Multi-parallel structure and a generalized conceptual model of livestock track network

Abstract

Striking networks of livestock tracks are commonplace in hilly rangelands throughout the world. Formed largely through biogenic processes, they transform micro-topography, soil properties, vegetation distribution, and forage behaviors of livestock, and have significant implications to hydrological and biogeochemical processes and livestock forage efficiency. The conventional conceptual model suggests that the network of livestock tracks is consisted of parallel and conjunctive tracks, with parallel tracks nearly parallel to the contour and connected by shorter, inclined conjunctive tracks. This conventional model of network of livestock tracks captures the most salient characteristics for some of the networks but not the full range of structural variations and possible mechanisms. We quantified goat track networks, which disconform to the conventional model, using a multi-parallel structure and proposed a generalized conceptual model of livestock track network. Livestock track networks consist of multiple groups of parallel tracks and the key properties of networks, scale and geometric complexity, are functions of animal body size as well as landscape heterogeneity. Network scale increases and geometric complexity decreases with body size, and geometric complexity increases with landscape heterogeneity. The generalized conceptual model can serve as a unifying framework for studies of various livestock track networks and potential mechanisms. It can also facilitate effective characterization of livestock track networks, monitoring of their structural changes, and assessment of policy implications to ecosystem services in hilly rangelands throughout the world.