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

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

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

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

Cheers
Darcy.

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

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.

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.

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?

A photo-series of our ingrowth core installation in Africa

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.

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

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

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