A forest composed of slow-growing trees stores more carbon, resists more disturbance, and supports more ecological complexity than a forest of fast-growing ones. Slow growers produce dense wood, develop deep root systems, create structural niches that fast-growing species cannot. They are the scaffolding of old-growth ecosystems. They are also the first to disappear under pressure.
Published in Nature Plants, Guo, Svenning, and colleagues analyzed more than 31,000 tree species globally and found that forests are becoming increasingly uniform, dominated by fast-growing “sprinter” trees while slow-growing, long-lived species disappear. The shift is driven by climate change, deforestation, and habitat loss, all of which favor species that grow quickly, reproduce early, and tolerate disturbed conditions. The tropical and subtropical regions face the most severe impacts — many slow-growing species with naturally small ranges are confined to limited areas and face total displacement.
The structural insight is about the relationship between growth rate and resilience at the ecosystem level. Fast-growing trees are individually successful — they colonize openings, reach reproductive age quickly, outcompete neighbors for light. But a forest composed entirely of sprinters is structurally fragile: shallow-rooted, low-density, carbon-poor, and lacking the complex vertical architecture that supports biodiversity. The optimization that favors individual trees degrades the system they compose. The forest is getting greener — faster-growing trees produce more leaf area — while simultaneously becoming less stable, less diverse, and less capable of long-term carbon storage. The appearance of vitality and the fact of decline are happening simultaneously, in the same forests, measured by different metrics.