方法对比

	On-Farm Agrobiodiversity Index	Land Equivalent Ratio
领域	Food Agriculture Studies	Food Agriculture Studies
方法族	Process / pipeline	Process / pipeline
起源年份	2008	1980
提出者	Devra Jarvis & colleagues (on-farm crop-variety diversity framework); diversity indices after Magurran	Roger Mead & Roger W. Willey
类型	Descriptive diversity-index pipeline for cultivated and reared diversity on farms	Descriptive index of relative land productivity
开创性文献	Jarvis, D. I., Brown, A. H. D., Cuong, P. H., Collado-Panduro, L., Latournerie-Moreno, L., Gyawali, S., et al. (2008). A global perspective of the richness and evenness of traditional crop-variety diversity maintained by farming communities. Proceedings of the National Academy of Sciences, 105(14), 5326-5331.	Mead, R., & Willey, R. W. (1980). The Concept of a 'Land Equivalent Ratio' and Advantages in Yields from Intercropping. Experimental Agriculture, 16(3), 217-228.
别名	On-Farm Crop Diversity Index, Agrobiodiversity Index, Farm Varietal Diversity Index, Cultivated Diversity Index	LER, Relative Yield Total, Land Equivalent Coefficient, Intercropping Land-Use Efficiency
相关	4	4
摘要	The on-farm agrobiodiversity index applies the mathematics of biological diversity — richness, evenness, and combined indices such as Shannon, Simpson and Margalef — to the crops, landraces, varieties and livestock breeds that farmers actually maintain in their fields and herds. Rather than counting wild species in an ecosystem, it quantifies cultivated and reared diversity: how many distinct crop species and varieties a farm grows, how evenly the area or production is spread across them, and how this compares between farms, communities and regions. Devra Jarvis and a large international team showed in 2008 that these measures of richness, evenness and divergence reveal substantial crop-variety diversity still maintained on farms worldwide and provide a sound basis for indicators of on-farm conservation. Built on Magurran's standard diversity formulas, the index turns agrobiodiversity into measurable, comparable numbers for research and policy.	The land equivalent ratio (LER) is the standard index for judging whether intercropping — growing two or more crops together on the same land — uses land more efficiently than growing each crop separately. Formalized by Roger Mead and Roger Willey in 1980, the LER expresses how much land would be required under sole cropping to produce the yields achieved by one unit of intercropped land. It is computed by dividing each component crop's intercrop yield by its sole-crop yield and summing these partial ratios across all components. An LER greater than one means the intercrop is more land-efficient than the corresponding sole crops, and the amount above one quantifies the land saved, giving agronomists a simple, interpretable, and widely used measure of the biological advantage of mixed cropping.