The impact of shrub browsing by mountain hare and reindeer in subarctic Sweden

Vowles, Tage; Molau, Ulf; Lindstein, Lars; Molau, Mathias; Björk, Robert G.

doi:10.1080/17550874.2016.1264017

Cited by 9 publications

(6 citation statements)

References 39 publications

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“…Growing season TDD were significantly higher in ambient plots and there was a significant negative correlation between mean shrub height and TDD at the reindeer-grazed heath sites, which is most likely an effect of increased shading. Although rodents and hares, which have been found to exert a strong browsing pressure on B. nana (Vowles et al 2016), were not prevented from accessing the exclosures, the exclusion of large herbivores had a significant effect on both shrub height and cover of tall shrubs at our sites. This suggests that even though the effect on ericoid shrub species was minor, reindeer browsing of tall, deciduous shrubs, could still impact key ecosystem functions such as shading, with knock-on effects for soil temperature and nutrient cycling.…”

Section: Exclmentioning

confidence: 82%

Expansion of deciduous tall shrubs but not evergreen dwarf shrubs inhibited by reindeer in Scandes mountain range

et al. 2017

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Summary One of the most palpable effects of warming in Arctic ecosystems is shrub expansion above the tree line. However, previous studies have found that reindeer can influence plant community responses to warming and inhibit shrubification of the tundra.We revisited grazed (ambient) and ungrazed study plots (exclosures), at the southern as well as the northern limits of the Swedish alpine region, to study long‐term grazing effects and vegetation changes in response to increasing temperatures between 1995 and 2011, in two vegetation types (shrub heath and mountain birch forest).In the field layer at the shrub heath sites, evergreen dwarf shrubs had increased in cover from 26% to 49% but were unaffected by grazing. Deciduous dwarf and tall shrubs also showed significant, though smaller, increases over time. At the birch forest sites, the increase was similar for evergreen dwarf shrubs (20–48%) but deciduous tall shrubs did not show the same consistent increase over time as in the shrub heath.The cover and height of the shrub layer were significantly greater in exclosures at the shrub heath sites, but no significant treatment effects were found on species richness or diversity.July soil temperatures and growing season thawing degree days (TDD) were higher in exclosures at all but one site, and there was a significant negative correlation between mean shrub layer height and soil TDD at the shrub heath sites. Synthesis. This study shows that shrub expansion is occurring rapidly in the Scandes mountain range, both above and below the tree line. Tall, deciduous shrubs had benefitted significantly from grazing exclosure, both in terms of cover and height, which in turn lowered summer soil temperatures. However, the overriding vegetation shift across our sites was the striking increase in evergreen dwarf shrubs, which were not influenced by grazing. As the effects of an increase in evergreen dwarf shrubs and more recalcitrant plant litter may to some degree counteract some of the effects of an increase in deciduous tall shrubs, herbivore influence on shrub interactions is potentially of great importance for shaping arctic shrub expansion and its associated ecosystem effects.

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Section: Exclmentioning

confidence: 82%

Expansion of deciduous tall shrubs but not evergreen dwarf shrubs inhibited by reindeer in Scandes mountain range

et al. 2017

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“…Ungulates hampered ecological succession, halted shrub encroachment and consequently affected negatively above‐ground carbon stocks of the shrub understorey. Reductions in shrub biomass and in shrub carbon stocks have been observed in other ecosystems browsed by wild ungulates in North America (e.g., mule deer Odocoileus hemionus (Huffman & Moore, ); wapiti Cervus canadensis , pronghorn Antilocapra americana , and mule deer Odocoileus hemionus (Singer & Renkin, )) and Europe (e.g., reindeer Rangifer tarandus ; Vowles, Molau, Lindstein, Molau, & Björk, ); roe deer Capreolus capreolus , and red deer Cervus elaphus (González Hernández & Silva‐Pando, ). Our results also showed that ungulate browsing significantly reduced the accumulation of twigs and leaves in litter, and therefore litter carbon stocks.…”

Section: Discussionmentioning

confidence: 83%

Ungulates mediate trade‐offs between carbon storage and wildfire hazard in Mediterranean oak woodlands

Lecomte

Caldeira

Catry

et al. 2018

Journal of Applied Ecology

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1. Ungulates influence ecosystem services in important ways, including by altering the amount of standing plant biomass and species composition. Browsing, for example, removes biomass and, in consequence, can decrease the risk of wildfires.The influence of ungulates on carbon storage is more complicated. Browsers reduce carbon stocks directly by consuming biomass, but if browsing reduces fine fuel loads, then long-term carbon storage may increase.2. We investigated how wild ungulates mediate trade-offs between carbon stocks and wildfire hazard in a Mediterranean oak woodland. We assessed the effects of deer (Cervus elaphus and Dama dama) on the colonization by gum cistus (Cistus ladanifer), a highly flammable Mediterranean shrub, through a long-term ungulate exclusion experiment. We established fenced (unbrowsed) and open (browsed) plots in areas whereshrubs were previously cleared, and compared shrub density, height, biomass, and above-ground carbon stocks 6 and 14 years after fencing.4. There were no significant differences in shrub density between treatments after 6 years of browsing exclusion but, by this point, height was already significantly greater in fenced plots. At the end of the experiment, shrub density and height were both significantly greater in fenced plots. Biomass and carbon stocks of gum cistus increased and reached a plateau in fenced plots, while in open plots biomass and carbon stocks increased initially but then decreased. Ungulates also prevented accumulation of litter carbon stocks, which was significantly higher in fenced plots after 14 years of browsing exclusion. 5.We also modelled fire behaviour in fenced and open plots. Browsing reduced fine fuel load, an important contributor to fire spread, by 80%. In browsed plots, modelled wildfire rate of spread, flame length, and fireline intensity decreased by 50%, 65%, and 90%, respectively, which also decreased the probability of canopy fire and of oak mortality.6. Synthesis and applications. By decreasing fire hazard and the probability of canopy fire, ungulates may ultimately increase ecosystem carbon stocks through improved adult oak survival. These critical, indirect trade-offs need to be assessed when addressing the effects of ungulates on ecosystems and the management of their populations. cork oak (Quercus suber). Woodland understorey was dominated by C. ladanifer, a Mediterranean shrub species, and annual grasslands primarily composed of grasses (e.g., Bromus madritensis, Gaudinia fragilis), with smaller proportions of forbs (e.g., Andryala integrifolia, Leontodon taraxacoides) and legumes (e.g., Vicia disperma, Ornithopus compressus). Cistus ladanifer is a highly flammable species because of the terpene-derived resin that impregnates its leaves and branches K E Y W O R D S above-ground biomass, Cistus ladanifer, ecosystem services, fire behaviour, fuel management, oak survival, shrub encroachment, ungulates | 701 Journal of Applied Ecology LECOMTE ET aL. S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be f...

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“…In this region, the winter is the season that is warming the most (Scharn, Brachmann, et al, 2021 ), which most likely does not affect birch growth itself, but may influence snow conditions. The thickness, continuity and duration, of the winter snowpack are common limiting factors for arctic vegetation as the snow provides shelter from the harsh winter climate (Wipf & Rixen, 2010 ), as well as protection from large herbivores such as mountain hare, ptarmigan, and reindeer (Christie et al, 2014 ; Nordengren et al, 2003 ; Rödel et al, 2004 ; Vowles et al, 2016 ). Browsing may have played a significant role in controlling birch growth (Kaarlejärvi et al, 2013 ; Løkken et al, 2019 ; Speed et al, 2011 ).…”

Section: Discussionmentioning

confidence: 99%

“…The area is grazed by mountain hare ( Lepus timidus ), rock ptarmigan ( Lagopus mutus ), lemming ( Lemmus lemmus ), and semi‐domesticated reindeer ( Rangifer tarandus ). Reindeers graze in the area from July to September with a density of approximately 2.3 reindeers/km 2 (Vowles et al, 2016 ).…”

Section: Methodsmentioning

confidence: 99%

Limited decadal growth of mountain birch saplings has minor impact on surrounding tundra vegetation

Scharn

Negri

Sundqvist

et al. 2022

Ecology and Evolution

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Temperatures over the Arctic region are increasing at three times the rate of the global average. Consequently, Arctic vegetation is changing and trees are encroaching into the tundra. In this study, we examine the establishment and growth of mountain birch ( Betula pubescens ssp. tortuosa ), which forms the treeline in subarctic Europe, and its impact on community composition across the treeline ecotone nearby Abisko, Sweden. Birch advancement along elevational gradients was studied by comparing data collected in 2016 with data collected 10 and 15 years previously. Species identity, cover, and phylogenetic relatedness were used to assess the impact of birch encroachment on community composition. Our results show that birch occurrence above the treeline did not affect plant community composition, probably owing to the observed lack of significant growth due to herbivore browsing, nitrogen limitation, or a reduction in snow cover. Independent of birch performance, the tundra community structure shifted toward a novel community dissimilar from the forest plant community found below the treeline. Taken together, our findings are explained by species‐specific responses to climate change, rather than by a linear forest advance. Future treeline advancements are likely more restricted than previously expected.

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The impact of shrub browsing by mountain hare and reindeer in subarctic Sweden

Cited by 9 publications

References 39 publications

Expansion of deciduous tall shrubs but not evergreen dwarf shrubs inhibited by reindeer in Scandes mountain range

Expansion of deciduous tall shrubs but not evergreen dwarf shrubs inhibited by reindeer in Scandes mountain range

Ungulates mediate trade‐offs between carbon storage and wildfire hazard in Mediterranean oak woodlands

Limited decadal growth of mountain birch saplings has minor impact on surrounding tundra vegetation

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