REPORT
Forests are a “weapon” against
climate change
climate change
Published on October 26th, 2015
Effective management of forests is one of the main measures of adaptation and mitigation in the context of climate change. The challenge is to enhance carbon fixation capacity in these ecosystems, while simultaneously operating at the level of fire prevention.
Forests are a key component within the international context of climate change. As explained by Domingos Lopes, forest engineer and researcher at the CITAB/ UTAD, "they are the most efficient machine to photosynthesise and to counter the exponential increase in atmospheric carbon dioxide resulting, mostly, from human activities".
If forests are great allies in the fight against climate change, they can also be its victims. In fact, the forest landscape as we know it could soon come to an end. Some trees are expected to disappear and be replaced by more resistant species that are better adapted to the forecasted conditions, namely temperature increase and precipitation decrease.
Among the most resilient species are the holm oak and the cork oak, whose ecological and economic importance at national level is well known. “The cork oak can be increasingly important for the country”, he predicts.
On the other hand, the maritime pine may be affected in several ways, either by frequent fires or by phytosanitary problems associated with the decrease in water availability and increased temperature.
On this matter, the expert selects two scientific areas where the country needs to invest more to make the work of the technicians who deal with forests more efficient: phytosanitation and genetic improvement. “Genetic improvement can be a weapon to oppose this trend that privileges some species and weakens others. There are researchers from various fields trying to understand the possibility of improving the species, making them, for example, more resistant to drought. It is a multidisciplinary work”, he indicates.
"No species can be undervalued"
In terms of carbon dioxide sequestration, are some species better than others? As a forest engineer, Domingos Lopes has been studying carbon fixation dynamics and the ability of different ecosystems to sequestrate carbon, in order to respond more effectively to the Kyoto Protocol. However, the answer is not straightforward.
“In this context, the carbon retention period should last as long as possible, that is to say, that in a complete analysis of the chain of forest material uses, the plantation has longer retention periods”, he explains.
For instance, “broadleaves, which have a lower growth rate and theoretically have a lower fixation capacity, have, on the whole, from the moment they are planted until they are cut down, a much longer [carbon] retention period.”
According to the researcher, “broadleaves are extremely interesting”, from this point of view: in addition to being ecosystems, they are very complete, and with a great biodiversity.”
However, “no species can be undervalued. Even eucalyptus plantations have carbon sequestration dynamics that are extremely interesting, and much attached to their growth rate”.
In other words, there are species with slower growth, but which are installed for a longer period of time, and others that have faster growth but whose life cycle is shorter, although both can make an important contribution to climate change.
“We're trying to figure out what we can do in each of these contexts to enhance what each has to offer. For instance, in a context of great danger of fire, one might think that cleaning the woods is a top priority. But at the same time, in a context of climate change and carbon fixation dynamics, shrubs are very important”, he says.
The expert supports the application of more effective forest management strategies to prevent fires, but enhancing its carbon fixation capacity.
“It is crucial to realise where it makes sense to clear the forests to reduce the risk of fire and promote greater plantation stability, but at the same time, enhance one of the components of the ecosystem that contribute to carbon fixation”, he concludes.
Measures to make forests more resistant to fire
If it is true that forests help mitigate the effects of climate change by capturing CO2, forest fires do just the opposite, by releasing the gas with greenhouse effect into the atmosphere.
“Fires can exacerbate climate change by releasing carbon that was contained in the vegetation and which is now transferred to the atmosphere. But this only happens if the fire regime changes. If fires start being more frequent in a relatively short time, the plants will not have time to absorb or re-establish this carbon and the carbon balance between vegetation and the atmosphere changes. When there is more CO2 in the atmosphere, we have a feedback mechanism, an enhancement of greenhouse effect and global warming”, depicts Paulo Fernandes, also of the CITAB-UTAD.
It is actually a kind of vicious cycle in which climate change contributes to the appearance of more fires, which in turn contribute to climate change.
Among the measures that can make forests more resistant to fire are, for example, “the reduction of biomass or fuel load” and “the introduction of discontinuity between the treetops and the ground, or between the tops of adjacent trees, using various techniques such as mechanical equipment to cut down afforestation, livestock grazing and controlled fire.” “If those areas burn, they will do so differently, which will enable firefighting”, claims the expert.
Another measure is to slowly alter the vegetation in order to have more fire-resistant species, namely autochthone species such as oaks, typical of the north of the country. “These are forests that once established, dispense prevention activities such as cleaning. By themselves, they are more fire resistant. They burn with more difficulty because they are more dense, with less shrubs and herbaceous vegetation, and they tend to be more humid. If they burn, they also have greater regenerative capacity”, he notes.
There is one catch: these species require more humidity and climate changes are going to reduce precipitation. So, at least in the south, these species will have more difficulty to develop, within a climate change framework. Still, in some regions, the expert believes that pine forests, for example, are likely to give way to oak forests.
One thing is certain: “If we want a forest that is more resilient to fire, we must start now. It takes a continued and persistent effort to have results.”
If forests are great allies in the fight against climate change, they can also be its victims. In fact, the forest landscape as we know it could soon come to an end. Some trees are expected to disappear and be replaced by more resistant species that are better adapted to the forecasted conditions, namely temperature increase and precipitation decrease.
Among the most resilient species are the holm oak and the cork oak, whose ecological and economic importance at national level is well known. “The cork oak can be increasingly important for the country”, he predicts.
On the other hand, the maritime pine may be affected in several ways, either by frequent fires or by phytosanitary problems associated with the decrease in water availability and increased temperature.
On this matter, the expert selects two scientific areas where the country needs to invest more to make the work of the technicians who deal with forests more efficient: phytosanitation and genetic improvement. “Genetic improvement can be a weapon to oppose this trend that privileges some species and weakens others. There are researchers from various fields trying to understand the possibility of improving the species, making them, for example, more resistant to drought. It is a multidisciplinary work”, he indicates.
"No species can be undervalued"
In terms of carbon dioxide sequestration, are some species better than others? As a forest engineer, Domingos Lopes has been studying carbon fixation dynamics and the ability of different ecosystems to sequestrate carbon, in order to respond more effectively to the Kyoto Protocol. However, the answer is not straightforward.
“In this context, the carbon retention period should last as long as possible, that is to say, that in a complete analysis of the chain of forest material uses, the plantation has longer retention periods”, he explains.
For instance, “broadleaves, which have a lower growth rate and theoretically have a lower fixation capacity, have, on the whole, from the moment they are planted until they are cut down, a much longer [carbon] retention period.”
According to the researcher, “broadleaves are extremely interesting”, from this point of view: in addition to being ecosystems, they are very complete, and with a great biodiversity.”
However, “no species can be undervalued. Even eucalyptus plantations have carbon sequestration dynamics that are extremely interesting, and much attached to their growth rate”.
In other words, there are species with slower growth, but which are installed for a longer period of time, and others that have faster growth but whose life cycle is shorter, although both can make an important contribution to climate change.
“We're trying to figure out what we can do in each of these contexts to enhance what each has to offer. For instance, in a context of great danger of fire, one might think that cleaning the woods is a top priority. But at the same time, in a context of climate change and carbon fixation dynamics, shrubs are very important”, he says.
The expert supports the application of more effective forest management strategies to prevent fires, but enhancing its carbon fixation capacity.
“It is crucial to realise where it makes sense to clear the forests to reduce the risk of fire and promote greater plantation stability, but at the same time, enhance one of the components of the ecosystem that contribute to carbon fixation”, he concludes.
Measures to make forests more resistant to fire
If it is true that forests help mitigate the effects of climate change by capturing CO2, forest fires do just the opposite, by releasing the gas with greenhouse effect into the atmosphere.
“Fires can exacerbate climate change by releasing carbon that was contained in the vegetation and which is now transferred to the atmosphere. But this only happens if the fire regime changes. If fires start being more frequent in a relatively short time, the plants will not have time to absorb or re-establish this carbon and the carbon balance between vegetation and the atmosphere changes. When there is more CO2 in the atmosphere, we have a feedback mechanism, an enhancement of greenhouse effect and global warming”, depicts Paulo Fernandes, also of the CITAB-UTAD.
It is actually a kind of vicious cycle in which climate change contributes to the appearance of more fires, which in turn contribute to climate change.
Among the measures that can make forests more resistant to fire are, for example, “the reduction of biomass or fuel load” and “the introduction of discontinuity between the treetops and the ground, or between the tops of adjacent trees, using various techniques such as mechanical equipment to cut down afforestation, livestock grazing and controlled fire.” “If those areas burn, they will do so differently, which will enable firefighting”, claims the expert.
Another measure is to slowly alter the vegetation in order to have more fire-resistant species, namely autochthone species such as oaks, typical of the north of the country. “These are forests that once established, dispense prevention activities such as cleaning. By themselves, they are more fire resistant. They burn with more difficulty because they are more dense, with less shrubs and herbaceous vegetation, and they tend to be more humid. If they burn, they also have greater regenerative capacity”, he notes.
There is one catch: these species require more humidity and climate changes are going to reduce precipitation. So, at least in the south, these species will have more difficulty to develop, within a climate change framework. Still, in some regions, the expert believes that pine forests, for example, are likely to give way to oak forests.
One thing is certain: “If we want a forest that is more resilient to fire, we must start now. It takes a continued and persistent effort to have results.”
By: Cláudia Azevedo