• Toby MarthewsIngrowth cores

    Dear all,

    There is a correction factor used for estimating fine root biomass bellow 30 cm depth which is 0.39*fine root biomass from 0-30 cm depth. The CF is mentioned in this paper:

    Galbraith D, da Costa ACL, Portela BTT, Levy PWM, Fisher
    RA, Meir P. In review 2013. Effect of imposed drought on
    root biomass and its distribution with depth in an Amazonian
    rainforest. Global Change Biology.

    I was wondering if any of you have the published version of this article?

    Thanks in advance for your help,

    Jhon

    • Thumb_photo0133
      Over 2 years ago

      Thanks a lot.

      Jhon

    • Thumb_photo0133
      Almost 3 years ago

      Hi Toby,

      Thanks as always.

      I was a bit confused because I found Jackson's value in the new version of RAINFOR-GEM manual. And before that I had read Galbraight's reference in Doughty's paaper (page 5): The production, allocation and cycling of carbon in a
      forest on fertile terra preta soil in eastern Amazonia
      compared with a forest on adjacent infertile soil. I thought that I could clarify it with Galbraight's paper.

      Roots is always a tricky stuff. After all, I will take Jackson's value into account because it sounds like a average of several assessments. I was wondering if you have that paper and could share it with me, please. It would be good to take a look on it.

      Thank you again.

      Jhon

    • Thumb_p6220034
      Almost 3 years ago

      One more thing: I know that the difference between 39% and 31% is small and less than the natural variability between forests for this factor. The reason why I'm suggesting rather to use Jackson's 31% is because that paper also suggested estimates for other biomes (which I copied into the manual) so this factor becomes biome-specific if you follow that. For me, this is much more ecological. Toby

    • Thumb_p6220034
      Almost 3 years ago

      Hi Jhon,

      There is the following rule of thumb in Malhi et al. ("The productivity, metabolism and carbon cycle of two lowland tropical forest plots in south-western Amazonia, Peru", Plant Ecol & Diversity). I imagine the Galbraith paper is referring to this '39% rule':
      "We also estimated that there is an additional 39% fine root NPP beneath our 30 cm ingrowth core, by extrapolating to 1 m depth assuming an exponential decay of root biomass and productivity with depth"
      this rule is equivalent to assuming 61% of all roots occur in the top 30 cm of the soil profile and may also be estimated from an equation used in the CLM model (as pointed out by Chris Doughty: see footnote p.58 of the Manual v3 and the same is encoded in rootbiomassf_s.m in the equation for dzz).

      I asked Dan Metcalfe about this 39% rule in 2012 and he said it came from data collected by Rosie Fisher at Caxiuana. However I emailed Rosie F at that time and she said that this didn't come from her data so there has always been a bit of confusion over where the 39% rule originally came from.

      After looking into this more deeply I found that Jackson et al. (1996) put the percentage of roots above and below 30 cm as 69%-31% rather than 61%-39% and that this is backed up by studies across tropical humid forests. That is why Jackson's estimate appears in the Table on p.58 of the Manual v3 and I recommend this to be used over the 39% rule.

      Therefore, in answer to your question: that 39% rule is used by several references, but I suggest rather to use the 31% rule of Jackson (which is in the GEM manual section 2.3).

      Hope this helps.
      Toby

  • Soil depth profileDendrometer bandsCoarse litter fallRAINFOR methodologiesGround coarse litter massStem respirationCensusIngrowth coresFine litter fallSoil respiration partitionningSoil respirationRhizotrons

    Dear All,

    A new version of the RAINFOR-GEM manual is now out and here is the link: http://www.tobymarthews.com/rainfor-gem-manual-v30.html (it'll move across to the permanent URL at http://gem.tropicalforests.ox.ac.uk/page/resources very soon).

    I hope this is useful!

    Best regards,
    Toby

  • CensusIngrowth coresSoil respiration

    Hello again,

    As part of my job at Peruvian Amazon Research Institute (IIAP), the last December it was organized a training workshop in GEM methods for cuantifying carbon stocks and fluxes in tropical forests. Several students and professionals with climate change interest learnt our protocols.

    Pictures show part of the data collection and analysis.

    Jhon

    Thumb_p1020901 Thumb_p1020904 Thumb_p1020909 Thumb_p1020919 Thumb_p1020932 Thumb_p1020937 Thumb_p1020938 Thumb_p1020952 Thumb_p1020962
  • Ingrowth coresCécile GirardinUnderstanding the carbon cycle of Andean Forests

    Hi Cecile,
    How can I send you the root scan?

    Cheers
    Darcy.

  • RAINFOR methodologiesIngrowth cores

    After a meeting yesterday at the OUCE in Oxford, we all suggest to add a Replacement Rotation to the in-growth core protocol in the manual:

    As has been discussed here before (Terhi, Chris and Dan Aug/Sep 2012: http://gem.tropicalforests.ox.ac.uk/postings?resource=ingrowth-cores ), over the course of time, in-growth cores become degraded: some soil is lost at each excavation and repeated searching through the core fragments the soil structure. So, we suggest to arrange a rotation so that 25% (i.e. 4 under the standard protocol) of the in-growth cores are replaced with new cores (at least 1 m away) every three months. At changeover, excavate the old core as before but discard the soil into the old core hole, dig a new hole and set up a new in-growth core there using the same cage. This has the added advantage of giving regular root stock data from new locations each time.

    Does anyone have any comments about this new requirement? Is anyone already doing this? Any suggested modifications?

    Toby

  • Ingrowth cores

    Jhon: thanks for your question. We frequently encounter this issue in the Andes plots. Yes, you should consider the two layers separately (and also the A and B horizons on the mineral soil). When you install a root-free core, put in the appropriate soil in layers to match the natural horizons of the soil. When you count roots, it is interesting to count how many are in each horizon though this is not essential.

  • Stem respirationSoil respirationIngrowth coresComprehensive description of the carbon cycle of African forests

    If you have had problems downloading data from your EGM-4, it may be that your computer has an old version of the PP Systems software (see message from Kathryn Jeffery). Try installing this software instead.

    Compress
  • Ingrowth coresRAINFOR methodologies

    Hi Terhi, Good question about the ingrowth cores. There's certainly nothing magical about the 4 retrievals in my paper. If anything, it would be nice to have them in a bit longer (5, 6) just to reassure ourselves that the production in the 5th 3-month interval is similar to the first interval, which it should be if the soil fertility/texture change is not a big problem. It would be good to change holes every once in a while, the challenge then will be to align the production estimates from the old set of holes with the new ones (i guess there be some divergence just due to chance spatial variation). Maybe one way will be to have one overlapping period when both the new and old holes are running. This would then allow you to zero the production estimates from the new holes to the pre-existing time series from the old holes. This could be quite a lot of extra work, though you may only have to do it every year or few years, also you could perhaps just do it on a subset of the cores. Does that make sense?

  • Ingrowth coresComprehensive description of the carbon cycle of African forestsWest African Forests

    A photo-series of our ingrowth core installation in Africa

    Thumb_img_20120329_130502 Thumb_img_20120329_130523 Thumb_sam_0420 Thumb_sam_0423 Thumb_sam_0425 Thumb_sam_0418 Thumb_sam_0426 Thumb_sam_0431 Thumb_sam_0450 Thumb_sam_0447 Thumb_sam_0449
  • Ingrowth cores

    Hi Terhi,
    This is a good point. We have seen decreases in fine root NPP over time at some of the longer running sites such as Tambopata (~5 years). However, it is difficult to say whether that is due to decreased nutrient supply or some other long term trend. I will try and look at some of the long term data and see if we can determine a time frame.

  • Ingrowth coresRAINFOR methodologies

    Hi Friends of Roots,

    I think this is a good question: how long can we use an in-growth core? In Dan's paper (Metcalfe et al. 2008, Plant Soil) they installed cores and reported the results of 4 retrievals (=12 months) but there was no implication that that was the maximum lifetime of an IC core.

    What is the longest amount of time a single IC core has been used and repeatedly excavated across the RAINFOR-GEM plots?

    Toby

  • Ingrowth coresRAINFOR methodologies

    Dear Friends of Roots,

    I have a question about in-growth cores. How long do you keep using the same soil and the same hole? I think the soil gets impoverished over time, when nutrients are removed along with the roots, and the texture might also change through the repeated searches. On the other hand, digging a new hole and establishing a new core every time is a lot of effort.

    It would be great to hear you thoughts on this.
    Cheers,
    Terhi

  • Soil depth profileDendrometer bandsCoarse litter fallRAINFOR methodologiesGround coarse litter massStem respirationCensusIngrowth coresFine litter fallSoil respiration partitionningSoil respirationRhizotrons

    Apologies for cross-posting: After much debate and revisions between here and Leeds, the new version (2.2) of the RAINFOR-GEM Intensive Plots manual has now been uploaded on a new subpage of http://gem.tropicalforests.ox.ac.uk/ (see "Resources" on the left).

    This replaces the version 2.0 uploaded on GEM in February and also Dan Metcalfe's original v1.0 of the manual uploaded on http://www.geog.leeds.ac.uk/projects/rainfor/pages/manuals_eng.html (under “Measuring tropical forest carbon allocation and cycling”) and http://www.eci.ox.ac.uk/research/ecodynamics/carbon-balance.php (under “Online Materials” halfway down).

    Hope this is useful for everyone!
    Toby