Long-term thermal sensitivity of Earth’s tropical forests

Abstract

The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (−9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth’s climate.

A Bornean peat swamp forest is a net source of carbon dioxide to the atmosphere

“…during the afternoon in line with long-term observations (Sullivan et al, 2020). Therefore, a warming climate may reduce tropical forest productivity as T can may reach a temperature threshold earlier in the day unless plants are able to acclimate to this temperature stress.…”

Complete or overcompensatory thermal acclimation of leaf dark respiration in African tropical trees

“…African tropical forests contribute significantly to the terrestrial carbon sequestration (Nyirambangutse et al, 2017;Sullivan et al, 2020). They currently take up approximately 0.63 tonnes of C per hectare per year, but due to increasing temperature and drought this carbon sink strength is predicted to decrease by 14 % by 2030 (Hubau et al, 2020).…”

Carbon dioxide loss from tropical soils increases on warming

“…Besides the clear take-home message that the responses of soil respiration processes under climate change should not be represented in Earth-system models only by simple Q 10 or Arrhenius functions, Nottingham and co-workers' study adds to recently accumulating evidence that tropical forests are unlikely to continue indefinitely to be carbon sinks as the world warms 11 . Tropical soil carbon does not receive as much attention as do the large and vulnerable soil-carbon stocks at high latitudes, which pose major concerns as a potential source of positive feedback to climate change 12 .…”