceae in southern Tunisia, and specifically in the montane rangeland chain of Matmata, is Stipa tenacissima L. This key plant species is used as fodder for local herds, particularly in seasons of low productivity or during dry years (Aloui 2006). In addition, the local population use leaves of this species for traditional practices, such as some artefacts (baskets, strings and shoes). Such uses are the main biotic cause of degradation that threatens the natural vegetation cover in this area. In addition to human pressures, S. tenacissima is subject to many abiotic climate or soil stresses. Over the next 50 years, Ben Mariem and Chaieb (2017) forecast a negative impact of climate on S. tenacissima ecosystems, due to severe loss of suitable habitats. To promote sustainability in these unique ecosystems, it is important to apply effective management regimes and to assess the adaptability of functional traits of the dominant plant species. The most common regime is to fence off areas to prevent grazing, but this can negatively affect plants and their communities (Tarhouni et al. 2017a, 2017b). Studies have shown that seasonal grazing, including strategic rest periods, is generally better for rangelands than long-term exclusion (Ouled Belgacem et al. 2019). In order to evaluate the vegetation behaviour and highlight adaptations to intense grazing, it is important to understand and predict plant responses through their functional traits that are easy to measure. In fact, some traits associated with resource acquisition, such as SLA (specific leaf area), LDMC (leaf dry matter content) and LA (leaf area), can provide important insights to the adaptation of plants to grazing (Diaz et al. 2001). This study aims to predict and evaluate the effect of three gra...

Responses of community traits and soil characteristics of Achnatherum inebrians-type degraded grassland to grazing systems in alpine meadows on the Qinghai-Tibet Plateau

“…Studies have also shown that continuous grazing leads to soil compactness, nutrient loss, inhibits compensatory growth of edible pasture, increases the proportion of inferior pasture, and decreases the diversity of community species, while reasonable grazing weakens the growth of dominant species in the community, provides survival opportunities for inferior species, increases community diversity, and then increases system productivity, which is not completely consistent with the our results (Zhang et al, 2022). Therefore, ecosystem function is closely linked to its biodiversity, but biodiversity does not necessarily provide the grazing services provided by ecosystems (Msadek, 2021).…”

Effects of Grazing on Water Erosion, Compaction and Infiltration on Grasslands

“…According to the FAO, there are no available global figures but, in the USA (with the world's 4th largest land area), livestock is responsible for an estimated 55% of erosion and sediment [3]. Various authors are concerned about water [4] and wind [5] erosion, loss of grass community diversity [6], protection of ecosystem services [7,8], impact on infiltration patterns [9], enhancing carbon sequestration capacity [10], responses of exclosure of livestock [11], etc.…”