You can get close but getting an exact weight will be virtually impossible. The actual weight will depend on the density of the wood species plus the moisture content.
A site with different species of woods with weights in kg/m^3 is:
http://www.simetric.co.uk/si_wood.htm
Multiply 8.119 by the weight shown in kg/m^3 for the wood your interested in. Multiply the answer by 0.001 to obtain tonnes.
Realize the answer will be a close approximation.
George