Relationship between primary productivity and temperature in broadleaved Pinus koraiensis mixed forest in Changbai Mountains of northeastern China

ObjectiveStudying the temperature sensitivity of ecosystem carbon cycle in the climate change scenario is one of the major subjects of global change ecology, which demands the incorporation of temperature acclimation of ecosystem productivity. Exploring the response of productivity to ambient temperature in the broadleaved Korean pine forest, a typical temperate forest ecosystem and an important carbon sink, is helpful for better understanding the fundamental processes of ecosystems in a changing environment, which will promote the accuracy of carbon cycle simulation of forest vegetation in China.

MethodIn this study, we investigated the temperature response of gross primary productivity, net ecosystem productivity and ecosystem respiration using flux data of a Korean pine forest in northeastern China from 2003 to 2011, and further explored the influence of environmental factors on the above three carbon processes.

ResultThe results suggested that both the temperature responses of gross primary productivity and net ecosystem productivity were one-peaked curves with their optimum temperatures (t_GPP and t_NEP) positively correlated with the maximum temperature in a year. For 1 ℃ increase in the maximum temperature, t_GPP and t_NEP increased by 0.41 ℃ and 0.66 ℃ in the interannual scale, respectively. Environmental factors such as annual precipitation, photosynthetically active radiation, and vapor pressure deficit had no significant effect on t_GPP and t_NEP, while summer precipitation might have the ability to mediate the effects of t_GPP caused by the rising temperature.

ConclusionTherefore, there was a thermal acclimation of photosynthesis at the ecosystem-level. Previous models might exaggerate the impact of climate change on carbon fluxes if ignoring the influence of photosynthesis thermal acclimation.