It depends on the time scale you are talking about and what the fate of the forest-sequestered carbon is.  Geologically, one would say that the forest (or any biomass, for that matter) is most important in global C cycling if it is buried into the sedimentary-rock record rapidly after sequestration from the atmosphere.  On the human time scale, a 50 y old forest accumulating X Pg of C will eventually emit that all back to the atmosphere as CO2 either gradually (decomposition) or catastrophically (fire).  At shorter time scales and without factoring the fate of the sequestered carbon, forests are only temporary storage units for carbon, and one has to really look at the soil processes beneath (where decomposition occurs)  to ascertain the time constant of carbon storage in such a system. 

Dear Ram,

may be think about an environment without these trees.

Then wind storms and droughts would be very much more serious.

We also have enough evidence to connect diminishing rainfall with even small logging events or other disturbances such as diminishing trees in an agroforestry system.

So the importance of sequestration is in addition to the above. Healthy well growing trees have that capacity and large scale interventions in forests have shown to be devastating for that sequestration. But yes, forest fires and infestations may have large impacts that are also on the rise due to climate change. More reason to give attention to diminishing these devastating factors.

But without the forests this earth would definitely be doomed.

Best wishes, Kees

I DO NOT think that carbon sequestration by reforesting can mitigate climate change even if "we" be able to reforest the whole world regardless temporal or/and spatial scales. The real problem is due to all that carbon stored for thousands / millions of years and "we" are putting into the atmospheric system right now and as Kenneth says not in the human scale we could avoid "global warming". Therefore we must be prepared to live with this problem adapting ourselves to this global change.

Yes. C fixed in stem is taken for human use. C fixed in leaves adds to soil. So, trees are the only means of protection from global warming.

@Kenneth M Towe, for some time if I accept this neither forest nor oceans are able to help than who or which things are able to help with global warming on any scale? and how we are able to buried significant amount of the organic carbon at that level where fossil fuels are? 

Dear all scientists,

Evolution of CO2 is always there from decomposition of organic materials. If it is decomposed anaerobically, it is converted to methane. The culprit of Global Warming is 'the methane' not the CO2 in my view. Methane emission from paddy fields is one of the most common problem. During harvesting of Paddy  farmers leave one feet stem in the field itself and plough back for improving soil fertility.  If un-decomposed organic matter is applied to soil, during the process of decomposition some part of CO2 evolved will convert as methane.  So the plants / trees are there for absorption of CO2 but no one absorbs methane. It is 8 times more culprit (heats up) than CO2.  My vision is 'If all of us make efforts to reduce methane we can post pone the ill effects of Global Warming'.  We have to stop burning of Coal. Because C is already sequestered there. We have to advice farmers to apply composted manure to crops instead half decomposed FYM.

What is the opinion of all of You!

Dear All,

this debate has been widely held so we do not necessarily have to start from the beginning.

Please see

http://debatepedia.idebate.org/en/index.php/Debate:_Reforestation_as_a_solution_to_global_warming#Pro.2Fcon_sources

There are still other reports on this discussion also.

Cheers, Kees

Totally agree with Rajakumar that methane has a global warming potential much higher than CO2, and therefore we have to pay attention to this gas. However, the residence time in the atmosphere of other greenhouse gases is very large (50-200 years for CO2), methane is just about 10 years, hence methane concentrations do not significantly increase even the great generation of this by cattle, rice paddies, swamps, etc. Although Ram's question is about carbon sequestration by forests and climate change mitigation. 

Victor Sir,

I you said rightly. 

Ram's question is about carbon sequestration by forests and climate change mitigation.

Please see the link :

http://www.ipcc.ch/ipccreports/sres/land_use/index.php?idp=32

KENNETH sir

Your statement is 100 % correct. But

Methylotrophs aerobically utilize C1 compounds by oxidizing them to yield formaldehyde

The methanotrophs are aerobic bacteria that oxidize methane as an energy source

Under anaerobic condition.........?

They can grow aerobically or anaerobically but the activity becomes very less under anaerobic condition as I understood.

So the Methane is the major GHG which has to be tackled by all means

Dear Dr Krishan

You are absolutely right about the lack of deeper studies as regards the carbon sink in forest soils/forest floors.

I can give some viewpoints to the lack of information and refer to over evaluation of a long-term investigation that we published in 2009. Canadian Journal of Forest Research 39; 962-975. Berg et al. ‘Sequestration of carbon in the humus layer of Swedish forests – direct measurements.’

There has been a strong opinion that the stored organic matter in forest soil, especially in organic layers generally is in a ‘steady state’. Thus - all litter that falls is also decomposed and there should not be any net change. A consequence for many scientists is that it is not meaningful to work on this. However, this opinion is completely unsupported and I have not managed to find any kind of support for it in the scientific literature.

We made an evaluation of the growth of humus layers in Sweden over a 41-year period and found a continuous growth that was highly significant. The average rate for the forested land of Sweden (23 million ha) was 251 kg C per hectare and year, which gives a sequestration rate 6.7 megatons C per year. The collected data includes land that has been managed and effects of wildfires has been included.

Additionally – in contrast to a popular opinion the sequestration rate increased with increase-ing mean annual temperature (MAT). The area includes both boreal and temperate forest, and has mainly two species of conifers, Scots pine and Norway spruce.

I intend to load the paper (above) to ReserachGate today.

Best regards

Björn Berg

I'd say that any forest may be observed as an reservoir. So if you cut it and burn it, you are releasing CO2. Likewise, if you grow new forest, it will  grab its share of CO2 from atmosphere. For old and unspoiled woods things may be in balance, with humus layers as a plus. Because the world woodland area is increasing, so is CO2 sinking capacity increasing - simple as that.

Now, to me it is largely a political, and not an academic question. The best way to see different approaches is in UNEP publication http://postconflict.unep.ch/publications/UNEP_Haiti-DomRep_border_zone_EN.pdf

It says a story of 2 countries sharing a same island and two opposing viewpoints towards forests and energy, resulting in total disaster on Haitian side, a phenomenon visible from space. Anyone remembers Haitian mangoes? Well, keep that memory. Soon you'll find them only there.

My country, Croatia, has forests at ~36% area. Estimation under Kyoto protocol skipped altogether the forest CO2 sink capacity for Croatia. Simultaneously wood is presented as a renewable energy. Now, please tell me how it is science, and not politics through and through.

It really depends on the growing stage of forests.

Young forest uptake a significant amount of carbon, but for mature forest, input and output tend to be balanced and under certain conditions, such as fire, can turn forest to a source

A few days ago I learned that firewood has 10 to 20 times less CO2 emission than natural gas for the same energy output (!) because it is a renewable source, and all the emission is attributed to fossil fuels consumed to bring the firewood from the woods to the stove.

In short, when a big wildfire burns and destroys vast areas of woodland, it is OK because its CO2 emission is exactly 0g CO2. But when a Canadair air plane comes to drop water on it, it is an environmental disaster because it runs on fossil fuels.

Of course, but in green hell wood fire produces no CO2.

Let me rephrase it a little... the way green dogma calculates CO2 emissions insults intelligence of the rest of us.

I just wonder why burning woods, if it is so good for environment, resulted in catastrophic soil erosion in Haiti, Madagascar and elsewhere.

The source I have at hand is at http://www.biomasstradecentre2.eu/available-literature/ and you'll find in the first brochure there, "Wood fuels handbook" all you need to start calculating. The CO2 calculation is at pg. 67.

You may draw your own conclusions.

I know, it is a bit conflicting. It happens to the rest of us all the time.

I always wonder why people say I said something when I did not.

Rüdiger, you imply I said burning forests is a good thing, which I never did. I merely implied that by metrics of the people in biofuels it is OK as firewoods - while in forests - have zero carbon.

So, how did you survive 50 stories jump?