Individual study: Growth, mortality and recruitment of purple needlegrass Nassella pulchra in response to prescribed autumn burns and spring or summer sheep grazing, Jepson Prairie Reserve, California, USA
Dyer A.R. (2003) Burning and grazing management in a California grassland: growth, mortality, and recruitment of Nassella pulchra. Restoration Ecology, 11, 291-296
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Other biodiversity: Use grazers to manage vegetation
A replicated, randomized, controlled study in 1988–1995 in grassland in central California, USA, found no consistent differences in mortality or basal area of purple needlegrass Nassella pulchra plants in sheep-grazed plots, compared to ungrazed plots. Plants: Needlegrass mortality was lower in spring-grazed plots, compared to ungrazed plots, for one combination of burning and topography (5% vs 15% annual mortality), and was higher in summer-grazed plots, compared to ungrazed plots, for another combination (3% vs 0%). Density of plants did not differ between grazed and ungrazed plots (0.3–1.0 plant/m2). The basal area of plants increased less in summer-grazed plots, compared to ungrazed plots (0% vs 110% increase), but there was no difference between spring-grazed and ungrazed plots (86–110% increase). Methods: In 1988–1995, six 20 x 20 m plots were ungrazed, six were grazed by sheep in spring, and six were grazed in summer. Half of the plots were burned in 1988, 1991, and 1994. The survival of 629 needlegrass plants was monitored annually (except for 1993), and 126–130 plants were measured in 1992 and 1995.
Other biodiversity: Use seasonal grazing
A replicated, randomized, controlled study in grassland in central California, USA, found no difference in purple needlegrass Nassella pulchra mortality in plots grazed by sheep in spring, compared to summer. Needlegrass density was higher in spring-grazed plots in some comparisons, and needlegrass size increased by more in spring-grazed plots, compared to summer-grazed plots. Plants: There was no difference in mortality between spring- and summer-grazed plots (0–15% annual mortality for all). Needlegrass density was greater in spring-grazed plots, compared to summer-grazed, when the plots were also burned (0.8–0.9 vs 0.3 plants/m2), but not when they were unburned (0.5–0.9 plants/m2). Average basal area of needlegrass plants increased by more in spring-grazed plots, compared to summer-grazed (86% increase vs no increase). Methods: In 1988–1995, eighteen 20 x 20 m plots were maintained. One-third were ungrazed, one-third were grazed by sheep in spring, and one-third were grazed in summer each year. Half of the plots were also burned in 1988, 1991, and 1994.