The Impact of Pine Forests on Soil Health

“The soil microbiome is similar to a rainforest in terms of its richness of species, bacteria and fungi,” says Steve Wakelin, Senior Scientist - Plant and Soil Microbiology at Scion “The diversity you’ll find there is greater than a coral reef; it’s the most hyper diverse environment in the world.”

Steve is working with fellow scientists at Scion on The Tree Root Microbiome Programme: At the root of climate-proofing forests, a five-year project to explore the potential of tree root microbiomes to enhance ecosystems and increase climate change resilience. These communities of microorganisms are being studied in relation to Pinus radiata or Monterey Pine. The insights Steve and his team are gathering are especially relevant for New Zealand’s pine plantation forests, including those used to source Abodo timbers.

“Like humans, trees are teeming with a myriad of microorganisms in, on and around them,” Steve says. “That community of microorganisms is called a microbiome, and it can profoundly affect the tree’s growth, physiology, health and ability to adapt to change. This research programme aims to build a greater understanding of the tree root microbiome, creating new insights and stimulating more research. It answers how trees can continue to grow and be resilient as the climate changes around them.”

A holistic understanding of the environments surrounding our trees and forests is essential in the battle against climate change, Steve says, as these ecosystems are immobile and typically long-lasting.

“The Tree Root Microbiome Programme represents a huge international effort to try and understand all the different relationships of microbiomes of radiata pine across the world. We’ve chosen that species because it is a good model system with a lot of pre-existing data, and it is the most widely planted tree globally. As we work to better understand how our forests will cope with the effects of climate change, this project allows us to look to our collaborators in places such as Australia or Portugal, where it’s hotter and drier than New Zealand, and learn how their pine forests are responding.”

"The role of a pine forest isn’t necessarily to support biodiversity in the same way as an indigenous forest, but the diversity of life in the soil is still incredibly high. People sometimes think pine forests create unhealthy soil, often because of what is visible above ground."

"This is largely because pine forest plantations are typically designed to close the canopy and have very little understory. Our view as humans is macroecological, but most of the diversity world is microorganisms that live in the soil. Depending on how you define it, soil health in a pine forest is very high and similar to what you would find in a native forest. The pH, for instance, is more similar to native forests than it is to a dairy or beef farm or, vineyard, or an apple orchard.”

In the case of Forest Stewardship Council®-certified rapidly renewable plantation forests such as those used by Abodo, the soils can be especially healthy, Steve says.

“These types of forests have a highly functioning microbiome that can support the high productivity of those systems and the ongoing ability to continue to harvest timber over a number of cycles."

"Because they are fast-growing, high-productivity sites, there’s a lot of carbon and a lot of energy moving through them from the trees into the soil; that lifts up the whole microbial biomass. There are a lot of microorganisms and activity because of the carbon flowing through those systems, so they’re very healthy in that regard. That’s why those systems are sustainably productive and can carry on over many rotations.”

Pine has a significant role to play in the future of energy and manufacturing, Steve says, as we work to divest from fossil fuels globally.

“The world needs an increasing supply of wood and fibre and energy from biomass. The demands on forests and soils are increasing massively, because of increasing populations and because of increased wealth and demand in developing countries."

"We have to make choices now about how we want to source our food and fibre, and pine forests are the least disruptive in those respects. From a productive point of view, they are the closest to natural forests of any productive system we have in New Zealand."

“Ultimately, the world has a decision to make. We can either extract the additional material we need from native forests and weather all the consequences of that, or we can set up land for highly productive, fast-growing forests that offer more productivity from a smaller footprint of land.

That way, we can preserve the biodiversity of our natural forests. If your values are focused around native biodiversity and retaining ecosystems, a good thing to do is to grow highly productive forests somewhere else so we can leave those natural ecosystems alone.”