Morgan Fraser J, Daigneault Adam J
Landcare Research, Auckland, New Zealand.
PLoS One. 2015 May 21;10(5):e0127317. doi: 10.1371/journal.pone.0127317. eCollection 2015.
Agriculture is important to New Zealand's economy. Like other primary producers, New Zealand strives to increase agricultural output while maintaining environmental integrity. Utilising modelling to explore the economic, environmental and land use impacts of policy is critical to understand the likely effects on the sector. Key deficiencies within existing land use and land cover change models are the lack of heterogeneity in farmers and their behaviour, the role that social networks play in information transfer, and the abstraction of the global and regional economic aspects within local-scale approaches. To resolve these issues we developed the Agent-based Rural Land Use New Zealand model. The model utilises a partial equilibrium economic model and an agent-based decision-making framework to explore how the cumulative effects of individual farmer's decisions affect farm conversion and the resulting land use at a catchment scale. The model is intended to assist in the development of policy to shape agricultural land use intensification in New Zealand. We illustrate the model, by modelling the impact of a greenhouse gas price on farm-level land use, net revenue, and environmental indicators such as nutrient losses and soil erosion for key enterprises in the Hurunui and Waiau catchments of North Canterbury in New Zealand. Key results from the model show that farm net revenue is estimated to increase over time regardless of the greenhouse gas price. Net greenhouse gas emissions are estimated to decline over time, even under a no GHG price baseline, due to an expansion of forestry on low productivity land. Higher GHG prices provide a greater net reduction of emissions. While social and geographic network effects have minimal impact on net revenue and environmental outputs for the catchment, they do have an effect on the spatial arrangement of land use and in particular the clustering of enterprises.
农业对新西兰的经济至关重要。与其他初级生产者一样，新西兰在努力提高农业产量的同时，保持环境的完整性。利用模型来探究政策对经济、环境和土地利用的影响，对于理解该部门可能受到的影响至关重要。现有土地利用和土地覆盖变化模型的主要缺陷在于，缺乏农民及其行为的异质性、社会网络在信息传递中所起的作用，以及局部尺度方法中对全球和区域经济层面的抽象处理。为了解决这些问题，我们开发了基于主体的新西兰农村土地利用模型。该模型利用局部均衡经济模型和基于主体的决策框架，来探究个体农民决策的累积效应如何影响农场转换以及集水区内由此产生的土地利用。该模型旨在协助制定政策，以塑造新西兰农业土地利用的集约化。我们通过模拟温室气体价格对农场层面土地利用、净收益以及环境指标（如新西兰北坎特伯雷胡鲁努伊和怀奥集水区主要企业的养分流失和土壤侵蚀）的影响，来说明该模型。该模型的主要结果表明，无论温室气体价格如何，农场净收益预计都会随着时间的推移而增加。预计温室气体净排放量会随着时间的推移而下降，即使在无温室气体价格的基线情况下也是如此，这是由于低生产力土地上林业的扩张。更高的温室气体价格能实现更大幅度的排放净减少。虽然社会和地理网络效应对于集水区的净收益和环境产出影响甚微，但它们确实会对土地利用的空间布局产生影响，尤其是企业的聚集情况。
