31 January 2018

Plantations in the Amazon could be more wildlife friendly if they were surrounded by natural forest, according to a prize winning PhD study

Vast areas of the Amazon tropic forest are being cleared for plantations with huge implications not only for biodiversity, but for how well the Amazon functions as an ecosystem. A study of dung beetle communities in eucalyptus plantations suggests that plantation ecosystems can be improved by retaining large tracts of natural forests surrounding production areas.

Dr Wallace Beiroz won the prize for the best ecology PhD at the Federal University of Lavras in Brazil, which runs a joint PhD programme with the Lancaster Environment Centre at Lancaster University.

Wallace carried out his research in massive patches of monoculture eucalyptus plantations in the middle of native forest in the Northeastern region of the Amazon: the Jari river basin at the border between Pará and Amapá State. He used dung beetles as the indicator species, to measure how well the ecosystem within the plantations was mirroring the natural system.

Dung beetles are important to an ecosystem because they play key roles in cycling organic matter - taking nutrients from above ground, where they can be washed away by rain, and digging them inside the soil, where they can be accessed by plants and microbial life.

Wallace studied both plantations which are surrounded by natural forest, and ones which are in the middle of cleared land, sampling the whole community of dung beetles over five years. Often biodiversity studies just look at which species are present, but Wallace wanted to assess how the mix of species contribute to ecosystem functioning.

So as well as recording the number of species in each plantation, he measured how much they weighed, whether they were nocturnal or diurnal and how they located and dealt with their dung - because each of these traits affects how effective the beetles are at cycling organic matter.

What he found was that even though plantations in the middle of natural forests didn’t necessarily have more species of dung beetle than those surrounded by cleared land, they tended to include species of beetle which are likely to recycle more organic matter, making them function more like natural forests.

“While each species of dung beetle is important for how the ecosystem functions, some are more important than others,” Wallace explains. “For instance if we have ten smaller species of dung beetle than will cycle less organic matter than ten big species.

“So with more natural forest around a plantation we have more functional diversity within the plantation, so we can have a better ecosystem that is more like a native forest.”

Wallace’s research suggests that retaining or restoring native areas in the landscape could facilitate species movement through plantations and provide ‘source’ habitats for colonisation of plantations by native forest species. He believes this finding has important implications for the sustainable management of plantations.

“Plantation owners spend a lot of money on fertilisers to provide nutrients to make the plantations more productive, but if they keep natural forest around the plantations they can have this service for free from the dung beetles.”

Wallace spent a year in the UK at the Lancaster Environment Centre as part of his PhD programme.

“It offered a big improvement in my career. I met so many researchers whose work I used to read in journal papers, who I still keep in touch with, so it was a great opportunity to build up a really nice professional network. On the personal side it’s awesome to have contact with another culture: it opens your mind to a lot of things, no words can explain the experience, everybody should do it.”

Wallace had four supervisors, one from Lavras, two from Lancaster and one from Oxford. “I had four big minds working with me, so I had five different points of view on my data, and lots of discussion, which improved it a lot.”

He feels the prize and the response of other scientists to his research makes it all worth while.

“Sometimes it feels like a PhD thesis just goes into an archive and nobody reads it, but I have already had other scientists get in touch about my thesis so it makes it worth all the effort. I’ve published the first chapter and the second chapter is under review in another journal.”

Wallace now has a post doctoral researcher role with the Federal university of Minas Gerais in Belo Horizonte in Brazil studying how bee, butterfly and dung beetle populations change at different elevations, using elevation as a proxy for climate change.