Regional loss of long-lived tree species reduces the capacity of the biosphere to store carbon over centuries

Forests account for most of carbon uptake on land and could mitigate the rise of atmospheric carbon by storing carbon in vegetation and soils, but not all forests are equally effective sinks. The longevity of carbon pools on land strongly influences whether the land is a source or a sink in Earth System Models, however because most tree species have lifespans in centuries, information on the longevity of forest carbon pools are sparse. We quantify the likely longevity of more than 60 species of tree common to temperate forests and use forest surveys centuries apart, dendrochronology and mathematical modeling to quantify the change in potential residence time of carbon stored in biomass over half a million km² of forest in the upper Midwest of the USA. We show that species with long lifespans, have been disproportionately lost from temperate forests of North America. This loss has in part been responsible for the loss of carbon currently stored in standing forest biomass, but current disturbance and land management policies may promote species that limit future carbon storage. The longevity trait may point the way to constraining one element of carbon turnover in ecosystems. While the current generation of land surface models would not distinguish between these different tree types with different potential lifespans, we show that using three well established Land Surface Models, including traits that approximate tree longevity leads to a 4-fold change in steady state biomass.