Responses of a remnant California native bunchgrass population to grazing, burning and climatic variation

Published source details Marty J.T., Collinge S.K. & Rice K.J. (2005) Responses of a remnant California native bunchgrass population to grazing, burning and climatic variation. Plant Ecology, 181, 101-112.
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This study is summarised as evidence for the following.

	Action	Category
	Other biodiversity: Use rotational grazing Action Link
	Other biodiversity: Use grazers to manage vegetation Action Link
	Other biodiversity: Use fewer grazers Action Link

Other biodiversity: Use rotational grazing

A replicated, controlled study in 1998–2000 in grasslands in north-central California, USA, found no difference in purple needlegrass Nassella pulchra mortality or density between plots with rotational grazing or continuous grazing, but there were some differences in plant size and reproduction. Plants: Needlegrass mortality and density did not differ between plots with rotational grazing or continuous grazing (data reported as model results). Plants in rotationally-grazed plots had more reproductive stems than plants in continuously-grazed plots, in two of three years (1.3–1.8 vs 0.4–0.5). Plants were taller under light rotational grazing, but shorter under heavy rotational grazing, compared to continuous grazing, in one of three years (data not provided). There were no differences in plant stem diameter. Methods: Thirty 20 x 20 m plots were grazed from January (in 1998) or December (1999, 2000) until May at a stocking density of 0.75 animal units/ha. Rotationally-grazed plots were grazed until 25% (lightly grazed) or 50% (heavily grazed) of the plant biomass was removed, and then they were rested for 35 days. Continuously-grazed plots had animals at all times. Thirty individual plants were measured each year and plant density was estimated using 3–5 quadrats/plots (1 x 1 m quadrats).
Other biodiversity: Use grazers to manage vegetation

A replicated, controlled study in 1998–2000 in north-central California, USA, found no differences in purple needlegrass Nassella pulchra survival or density in grazed areas, compared to ungrazed areas. Plants had fewer reproductive stems and were shorter in grazed areas, compared to ungrazed areas. Plants: Needlegrass mortality and density did not differ between grazed and ungrazed plots (data reported as model results). Needlegrass plants in grazed plots had fewer reproductive stems, compared to in ungrazed plots (1.5–5.2 vs 0.4–4.1). Plants were shorter in grazed plots, compared to ungrazed plots (data not provided). Stem diameter did not differ between grazed and ungrazed plots (2.6–3.6 cm). Methods: Forty 20 x 20 m plots were either ungrazed, continuously grazed, or rotationally grazed from January (1998) or December (1999, 2000) until May, at a stocking density of 0.75 animal units/ha. Continuous grazing maintained animals on the plots at all times, whilst rotational grazing removed either 25% or 50% of plant biomass, with 35 days rest between rotations. Thirty individual plants were measured each year and plant density was estimated using 3–5 quadrats/plot (1 x 1 m).
Other biodiversity: Use fewer grazers

A replicated, controlled study in 1998–2000 in north-central California, USA, found no differences in purple needlegrass Nassella pulchra survival or density in lightly, compared to heavily, grazed areas. In one of three years, plants in lightly grazed plots had more reproductive stems and were taller than those in heavily grazed plots. Plants: Needlegrass mortality and density did not vary between grazed and ungrazed plots (data reported as model results). Plants in lightly grazed plots had more reproductive stems, compared to those in heavily grazed plots in one of three years (4 vs 2). Plants were also taller in lightly grazed, compared to heavily grazed, plots in one of three years (data not provided). Plant stem diameter did not vary between lightly and heavily grazed plots (data not provided). Methods: Twenty 20 x 20 m plots were rotationally grazed from January (in 1998) or December (1999, 2000) until May at a stocking density of 0.75 animal units/ha. Plots were grazed until 25% (lightly grazed) or 50% (heavily grazed) of plant biomass was removed and then rested for 35 days. Thirty individual plants were measured each year and plant density was estimated using 3–5, 1 x 1 m quadrats in each plot.