Individual study: Vegetation dynamics in burnt heather-gorse heath under sheep and goat grazing regimes in the San Isidro mountain range, Asturias, Spain
Jáuregui B.M., Celaya R., Garcia U. & Osoro K. (2007) Vegetation dynamics in burnt heather-gorse shrublands under different grazing management with sheep and goats. Agroforestry Systems, 70, 103-111
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Change type of livestock
A controlled study in 2001–2003 in a heathland affected by burning in northern Spain (Jauregui et al. 2007) found that grazing with sheep instead of goats led to an increase in the cover of gorse Ulex europeaus and lower cover of herbaceous plants, but to no difference in the cover of heather Calluna vulgaris or in total plant biomass. After two years, gorse cover in plots grazed by sheep (27% cover) was higher than that in plots grazed by goats (14% cover). Cover of herbaceous plants was lower in areas grazed by sheep (27% cover) than those grazed by goats (42% cover). However, heather cover did not differ from between areas grazed by sheep (1% cover) and areas grazed by goats (1% cover). Plant biomass also did not differ significantly between areas grazed by sheep (10 tonnes/ha) and areas grazed by goats (9 tonnes/ha). In 2001 eight 0.3 ha plots were established with Gallega sheep, and eight plots with Cashmere goats. Stocking rate was approximately 10 animals/ha. Plant cover was recorded every year in 2001–2003 using point quadrats placed along six 13-metre-long transects in each plot. The vegetation in five randomly placed 0.2 m2 quadrats was harvested and dried for biomass estimation.
(Summarised by Phil Martin)
Other biodiversity: Use grazers to manage vegetation
A replicated study in 2001–2004 in shrublands in northwest Spain found that plant biomass decreased in plots grazed by sheep or goats. Plants: Cover of herbaceous vegetation declined in years three and four under both goat and sheep grazing (goat grazing: decline from 35% to 21%; sheep grazing: 34% to 11%). Implementation options: After two years of grazing, there was no difference in total biomass in plots grazed by goats, compared to sheep (9,000–14,400 kg dry matter/ha), but, after four years, less biomass was found on plots initially grazed by goats, irrespective of current grazers (10,900–11,400 vs 14,200–14,400 kg/ha). More biomass was herbaceous in plots grazed by goats, compared to those grazed by sheep, after both two and four years, and the biggest difference was between plots consistently grazed by goats or sheep (27% vs 14% after two years; 37% vs 14% after four). After both two and four years, cover of herbaceous vegetation was higher in plots grazed by goats in the first two years, compared to those grazed by sheep (42% vs 27% after two years; 21–35 vs 17–19% after four). Heather contributed more biomass after two years on goat grazed, compared to sheep grazed plots (23% vs 13%), but there was no difference after four years (9% in all). Cover of heather did not vary between goat and sheep grazed plots (1%). Less western gorse Ulex gallii was found in plots grazed by goats, after two and four years (the biggest differences between plots consistently grazed by goats, compared to sheep: 14% vs 20% cover after two years; 24% vs 44% cover after four years). Gorse was a smaller percentage of plant biomass in plots grazed by goats, compared to sheep, in the first two years (46% vs 70% after two years) but not in the last two years (73% vs 53% after four years). Methods: Four plots (1.2 ha each) in a gorse-dominated shrubland were burned in May 2001 and then grazed by either Gallega sheep or Cashmere and local-breed goats (two plots each, 12 animals/plot). Plots were grazed in two periods: first in October 2001–January 2002 and May–November 2002, and second in May–November 2003 (at a lower stocking density) and June–October 2004. In the second seasons the plots were split in half: one half received the same treatment and the other half was grazed by the other species. Vegetation cover was measured eight times/plot (six 13 m transects). Biomass was measured at six points in 2003 and 2004 (five 0.2 m2 transects).