[Terrapreta] forests vs. grasslands

[Sean K. Barry]

Hi Brian,

Yes, I think you have made a compelling analysis.  There is much in your statements calling references to what appear to be valid works.  These references do support your thesis.  Thank you for presenting your argument this way.  I think I agree with it, a lot.
I like this way.  I think it shows that you have researched deeply the subjects at hand.

You've not tied into this, however, how you think Terra Preta can help the situation.  The situation I mean is the rising levels of GHG.  How do you propose that forming Terra Preta is going to help?  You say there is a fall coming?  What do you mean "fall"?  Past posts from you claim that increased CO2 levels should be a boon for plants.  Increased temperatures will promote decomposition, increasing atmospheric CO2 concentrations, and that again helping plants grow even more.  Do you suspect growing seasons will lengthen in areas further north?  Can you show that soils can provide the nutrient inputs to sustain the promised growth that CO2 can bring?
You said it yourself, that CO2 is not the only limiting factor.  What happens with CO2 levels, do you think, and plant growth, when other limits come to force?

Here is a tough question?  One we beat the crap out of earlier this week and never really came to an answer.  When plants grow better in the increased atmospheric CO2 concentrations (and I do know that they can!), will the increased uptake of CO2 reduce the atmospheric concentrations?   If the CO2 concentrations reduce, will the plants not grow so much?  Do you have a "full system"  analysis here?

>From your analysis, have you formed a plan, which uses Terra Preta to remediate the problem of rising GHG concentrations?

Best Regards,

SKB
  ----- Original Message ----- 
  From: Brian Hans<mailto:bhans at earthmimic.com> 
  To: Terrapreta at bioenergylists.org<mailto:Terrapreta at bioenergylists.org> 
  Sent: Saturday, September 22, 2007 4:29 PM
  Subject: Re: [Terrapreta] forests vs. grasslands


  Lets recreate what happened David.

  I said, "
  forests tend to hold their biomass within the above ground parts and prairies/grasslands/ag. tend to hold biomass closer to or below the ground level. "

  You said, 'not true.  a very bad generalization'

  I said " 
  So...prairies dont hold their biomass underground and forest generally dont hold their biomass above ground? You got something to back that hypothesis up? I offered my data...where is yours? "

  You said " 
  you are over-reacting, over-reaching, and reading logic into my statements that isn't there -- a technique that makes real communication difficult, if not impossible.  i can't recall making any such statements about prairie and savannas.  put a leash on your inflamed thinking and just stick to the facts as expressed.

  forests can hold tremendous biomass, depending on the tree type and soil type.  there are some trees that have wide-spreading roots that don't penetrate more than a few inches below the ground surface.  many oaks, hemlock and spruce are in this category.  but there are other trees such as ash and maple that send deep roots into the subsoil and mine minerals and groundwater up to the surface.  this same variety in root behavior holds true for annual and perennial herbs and grasses, and which one grow varies with certtain soil and environmental conditions.  ideally, a plant community contains members of each class of rooting vegetation, but not always.

  certainly much of the amazon has soil and tree types that are shallow, spreading roots, so not much depth is created for the organic layer to store carbon, other minerals and water.  strip away and burn the trees and understory and the poor subsoil is exposed, with little capacity to hold nutrients.  thus, we have rapidly spreading slash-and-burn farming devastating the rainforest, leaving behind a near-desert.

  however, in deserts, trees get established that do have deep roots that reach down to access water and minerals buried under the sands.  such deep rooted trees are also common in mountainous zones whenever soil gets started in ravines and crevices.

  so, it is hard to generalize given, the adaptive diversity of nature.  nonethess, the mere presence of abundant thick coal seams worldwide is generous evidence of the carbon-sequestering potential of trees and forests.

  I say:
  I still dont see any data...just opinion but I'll address this anyhow because its important to the concept of terra preta. 

  First lets start here... http://www.news.cornell.edu/releases/April01/biomass.bpf.html<http://www.news.cornell.edu/releases/April01/biomass.bpf.html>    This basically says forests are forest in terms of standing biomass, boreal or tropical. Now onto the root to shoot ratio of below ground biomass to above ground biomass. http://svc237.bne113v.server-web.com/calculators/treecarbonhow.htm<http://svc237.bne113v.server-web.com/calculators/treecarbonhow.htm>   According to the IPCC, the R:S ratio for trees are .2 - .25. This means that ~ 4 to 5 times more biomass is above ground than is below ground. This is why I say 'forests tend to hold their biomass within the above ground parts' 


  When we look at the R:S ratio of grasslands http://www.ipcc-nggip.iges.or.jp/lulucf/cop9/Chp3/Chp3_4_COP9.pdf<http://www.ipcc-nggip.iges.or.jp/lulucf/cop9/Chp3/Chp3_4_COP9.pdf>  Pg 7, we get numbers like 4.0 - 1.6 for true grasslands and lesser for savanna (tho the definition of savanna is dubious for the IPCC but that is for another thread).   Which means that there is 4 to 1.6 times as much biomass below ground than is above ground. This is why I say 'prairies/grasslands/ag. tend to hold biomass closer to or below the ground level.'

  Now lets move to biomass decay in soils. As one moves farther away from the equator, soils biota has a harder time keeping up with digestion of biomass because of temperature. Why do I say this? http://www.terradaily.com/reports/Developing_Discussion_On_Soil_Carbon_Decomposition.html<http://www.terradaily.com/reports/Developing_Discussion_On_Soil_Carbon_Decomposition.html>   Quoting Dr. Davidson 'If you unplug your refrigerator, you can demonstrate that your food, which is basically organic matter, spoils more quickly when it is warm.' This concept is the exact concept to fear if one fears GHG's (as I do...I think we are heading for a nasty fall). As the earth warms ever farther north (and only slightly to the south because there isnt as much landmass) more and more of that undigested biomass is going to be digesting away...turning the soils everymore like tropical soils...IE mainly devoid of fixed carbon because the bugs at them all and coughed up CO2. An overall view of soil carbons from around the world is not an easy task. The only place I have been able to find these #'s are the previous linked site. http://www.geology.iastate.edu/gccourse/chem/carbon/images/carboncontent1.gif<http://www.geology.iastate.edu/gccourse/chem/carbon/images/carboncontent1.gif>   As one can clearly see in the last link, as you move away from the equator, more soil carbon. 

  Does that clear up my position based on not only my years of research but also based in data from peer reviewed organizations and papers?

  Brian Hans

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