Purpose Direct land use change (dLUC) can contribute significantly to carbon footprint and life cycle assessment results. A tool that covers all crops grown in all countries is important to provide high-quality and consistent inventory data but comes with significant challenges managing data. This analysis shows that the use of such high-level data in a commonly used tool to assess dLUC emissions, developed by Blonk Consultants, results in inappropriate dLUC emission factors for Australian production. Methods The review process involved assessing each parameter used in the tool to ascertain whether local Australian data could be implemented. Four parameters were identified, covering soil and climate type, carbon stock in living forest and variation in crop land use. The tool was modified using updated parameters to evaluate the variation in results. Results and discussion The carbon stock in living forest was found to be considerably overestimated. To determine climatic region and soil type, the tool uses the whole area of Australia, while in practice, agricultural production occurs in only a certain proportion of the country with a significantly different climate and soil profile. This second adjustment modifies the reference values for soil organic carbon. Another significant factor was found to be the approach used to calculate cropland expansion. Australian cropping systems include a significant fraction of temporary pasture in rotation schedules with crops and temporary fallow land, which means that cropland encompasses more than the sum of areas harvested for individual crops. On the other hand, summing the area harvested of all crops may result in double counting of land used for cropping where there is more than one crop a year. Finally, using a 3-year rolling average to estimate land use creates a high level of uncertainty for a country where decadal rainfall patterns determine the way land is used in any 3-year period. Conclusions Greenhouse gas emissions associated with dLUC were estimated to be 82% lower than the result from the tool, when local country-specific data were used. The identified issues could be relevant for other countries. The approach to estimating dLUC could be improved by using local data for carbon stock in forests; the use of aggregated land use categories to estimate expansion and contraction of cropping area over time; and the use of a longer period for estimating the averages on which trends in dLUC are based, so that the impact of drought years is evened out.

中文翻译：

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改进直接土地利用变化计算：澳大利亚案例研究

目的直接土地利用变化 (dLUC) 可以对碳足迹和生命周期评估结果做出重大贡献。涵盖所有国家/地区种植的所有作物的工具对于提供高质量和一致的清单数据很重要，但在管理数据方面面临重大挑战。该分析表明，在 Blonk Consultants 开发的评估 dLUC 排放的常用工具中使用此类高级数据会导致澳大利亚生产的 dLUC 排放因子不合适。方法 审查过程包括评估工具中使用的每个参数，以确定是否可以实施澳大利亚当地数据。确定了四个参数，涵盖土壤和气候类型、活林中的碳储量和作物土地利用的变化。该工具使用更新的参数进行了修改，以评估结果的变化。结果与讨论 发现活森林中的碳储量被大大高估了。为了确定气候区域和土壤类型，该工具使用了澳大利亚的整个地区，而在实践中，农业生产仅发生在该国气候和土壤剖面显着不同的一定比例的地区。第二次调整修改了土壤有机碳的参考值。另一个重要因素是用于计算耕地扩张的方法。澳大利亚的耕作系统包括很大一部分临时牧场与农作物和临时休耕地轮作，这意味着农田所包含的面积超过了用于单个作物的收获面积的总和。另一方面，将所有作物的收获面积相加可能会导致对一年多于一种作物的耕作土地进行重复计算。最后，使用 3 年滚动平均值来估计土地利用会给一个国家带来高度的不确定性，因为十年降雨模式决定了任何 3 年期间土地的使用方式。结论 使用当地国家特定数据时，与 dLUC 相关的温室气体排放估计比该工具的结果低 82%。确定的问题可能与其他国家有关。通过使用当地森林碳储量数据，可以改进估算 dLUC 的方法；使用汇总的土地利用类别来估计种植面积随时间的扩张和收缩；以及使用更长的时间来估计 dLUC 趋势所基于的平均值，