TY - JOUR
T1 - The response of spider (Araneae) assemblages to structural heterogeneity and prey abundance in sub-montane vegetation modified by conservation grazing
AU - Dennis, Peter
AU - Skartveit, John
AU - Kunaver, Anja
AU - McCracken, D. I.
N1 - Submitted on 29 August 2014; MS #GECCO-D-14-00081R1; accepted for publication, 19 March 2015; Proofs checked and returned.
PY - 2015/1
Y1 - 2015/1
N2 - The effect of experimental livestock grazing regimens (4 treatments x 6 replicates) on spiders via habitat structure and prey abundance was investigated on sub-montane habitats in the Southern Highlands of Scotland. The study, 2002-04 included a baseline survey under the prior, commercial sheep grazing regimen and two assessments of spider assemblages post-treatment: commercial stocking density of sheep; 1/3 stocking density with sheep; 1/3 stocking density cattle with sheep; and no grazing. Spiders were sampled with a suction sampler, five sucks at each of 25 sample units by 24 plots (600 samples in 2003 and 2004, ca. 300 in 2002). Spider abundance and species richness increased under reduced stocking density, mixed herbivore and ungrazed treatments indirectly via changes in vegetation structure and prey abundance. The results refuted a meta-analysis that concluded species richness of spiders is unaffected by grazing. Grazing regimens caused turnover in species composition more than the net difference in species richness suggested, implying that no single, optimal grazing regimen will support as many species as a patchwork under varied grazing management. Conservation grazing benefits spiders and will have significant benefits for food webs in sub-montane ecosystems but the period to equilibrium after changes to grazing requires further investigation.
AB - The effect of experimental livestock grazing regimens (4 treatments x 6 replicates) on spiders via habitat structure and prey abundance was investigated on sub-montane habitats in the Southern Highlands of Scotland. The study, 2002-04 included a baseline survey under the prior, commercial sheep grazing regimen and two assessments of spider assemblages post-treatment: commercial stocking density of sheep; 1/3 stocking density with sheep; 1/3 stocking density cattle with sheep; and no grazing. Spiders were sampled with a suction sampler, five sucks at each of 25 sample units by 24 plots (600 samples in 2003 and 2004, ca. 300 in 2002). Spider abundance and species richness increased under reduced stocking density, mixed herbivore and ungrazed treatments indirectly via changes in vegetation structure and prey abundance. The results refuted a meta-analysis that concluded species richness of spiders is unaffected by grazing. Grazing regimens caused turnover in species composition more than the net difference in species richness suggested, implying that no single, optimal grazing regimen will support as many species as a patchwork under varied grazing management. Conservation grazing benefits spiders and will have significant benefits for food webs in sub-montane ecosystems but the period to equilibrium after changes to grazing requires further investigation.
KW - montane ecology
KW - habitat heterogeneity
KW - calcifuge grassland
KW - sub-montane mire
KW - domesticated herbivores
KW - suction sampling
UR - http://hdl.handle.net/2160/28381
U2 - 10.1016/j.gecco.2015.03.007
DO - 10.1016/j.gecco.2015.03.007
M3 - Article
SN - 2351-9894
VL - 3
SP - 715
EP - 728
JO - Global Ecology and Conservation
JF - Global Ecology and Conservation
ER -