Effet du repos pastoral sur la diversité floristique et la capacité fourragère des parcours du Parc National d’Ifrane (Maroc)

Effect of grazing exclusion on floristic diversity and forage production of rangelands in Ifrane National Park (Morocco)

The investigation conducted in the Aghbalou Laarbi forest within Ifrane National Park (INP) compares a ten-year grazing exclusion zone with a continuously grazed area to assess the effect of pastoral rest on the restoration of rangeland structure, productivity, and floristic diversity. The initial degraded state corresponds to formations subjected to overgrazing (>90%), representative of 74% of degraded forest. The reference ecosystem is defined by the climax community of Lonicero arboreae-Cedretum atlanticae and Junipero thuriferae-Quercetum rotundifoliae (26% forest, near-climax stage) exhibiting tri-stratified structure and maturity indicator species. The methodology integrates assessment of density, cover, phytomass, and floristic diversity per stratum, with multivariate statistical analyses. Results demonstrate a highly significant treatment effect, with density emerging as the most discriminating parameter (R² = 0.297). Grazing exclusion generates 2,070.1 kg DM/ha versus 413.3 kg DM/ha in the grazed zone. The Shannon-Weaver index increases from 2.11 to 3.57. Maturity indicator species (Dactylis glomerata, Koeleria vallesiana, Poa bulbosa, Thymus spp.) dominate under grazing exclusion, while Vulpia geniculata and Hordeum murinum prevail in grazed areas. Pastoral rest constitutes an effective lever for ecological restoration toward the reference state of INP rangelands.