Introduction

Cattle ranching is historically and geographically the most extended land use in Colombia with up to 35 million hectares dedicated to this activity (Tecnoserve?). As such, it is considered one of the main drivers of biodiversity loss and the largest source of CO₂ emissions in the country (Emission report). Thus, how these areas are managed may have a large impact of future biodiversity loss and carbon emissions. Considering that the cattle ranching sector is highly commited to lead a transition towards sustainable use models and stop deforestation, this research aims to evaluate the impact of implementing three management scenarios on the protection species, species diversity and carbon stocks, providing a roadmap for future conservation action in cattle ranching landscapes.

Methods

Land cover data and scenarios.- In this research, original (Etter et al. 1998), current (IDEAM) and future (Zuluaga & Etter 2018) land covers under three management scenarios were considered (Figure 1). In each time slice, land cover was divided into forested and open ecosystems (pastures, croplands, savannas, grasslands and shrublands).
The three management scenarios devised by Zuluaga & Etter (2018) considered three cattle ranching management categories: exclusion, restriction and suitable. For exclusion areas, we assummed that if the land was suitable for another agricultural use, according to UPRA (XXXX), it would continue being an open ecosystem, otherwise its original land cover would be fully restored. For restriction areas, we assummed 50% of the original forest would be restored to its original state and the remainder would continue being used for cattle ranching.

Figure 1: Left, current ecosystem transformation for cattle ranching. Right, conservationist management scenario.

Biodiversity analysis.- we used IUCN range maps and habitat use information for 1244 bird species that occur in continental Colombia. We produced species maps based on each species affinity for forested or open habitats and existing land covers for all 5 scenarios considered. Then, we stacked the maps for each time slice to produce species richness estimations. We compared species richness through time only for areas were pastures were artificial, thus natural pastures (e.g. east plains) were excluded.

Gap analysis.- To evaluate the gain from managing cattle ranching areas at the species level, we compared the existing representation of species in the protected area system (RUNAP), in current artificial pastures (assuming no further deforestation) and under the implementation of management scenarios. Representation targets were set at 100% if species current ranges were <1000 km^2 and 10% when current range > 250.000 km^2. For intermediate ranges, representation targets were derived using a logarithmic interpolation (Rodrigues et al. 2004).

Carbon stock analysis.- We estimated the potential carbon stocks in areas currently with artificial pastures for each time slice by using the emission factors available for each Holdridge’ forest type (XXXX) and for pastures for each natural region of Colombia.

Results and Discussion

Figure 2: Left, current average species richness. Right, trends in average species richness.

Bird richness in cattle ranching areas has decreased on a 31.7% on average as a consequence of historical land transformation (Figure 2). Under management scenarios, richness could increase from 1.4 - 8.8%. This uptake in richness could be further improved by implementing sustainable cattle ranching practices, such as sylvopastoral systems, live fences and trees in pastures, which have been shown to increase bird richness as much as 29%. Caveat: we assumed that IUCN maps represent the historical extent of species ranges. In reality, they may omit areas that were once suitable.

Only 5 species threatened species and 371 in total met their representation target in the existing protected area system. Avoiding deforestation by itself, could help achieving representation targets for 297 more species, including 7 threatened species. Implementation of restrictive and conservationist management scenarios, would drive species representation up to 191% and threatened species representation by 300% (Table 1).

Carbon stocks in cattle ranching areas have decreased on average by 81.6% from deforestation. Management of these areas could increase carbon stocks by 12.5-79.7% (Figure 1. MORE DIEGO

Figure 3: Estimated trend in carbon stocks

References

Etter 2008 Etter & Zuluaga. 2018 IDEAM Corine Tecnoserve Emissions report IUCN maps