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The SFS Center for Sustainable Development Studies in Costa Rica has done research on the ecological impacts of the extraction of heart of palm from different palms, especially from the species Euterpe precatoria (Arecaceae).

This palm is abundant in the rainforests of tropical America from Belize to Bolivia, from sea level to 1150m. In Costa Rica, Euterpe is subject to illegal extraction due to thequality and flavor of its heart of palm. Poachers cut down the soft palm stem and remove the top part, which consist of the apical meristem and the rolled, developing new leaves. The removed tissueis very soft, can be eaten raw, and tastes like artichokes. Theheart of palm of Euterpe tastes like homemade butter, justifying its local name (palmito mantequilla, or butter palm). The extraction of the palm heart results in the death of the individual. The development of programs for conservation and sustainable management of the species requires basic knowledge of the population structure, growth rates, and allometric relationships of this palm species.

Palm heart seized from poachers in Braulio Carrillo National Park, Costa Rica.

Euterpe precatoria shows high density in disturbed and secondary forests compared with pristine, primary forests. Forests where poachers cut Euterpe resemble naturally disturbed forests, and thus, have higher density of this palm. Poachers go after the largest and tallest individuals, which are usually the reproductives, to maximize the amount of extracted heart of palm. In extraction bouts lasting 2-3 days, they can harvest up to 300 adults. The removal of adults releases juveniles and seedlings from competition with larger palms, favoring their growth, increasing Euterpe’s density at extracted sites. This decreases forest diversity and delays the natural regeneration of extracted sites.

Monitoring seedling growth of E. precatoria by SFS students

The extraction of reproductive individuals eventually affects population viability and genetic structure, affecting the ability of this palm to maintain genetically viable population, capable of adapting to environmental changes. Euterpe is able to show fine local adaptation, but this capacity will be undermined under heavy extraction regimes.

Euterpe grows very slowly in primary forests and deep shade, fares better under intermediate light, and increases growth and seedling density with disturbance and high light, either natural or anthropogenic. Agroforestry systems could function for harvesting palm heart, thereby reducing illegal harvesting from protected areas. In an agroforestry system in Guápiles, we observed that palms grown in full sun (2.83 m, SD = 1.17) doubled in height relative to palms growing under shade (1.15 m, SD = 0.48), and increased stem height at a rate of 92 cm/year, whereas shade palms increased 32 cm/year. Although Euterpe grows faster under sun, the species´ capacity to cope with commercial harvesting is still very limited. Extraction should be done at low intensities for recreational purposes and for maintaining local traditions.

Illegal extraction will continue. We just recently learned of a new extraction event in Braulio Carrillo National Park, which we will explore in the next few weeks. Illegal extraction peaks during the Holy Week or Easter, since palm heart traditionally replaces meat during this religious celebration.

After years of studying the growth of this palm in the natural forest and under agroforestry conditions, it is clear that more education is necessary to deter poachers from continuing destructive practices. Palms provide a variety of non-timber forest products to local farmers, with palm heart being one of them. They also provide keystone resources for wildlife and are responsible for maintaining much of the stability of food webs in the tropics. Studying the basic population biology of this species and its growth pattern is critical to orient conservation, protection and management policies.

References
Avalos, G. 2007. Changes in size preference of illegally extracted heart of palm from Euterpe precatoria (Arecaceae) in Braulio Carrillo National Park, Costa Rica. Economic Botany 61 (1): 96-98.
Sylvester, O. & G. Avalos. 2009. Illegal Palm Heart (Geonomaedulis) Harvest in Costa Rican National Parks: Patterns of Consumption and Extraction. Economic Botany 63(2): 179-189.
Avalos, G. and M. Fernández. 2010. Allometry and stilt root structure of the Neotropical palm Euterpe precatoria (Arecaceae) across sites and successional stages. American Journal of Botany 97(3): 1-8.
Sylvester, O. & G. Avalos. 2012. Notes on the Ethnobotany of Costa Rica´s palms. Palms 56(4): 190-201.
Avalos, G., M. Fernández-Otárola & J.T. Engeln. 2013. Successional stage, fragmentation, and exposure to extraction influence the population structure of Euterpe precatoria (Arecaceae). Revista de Biología Tropical 61(3): 1415-1424.
Fernández-Otárola, M. & G. Avalos. 2014. Demographic variation across successional stages and their effects on the population dynamics of the neotropical palm Euterpe precatoria. American Journal of Botany 101 (6): 1023-1028.
Avalos, G. 2015. Growth of the neotropical palm Euterpe precatoria Mart. in an agroforestry system in Costa Rica. Ecotropica (in rev).