Table 1.

Herbivore diversity contrasts considered in the systematic review, based on functional groups of herbivores (F1, F2, F3, and invertebrates [inv])

Numerical change	Identity of change	Herbivore diversity contrast	N of records
0	No contrast	F1, F2, F3 | F1, F2, F3	1(23)
		F2 | F3	1(4)
		F2, F3 | F2, F3	6(60)
		F2, F3, inv | F2, F3, inv	2(19)
		F3 | F3	2(9)
		F3, inv | F3, inv	1(2)
		inv | inv	3(16)
1	F1	F1 | zero	55(703)
		F1, F2 | F2	2(16)
	F2	F2 | zero	17(231)
	F3	F2, F3 | F2	19(643)
		F3 | zero	58(906)
		F3, inv | inv	1(4)
	inv	inv | zero	14(150)
2	F1 and F2	F1, F2 | zero	1(1)
	F1 and F3	F1, F2, F3 | F2	1(41)
		F1, F3 | zero	6(65)
	F2 and F3	F2, F3 | zero	45(793)
3	F1, F2 and F3	F1, F2, F3, inv | inv	1(27)

Functional groups were defined by [5] and represent: F1 limnic-habitat associated herbivores, migrating outside the Arctic for winter, with undifferentiated guts and feeding mainly on graminoids (waterfowl; paragon Anser anser); F2 immobile, burrowing species with hindgut fermenting digestive physiology (paragon Synaptomys borealis); and F3 large-bodied facultative-generalist species for which shrubs and lichens are an important diet component (paragon Lepus timidus). Numerical change indicates the difference in groups between high and low diversity areas reported in each study. Identity of change describes which group of herbivores differed between high and low diversity areas. Herbivore diversity contrast specifies the groups of herbivores present in high and low diversity areas (high | low). Number of records indicates how many articles and studies (in brackets) reported each type of contrast. Note that some articles and studies had “no contrast” even if they passed the eligibility criterion for comparator; studies with “no contrast” were not considered in further analyses