New report sheds light on which species and planting circumstances are best to leverage the crucial role of trees to humanity.
Around the globe, tree diversity is declining. Last year’s State of the World’s Trees report found that of the more than 60,000 known tree species, at least 17,500 are threatened with extinction. This dwindling of diversity is damaging our planet’s ecosystems – and ourselves – as well as constraining options for successful adaptation to the changing climate. Though several tree-planting initiatives are in place, there is a need for guidance and further funding.
In that context, at the Global Landscapes Forum (GLF)’s annual Climate event, held alongside the United Nations Climate Change Conference (COP27) in Sharm El-Sheikh, Egypt, the Global Crop Diversity Trust (Crop Trust), the Botanic Gardens Conservation International (BGCI) and the Center for International Forestry Research–World Agroforestry Centre (CIFOR-ICRAF) launched a new report: ‘Conserving and using tree diversity for global climate change adaptation and food system resilience.’
The report was written by Lex A. J. Thomson, an agroforestry and forestry scientist, botanist and rural development advisor, who is currently an associate with the Australian Centre for Pacific Islands Research. “We’ve been gifted with this remarkable tree diversity, which can be used for so many different purposes,” he said. What’s more, he emphasized, “diversity is very important for everything from disease and insect resistance to increasing levels of climate change.”
Sarada Krishnan, a coffee scientist and Director of Programs at the Crop Trust, said a key part of boosting diversity is building seed sources and private nurseries that can meet demands for high-quality germplasm from farmers and reforestation projects. Further, “we need to look at species–rich multistrata approaches to agroforestry systems,” she said, “and ensure that we’re using local indigenous trees as bases.”
Paul Smith, a plant ecologist and the Secretary General of the Botanic Gardens Conservation International (BGCI), pointed out that while large swathes of the globe have been committed for afforestation in line with reforestation and climate mitigation pledges, the majority of this is set to become commercial plantations – usually of exotic species. “We know how to grow around 18,000 different tree species. But in mainstream forestry, we use a tiny fraction of that” – most of which are exotic species that can have damaging impacts on local ecosystems. “Native tree species can deliver much better ecosystem functioning biodiversity and resilience effects.”
Ramni Jamnadass, a tree resources scientist based at the Center for International Forestry Research–World Agroforestry Centre (CIFOR-ICRAF), drew attention to the financial context surrounding the issue. “Tree diversity is a key contribution to solving some of our global problems,” she said. “However, the resource is under severe threat. There is a massive need for planting materials, and the mechanisms and programs that support the investment in tree planting material really pay off – the cost-benefit ratio and the net benefits are high.”
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