Changes in vegetation of flooded savannas subject to cattle grazing and fire in plains of Colombia

A HUERTAS HERRERA; B BAPTISTE BALLERA; M TORO; MV LENCINAS; G MARTÍNEZ PASTUR; H HUERTAS RAMIREZ

Land

MDPI

Lugar: Bern; Año: 2021 vol. 10

Cattle grazing and fire are common types of management on natural ecosystems, generatingseveral threats to the conservation of native vegetation (e.g., changes in species richness, cover, andabundance, mainly of bovine-palatable species). In this work, we analysed the response of thestructure and composition of vegetation managed with different cattle stocking rates and fire in thesavanna ecosystems of Colombia. The study was located in the eastern area of the Llanos region,where savannas were subjected to grazing and burning. Regarding grazing, we classified the areaaccording to the cattle stocking rate (Bos indicus ~300 kg): NG = non-grazed, LS = low stockingrate (0.5 ind ha􀀀1 yr􀀀1), and HS = high stocking rate (1.0 ind ha􀀀1 yr􀀀1). Controlled artificialburning was applied in all the area at the beginning of the study, and surveys were conducted in thesame plots at pre-burn (t0) and four post-burn times (t1, t2, t3, t4), at 15, 45, 75 and 105 days afterburning. Vegetation composition (species list, life-form, palatability) and structure (bare soil andvascular plant ground covers, species height and richness) were recorded at each sampling. Datawere compared through ANOVAs and multivariate analyses. We found 53 species in total: 26 in thepre-burn treatment and 44 in the post-burn treatments, detecting an increase of 18 species consideringall treatments. Seven natives and two exotic species represented the dominant cover (>50%). LSand HS had the highest number of palatable species in t0 (seven species) compared with NG (twospecies), but this became similar after burning (14 species in NG, 12 in LS, and 11 in HS). ANOVAsand multivariate analyses showed that plant assemblages were significantly different accordingto the grazing treatment, and more homogeneous in pre-burn than in post-burn periods. Cattlegrazing favored higher covers of dominant palatable species (e.g., Axonopus purpusii) compared withNG, but many native species with high palatability only recovered within the system after burning.In the context of the current management proposals, the search for new alternatives other thanintensive cattle grazing and burning is needed to reconcile human production activities, internationalcommitments against climate change and biodiversity conservation in the savanna landscapes.