Urgent Need for Warming Experiments in Tropical Forests
Although tropical forests account for only a fraction of the planet’s terrestrial surface, they exchange more carbon dioxide with the atmosphere than any other biome on Earth and thus play a disproportionate role in the global climate. Over the next 20 years, the tropics will experience unprecedented warming, yet exceedingly high uncertainty persists about their potential responses to this imminent climatic change. In a recent study, researchers investigated overall model uncertainty of tropical latitudes and explored the scientific benefits and inevitable trade-offs inherent in large-scale manipulative field experiments. With a Coupled Model Intercomparison Project Phase 5 analysis, they found that model variability in projected net ecosystem production was nearly three times greater in the tropics than for any other latitude. Through a review of the most current literature, they concluded that manipulative warming experiments are vital to accurately predict future tropical forest carbon balance, and they further recommend establishing a network of comparable studies spanning gradients of precipitation, edaphic qualities, plant types, and land use change. In addition, they provide arguments for long-term, single-factor warming experiments that incorporate warming of the most biogeochemically active ecosystem components (i.e., leaves, roots, and soil microbes). Hypothesis testing of underlying mechanisms should be a priority, along with improving model parameterization and constraints. No single tropical forest is representative of all tropical forests; therefore, logistical feasibility should be the most important consideration for locating largescale manipulative experiments.
Cavaleri, M. A., S. C. Reed, W. K. Smith, and T. E. Wood. 2015. “Urgent Need for Warming Experiments in Tropical Forests,” Global Change Biology 21 (6), 2111–21. DOI: 10.1111/gcb.12860.