Trees provide a range of ecosystem services that benefit both farmers and biodiversity. Photo: World Agroforestry Centre

Most of us would agree that human wellbeing depends to a large extent on healthy ecosystems and the services they provide. For example, fertile soil enables us to grow food crops, and nutrient cycling in watersheds is needed for water purification to ensure we have clean water to drink. But what role does biodiversity play in ecosystem services and how does this affect our wellbeing?

A chapter in the recently released, Handbook of Ecosystem Services, attempts to unravel the complexities associated with how a large variety of ecosystem services at multiple scales and in multiple ways interact with biodiversity.

For a start, biodiversity underpins the services provided by ecosystems. If biodiversity declines, this impacts on ecosystem services, and in many cases, human wellbeing. One specific example is that of wild insect pollinators. If their populations decline, this can directly affect the ability of trees to produce fruits which are an important component of human diets.

However the authors of the chapter: The links between biodiversity and ecosystem services suggest we have very limited understanding of the relationship between biodiversity and how ecosystem services are delivered. What facets of biodiversity link to ecosystem functions underpinning ecosystem services, what are the trade-offs between positive and negative effects of changes in biodiversity and how do these impact on the provision of ecosystem services? How too can biodiversity studies be best matched to the scales at which ecosystems services are manifested and managed?

Among the authors of the chapter is Edmundo Barrios, soil ecosystem senior scientist with the World Agroforestry Centre, who is particularly interested in how the ‘hidden’ biodiversity in soil helps deliver the important ecosystem service of soil fertility, which is critical to agriculture.

“Living in the soil is an extremely diverse soil biota, ranging from invisible microorganisms to soil macro-fauna, such as earthworms and termites,” explains Barrios. “This biota is the principal driving agent of soil organic matter decomposition and nutrient cycling.”

Soil biota has a direct impact on soil carbon storage, greenhouse gas emissions and water filtration. It can improve how crops and native plants acquire nutrients and it can influence plant health through the biological control of pests and diseases brought about by natural predators and parasites.

Through his research, Barrios has been able to reveal that the soil biodiversity-ecosystem service relationship appears to be less related to species richness and more dependent on certain key species or species with particular functional traits.

“Among different species of soil organisms, we can distinguish four major functional assemblages: decomposers, nutrient transformers, ecosystem engineers and bio-controllers. Each of these is responsible for driving the four major aggregate ecosystem functions­ carbon transformations, nutrient cycling, soil structure maintenance and biological population regulation­ that contribute to most soil ecosystem benefits to society. Until recently, linkages between soil biodiversity and ecosystem services received little attention, but it is becoming increasingly evident that soil biodiversity is critical for a sustainable human existence.”

Barrios explains how developing a better understanding of the links between biodiversity and ecosystem services will be of critical importance in coming years, with an increasing global population and climate change expected to affect biodiversity, ecosystems and ecosystem services.

Sustaining agricultural production amid these challenges will rely on the resilience of ecosystem services, which in turn depends on the resilience of functions driven by biodiversity.

“Maintaining soil fertility relies on the resilience of the different functions driven by components of soil biodiversity that support crop production,” explains Barrios. “But it is also influenced by soil type and factors such as the types of crops that are grown, how densely they are cultivated, the diversity within agricultural systems (e.g. monocropping vs intercropping), how land is managed and what inputs are used.”

“If we can understand how changes in biodiversity affect functions underpinning individual services, and the possible trade-offs, complementarities and synergies, then we can develop better policies and strategies to manage landscapes and agroecosystems which maximize yields without leading to degradation.”

The chapter suggests that studying agricultural practices, such as agroforestry, which “embrace ecological intensification through relatively high, but manageable, levels of above-ground and below-ground biodiversity” would help to build knowledge about how plants and soil interact to provide ecosystem services required for sustainable agriculture.

A long-term participatory research project, across a network of sites with contrasting social and ecological conditions, is proposed in the chapter. Researchers would use a common experimental design to monitor biodiversity, different bundles of services and the flow of benefits to societies. This, the authors of the chapter say, would help to fully assess the contributions of biodiversity to ecosystem services and people’s wellbeing.

Human wellbeing and how ecosystem services connect people with nature is a common theme running through the Handbook of Ecosystem Services. Comprising more than 50 chapters and 7 briefing notes that integrate natural and social science (including economics), the handbook aims to demonstrate how a better understanding of the relationship between people and nature will be important for dealing with future challenges such as sustainability, food security, health and poverty reduction, and the creation of a green economy.

Topics in the handbook range from the theory and practice of ecosystem services to how ecosystem services are defined, measured and valued, and who are the beneficiaries. There are specific chapters on different ecosystems and their services, including fresh water, forests, drylands and grasslands. Considerable emphasis is given to policy, decision-making and planning issues related to ecosystem services.

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The handbook is published by Routledge and the chapter on the links between biodiversity and ecosystem services is the result of the Working Group on Biodiversity and Ecosystem Services of the Ecosystem Services Partnership.

For information on the book and how to order copies, visit: https://www.routledge.com/products/9781138025080

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A methodological guide for blending local and technical knowledge on soil fertility management