Establishment of native forage grasses for grassland restoration in the Pampa Austral

Abstract

Introduction: A major challenge in seed-based restoration is ensuring that seeds germinate and develop into persistent individuals.Few studies have addressed seed-based restoration in degraded grasslands of the Pampa Austral, Argentina.Objectives: This study evaluated field establishment of four native perennial forage grasses (Nassella longiglumis, N. neesiana,N. tenuis, and Piptochaetium napostaense) sown at different densities and compared them with one exotic commercial grass, Thinopyrum ponticum.Methods: Seeds were sown in furrows in 1 m 2 mplotsinMarch2023.Threesowingdensities (200, 350,and 500 germinable seeds/m2)weretestedina completely randomizeddesignwithfivereplicates foreach treatment.Thenumberofindividualsper square meterandpercentage of establishment were monitored during the first year, and furrow cover was measured in April and November 2024.Results: The highest numbers of germinated seedlings and establishment percentages were recorded shortly after sowing, followed bya decrease. After 1 year, N. longiglumis and N. neesiana exhibited the highest values of individuals per square meter, establishmentpercentage, and cover. While the number of individuals and cover percentage increased with increased sowing density, establishmentpercentage showed a slight decline at higher densities. Nassella longiglumis and N. neesiana outperformed the commercial species,indicating their potential suitability for restoration, including years with below-average spring rainfall.Conclusions: Native grasses can perform as well as, or even better than commercial species under local conditions. The study providespractical evidence that incorporating native species into restoration planning in the Pampa Austral is a viable strategy.Implications for Practice: Large-seeded species should be prioritized in restoration projects, as they enhance establishment successand increase ground cover. Native forage grasses established as successfully as the commercial species, even under below-averagespring rainfall, highlighting their suitability and potential value for restoration programs in the Pampa Austral. Seeding at500 germinable seeds/m2 increased both the number of established individuals and furrow coverage, resulting in improved restorationperformance. Selecting optimal seeding densities is therefore essential to balance seed resource availability, economic costs, and longterm restoration success, particularly in regions where seed supply is limited and strategic use is required to maximize ecological andfinancial efficiency.