Management of the nature reserve network in Jordan by the Royal Society for the Conservation of Nature (RSCN) requires information on the productivity and diversity of each reserve. Moreover, calculation of biomass is becoming increasingly important, not only for local firewood estimates, but also in a global context of determining carbon management options. Accordingly, we developed a 200-m grid for the systematic random selection of sample sites within the recently established 12 km² Ajloun Reserve, in the evergreen oak zone of northern Jordan. The method applied can be used in a variety of ecosystems and is in accord with local resources of staffing and training. In order to develop a method to compare these ecosystems across broad areas, we used high resolution satellite imagery to make ocular estimates of tree volume (as a depiction of biomass) for all 167 grid points falling within the reserve. A subset of 57 grid points was randomly selected and field sampled for calibration of the ocular estimates. Diameter and species were recorded for all trees in each sample. Stem counts were made by species for all tree regeneration (stems < 2.0 cm diameter). Following the inventory, a correction coefficient was identified according to the disparity between ocular estimates and volume estimates generated from field data, and then applied to all remaining grid points. Volume averaged 2.5 m³/ha (12.4% sample error using a 95% confidence interval). Using this method, biomass estimates can be extrapolated across landscapes in order to compare them. The permanent sampling network we established is relatively easy to maintain over time, and also provides a monitoring framework for other studies, including wildlife and rare plants. Repeat sampling (n = 12 points) in 2008 showed results similar to those of 2007, except for a decrease in the proportion of oaks in the 2.0 to 4.9 cm class.