Posted: 08 Oct 2015 11:25 AM PDT
Record-breaking temperatures and droughts are directly affecting ecosystems worldwide, an international research team of life scientists reports. An international research team led by UCLA life scientists has, for the first time, quantified the direct influence of climate on the growth of ecosystems around the globe. The paper also restores scientific consensus to the fact that record-breaking temperatures and droughts directly affect ecosystems — which was called into question by a 2014 University of Arizona paper in the journal Nature. …The new study, which was funded by the National Science Foundation, was published this week in the journal Global Change Biology. The growth of whole ecosystems — the accumulation of new growth in a forest, shrub land or grass land — is referred to by scientists as net primary productivity. NPP is greater in the tropics than in the arctic because productivity responds directly to climate in much the same way that individual plants do. This means that the growth of ecosystems would respond rapidly to climate change. And because forests take up carbon dioxide from the atmosphere, even as their growth responds to climate, they play a role in determining ongoing climate change. In challenging that point of view, the Arizona researchers found no correlation between NPP and climate, after accounting for the influence of forest mass and age. They concluded that the correlation of NPP with climate was a coincidence or an illusion that arose simply because larger forests tend to be located in warmer, moister climates, and because larger forests have faster growth. But the UCLA-led study found definitively that NPP responds strongly and directly to climate. The implication of the new research is that climate change will have strong and immediate effects on forest productivity because climate strongly affects NPP, independent of the mass of the forest and its age. “Our analysis shows that the direct influence of climate on NPP globally is undeniable and enormous,” said Lawren Sack, a UCLA professor of ecology and evolutionary biology in the UCLA College and senior author of the research. “Our models can explain at least half of the global variation in NPP, with a major proportion attributable to climate, independently of biomass.”…
Chengjin Chu, Megan Bartlett, Youshi Wang, Fangliang He, Jacob Weiner, Jérôme Chave, Lawren Sack. Does climate directly influence NPP globally?
Global Change Biology, 2015; DOI: 10.1111/gcb.13079