Plant distribution pattern across the forest-tundra ecotone: The importance of treeline position

Hofgaard, Annika; Wilmann, Bodil Helene

doi:10.1080/11956860.2002.11682725

Cited by 38 publications

(34 citation statements)

References 24 publications

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“…2). This highlights the interaction between treeline position, as a key community determinant, and land use, as a key ecosystem driver in determining community structure (Hofgaard & Wilmann 2002;Camarero, Guti errez & Fortin 2006;Batllori et al 2009). …”

Section: B U F F E R I N G B Y H E R B I V O R Ymentioning

confidence: 99%

The response of plant diversity to grazing varies along an elevational gradient

2013

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Summary1. Species richness of plants generally decreases along elevational gradients or peaks at intermediate elevations. Land use including grazing by wild and domestic herbivores also affects plant communities and diversity, but how grazing affects plant diversity along elevational gradients is less clear. 2. Using a field experiment along an elevational gradient in Norway, we tested whether the impact of grazing on plant diversity interacts with elevation. Vascular plant communities were sampled following 10 years of experimental sheep grazing (decreased/ceased, maintained and increased densities of 0, 25 and 80 sheep km À2 ) and compared with pre-experimental baseline data.3. The impact of grazing on species richness (alpha diversity) was investigated at the species level, and temporal community variance was used to investigate community stability (temporal beta diversity). Spatial community variance (spatial beta diversity) at the enclosure level was used to test whether community homogenization differed between treatments. 4. Species richness and temporal stability varied between treatments and along the elevational gradient. Where grazing was ceased, species richness declined by up 3.7 species at low elevations and increased by up to 3.5 species at high elevations, whilst where grazing was maintained or increased, changes were less extreme along the elevational gradient. 5. Temporal stability of plant communities was highest at low elevations and lowest at high elevations where grazing was reduced. There were no clear differences in spatial homogenization between grazing treatments, although spatial species turnover increased in heathlands where grazing decreased. 6. Synthesis. This study shows that the effect of grazing on plant diversity varies with elevation, and grazing herbivores can thus directly affect elevational patterns of plant diversity. Grazing can buffer changes in plant communities and species richness, even in the face of other environmental drivers such as climatic warming.

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Section: B U F F E R I N G B Y H E R B I V O R Ymentioning

confidence: 99%

The response of plant diversity to grazing varies along an elevational gradient

2013

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“…The boundary between the closed forest and the tundra is a distinct ecotone, influencing the physical conditions as well as the distribution of species, including the field layer vegetation (Hofgaard and Wilmann 2002). Because tundra-growing B. nana increased dramatically, whereas V. myrtillus, occurring only in the forests, did not respond to warming, the initial differences in community composition led to opposing effects of warming on community structure with increased dominance of E. hermaphroditum in the forest and decreased dominance in the tundra.…”

Section: Plant Community Compositionmentioning

confidence: 99%

Effects of Warming on Shrub Abundance and Chemistry Drive Ecosystem-Level Changes in a Forest–Tundra Ecotone

et al. 2012

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Citation for published item:urlej¤ rviD iF nd fxterD F nd rofgrdD eF nd rytteornD rF nd uhittunD yF nd woluD F nd j¤ ogerstenD F nd ookeyD F nd ylofssonD tF @PHIPA 9i'ets of wrming on shru undne nd hemistry drive eosystemElevel hnges in forestEtundr eotoneF9D iosystemsFD IS @VAF ppF IPIWEIPQQF Further information on publisher's website:The nal publication is available at Springer via http://dx.doi.org/10.1007/s10021-012-9580-9.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract:Tundra vegetation is responding rapidly to on-going climate warming. The changes in plant abundance and chemistry might have cascading effects on tundra food webs, but an integrated understanding of how the responses vary between habitats and across environmental gradients is lacking. We assessed responses in plant abundance and plant chemistry to warmer climate, both at species and community levels, in two different habitats. We used a long-term and multisite warming (OTC) experiment in the Scandinavian forest-tundra ecotone to investigate (i) changes in plant community composition and (ii) responses in foliar nitrogen, phosphorus, and carbon-based secondary compound concentrations in two dominant evergreen dwarf-shrubs (Empetrum hermaphroditum and Vaccinium vitis-idaea) and two deciduous shrubs (Vaccinium myrtillus and Betula nana). We found that initial plant community composition, and the functional traits of these plants, will determine the responsiveness of the community composition, and thus community traits, to experimental warming. Although changes in plant chemistry within species were minor, alterations in plant community composition drive changes in community-level nutrient concentrations. In view of projected climate change, our results suggest that plant abundance will increase in the future, but nutrient concentrations in the tundra field layer vegetation will decrease. These effects are large enough to have knock-on consequences for major ecosystem processes like herbivory and nutrient cycling. The reduced food quality could lead to weaker trophic cascades and weaker top down control of plant com-munity biomass and composition in the future. However, the opposite effects in forest indicate that these changes might be obscured by advancing tree-line forests.

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“…The tree line is a complex ecotone that comprises not only tree species at the edge of their geographic distribution, but also a diverse assortment of understory plants and growth-forms (Körner, 2003). Relatively little is known about how non-tree community composition changes across elevation gradients (Hofgaard and Wilmann, 2002;Bruun et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, more abrupt, or non-linear, patterns observed in plant communities-as would be the case if a boundary occurred across the ecotone where plant communities are not similarcould potentially indicate a biotic or abiotic barrier (e.g., temperature threshold or herbivory). Since different vegetation layers can respond differentially to climate change (Hofgaard and Wilmann, 2002;Pardo et al, 2013), observed patterns of plant communities across an ecotone are often complex and difficult to explain (Batllori et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…The distribution of plant species within the tree-line ecotone is in part related to local site characteristics that are linked to climate, either directly (e.g., air and soil temperature, frost damage, winter and summer precipitation, snow depth and duration, snowmelt timing) or indirectly (e.g., soil nutrients and seedbed composition; Hofgaard and Wilmann, 2002;Körner, 2003). Climate change is altering many of these local characteristics.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Complex Changes in Plant Communities across a Subarctic Alpine Tree Line in Labrador, Canada + Supplementary Appendix Table (See Article Tools)

Trant¹,

Lewis²,

Cranston³

et al. 2015

ARCTIC

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ABSTRACT. As climate warms, abiotic factors, as well as plant community and biodiversity structure, may constrain or promote the movement of ecotone boundaries. Our study sought to examine how plant communities change across the tree-line ecotone of the Mealy Mountains in Labrador, Canada. We established eight transects (50-100 m in length) along an elevation gradient in three tree-line zones (forest, forest-tundra, and alpine-tundra) and recorded all species and cover of vegetation in contiguous 1 × 1 m quadrats. Companion abiotic parameters of nutrients and soil temperature were also measured. The absence of abrupt changes in important soil nutrients and growing season temperatures suggests that these factors do not limit tree species establishment beyond the current tree line. Vegetation cover and richness, however, were highly variable and in some cases changed non-linearly across the tree-line ecotone. Tree cover and species density generally decreased with elevation, while some field layer species (< 25 cm in height) increased; the latter change seems to be influenced by ground shrubs rather than herbaceous species. As expected, transects separated by the greatest difference in elevation were the least similar (higher beta diversity/species turnover); however, species turnover between the forest and forest-tundra transects was higher than it was between forest-tundra and alpine-tundra transects, even though the latter were separated by a greater elevation. Community structure and species turnover vary greatly across a tree line with the greatest differences between the forest and the forest-tundra, suggesting a biotic or abiotic barrier. While our ability to predict how the tree line will respond to continued climate change is complicated by these patterns in plant communities, the potential barriers investigated and others identified will be a useful focus for future studies.Key words: climate change; forest-tundra ecotone; Labrador; Mealy Mountains; soil temperature; species turnover RÉSUMÉ. Au fur et à mesure que le climat se réchauffe, les facteurs abiotiques de même que la structure des communautés végétales et de la biodiversité pourraient contraindre ou promouvoir le mouvement des délimitations des écotones. Notre étude cherche à examiner comment les communautés de plantes changent dans l'écotone de la limite forestière des montagnes Mealy au Labrador, Canada. Nous avons établi huit transects (de 50 à 100 m de longueur) le long d'un gradient d'altitude chevauchant trois zones de la limite forestière (forêt, toundra forestière et toundra alpine), puis répertorié toutes les espèces et la couverture végétale se trouvant dans des quadrats contigus d'un mètre sur un mètre. Nous avons également mesuré les paramètres abiotiques des éléments nutritifs et des températures du sol connexes. L'absence de changements abrupts en ce qui a trait aux importants éléments nutritifs du sol et aux températures de la période de croissance suggère que ces facteurs ne limitent pas l'établissement des espèces d'arbres au-de...

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Plant distribution pattern across the forest-tundra ecotone: The importance of treeline position

Cited by 38 publications

References 24 publications

The response of plant diversity to grazing varies along an elevational gradient

The response of plant diversity to grazing varies along an elevational gradient

Effects of Warming on Shrub Abundance and Chemistry Drive Ecosystem-Level Changes in a Forest–Tundra Ecotone

Complex Changes in Plant Communities across a Subarctic Alpine Tree Line in Labrador, Canada + Supplementary Appendix Table (See Article Tools)

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