From Treeless Pastures to Silvo-pastoral Systems: The Extent and Drivers of Tree Management Styles

Abstract

In the Neotropics, cattle ranchers incorporate trees into their pastures management but to different degrees. We ask: why are there different tree densities across the cattle pastures? We develop a socio-ecological framework, and apply this framework to analyze the case study of 54 farmers in the Republic of Panama. The rural landscape of Panama is dominated by cattle ranching and previous studies had shown that farmers incorporate trees into their pasture management. The dynamics between tree cover and cattle density (or other drivers) are unknown. Our framework proposes that the dynamics may be linear, non-linear monotonic or multivalued. Multivalued dynamics are characterized by hysteresis which happens when the system is resilient to any perturbation. A zone of hysteresis is created where two stable equilibrium points are possible, the high and the low tree cover states. Examples in nature and restoration ecology indicate that the relationship between trees and drivers are likely to be hysteretic. Bimodality in the frequency distributions of tree cover is an indicator that the underlying dynamic is hysteresis and that the there are two styles of tree management. Total tree cover across the 54 farms is not bimodal. The total tree cover is broken down into 7 tree landscape patterns indicating that farmers employ different strategies to incorporate trees into their farm management. Dispersed trees on pastures has modest bimodality because only 2 farms compose the high tree density mode. The live fence shows clear bimodality. Reported cattle densities does not predict tree cover area. We did not find clear evidence for tree cover states, but of tree management but farmers are managing trees at different densities. In the 1900s, Chayanov proposed that the amount produced by the family farm is governed by balances, whereas in the capitalist farm, the amount produced is governed by profit maximization. The 54 ranchers make decisions about tree management similar to the balances proposed by Chayanov. Farmers prefer multi-functional shade trees because there is a cost to shade on the total production and because they have to navigate regulatory tree conservation policies.