Department of Agricultural and Applied Economics, University of Wyoming, Laramie, WY 82071, USA.
Conserv Biol. 2011 Apr;25(2):276-84. doi: 10.1111/j.1523-1739.2010.01618.x. Epub 2010 Dec 16.
Much of the remaining grassland, particularly in North America, is privately owned, and its conversion to cultivated cropland is largely driven by economics. An understanding of why landowners convert grassland to cropland could facilitate more effective design of grassland-conservation programs. We built an empirical model of land-use change in the Prairie Pothole Region (north-central United States) to estimate the probability of grassland conversion to alternative agricultural land uses, including cultivated crops. Conversion was largely driven by landscape characteristics and the economic returns of alternative uses. Our estimate of the probability of grassland conversion to cultivated crops (1.33% on average from 1979 to 1997) was higher than past estimates (0.4%). Our model also predicted that grassland-conversion probabilities will increase if agricultural commodity prices continue to follow the trends observed from 2001 to 2006 (0.93% probability of grassland conversion to cultivated crops in 2006 to 1.5% in 2011). Thus, nearly 121,000 ha (300,000 acres) of grassland could be converted to cropland annually from 2006 to [corrected] 2011. Conversion probabilities, however, are spatially heterogeneous (range 0.2% to 3%), depending on characteristics of a parcel (e.g., soil quality and economic returns). Grassland parcels with relatively high-quality land for agricultural production are more likely to be converted to cultivated crops than lower-quality parcels and are more responsive to changes in the economic returns on alternative agricultural land uses (i.e., conversion probability increases by a larger magnitude for high-quality parcels when economics returns to alternative uses increase). Our results suggest that grassland conservation programs could be proactively targeted toward high-risk parcels by anticipating changes in economic returns, such as could occur if a new biofuel processing plant were to be built in an area.
大部分剩余的草原，尤其是在北美，都是私人所有，其转变为耕地主要是受经济驱动。了解土地所有者将草原转变为耕地的原因，可以促进更有效地设计草原保护计划。我们构建了一个关于美国中部草原区（ Prairie Pothole Region ）土地利用变化的经验模型，以估计草原转变为替代农业用地（包括耕地）的概率。这种转变主要受到景观特征和替代用途的经济回报的驱动。我们对草原转变为耕地的概率（1979 年至 1997 年平均为 1.33%）的估计高于过去的估计（0.4%）。我们的模型还预测，如果农产品价格继续遵循 2001 年至 2006 年观察到的趋势，草原转变为耕地的概率将会增加（2006 年草原转变为耕地的概率为 0.93%，2011 年为 1.5%）。因此，从 2006 年到[修正]2011 年，每年可能有近 121000 公顷（300000 英亩）的草原转变为耕地。然而，转换概率在空间上是不均匀的（范围为 0.2%至 3%），这取决于一个地块的特征（例如，土壤质量和经济回报）。具有较高农业生产质量的草原地块比质量较低的地块更有可能转变为耕地，并且对替代农业用地经济回报的变化更为敏感（即，当替代用途的经济回报增加时，高质量地块的转换概率会增加更大幅度）。我们的研究结果表明，如果在某个地区新建一个生物燃料加工厂等，经济回报发生变化，草原保护计划可以通过预测这些变化，有针对性地优先针对高风险地块。
