Protecting the Breadbasket with Trees? The Effect of the Great Plains Shelterbelt Project on Agriculture
研究1935-1942年美国大平原防护林项目对农业的影响，发现防护林覆盖率提高导致耕地转为牧场，牲畜收入增加而作物减产，主要源于灌溉技术采用受阻。
Wind erosion is detrimental to agriculture. Planting shelterbelt trees is a common strategy to protect vulnerable areas. I estimate the impact of shelterbelts on agriculture while instrumenting the endogeneity of planted location with a designated zone under the Great Plains Shelterbelt Project—a massive tree-planting operation implemented in 1935–1942. I find a shift from cropland to pasture associated with higher shelterbelt coverage due to differential productivity changes in livestock and crop production. The revenue increase from livestock was contributed by cattle, while the decline in crop production mainly occurred in western counties owing to obstacles to adopting new irrigation technology.