Rangeland condition monitoring, aka residual dry matter or RDM monitoring, is an essential, collaborative task involving the Conservancy, Tejon Ranch Company and representatives of both of Tejon’s cattle-grazing operations. Measurements are generally made in the autumn of each year just prior to the arrival of winter precipitation. 

 

The overall intent of the monitoring is to ensure the structural integrity of the Ranch’s grazing lands is maintained in such a way that promotes their long-term sustainability, both from an operational and an ecological perspective.

 

To achieve this, sufficient biomass, generally in the form of palatable grasses and forbs, must be retained such that the risks of soil erosion and landscape degradation are minimized, if not eliminated. Because soil erosion prevention is a key objective, steep terrain generally requires more residual dry matter, with gently sloping areas requiring less. Soil type and depth are key factors as well. On a landscape as topographically complex as Tejon Ranch’s, and with pasture sizes ranging from a few hundred to tens of thousands of acres, residual dry matter can vary significantly, even within the same pasture.