Farming practices drove biodiversity gains - study
Although humans are to blame for nature’s recent decline, a new study has shown that for millennia, European farming practices drove biodiversity gains, not losses.
Despite drives to counter the trend, UK ecosystems continue to deteriorate or show no change, scientists at the Scientists at the UK Centre for Ecology and Hydrology have stated this week.
The conclusion follows analysis of trends in animal and plant species provided by about 100 different organisations, including government agencies, research institutes, voluntary groups and citizen science schemes such as the UK Butterfly Monitoring Scheme.
However, perhaps paradoxically, a team of researchers at the University of York have fund in Europe, floristic diversity and human populations have grown in tandem for millennia.
The academics say disturbance intensity and habitat heterogeneity potentially explain this phenomenon, though there is a lack of understanding of how human land use intensity affected biodiversity at numerous spatial scales over the Holocene.
The York researchers examined the relationships between anthropogenic vegetation change and floristic diversity over the last 12 millennia in Europe, at multiple spatial scales.
The study comprised the scrutiny of the spatio-temporal dynamics of, and relationships between, floristic richness, evenness and compositional turnover with an index of anthropogenic vegetation change since 11,700 calibrated years before present, analysing 7,853 pollen samples from 213 sites.
The York team evaluated how changes to the proportional site occupancies of human-associated and other taxa related to diversity patterns.
It found floristic richness, evenness, and compositional turnover increased from 9,000 years ago to 1850.
Temporal increases in richness and evenness were positively associated with the anthropogenic vegetation index in the majority of vegetation zones and sites, whereas compositional turnover was only associated with the anthropogenic index at the site level.
It also found Holocene site occupancies of all human-associated taxa were positively associated with biodiversity gains, whereas the results for other taxa (that were not associated with people) were mixed.
Following the onset of warmer Holocene conditions, floristic diversity initially declined, while subsequent increases were positively associated with human impacts over the vast majority of Europe.
From the mid-Holocene onwards, farming populations increasingly disturbed European landscapes – perhaps replicating the now-lost megafaunal disturbance regimes – to produce patchy and increasingly diverse vegetative communities, the legacies of which are still present today.
Dr Jonny Gordon, a Postdoctoral Research Associate in the Leverhulme Centre for Anthropocene Biodiversity and lead author of the new paper, said the models showed that humans were the most important force affecting plant biodiversity over the last 12,000 years in Europe - and their effect was overwhelmingly positive.
He said: “We think that as farming communities expanded from Turkey into Southern Europe, and then into Northern and Western Europe, they chopped down some of the forest that met them, planted crops and grazed their sheep and cows.”
Rather than harming the diversity of Europe’s plant communities, Dr Gordon explains that this partial clearing of trees was beneficial. By opening up the canopy, early farmers created a “mosaic” of habitats - a patchwork landscape that made space for a range of other plants that could not survive in dense forests.
“Where there was once mainly forest, there were now smaller patches of forest interspersed with new fields of crops, such as wheat, weeds that grew around the edges of these fields, as well as species that thrived in meadows and when grazed. A farmed Europe had a wider range of habitats for plants to live in than an unfarmed Europe.”
Dr Gordon believes these findings challenge the common assumption in conservation that human influence must be removed for ‘nature’ to thrive – a concept embedded into many ‘restoration’ strategies, such as rewilding. Instead, the research suggests that in a European context, low-intensity, traditional farming methods practised over multiple millennia were the very driver of the elevated biodiversity levels that conservation today seeks to protect.
“This provides hope for the future,” he says. “Humans need not be in opposition to biodiversity; in fact, if you consider the last 12,000 years, our work shows that humans and biodiversity can thrive together.”