<p>1</p><p>Appendix 7 PCA, distribution and abundance of crops in study area</p><p>We were interested in how crop diversity is spread across the study area and the relationship of crop diversity to geographic, agroecological and social factors. In the survey, farmers listed the major crops they planted and the area planted to each crop. </p><p>After tartary buckwheat, the major crops planted by farmers in our study were potato, maize, and turnip (Table 1). Using crop planted area as a measure of abundance, we performed principal component analysis of abundance data using the princomp function in R. The Hellinger transformation was used to transform data prior to ordination. Biplots of the principal component analysis of crop abundances show tartary buckwheat is associated with potato, rutabaga, and oats. </p><p>(In the figure, oat and rutabaga are plotted on top of one another and are difficult to read.) Although Yi farms are spread across the ordination space, we observe some clustering on the right side of the plot, in the same vector direction as oats, rutabaga, potato, and tartary buckwheat (Figure 1). 2</p><p>Table 1. Frequency of occurrence of each crop in the sample households, n=228</p><p>Frequency of Number of Common name Botanical name households (%) households Tartary Fagopyrum tataricum 94.3 215 Buckwheat Potato Solanum tuberosum 83.3 190 Maize Zea mays 60.5 138 Turnip Brassica rapa 57.5 131 Radish Raphanus sativus 41.7 95 Walnut Juglans spp. 41.2 94 Oat Avena sativa 39.5 90 Polebean Phaseolus vulgaris 33.8 77 Soybean Glycine max 30.7 70 Sichuan Zanthoxylum spp. 29.8 68 Pepper Wheat Triticum aestivum 28.1 64 Barley Hordeum vulgare 27.2 62 Greenbean Phaseolus vulgaris 24.6 56 Rapeseed Brassica napus 23.7 54 Chili Capsicum annum 23.2 53 Rutabaga Brassica napus var. napobrassica 20.2 46 Amaranth Amaranthus spp. 14.5 33 Rice Orzya sativa 14.5 33 Fava Vicia faba 11.4 26 Fruit Various including Malus spp, 11 25 Pyrus spp Quince Cydonia oblonga 10.5 24 Medicine Various 9.6 22</p><p>Figure 1 PCA of crop abundances, grouped by ethnicity. Filled circles represent Yi farms and open circles represent non-Yi farms. Abbreviations: TBW = tartary buckwheat, SCPepper = </p><p>Sichuan Pepper. n = 217 3</p><p>2 . 5 radish chili rice greenbeanfava potato</p><p>TBW maize soybean yi 2 walnut 0 C 0 . 0 P barley rapeseed 1 rutabagaoat fruit amaranth SCPepper wheat turmedicinenip polebean</p><p> quince − 2 . 5</p><p>− 2 0 2 4 P C 1</p><p>Crop Abundances also display an elevational gradient running roughly from the top right (low elevation farms) to the bottom left (high elevation farms) (Figure 2). </p><p>Chili, maize, rice, fava soy, and green beans are associated with low elevation farms and oat, rutabaga, turnip, medicine, TBW and potato are associated with high elevation farms. 4</p><p>Figure 2 PCA of crop abundances with symbols filled on a continuous gradient according to farm elevation. n = 217</p><p> radish 2 rice greenbean potato chili</p><p>TBW fava maize elev soybean</p><p>0 walnut 3 0 0 0 2</p><p>C barley P rapeseed fruit 2 5 0 0 roatutabaga SCPepper amaranth 2 0 0 0 turnipmedicine wheat</p><p>− 2 polebean quince</p><p>− 4</p><p>− 2 0 2 4 P C 1</p><p>Much of the variation defined by the PCA is also related to the local context of each particular geographic area (Figure 3). 5</p><p>Figure 3 PCA of crop abundances with points coded by geographic area in Yunnan. n</p><p>= 217</p><p> radish 2 rice greenbean potato chili geog TBW fava maize 1 soybean 2 3 0 walnut 2 4 C barley P rapeseed fruit 5 roatutabaga 6 SCPepperamaranth 7 medicine wheat turnip 8 − 2 polebean quince</p><p>− 4</p><p>− 2 0 2 4 P C 1</p>