Fernando, por favor veja Viera et al. (2008) e referências citadas.

VIEIRA, Simone Aparecida et al. Estimation of biomass and carbon stocks: the case of the Atlantic Forest. Biota Neotrop. [online]. 2008, vol.8, n.2 [cited  2014-07-07], pp. 0-0 . Available from: . ISSN 1676-0603.  http://dx.doi.org/10.1590/S1676-06032008000200001.

The problems of allometric equations are site and species specific, so that why the same allometric equations for the trees (dicotyledons) didn't work in your case. I found one research on oil palm (only one species but it's palm-monocotyledon) Henson et al., 2012. The estimation of frond base biomass (fbb) of oil palm. You could apply this method in your study. I think there are two main types of palm habits: high standing stem like Attalea sp. and multi-stem like Oenocarpus sp. This is another challenge for you. If you have enough time and funding I think it would be great to sampling the palm biomass (excavation technique), then you will get more accurate equations that you develope for your study site. This is so interesting, I hope my answer help. 

Dear  Chadtip Rodtassana

Thank you for your ansver. 

But i need to know how others researchers are doing to estimate the biomass of palm trees. For me, so far from palm biomass has been forgotten or wrongly estimated. I'm asking my colleagues to see if that is what is happening.

You may use: B=exp(-1,170-2,119*ln(DAP)) developed by Brown 1996 to estimate biomass in palms in Agroforestry Systems. If you work with natural forests or need more detail, I suggest you contact Rosa Goodman of the School of Geography, University of Leeds, UK ([email protected]). She is currently leading an article on this subject, using an extensive dataset of directly-measured arborescent palms from the Amazon to check different models for the estimation of biomass and carbon.

I noticed Goodman and colleagues already published the paper I mentioned. I'm attaching a link. I´m sure it will give provide useful information.

http://www.rainfor.org/upload/publication-store/2013/Goodman/Goodman_et_al_Amazon_palm_biomass_allometry_FEM_2013.pdf

Dear Vincent

I use a model developed here at National institute for amazonian research, this model have n=1200  SE=4.8%  R2=9.7

Thanks a lot for your paper.

My question is to know how the other resercher estimates biomass of palms in tropical forests.

yes I have done this in all projects to date where palms are a significant component and basically as said above we developed local ones--best to do allometry only on height--either height of main stem (my usual method) or total height but stem is easier.  And basically need to make local ones unless your particular species has already been analyzed or your species of interest is very similar to those that exist.  we did palm equations for forests in Belize (two type) and in Bolivia (1 type)

for Attalea cohune

Eq.1 y (kg/palm) =

302.6*ln(stem height in m)+276.93

r2=0.84

For Chrysophylla sp

y = 0.8966x - 0.3798

R² = 0.944

Hope this helps a little

Dear Silva,

As it was said earlier, if the growth becomes site-specific, the best thing to do is to calibrate an existing suitable model to your local conditions. You have to take some measurements for that, but still worth doing so

Upul 

Hi,

My colleague is doing biomass inventory on ToF (Trees outside Forests), including palm. You may contact him: Sebastian.Schnell at slu.se

I want to thank all the answers and share a new study published on allometry palm trees

http://www.mdpi.com/1999-4907/6/2/450