In many tropical regions, primeval forests rich in species are being destroyed to make room for agricultural land. This is not only bad for biodiversity, but often does not even result in an additional yield for the farmers. This is shown by a study published in the journal “Nature Communications”, in which researchers compared the ecological and economic aspects of vanilla cultivation in Madagascar.
A good 8,000 tons of vanilla are produced worldwide every year – the largest share comes from Madagascar. However, since there is only little space on the West African island, more and more forests are being cleared to free up the land for agriculture. For biodiversity, however, this is like a super meltdown, since there is a particularly high level of biodiversity in the isolated tropical forests. This also includes some endemic species – i.e. those that do not occur anywhere else in the world.
“Source of income for tens of thousands of small farmers”
A research team led by Annemarie Wurz from Phillips University in Marburg has now investigated the specific effects of vanilla cultivation in north-eastern Madagascar on local biodiversity and the economic situation of the small farmers living there. The study focused in particular on the comparison between existing fallow land and forest areas specially cleared for agriculture. How productive agriculture is on the respective soils plays a particularly important role for the local farmers, since they usually find it difficult to live on their income due to unfair payments.
“In Madagascar, the export of vanilla is an important source of income for tens of thousands of small farmers. Intensive cultivation on fallow land can be a way of escaping poverty,” explains Annemarie Wurz. According to the results of the study, the cultivation of the already exposed areas has no disadvantages compared to former forest areas. “Farmers don’t have to clear land to achieve high yields, but can enhance the fallow land by growing vanilla,” says Wurz.
Almost 40 percent more endemic species
The scientists used the distribution of various birds, amphibians, reptiles, butterflies and ants to study the ecological effects of growing vanilla in cleared forest areas or on wasteland. The biodiversity of the trees and herbaceous plants growing there was also included in the statistics. The result: “Agricultural areas planted in forests are home to a total of 23 percent fewer species and even 47 percent fewer endemic species than primeval forests,” the researchers report. “In contrast, those planted on fallow land had 12 percent more species overall and 38 percent more endemic species than fallow land.”
According to the scientists, high tree cover has a particularly positive effect on biodiversity. With dense vanilla planting, the biodiversity of tree and reptile species fell again. Nevertheless, according to the study, agriculture on fallow land represents an economically equivalent alternative to cleared tropical forests. “Promoting vanilla cultivation on fallow land is ecologically and economically important,” explains co-author Ingo Grass from the University of Hohenheim. “It can contribute to the current restoration of ecosystems. The study also shows ways in which biodiversity can be preserved and promoted outside of protected areas.”
Source: University of Göttingen, Article: Nature Communications, doi: 10.1038/s41467-022-30866-8