By Nalau Bingeding

Climate change and carbon trade have now added a new dimension to the forestry profession. The significance of forests in mitigating climate change means that foresters and forest scientists must rise above expectations to address this issue that will determine the future existence of life on Earth.

In Papua New Guinea (PNG) most forestry activity is confined to natural forests, while forest plantations bear little significance. Moreover, plantation activities are erratic and contribute very little to government coffers compared to logging of natural forests. Therefore, there is little incentive in the development of forest plantations in Papua New Guinea.

However, with the advent of climate change, forest plantations will become as important as natural forests. Other than being used primarily to produce mostly timber, forest plantations can now be used for carbon sequestration and trade. Forest plantations will become more economical because they will derive revenue from both timber production and carbon trade.

Mitigation of climate change

Climate change can be addressed through the concepts of “cap and trade” and “carbon sinks”. With cap and trade, emissions from fossil fuel and agriculture are reduced over time with companies making successive reductions in carbon emissions and trading them as credits on the carbon markets. Carbon sinks involves the use of forests to filter out atmospheric carbon and storing them in the biomass of trees, and carbon credits derived from the carbon sinks are traded on carbon markets.

For developing countries with low fossil fuel and agriculture emissions but high deforestation rates, carbon sink is the mechanism by which they can contribute to the international effort in mitigating climate change.

Computer models have projected that the use of “cap and trade” alone is not sufficient to bring global temperatures below the 2oC threshold. Some 20 percent of the world’s greenhouse gas emissions are from deforestation and degradation of tropical forests, and it is believed that unless this issue is adequately addressed global temperatures will keep on rising.

This is why REDD (Reduced Emissions from Deforestation and Degradation of forests) has gained much media publicity while forest plantations have been given little attention. A report by the Clinton Foundation shows that forestation projects (forest plantations) have the same potential as REDD and can be used alongside REDD to mitigate climate change.

Afforestation and forest plantations

The main reason why forest plantations were established were for industrial use (sawn timber, plywood), domestic use (firewood, poles), environmental protection (soil erosion control, windbreaks), and as part of other landuses for amenity, shade and so on.

Today, there is another reason for the need to develop plantations and that is to sequester as much carbon as possible in order to mitigate climate change. This is why afforestation has become an important agenda item in the climate change debate.

Afforestation is defined as planting of trees on land where there has been no forest for at least 50 years. PNG has 3.2 million hectares of grassland and savannah, some percentage of which can be converted to forest plantations.

Afforestation of grassland in PNG has been done mainly with Pinus species from Central America, the Carribean and Southeast Asia. In the highlands Pinus patula is mostly planted, while Pinus carribaea and Pinus merkusii are mostly planted in the lowlands. These species have the ability to tolerate harsh environmental conditions on grasslands, such as low nutrients in the soil, shallow topsoil, and occasional fires.

There are few native species that can thrive on grasslands. But Pinus species have thrived and in the process have rehabilitated soils on grasslands in both the highlands and lowlands of PNG.
The Pinus species has no market in terms of tropical timber trade, but tropical hardwoods such as Kwila and Rosewood are in demand. Thus, it would be practical to plant the Pinus species as first rotation crops on grasslands and when the soil is rehabilitated, then plant the high demand tropical hardwoods such as Kwila and Rosewood.

By capturing more grassland through this process, we may eventually end up exporting tropical hardwoods from plantations in the next 20–30 years. Consequently, we may alleviate logging of natural forests for tropical hardwoods. With carbon plantations, our objective is to sequester as much carbon as possible within the shortest time possible, in order to prevent global warming reaching the 2o C threshold. For this to happen we need to go beyond ordinary plantation development in this country. We need to harness the power of clonal forestry and the use of elite families in family forestry.

Clonal forestry is the planting of trees of the same genetic makeup in a single plantation, usually derived from cuttings or tissue cultured material of a tree that is superior in growth and other desired traits. Family forestry refers to planting of trees with seeds collected from mother trees, while the use of elite families is where only seeds from mother trees that have proven superiority in terms of growth and other desired traits are used.

The Papua New Guinea Forestry Authority (PNGFA) should use genetic improvement to enhance plantation development and should also breed trees that grow quickly and can adapt to harsh environmental conditions to use for plantations on grasslands.

Accumulation of biomass in forest plantations is a function of growth and survival rates, thus the use of families and clones that have high survival and growth rates on grasslands will result in more carbon sequestration. Consequently, our forest plantations will be able to produce more carbon stocks and the credits can be traded on carbon markets.

Carbon sequestration

The graph on the rights shows that, with carbon plantations, we want to accumulate more volume of wood in the plantations from age t0 through age tn. However, at age tn volume increment in the carbon plantation begins to diminish. Therefore, the trees in the plantations at age tn will have to be cut, as there is little value in keeping them because they will sequester little or no atmospheric carbon at all.

Carbon sequestration in plantations

Conversely, the graph on the left shows that maintaining traditional plantations for producing timber will not effectively sequester atmospheric carbon. Some of the carbon sequestered is lost through the process of thinning at ages t1 and t2, which results in carbon leakage. In carbon trade we want to avoid carbon leakage as much as possible, therefore traditional plantations will not effectively sequester carbon.

Theoretically, forest plantations can be used to effectively sequester atmospheric carbon. Something the PNGFA could do by utililising its intellectual, technical and financial resources and venturing into the development of carbon plantations in Papua New Guinea.

Apart from REDD, we could also tell the world that we can afforest our grasslands for carbon sequestration and contribute to the international effort in mitigating climate change.

Nalau Bingeding is research fellow in the social and environmental studies division at the National Research Institute.

This article was published with permission from National Research Institute of Papua New Guinea. NRI website can be accessed at www.nri.org.pg

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