Christchurch-based scientist Susan Wiser is part of a team of scholars from 90 institutions around the world to have had a paper published in the influential Science journal that reveals a continued loss in tree biodiversity would result in an accelerating decline in forest productivity worldwide.
The team consolidated field-based forest inventory data from 777,126 permanent sample plots in 44 countries containing more than 30 million trees and discovered that conserving diverse forests, not only retains a species-rich environment, but also maintains the forests’ output and services for future generations.
They found that when the number of tree species increases, so does the amount of timber that the forest produces.
They also found the opposite to be true – a decline in tree diversity would result in an accelerating decline in wood production.
Dr Wiser is a plant ecologist for Landcare Research, a Crown Research Institute that specialises in land-based environmental science.
Dr Wiser, who manages Landcare Research’s National Vegetation Survey (NVS) Databank, provided data from over 300,000 trees from more than 4000 permanent sample plots spanning the variety of New Zealand forest types. These plots were established from 1969-2007 and had measurement spans ranging from five to 43 years.
The global study calculated that the amount of loss in productivity that is associated with the loss of tree species richness would have an economic value of up to a $500 billion per year across the world.
That amounts to more than double what it would cost to implement effective protection and management of the Earth’s terrestrial sites of global conservation importance.
This finding highlights the need for a worldwide re-assessment of forest management strategies and conservation priorities and the need to explore the influence of tree species diversity on other values, such as food production and other persistence of native biota.
The research also marks the first major accomplishment of the team, formally known as the Global Forest Biodiversity Initiative (GFBI). Established in 2016, GFBI is an international, interdisciplinary, and multi-stakeholder research collaborative that aims at better understanding broad-scale patterns and processes associated with the planet’s four billion hectares of forested ecosystems.
The study was led by Jingjing Liang of West Virginia University, Peter B. Reich at the University of Minnesota and Thomas W. Crowther at the Netherlands Institute of Ecology. The trio also coordinates the initiative, which supports data sharing, policy making and cutting-edge research in forest sciences.
Dr Wiser said: “For New Zealand, the study also highlights the importance of our collections and databases, not just in underpinning New Zealand policy but in helping understand global patterns of tree diversity and productivity and how New Zealand fits in this global context. As such, it capitilises on the investment the New Zealand government has made over the years in long-term ecological measurements and ensuring that these data are securely archived and available.”