Water-forest interactions complex but crucial in ecosystem service delivery

Soil is poured into bags in Kenya. CIFOR/Patrick Shepherd

Planting trees among the maize and bean crops of her smallholder farm in Kenya has helped Margaret Muchanga to increase yields, improving her family’s food and financial security and offering lessons in agroforestry that she can share with her community and spread the benefits.

“I can feed my children and now it’s becoming interesting to my neighbors and the community. They ask how it works, how it benefits me,” Muchanga told attendees at the recent webinar Agroforestry – scaling up a nature-based solution for water? This was the final in a Forest-Water Champions Network trilogy examining the role of forest-water interactions in delivering ecosystem services that contribute towards successful landscape restoration and climate change mitigation/adaptation.

“(Agroforestry) is growing in my area,” said Muchanga, whose farm — almost a hectare in size — is planted with maize, beans, coffee, bananas and fodder crops as well as a woodlot and four dairy cows to help support her family of five children. Training in agroforestry by Vi Agroforestry helped Muchanga choose what trees to plant – trees that, along with mulching, have improved soil water availability and soil fertility by reducing erosion.

The webinar was held in June, to precede World Water Week August 23-27. It focused on agroforestry – farming systems with trees – as a nature-based solution (NBS) used for centuries to improve food security and livelihoods while maintaining ecosystem functions, such as water regulation and biodiversity.

Despite the promise of agroforestry, the relationship between forests, trees and water is complex and scale-dependent, said Meine van Noordwijk, a research fellow at World Agroforestry (ICRAF). Challenges include a better understanding of how potential benefits interact, what are the trade-offs, and potential synergies, he said. Agroforestry must also be better understood at various scales, from farm to landscape level.

“Cycles of water are closely linked to carbon and nutrient cycles and we need to see how they interact before we can fully understand landscape-scale functions and services,” he added.

Alok Sikka of the International Water Management Institute (IWMI) and Shiv Dhyani of ICRAF discussed how India’s national water policies have enabled uptake of agroforestry as an NBS providing multiple co-benefits, including improved integrated watershed management. Water-related ecosystem services include cultural benefits, such as ecotourism and recreation; supporting services, including evapotranspiration and soil-moisture infiltration; provisioning services, such as drinking water; and regulating services related to climates, micro-climates and floods, said Sikka.

Since India began agroforestry research in the 1960s, it has provided half of the country’s fuelwood supplies, two-thirds of its timber, multiple ecosystem services, and ultimately contributed to a first-of-its-kind national agroforestry policy that Sikka described as a key enabler of NBS, promoting ecological stability.

Agroforestry does not provide a single, best answer, but its diversity is a strength, concluded Elaine Springgay, forestry officer at the U.N. Food and Agriculture Organization (FAO). It’s also an adaptable concept that can be tailored to socio-economic and environmental objectives.

A better understanding of the forest-water relationship has been a key goal of the Champions network. It was initiated and coordinated by FAO, the International Union for Conservation of Nature (IUCN), and the Stockholm International Water Institute (SIWI). It includes the Center for International Forestry Research (CIFOR) and other institutions.

Its webinar series began in October with Forest-Water Nexus Supporting Biodiversity, which highlighted forest-water connections  and the implications for biodiversity. For example, altering the landscape changes water flows, above and below ground, while restoring ecosystems can improve water availability, storage and quality — but only if the hydrological functions and services that ecosystems provide are considered.

Failure to do so risks jeopardizing the U.N. Decade on Ecosystem Restoration 2021-2030; no restoration or protection activity can succeed without protecting and improving hydrological functions and water management and services.

“A transformation is needed, from conventional forest management approaches focused on biomass production, to the recognition of forests as natural infrastructure where ecosystem services delivery, especially water, is a primary management objective,“ Springgay said.

Forests, as “natural infrastructure,” and their management can provide NBS for a range of water-related societal challenges. The extent and effectiveness of NBS was discussed at the second webinar, Are forests crucial to reaching our climate targets?. Participants considered how to harness forests as NBS for water, to build resilient landscapes, and deliver a low-carbon future. Proponents say NBS should play a key role in climate discussions, including the COP26 U.N. climate summit in November.

Increasingly, countries are including NBS in their nationally determined contributions (NDCs) to the Paris Agreement on climate change, said Catherine Martini of the NDC Partnership, during the April webinar. However, she added, details on the scope and process of implementing country actions on NBS are sketchy.

Forested watersheds provide an estimated 75 percent of the world’s accessible freshwater resources and over half the Earth’s population depends on these for domestic, agricultural, industrial and environmental purposes. Population growth is increasing pressure on water ecosystem services from forests, contributing to tree-cover loss, land conversion and degradation, increasing demands for water — all exacerbated by climate change. This highlights the forest–water nexus as a human issue that requires urgent socio-political attention.

“A large proportion of humanity has difficulties accessing and obtaining clean water to meet their basics needs – a problem expected to worsen due to climate change and as industries, energy production and households are predicted to increase their water consumption,” Lotta Samuelson, SIWI Program Manager and Team Lead Landscapes, said during the first webinar.

“Trees and forests are fundamental for the hydrological cycle and hence, for productive landscapes that provide food and raw materials for households and industries alike. Restoring degraded landscapes, and managing them for water, is crucial for achieving Agenda 2030 and the Paris Agreement.”

Existing research and knowledge, including traditional and local knowledge, should be applied to help prioritize how forests should be managed in symbiotic relationships with water-related ecosystem services, such as soil erosion control, flood reduction and groundwater. More research and monitoring of forest-water interactions in multi-functional landscapes is essential and should be a requirement of restoration and landscape initiatives. This demonstrates the multiple challenges that exist in relation to the forest-water interconnections, said James Reed, a CIFOR scientist.

“Just recognizing the forest-water nexus is not enough,” said Reed. “We must improve our ability to design, implement, and learn from landscape approaches that both rely on the relationships between forests and water, and impact them.”

A social-ecological systems approach would address resilience, climate, mosaic landscapes plus people, supported by integrated monitoring frameworks that include water in national forest monitoring systems and incorporate natural forests as sources of water supplies.

“We should challenge many of the assumptions around forests and water through better collaborative science,” said James Dalton, Director, Global Water Programme at IUCN. “Central to this goal must be the recognition of water as a resource that trees both require and provide.