Annual Grassland Forage Productivity

Ranchers and range managers in California depend heavily on annual production of natural forage, or herbage, from grasslands-but to best utilize this forage they must understand the seasonal productivity of the annual grassland ecosystem. Intensive studies carried out on the San Joaquin Experimental Range in the 1970's led to the development of models which provide much new insight into seasonal forage productivity. Thus, we can now describe typical patterns of forage production (grasses and forbs) which, while not all-inclusive, are correct in a general sense and are of great value in range management. Four factors-precipitation, temperature, soil characteristics, and residue-largely control forage productivity and seasonal species composition. These factors also change the timing and characteristics of the four distinct growth phases: break of season, winter growth, rapid spring growth, and peak forage production. Many of these patterns can be used to guide management decisions. As the season progresses, the patterns become set and the outcome more predictable.