Primary Article: Rocha, J. S. et al. (2019), The conservation value of cacao agroforestry for bird functional diversity in tropical agricultural landscapes. Ecology and Evolution, 1-11. doi:10.1002/ece3.5021
Featured Image: Cacao pod, Rachel Kramer, flickr.com
Chocolate: delicious but damaging
When faced with the important decision of chocolate or vanilla-flavored sweets, I will pretty much always choose chocolate.
Many of my fellow Americans seem to be on the same page- together, we consume about 18% of the world’s chocolate, more than the entire Asia-Pacific region combined.
Although a large portion of the world’s chocolate is consumed in the US and Europe, most cacao beans are produced in tropical regions of the Americas, West Africa, and Asia. Chocolate doesn’t have a great environmental record. Shipping cacao beans around the world creates a large carbon footprint, and the tropics have been heavily deforested to make room for cacao plantations. Additionally, the chocolate industry is associated with human rights violations, including child labor and unfair wages for workers.
There are many individuals and organizations working to make the chocolate industry more environmentally sustainable and fair to workers. For example, agroforestry is a cacao production method that grows beans alongside intact native trees and plants. This method is more sustainable than monoculture, where native trees and vegetation are clear-cut and replaced with cacao trees.
When compared with monocultures, agroforestry methods are better at preserving biodiversity (a high amount and variety of plants and animals), conserving soil, and even producing higher yields. However, how does the biodiversity of agroforestry systems hold up when compared to old-growth forests?
Chocolate farms and bird biodiversity
Rocha et. al. wanted to address the question: Are sustainable cacao agroforestry methods effective in preserving bird biodiversity, compared to pristine old-growth forests?
When we think of biodiversity, we typically think of taxonomic biodiversity- the variety and number of species present in an ecosystem. However, this study focused on functional diversity, which aims to measure species’ jobs and resource use within ecosystems. It is important to have a lot of species, but it is also important that they fulfill a variety of niches. This means that they do a wide variety of jobs and don’t all eat the same food, live in the same place, or have babies at the same time. It wouldn’t be good if everyone in New York City ate pizza and only pizza- fruits and veggies would rot on supermarket shelves, and there’d be pepperoni shortages of dire proportions! And just like a variety of occupations (teachers, sanitary workers, doctors, police officers) keep a town running, plants and animals do different jobs to keep an ecosystem healthy.
In this study, the researchers compared the functional biodiversity of old-growth forests to that of cacao agroforestry plantations. It has been shown that agroforestry promotes higher numbers of species and types of habitats than monoculture farms. But how does the biodiversity of agroforestry compare to surrounding old-growth forests?
The scientists chose two sites in Brazil’s northeastern cacao-producing region. One site was located near the Una Biological Reserve, a large protected native forest fragment. The second site was located in a region composed mostly of agroforestry plantations, with just a few small forest fragments scattered throughout. Bird surveys were conducted to figure out which species were present in each area.
In order to quantify diversity of the bird populations at each site, the scientists classified the animals based on how they found food, where they found it, the quantity of resources they consumed, and other behaviors. The researchers relied on previously published scientific literature to figure out which birds had which traits. They analyzed the functional diversity of the bird communities at each site as a whole, then did analyses for 4 subsets: a) forest specialists, b) habitat generalists, c) seed dispersers, and d) invertebrate (insect/bug) removal.
Although a better choice than monoculture, agroforestry may reduce numbers of some types of birds
Lower functional diversity was found in bird communities that contribute to seed dispersal (fruit-eaters) and invertebrate removal (bug-eaters), compared to the surrounding old-growth forests. These are both ecologically important groups, and important for maintaining healthy cacao growth. Invertebrate removers eat insects that can harm cacao trees, and fruit-eaters benefit cacao trees by helping keep the surrounding plant community healthy and thriving.
The researchers also found evidence that forest generalists have replaced specialists in both agroforestry and old-growth forest areas. This trend results from the region’s history of intensive agriculture, and may explain why there was not a greater difference in functional diversity when comparing agroforestry to old-growth forests.
Even small agroforestry areas were correlated with a decrease of fruit-eating and insect-eating birds. These types of birds have important jobs, so the researchers recommended that conservation efforts prioritize these species.
Functional and taxonomic diversity are best maintained in small agroforestry systems surrounded by large mature forests. While even small agroforestry systems are less biodiverse than untouched forest, they are more diverse and sustainable than monocultures.
How to help?
If you’d like to support sustainable cacao farming practices, and promote fair labor within the cacao and chocolate industries, choose chocolate with Rainforest Alliance and Fair Trade certifications.