Grass Diversity and Pasture Quality Baseline Assessement in Central Madagascar

Poaceae family contributes to Madagascar’s biodiversity hotspot with 217 of 541 grass species endemic to the island, although their forage value is unknown, at least in the scientific literature. Our research aims 1) to describe the diversity of native and endemic grasses thereby recognising the role of grass species diversity in forage and ecosystem management and 2) to provide new knowledge about pasture management based on the relationship between grazing capacity and productivity within experimental pastureland plots under different fire and grazing treatments. Our study seeks to provide information to inform improvements in livestock nutrition via grazing management of natural pastures in central Madagascar, specifically around the Ankafobe, Ibity and Itremo Protected Areas. Sampling in different grassy habitats was undertaken to develop a grass checklist and overview of grass diversity across the project sites. Further, in the communal and experimental pastures standardised grass surveys were carried out to compare grazing capacity and biomass productivity in the experimental pastures. Our regional survey recorded 123 Poaceae species during the first year: including 90% native species (of which 34% were endemic) and 10% introduced species. Thirty species, all C4 and belonging to PACMAD clade, are found within established pasture grasslands. Across communal pastures the most frequently recorded species and thus most frequently grazed are Loudetia simplex, Aristida rufescens, Panicum luridum, Schizachyrium sanguineum, Hyparrhenia rufa and Aristida tenuissima – these species are predominantly associated with fire. The grazing capacity baseline, at about 0.7 to 0.8 ha/zebu/year, is similar across all experimental sites that are also characterised by having a similar climate, acidic soils with low nitrogen and phosphorus, and., Annual biomass production appears to be driven by fire frequency: at both Itremo and Ankafobe, where fire is an annual occurrence, biomass yield is 2.4-2.9t/ha whereas at Ibity, where fire frequency is fire every 3-4 years, biomass productivity is 6.9t/ha. However, it is unclear how these productivity estimates relate to forage quality; the relationship will be the subject of future work