The past half a century has witnessed an increased exodus of human populations from rural to urban areas, with over 55 percent of the world’s population currently living in cities (a percentage expected to rise to 68 percent by 2050). A major effect of this gradual decrease in rural populations is that the land they leave behind leads to a significant increase in abandoned fields and pastures, forestry areas, factories, mines, or even entire human settlements.
A new perspective piece published in the journal Science has recently investigated how biodiversity is affected by land abandonment and what this entails 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,” said study lead author Gergana Daskalova, a research fellow in Biodiversity, Ecology, and Conservation at the International Institute for Applied Systems Analysis (IIASA).
“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.”
Although the precise amount of abandoned land around the globe is unknown, scientists estimate that it could comprise up to 400 million hectares (nearly half the size of Australia). Most of this land is in the Northern Hemisphere, with 117 million ha in the former Soviet Union alone.
According to the experts, the effects such abandoned areas have on biodiversity are complex, and can be both positive and negative. For instance, in abandoned areas that were previously intensively farmed and where biodiversity was low, plant life, birds, and invertebrates which can easily survive in disturbed ecosystems have a new chance to thrive.
Moreover, if the abandonment of such crop fields is coupled with people leaving the region or with wildlife reintroductions, major rewilding can occur, with the possible return of large herbivores and carnivores. However, not all abandoned land can recover without help, and some of the land that used to be intensively farmed may never fully recover.
The researchers emphasize that land abandonment can also have negative consequences for biodiversity. For example, in areas previously used for low-intensity, or subsistence farming for extended periods of time, the close ties between the people and the land have often created interdependent ecosystems that break down after people depart, possibly leading to the loss of locally rare species or the proliferation of only one or two species at the expense of others.
Moreover, any gains in biodiversity on abandoned land can be quickly reversed if land is recultivated or repurposed, as it currently happens with finding new industrial uses for abandoned land, such as large-scale bioenergy, wind, and solar energy production.
Thus, finding the best use for abandoned land needs to balance conservation benefits, human livelihoods, and sustainability. To identify the most efficient ways of balancing these factors, biodiversity changes on abandoned lands should be included in regional and global assessments, policies, and scenarios. Finally, in cases where abandoned land is reused, economic needs should be carefully balanced with restoration and conservation goals.
“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,” said Daskalova.
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.”
Biodiversity refers to the variety of life forms and ecosystems on Earth, including plants, animals, microorganisms, and the ecological processes that support them. It encompasses the genetic, species, and ecosystem levels of biological organization. Here are some key points about biodiversity:
Biodiversity is crucial for the health and stability of ecosystems and provides numerous benefits to humans. It supports the functioning of ecosystems, such as nutrient cycling, pollination, and soil formation.
Biodiversity also contributes to essential ecosystem services like clean air and water, climate regulation, and natural disaster mitigation. Additionally, it has aesthetic, cultural, and recreational value and serves as a source of food, medicine, and other resources.
Biodiversity is often described at three levels: genetic diversity, species diversity, and ecosystem diversity.
This refers to the variety of genes within a species. Genetic diversity enables populations to adapt to changing environments, enhances resistance to diseases, and improves overall species resilience.
This refers to the variety of different species present in a particular region or on Earth as a whole. Higher species diversity generally indicates a healthier ecosystem.
This refers to the range of different ecosystems in a given area or across the planet. Ecosystem diversity encompasses various habitats, such as forests, grasslands, wetlands, coral reefs, and deserts.
Biodiversity is facing significant threats, primarily due to human activities. Some of the major drivers of biodiversity loss include habitat destruction, deforestation, pollution, climate change, invasive species, overexploitation of natural resources, and unsustainable agricultural practices.
These factors can lead to species extinctions, disrupt ecosystems, and have cascading effects on the overall functioning of the planet.
Protecting and conserving biodiversity is crucial for the well-being of both ecosystems and human societies.
Conservation efforts involve the establishment of protected areas, habitat restoration, sustainable land and resource management practices, wildlife conservation initiatives, and international agreements and conventions. Public awareness, education, and participation are also essential for promoting biodiversity conservation.
Biodiversity hotspots are regions that are exceptionally rich in species but also highly threatened. These areas contain a significant number of endemic species (species found nowhere else) and have experienced significant habitat loss. Examples of biodiversity hotspots include the Amazon rainforest, the Coral Triangle, the Western Ghats of India, and the Cape Floristic Region in South Africa.
Indigenous peoples and local communities often have profound traditional knowledge and practices that contribute to the conservation and sustainable use of biodiversity. Recognizing and involving these communities in conservation efforts can lead to more effective and equitable outcomes.
Preserving and restoring biodiversity is crucial for ensuring the long-term health and sustainability of our planet. It requires collective global efforts, policy interventions, and individual actions to protect and conserve the Earth’s rich natural heritage.
By Andrei Ionescu, Earth.com Staff Writer
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