The lands they toiled on are sometimes left idle when people leave their rural lives behind to seek their fortunes in the city or when agriculture is no longer profitable. The importance of abandoned lands in evaluating global restoration and conservation goals is highlighted in a recent viewpoint essay published in Science. It demonstrates how these abandoned sites may both present opportunities and threats for biodiversity.
The past 50 years have seen an increased exodus of populations from rural to urban areas. Today, 55% of the world’s population lives in or around cities and this proportion is expected to expand to up to 68% by 2050.
Of course, there are many reasons why individuals choose to leave their rural communities and relocate to cities, such as socioeconomic and political change, the decline of subsistence farming, and environmental problems.
The land they leave behind, as a result of the ongoing decline in rural inhabitants, contributes to an increase in the number of abandoned farms and pastures, forestry areas, mines, factories, and even entire human communities.
IIASA researcher Gergana Daskalova and Johannes Kamp, a researcher at the University of Göttingen in Germany, took a closer look at abandoned land in other words land on which human activities have ceased to explore how biodiversity is influenced, and what this means for ecology and conservation.
“The factors that drive depopulation and consequently also land abandonment are intensifying due to issues like climate change and the rapidly changing geopolitical landscape. The Russian invasion of Ukraine, for example, has already created new abandonment hotspots. Abandonment is a globally important process. The scale at which this is happening around the world urged us to put the spotlight on the places people have left behind as a potential source of future solutions for conservation, while also protecting human livelihoods,” Daskalova explains.
It is important for future models and scenarios aimed at predicting the positive versus negative effects of abandonment on biodiversity to take into account whether the land is likely to remain abandoned and what the feedbacks between abandonment, biodiversity, human values, and livelihoods entail. As global conversations around this topic continue, we can look to abandoned lands as the product of centuries of interactions between people and nature, and create incentives not just for conservation, but also for land stewardship and the preservation of both social and ecological values.Gergana Daskalova
The actual amount of uninhabited land worldwide is unknown, but the authors estimate that it might be as much as 400 million acres, or an area about half the size of Australia. Most of this abandoned land is in the Northern Hemisphere, of which around 117 million ha falls within the former Soviet Union.
The effect that abandoned areas have on biodiversity can be both positive and negative. The places where intensive farming was previously practiced and where there was little biodiversity are expected to see the greatest gains. The reintroduction of plant life, birds, and invertebrates that can survive in newly disrupted ecosystems will likely be the first changes seen in these regions.
Rewilding may result, with the potential return of large herbivores and even carnivores, if the abandonment of these agriculture areas is accompanied with evictions from the region or the reintroduction of animals.
However, the authors draw attention to the fact that not all abandoned land will recover on its own and that some previously intensively farmed land would never be able to revert to its former state.
The biodiversity, as well as human culture and tradition, may be negatively impacted by land abandonment. For example, in regions that have long been used for low-intensity, or subsistence farming, the close ties between the people and the land have created interdependent ecosystems that disintegrate after people leave, resulting in the extinction of regionally rare species or the expansion of just one or two dominant species at the expense of others.
“Because abandonment usually happens out of sight, there is still so much we do not know about its imprint on the planet. We are currently working in Bulgaria, the quickest depopulating country in the world, to determine what types of plants, birds, and other biodiversity return to villages long after the last house lights have been turned off,” Daskalova notes.
Any gains in biodiversity on abandoned land can unfortunately be very quickly undone when land is recultivated or repurposed and, according to the authors, there is growing pressure to find new industrial uses for abandoned land, such as large-scale bioenergy, wind, and solar energy production, often in just over a decade after abandonment.
The authors also emphasize that determining the optimal use for abandoned land will need weighing the advantages for sustainability, human livelihoods, and conservation.
Therefore, it is essential that assessments, policies, and scenarios at the regional and international levels take biodiversity change on abandoned land into account. Where abandoned land is reused, special care should be given to ensure that economic demands and restoration and conservation objectives are balanced.
“It is important for future models and scenarios aimed at predicting the positive versus negative effects of abandonment on biodiversity to take into account whether the land is likely to remain abandoned and what the feedbacks between abandonment, biodiversity, human values, and livelihoods entail. As global conversations around this topic continue, we can look to abandoned lands as the product of centuries of interactions between people and nature, and create incentives not just for conservation, but also for land stewardship and the preservation of both social and ecological values,” Daskalova concludes.