Integrating spatio-temporal variation in resource availability and herbivore movements into rangeland management: RaMDry-An agent-based model on livestock feeding ecology in a dynamic, heterogeneous, semi-arid environment

摘要

Fast growth of the human population puts high pressure on pasture habitats due to increasingly high grazing intensities on shrinking grazing land. Adapted herbivore management is needed to maintain the long term productivity of the rangeland ecosystem, especially in dry climates where precipitation is highly erratic and where forage yield and quality of the pasture are highly dynamic. We used an agent-based approach to develop a spatially explicit model for a case study region in Madagascar. Our model "RaMDry" integrates the movements and feeding metabolism of domesticated ruminants in order to assess the potential of adaptive livestock production in a highly dynamic, heterogeneous, semi-arid rangeland system. It evaluates the additional metabolic energy costs due to pastoral herd movements in search of forage, incorporates seasonal dynamics in forage quality in terms of feed digestibility and relates forage availability and quality to climatic conditions. In the presented study, we focused on describing the processes simulated in RaMDry in detail, simplifying model conditions by implying free-ranging conditions. We verified the results of the model through global and local sensitivity analysis and pattern oriented modeling and compared findings with observed patterns and existing data from literature. Our model provides a useful tool to assess strategies and effects of locally adapted herd and rangeland utilization for sustained food security and household economy of livestock keepers in the semi-arid tropics and sub-tropics. Subject for further analysis of the model is its capability to simulate different management strategies and climatic conditions as well as the development of the models' capacity to predict accumulative effects of environmental degradation. (C) 2017 Elsevier B.V. All rights reserved.