Estimation of forage yields of some range plant species by plant height and diameter measurements

Knowledge of forage production is one of the most important factors in range management program. Direct measurement of forage production is rather expensive and time consuming. The major objective of this study was to fit a model and to estimate the annual forage production of 19 shrub and forbs species. In Kashmar flood spreading area of Khorasan province. Annual forage production of 30 plants of each species were measured and compared with measurements of plant height and crown diameter at flowering stages and multiplication of the values of these two factors. Results showed that plant height times crown diameter in all species except Poa bulbosa and Polygonum arenastrum are a good estimation of forage yield and dry matter production. In general there was a positively significant linear relationship between forage production and crown diameter or plant height * crown diameter for all species under study (P< 0.05). An exponential model for forage production of Scoriala orientalis, Artemisia siberi and poteropyrum olivieri were detected. These results suggest that a linear or exponential model based on annual growth (height and crown diameter) is a good estimation of forage production if adequate sampling and suitable time is considered.