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Carbon fixation increases in response to
temperature
temperature
Published on October 27th, 2015
The dynamic of carbon fixation by trees changes in response to climate factors. This is one of the results of an international study with the participation of Portuguese researchers.
A new study, involving three researchers from the Centre for Functional Ecology of the University of Coimbra, relates the formation and growth of tree rings with climate conditions (particularly with temperature) and with carbon sequestration.
The article, entitled “Woody biomass production lags stem-girth increase by over one month in coniferous forests”, and recently published in the journal “Nature Plants”, allows for a better understanding of carbon fixation dynamics and the global carbon cycle, thereby contributing to an understanding of the role of forests in mitigating climate change.
As one of the authors of this study, Cristina Nabais, explains “the growth of the trunks has two phases: the first phase, where the formation of cells that will constitute the growth ring occurs, which is noticeable due to an increase in the circumference of the tree; and the second phase, which is extremely important, and during which carbon accumulation in these cells occurs, with an increase of the mass of trees.”
This study sought to understand precisely the formation mechanism of the rings and of the capture and fixation of atmospheric carbon, which turns the tree trunks into large long-term carbon reservoirs. It should be noted that the formation of forest biomass consumes about 15% of anthropogenic carbon dioxide (CO2) each year.
Researchers detected a positive correlation between temperature and carbon fixation. “If temperature increases, the amount of fixed carbon increases in the cells that will form part of the growth rings. Carbon fixation rate increases in response to temperature”, clarifies Cristina Nabais.
However, it is known that an increase in temperature also leads to increased evaporation and, if water is not available, there will be a reduction in photosynthesis, with the consequent reduction of carbon capture. And no doubt that in the Mediterranean, water is a major limiting factor to take into account.
Mediterranean forests are more climate “friendly”
Another of the study's findings points to a discrepancy between carbon fixation dynamics in Mediterranean forests (among which are the Portuguese forests) and in temperate forests.
“There is a gap between the first growth phase in volume and the second phase (carbon deposition). This time-lag is much higher in Mediterranean forests, compared to the northern temperate forests of Europe, in colder areas”, continues to explain the coordinator of the Portuguese team.
According to Cristina Nabais, this work provides “a much finer quantification of the contribution of trees in different climates to the carbon cycle”. On the other hand, it enables a better understanding of the difference between the forests of northern Europe and Mediterranean forests. The latter can “work and fix carbon for a longer period of time”.
Finally, the researchers suggest that the expected changes in climatic factors can alter the dynamics of growth of forests and carbon sequestration in the future. The good news is that with global warming forests, particularly those in northern Europe, may also fix more carbon, helping to combat the problem. This fact further emphasises the increasingly central role of forests in mitigating the effects of climate change.
This study brought together 33 researchers from 12 countries (Austria, Canada, China, Slovenia, Spain, Finland, France, Portugal, Czech Republic, Russia and Switzerland). It was essentially done in coniferous forests.
The purpose of the group of the University of Coimbra is to continue the study in order to relate the growth of tree rings with the annual variation of climate conditions.
By: Cláudia Azevedo
The article, entitled “Woody biomass production lags stem-girth increase by over one month in coniferous forests”, and recently published in the journal “Nature Plants”, allows for a better understanding of carbon fixation dynamics and the global carbon cycle, thereby contributing to an understanding of the role of forests in mitigating climate change.
As one of the authors of this study, Cristina Nabais, explains “the growth of the trunks has two phases: the first phase, where the formation of cells that will constitute the growth ring occurs, which is noticeable due to an increase in the circumference of the tree; and the second phase, which is extremely important, and during which carbon accumulation in these cells occurs, with an increase of the mass of trees.”
This study sought to understand precisely the formation mechanism of the rings and of the capture and fixation of atmospheric carbon, which turns the tree trunks into large long-term carbon reservoirs. It should be noted that the formation of forest biomass consumes about 15% of anthropogenic carbon dioxide (CO2) each year.
Researchers detected a positive correlation between temperature and carbon fixation. “If temperature increases, the amount of fixed carbon increases in the cells that will form part of the growth rings. Carbon fixation rate increases in response to temperature”, clarifies Cristina Nabais.
However, it is known that an increase in temperature also leads to increased evaporation and, if water is not available, there will be a reduction in photosynthesis, with the consequent reduction of carbon capture. And no doubt that in the Mediterranean, water is a major limiting factor to take into account.
Mediterranean forests are more climate “friendly”
Another of the study's findings points to a discrepancy between carbon fixation dynamics in Mediterranean forests (among which are the Portuguese forests) and in temperate forests.
“There is a gap between the first growth phase in volume and the second phase (carbon deposition). This time-lag is much higher in Mediterranean forests, compared to the northern temperate forests of Europe, in colder areas”, continues to explain the coordinator of the Portuguese team.
According to Cristina Nabais, this work provides “a much finer quantification of the contribution of trees in different climates to the carbon cycle”. On the other hand, it enables a better understanding of the difference between the forests of northern Europe and Mediterranean forests. The latter can “work and fix carbon for a longer period of time”.
Finally, the researchers suggest that the expected changes in climatic factors can alter the dynamics of growth of forests and carbon sequestration in the future. The good news is that with global warming forests, particularly those in northern Europe, may also fix more carbon, helping to combat the problem. This fact further emphasises the increasingly central role of forests in mitigating the effects of climate change.
This study brought together 33 researchers from 12 countries (Austria, Canada, China, Slovenia, Spain, Finland, France, Portugal, Czech Republic, Russia and Switzerland). It was essentially done in coniferous forests.
The purpose of the group of the University of Coimbra is to continue the study in order to relate the growth of tree rings with the annual variation of climate conditions.
By: Cláudia Azevedo