Tropical crops: Cautious optimism

In their Perspective “A double-edged sword for tropical forests” (3 October, p. [38][1]), L. R. Carrasco et al. warn that the development of high-yielding tropical crops such as oil palm may accelerate tropical deforestation. We believe that the situation may not be as dire as it seems. The genetic yield potential of oil palm does not currently limit production in Malaysia, Indonesia, or the countries in which Malaysian and Indonesian companies are expanding (such as Liberia). The main constraint to production is labor availability. In Malaysia, a large part of the plantation workforce is hired on a daily ad hoc basis. Given that ripened fruit needs to be harvested and milled within 48 hours, a lack of harvesters on any particular day delays processing and compromises fruit quality and yield. Consequently, the yield potential of oil palm is rarely fully realized in existing plantations. ![Figure][2] Oil palm harvest in Malaysia. PHOTO: CRAIG MOREY/FLICKR Citing a modeling study by Villoria et al. ([ 1 ][3]), Carrasco et al. argued that by closing the oil palm yield gap, Indonesia and Malaysia are projected to lose 65,000 ha of forests to oil palm under current global oil crop demand. However, this figure assumes no yield increases for other oil crops globally or for oil palm outside of Indonesian and Malaysia. Under a more realistic scenario that incorporates plausible yield increases for all crops, 1,800,000 ha of forest are spared globally, including both Indonesia and Malaysia ([ 1 ][3]). Of greater concern to us—and noted by Carrasco et al. —is the possibility that genetic “improvements” will increase the temperature and moisture ranges at which oil palm can profitably be grown. Such improvements would indeed open up previously spared ecosystems to agricultural conversion. This, far more than boosting the yields of oil palm in already-planted areas, strikes us as the critical threat to biodiversity. 1. [↵][4]1. N. B. Villoria, 2. A. Golub, 3. D. Byerlee, 4. J. Stevenson , Am. J. Agric. Econ. 95, 1301 (2013). [OpenUrl][5][CrossRef][6] [1]: /lookup/doi/10.1126/science.1256685 [2]: pending:yes [3]: #ref-1 [4]: #xref-ref-1-1 "View reference 1 in text" [5]: {openurl}?query=rft.jtitle%253DAm.%2BJ.%2BAgric.%2BEcon.%26rft.volume%253D95%26rft.spage%253D1301%26rft_id%253Dinfo%253Adoi%252F10.1093%252Fajae%252Faat034%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [6]: /lookup/external-ref?access_num=10.1093/ajae/aat034&link_type=DOI