Agricultural intensification and land use change: assessing country-level induced intensification, land sparing and rebound effect

In the context of growing societal demands for land based products, crop production can be increased through expanding cropland or intensifying production on cultivated land. Intensification can allow sparing land for nature, but it can also drive further expansion of cropland, i.e. a rebound effect. Conversely, constraints on cropland expansion may induce intensification. We tested those hypotheses by investigating the bidirectional relations between changes in cropland area and intensity, using a global cross-country panel dataset over 1961-2016. We used a cointegration approach with additional tests to disentangle long and short-run causal relations between variables, and total factor productivity and yields as two measures of intensification. Over the long run we found support for the induced intensification thesis for low income countries. In the short run, intensification resulted in a rebound effect in middle-income countries, which include many key agricultural producers strongly competitive in global agricultural commodity markets. This rebound effect manifested for commodities with high price-elasticity of demand, including rubber, flex crops (sugarcane, palm oil and soybean), and tropical fruits. Over the long run, strong rebound effects remained for key commodities such as flex crops and rubber. Staple cereals such as wheat and rice manifested significant land sparing. In low-income countries, intensification driven by increases in total factor productivity was associated with a stronger rebound effect than yields increases. Agglomeration economies may drive yields increases for key tropical commodity crops. Our study design could allow addressing other complex long and short run causal dynamics in land and social-ecological systems.

Methods
This database has been created by gathering variables retreived from: i) Well known data sources such as the World Bank, the Food and Agriculture Organization and the United States Department of Agriculture; ii) Less well known data sources iii) Other researchers' work. These data was downloaded and stored on a commond folder. Afterwards, the data was gathered and homogenized (same format and country names) on a unique database using STATA sofware.

在社会对陆地源产品需求日益增长的背景下，可通过扩张耕地面积或提升现有耕地的生产集约化水平来增加作物产量。生产集约化既可为自然保护留存土地，却也可能推动耕地进一步扩张，即产生反弹效应。反之，耕地扩张受限的约束条件则可能诱使生产集约化行为。本研究基于1961-2016年的全球跨国面板数据集，通过探究耕地面积变化与生产强度变化之间的双向关联，对上述假说开展检验。我们采用协整分析方法辅以额外检验，以厘清变量间的长期与短期因果关系，并选取全要素生产率（Total Factor Productivity）与单产作为生产集约化的两项衡量指标。长期来看，我们的结果支持低收入国家的诱发性集约化假说。短期而言，中等收入国家（包含众多在全球农产品市场中极具竞争力的核心农业生产国）的生产集约化会引发反弹效应。这一反弹效应在需求价格弹性较高的农产品中尤为显著，包括橡胶、弹性作物（甘蔗、棕榈油与大豆）以及热带水果。长期来看，弹性作物与橡胶等核心农产品仍存在显著反弹效应。小麦、水稻等主粮作物则表现出显著的土地留存效应。在低收入国家，由全要素生产率提升驱动的生产集约化，相比单产提升更易引发更强的反弹效应。集聚经济可能推动核心热带经济作物的单产提升。本研究的设计框架可用于探究土地系统与社会-生态系统中其他复杂的长期与短期因果动态关系。

方法
本数据集通过整合多源变量构建而成，数据来源包括：i）知名数据源，如世界银行、联合国粮食及农业组织、美国农业部；ii）小众数据源；iii）其他研究者的研究成果。所有数据均被下载并存储至公共文件夹中，随后借助STATA软件完成数据整合与标准化处理（统一格式与国家名称），最终形成单一统一的数据集。