Effects of Fall Clipping or Burning on the Distribution of Chemical Constituents in Bluebunch Wheatgrass in Spring

Abstract

We examined the effects of fall clipping or burning on chemical constituents and their distribution in bluebunch wheatgrass the following spring. The study was made in both a big sagebrushbluebunch wheatgrass and a Douglas fir-bluebunch wheatgrass community. The concentration of mineral constituents (nitrogen, phosphorus, calcium and magnesium) was lower while the concentration of fibrous constituents (acid detergent fiber, neutral detergent fiber and lignin) was higher in leafy material at the top of the plant. In the big sagebrush community, the differences among treatments were generally greater in the lower segments of plants. Generally, the mineral constituents increased while the fibrous constituents decreased from the control to the clipped to the burned treatment. The treatment effect was more variable in plants from the Douglas fir community. Burning causes an increase in mineral constituents and digestibility (Daubenmire 1968; Pearson et al. 1972) whereas grazing does not appear to affect plant chemistry (Rickard et al. 1975; Willms et al. 1980). There is no information available on the vertical distribution of chemical constituents in bluebunch wheatgrass (Agropyron spicatum) and little information that compares the effects of burning or grazing on plant chemistry. A study was made to determine the effects of fall clipping or burning on plant chemistry and on the distribution of chemical constituents within the plant.