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Providing evidence to improve practice

Individual study: Spring-fed wetland and riparian plant communities respond differently to altered grazing intensity

Published source details

Jackson R.D. & Allen-Diaz B. (2006) Spring-fed wetland and riparian plant communities respond differently to altered grazing intensity. Journal of Applied Ecology, 43, 485-498


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 fewer grazers Mediterranean Farmland

A replicated, randomized controlled study in 1993–2002 in wetlands in central California, USA, found lower plant diversity in one of two habitats in lightly, compared to moderately, grazed plots. Herbaceous plant cover increased in lightly, but decreased in moderately, grazed plots. Species composition of plant communities differed, but variability did not, between lightly and moderately grazed plots for one of two habitats. Plants: Two measures of plant diversity were lower in lightly, compared to moderately, grazed plots alongside creeks, but not at springs (data reported as model results). Herbaceous plant cover increased over time in lightly grazed plots, but decreased in moderately grazed plots (data reported as model results). The species composition of plant communities varied between lightly and moderately grazed plots (data reported as ordination results). Plant community variability did not differ between lightly and moderately grazed plots (data presented as coefficients of variation). Methods: In 1993, three wetlands in each of three watersheds were assigned to either light grazing (reducing dry matter to 250 g/m2) or moderate grazing (reducing dry matter to 150 g/m2). Plots of 2–5 ha were established at springs and creeks in each wetland. Vegetation biomass was sampled each year in 1993–1998 from three 0.0625 m2 quadrats in each plot and plant communities sampled with transects in 1993–2002.

 

Other biodiversity: Exclude grazers Mediterranean Farmland

A replicated, randomized, controlled study in 1993–2002 in wetlands in central California, USA, found higher plant diversity in plots with cattle excluded, compared to grazed plots. Herbaceous plant cover increased over time in ungrazed plots, and lightly grazed plots, but decreased in moderately grazed plots. The species composition of plant communities differed between ungrazed and grazed plots, for one of two habitats. Plants: One measure of plant diversity along creeks was higher in ungrazed plots, compared to grazed plots. Another measure along creeks was lower in ungrazed plots, compared to moderately but not lightly grazed plots. There were no differences in diversity at springs. Herbaceous plant cover increased over time in ungrazed and lightly grazed plots, but decreased in moderately grazed plots (data reported as model results). The species composition of plant communities differed between ungrazed and grazed plots for creeks, but not springs (data reported as statistical results). Plant communities showed more variability over time in ungrazed, compared to grazed plots (data presented as coefficients of variation). Methods: In 1993, three wetlands in each of three watersheds were assigned to light grazing (reducing dry matter to 250 g/m2), moderate grazing (reducing dry matter to 150 g/m2), or no grazing (grazers excluded). Plots of 2–5 ha were established at springs and creeks in each wetland. Vegetation biomass was sampled each year in 1993–1998 from three 0.0625 m2 quadrats in each plot, and plant communities were sampled with transects in 1993–2002.