Securing Nature’s Contributions to People requires at least 20%–‍25% (semi-)natural habitat in human-modified landscapes

A new study from the Earth Commission reveals that unless (semi-)natural spaces within human-modified areas are strategically created and maintained, people will miss out on the many regulating and non-material benefits that nature provides. Authors conclude that only one third of human modified-lands meet this level today.

While conservation efforts usually focus on protecting the 50% of the Earth’s land surface that remains intact, or wild natural habitats, researchers from the Biosphere interactions working group argue that conservation in agricultural and urban lands is just as important and cannot be overlooked.

Often, removing nature is seen as a way of improving human well-being, for instance by providing more space for agriculture, homes and businesses. However, these plans fail to sufficiently recognise the decline in human well-being that these changes to the natural environment incur.

Enhancing well-being

As lead author Dr Awaz Mohamed says: “The global community needs to look beyond just protected and intact natural areas when talking about biodiversity, to recognise the vital presence of nature in the landscapes (the cultivated lands, the cities and countryside) that people live in. Because human survival is dependent on the functioning of these landscapes. These living mosaics provide all people with food, clean water and air, and protection from climate extremes and natural hazards, thereby enhancing overall well-being.”

Nature’s Contributions to People (NCP) play significant roles in agricultural and urban landscapes. The authors explore six crucial NCP that can be promoted through nurturing (semi-)natural habitats: (1) pollination, (2) pest and disease control, (3) water quality regulation, (4) soil erosion control, (5) natural hazards mitigation, and (6) physical and psychological beneficial experiences for individuals who spend time in natural environments.

The authors conducted an extensive literature review to pinpoint the minimum level of ‘functional integrity’ required to maintain the provision of these NCP. Functional integrity is the capacity of an area to provide and sustain NCP based on habitat quantity, quality and spatial configuration.

This means that for crucial contributions to people to be maintained it is not only important that some nature is present in human-modified landscapes, it also matters how much habitat is present (e.g., the percentage of the landscape it covers), what quality of habitat it is (e.g., complex diverse, floral, forest, grassy) and finally the spatial arrangement or the placement of these habitats (how accessible these habitats are to humans and mobile organisms, and where they should be positioned).

Dr Mohamed explains, “Habitats strategically located in  landscapes can significantly reduce the frequency, risk and impact of natural hazards such as shallow landslides, floods and soil erosion. Habitats in agricultural landscapes provide crucial space for pollinators and pest-regulating organisms. Habitats in urban ecosystems, in the form of green spaces and parks, can provide functions such as physically and psychologically beneficial experiences that contribute significantly to well-being.”

Through their review and synthesis of the existing evidence, the authors discovered that a minimum level of 20%–25% of (semi-)natural habitat per square kilometre needs to be present in a human-modified landscape in order for NCP to be maintained.

They stress that 20%–25% of (semi-)natural habitat  is the minimum level, not the optimal level required to meet adequate NCP demand . The authors found that if this level falls below 10%, most of the studied benefits provided by nature are almost completely lost; which is the case with around 50% of global human-modified lands today.

The authors also investigated  European Space Agency satellite-based land cover data, to analyse what proportion of human-modified land is currently operating at this 20%–25% level of functional integrity. The study finds that only one-third of global human-modified lands meet the minimum level for NCP provision. Dr Mohamed says that these findings “emphasise the urgent need for policy interventions to restore and regenerate ecosystem functions and their contributions to human well-being in the two-thirds remaining area”. 

Informing nature and people positive policy-making

The study can be used to inform policy interventions, as it provides the first comprehensive and widely applicable measurement of a minimum level of functional integrity across several NCP and a wide range of landscapes. This framework can serve as a general guide to identify priority locations for effective and targeted conservation and restoration strategies, which promote sustainable NCP provisions and safeguard the well-being of people reliant on these ecosystems. Specific approaches to enhance NCP vary depending on the context, but may include for instance:

  • strategically placing small patches of habitat in human-modified landscapes such as, hedgerows, no-mow zones around field margins or other practices combined with innovations such as precision agriculture practices;
  • reducing landslide risk by targeted planting of deep-rooted vegetative cover on steep slopes, protecting green spaces and parks in cities;
  • placing vegetation buffers along waterways to capture sediment and pollutants, among many other potential tools.

The authors highlight that when deciding on and implementing such strategies, it is essential to adapt and adopt practices best suited to local context and conditions rather than prescribing a single practice to be applied globally. The study argues that localised approaches are essential for maintaining NCP provisioning in an effective and equitable way.

Taking the importance of NCP and (semi-)natural habitats more seriously in conservation efforts will not only benefit people’s well-being, it will also help to restore habitats and their ecosystem functions and contribute to halting biodiversity loss by restoring landscape connectivity. This work will ultimately strengthen the resilience of agricultural and urban areas towards climate change.

Read the full article in One Earth here.

The Earth Commission is the scientific cornerstone of the Global Commons Alliance.

Additional quotes from authors

Co author David Obura, Director of CORDIO East Africa and now Chair of The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) IPBES says “One of the key transformations needed in conserving nature is that people understand and appreciate how fundamentally it supports their lives and livelihoods. This potentially ‘magic number’ of 25% high-functioning nature in every square kilometre could help drive actions at local levels – within communities, by landowners and local authorities – to sustain and restore nature that is crucial for the wellbeing of every person at local levels, and adds up to help meet the global targets and goals set for nature conservation, sustainable use and transforming our economies to function within the biophysical limits of our planet.”

Co author Peter Verburg, Professor Environmental Geography, Institute for Environmental Studies (IVM), VU University Amsterdam, stresses that “the study shows that by restoring landscape features in cities and agricultural lands on a relatively small area large gains in services that enhance the resilience of the prime functions of these lands can be achieved. It is a no-brainer to also invest in strengthening nature in these landscapes”

Co author Fabrice DeClerck, Science Director at EAT, and Principal Scientist of the CGIAR continues: “We know that food systems today are struggling to provide healthy diets and farmer communities are increasingly dependent on pesticides to maintain yields. Fruits, nuts and vegetables are globally underproduced by 75-150%. The nitrogen and phosphorus boundaries are significantly transgressed with 80% of the pressure coming from food production. Halting erosion and nutrient pollution, reducing dependence on biocides, and increasing the production of pollinator dependent nut, fruits and vegetables cannot be achieved without biodiversity embedded in agricultural lands.