Phytomass is defined as the above-ground component of grass. Its quantity across the reserve is integral in correlating grazer numbers and primary production as well as assisting with fire management. The arid savannah requires approximately 2 500kg of phytomass per hectare to sustain an ecologically viable fire. Too much phytomass will result in fires that are too hot and therefore destructive. Too little phytomass will result in cool fires that will perpetuate bush encroachment.
Volume of phytomass across the reserve has been recorded since 2009 and using this data-set it is possible to follow the trend in phytomass volume over the 5-year period. From 2009 to 2012 an overall increase in phytomass volume has been seen and may be attributed to recovery from excessive grazing regimes and high rainfall. Phytomass volume may be looked at alongside grazer populations established in the annual game counts and rainfall, as these factors are known to influence primary production.