Monday, April 13, 2015

Saving Forests is more Effective than Planting New Trees

Well obviously.  Burning off many feet of organic matrix and replacing it all with a young forest able only to sustain a few inches might have that effect.

Far better to properly manage old growth forest in the first place.  Just collecting the waste and chipping it provides wood pulp while improving general productivity  That has never happened but it now can happen.  It requires a regulatory regime that rewards superior husbandry.

A correct soil philosophy has been missing in our protocols and that needs to be addressed.  Once that happens the rest follows naturally.

Saving forests is more effective than planting new trees

Mar 25, 2015

Reducing deforestation is much more effective at climate-change mitigation than afforestation. That's according to researchers who have, for the first time, estimated the net carbon uptake from deforestation or afforestation by accounting for both nitrogen and phosphorus limitation worldwide.

The effectiveness of afforestation in reducing global warming depends on how much additional carbon dioxide the forested land takes up. For example, the rate of carbon uptake by trees in a warm and nutrient-rich environment will be much higher than that where it's cool and nutrient-poor.

"Only a few studies of the effect of afforestation on global warming have included nitrogen limitation," said Ying-Ping Wang from CSIRO Ocean and Atmosphere Flagship, Australia. "And there are no studies that include phosphorous limitation. Therefore, those studies will ove

Wang and his colleagues recently implemented a global model of carbon, nitrogen and phosphorus cycles in land biospheres into a simple Earth-system model. In a paper in Environmental Research Letters (ERL), they use this model to assess how effective afforestation really is if nutrient limitation is accounted for.

"Our work showed that nutrient limitation can significantly reduce both the carbon uptake of afforestation and the carbon loss of deforestation in terms of the global terrestrial carbon balance," said Wang. "Therefore in a nutrient-limited world, reducing deforestation is much more effective for climate mitigation than afforestation, particularly in the tropics."

The research team looked at two representative concentration pathways (RCPs): a reforestation scenario where emissions peak around 2040, then decline (RCP4.5), and a deforestation scenario where emissions continue to rise throughout the 21st&nsp;century (RCP8.5).

Globally, the increase in forest area in the reforestation scenario (RCP4.5) would be similar to the decrease in forest area in the deforestation scenario (RCP8.5) from 2006 to 2100, but the geographic locations of the forest change are quite different. Most of the afforestation would take place in the temperate and boreal regions, whereas most deforestation would occur in the tropics and the southern hemisphere. The study found that the net carbon emission from deforestation would be about twice as much as the net carbon uptake from reforestation from 2006 to 2100.

Specifically, inclusion of nitrogen and phosphorous cycling reduces carbon uptake in RCP4.5 from 55 Pg of carbon to 21 Pg C when including the full carbon, nitrogen and phosphorous cycles; or the emissions in RCP8.5 from 72 Pg C to 56 Pg C.

"While we were expecting to find a change as a result of nutrient limitation, we were quite surprised by the large response to nutrient limitation for both deforestation and afforestation," said Wang. "Our work shows that it is much more effective for climate mitigation to protect existing tropical and subtropical forests than planting trees in temperate and boreal regions where tree growth is slower and is more strongly limited by nutrients than in the tropical and subtropical regions."

Related links
Nitrogen and phosphorous limitation reduces the effects of land use change on land carbon uptake or emission, Ying-Ping Wang et al 2015 Environ. Res. Lett. 10 014001
Ying-Ping Wang, CSIRO Ocean and Atmosphere Flagship
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What's the value of afforestation and bioenergy carbon capture and storage?
Insight: can afforestation mitigate climate change?
Nitrogen has key role in estimating CO2 emissions from land use change

About the author

Nadya Anscombe is a contributing editor toenvironmentalresearchweb.

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