Whether dazzlingly red, deep green or ghostly pale, the richness of a tropical forest provides butterflies with a diversity of habitats in which to communicate, camouflage and reproduce. As humans replace tropical forests with environments such as eucalyptus monocultures, however, those requirements are changing. In a plantation, the ecological backdrop is stripped bare and drab species do better. Being bland \u2013 like your surroundings \u2013 becomes an advantage.<\/p>\n
The difference is stark, researchers say. \u201cYou feel alive in the tropical forest, everything is wild \u2013 you never know what you are going to find,\u201d says Garc\u00eda-Roa. \u201cWhen you arrive at a eucalyptus plantation it\u2019s very frustrating \u2013 you can feel that things are not happening as they should be in a natural ecosystem. Animals are not around, and sounds are not as they should be.\u201d<\/p>\n These preliminary findings are part of a broader body of research into \u201cdiscoloration\u201d, which examines how nature loss is altering the colours of the natural world.<\/p>\n Butterflies are an ideal subject for study because they are among the most colourful organisms in the world. They display a vast array of colours across habitats, respond quickly to environmental changes and are easy to monitor.<\/p>\n Colour isn\u2019t just about aesthetics, it has important evolutionary functions. In a broader trend, ecosystems that once supported many colours are becoming more muted as they are degraded, simplified and polluted by humans. Coral reefs are bleaching, oceans are becoming greener \u2013 even rainbows are predicted to become less visible in densely populated and polluted areas.<\/p>\n One obvious thing is that in eucalyptus plantations, butterfly communities are dominated by brown-coloured species Nature\u2019s palette is always changing in response to natural selection pressures. A notable mid 20th-century example is the peppered moth, which turned black during the Industrial Revolution to fit in with the sooty surroundings. But there are likely to be more rapid and widespread changes ahead due to human activity. \u201cEven planet Earth itself is losing brightness as seen from space. It is truly remarkable and concerning how interconnected these processes are, and how every impact cascades into further consequences,\u201d says Ricardo Spaniol from the Federal University of Rio Grande do Sul.<\/p>\n So far, researchers have identified 21 species in eucalyptus plantations and 31 in the natural forest, although there are many yet to be identified. They studied forests and plantations in the Brazilian state of Esp\u00edrito Santo, north of Rio de Janeiro. \u201cOne thing that is obvious is that in eucalyptus plantations, butterfly communities are dominated by brown-coloured species,\u201d says lead researcher, Maider Iglesias-Carrasco from the University of Copenhagen. There was a \u201cgeneral feeling of emptiness\u201d in the plantations, she added.<\/p>\n Researchers first discovered that being colourful in the Amazon may be turning into a disadvantage in 2019. Spaniol spent several weeks in the rainforest, and his team discovered butterfly species changed significantly depending on their environment, and their colours followed suit.<\/p>\n \u201cThe most colourful species are often the first to disappear locally after deforestation, probably because of the loss of native vegetation and their increased exposure to predators. This represents an accelerated process of discoloration in Amazonian butterfly communities,\u201d says Spaniol.<\/p>\n Butterflies that persisted in deforested areas typically had brown or grey wings and bodies. In a preserved forest, however, a dazzling array of very colourful butterflies were found alongside the duller ones. Researchers did not expect to find such a clear and consistent pattern, and say it opened up a new area of research on how habitat loss can shape diversity.<\/p>\n \u201cDiscovering that forests are losing their colours was frightening and revelatory,\u201d says Spaniol. \u201cIt felt like we were uncovering a hidden dimension of how species respond to environmental change, a dimension that had remained invisible until then, but is incredibly rich.\u201d When the colour diversity decreases, it may signal the erosion of ecological functioning.<\/p>\n Butterflies are often considered indicators of broader biodiversity trends, says Spaniol: \u201cA decline in their colour diversity may reflect a loss of complexity in ecosystems as a whole, with potential cascading effects on other organisms and ecological processes.\u201d<\/p>\n From the Amazon rainforest to California to Spain, monoculture forests are being grown over huge areas. According to one estimate, eucalyptus plantations \u2013 among the most common type, farmed for wood pulp, timber and toilet paper \u2013 cover at least 22m hectares (54m acres) around the world.<\/p>\n Researchers don\u2019t know whether the impact of plantations is homogeneous across the planet. \u201cCoffee and banana plantations are always green, and people associate green with nature, but they are not [natural],\u201d says Garc\u00eda-Roa.<\/p>\n If nothing is done to protect native habitats and prevent the further loss of forests, many of the most colourful and ecologically specialised species of butterfly could disappear, leaving behind only a few generalist species. \u201cThis would mean not only a loss of beauty, but also the disruption of important ecological interactions that depend on colour signals,\u201d says Spaniol.<\/p>\n However, this outcome is not inevitable. Spaniol\u2019s research found that forested habitats in the Amazon rainforest that have been regenerating for 30 years after being used as cattle pasture showed a remarkable increase in butterfly colour diversity. \u201cWe still have the opportunity to restore this colourful world,\u201d he says.<\/p>\n
\nMaider Iglesias-Carrasco, researcher<\/p><\/blockquote>\n