Assuming you measure on the ground.

For carbon in the above ground parts of trees see attached from Italy; for grassland/crop above ground plant parts you may take Dry Matter as measured in Spain and take 45% as carbon.

The complexity comes from carbon in roots, soil and (dwarf)shrub formations.

Article Nitrogen and phosphorus limited production of cereals and se...

Article Carbon Stock of European Beech Forest; A Case at M. Pizzalto, Italy

If you go to the Verified Carbon Standard (VCS) web site and look up the standard method called "The Earth Partners Soil Carbon Quantification Method", this will give you the standard method we have authored and use to measure carbon stocks on landscapes.

Can you expand your question a bit?

Dear Newton

You may refer the following links in the context of forest.

Regards

rajiv

Article Forest biomass extraction for livestock feed and associated ...

Article Emission Removal Capability of India’s Forest and Tree Cover

Article Changes in Distributions of Carbon in Various Forest Types o...

Article Carbon Balance Assessment in Indian Himalayan Managed Forest...

Equations varry based on species (species specific) and general equation.General may also depend on the geographical and climatic conditions of the area. Check on Brown, 1997- for forests, Chave et al., 2005, 2009 and 2014. For non forest areas (I guess you meant trees on farms/agricultual lands) Check on Kuyah et al., 2012, 2012a, 2012b, 2014, 2016. Find some of the attachements here

check this publications

Article Allometric Models Based on Bayesian Frameworks Give Better E...

Chapter Quantifying Tree Biomass Carbon Stocks and Fluxes in Agricul...

Newton

Para áreas florestadas há equações de regressão que utilizam parâmetros fitossociológicos. Tive uma aluna de graduação que escreveu sobre isso há alguns anos.

Article SEQUESTRO DE CARBONO EM DIFERENTES FITOFISIONOMIAS DO CERRADO.

Thanks, guys.

Cheers!

N