Environmental and Biotic Determinants of Growth and Height of Arctic Willow Shrubs along a Latitudinal Gradient

Pajunen, Anu

doi:10.1657/1938-4246-41.4.478

Cited by 34 publications

(34 citation statements)

References 66 publications

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“…He has published several studies on changes in the Arctic vegetation (e.g., Pajunen et al 2010;Myers-Smith et al 2011;Forbes 2015;Virtanen et al 2015). Anu Pajunen defended her thesis on willow-characterised shrub vegetation in tundra and its relationship to abiotic and biotic factors (e.g., Pajunen 2009;Pajunen et al 2008Pajunen et al , 2010 at University of Oulu under the supervision of Risto Virtanen, Bruce Forbes, and Jari Oksanen. She collected vascular plants (OULU) at the Yamal Peninsula.…”

Section: Arctic Siberiamentioning

confidence: 99%

Finnish botanists and mycologists in the Arctic

Väre

2017

Arctic Science

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Finnish botanists and mycologists have studied Arctic areas and timberline regions since the beginning of the 18th century. Most expeditions to the Kola Peninsula were made between 1800 and 1917 and until 1945 to Lapponia petsamoënsis on the western rim of the Kola Peninsula. Since those years, these areas have been part of the Soviet Union or Russia. Svalbard and Newfoundland and Labrador have been studied repeatedly as well, Svalbard since the 1860s and Newfoundland and Labrador since the 1930s. This article focuses on Finnish collections. These are deposited in the herbaria of Helsinki, Turku, and Oulu universities, except materials from the Nordenskiöld expeditions, which were mainly deposited in Stockholm. Concerning the Kola Peninsula, collections at Helsinki are the most extensive. The exact number of specimens is not known, but by rough estimation, the number is about 60 000, with an additional 110 000 observations included in the database. These expeditions have provided material to describe 305 new taxa to science, viz. 47 algae, 78 bryophytes, 25 fungi, 136 lichens, and 19 vascular plants. This number is an underestimate, as many new species have been described in several separate taxonomic articles. At least 63 persons have contributed to making these collections to Finnish herbaria. Of those, 52 are of Finnish nationality.Key words: bryophytes, fungi, vascularplants, Finnish, Arctic.Résumé : Les botanistes et les mycologues finlandais ont étudié les régions arctiques et les régions de limite forestière depuis le début du 18 ème siècle. La plupart des expéditions à la presqu'île de Kola ont été faites entre 1800 et 1917 et jusqu'à 1945 à Lapponia petsamoënsis sur la côte ouest de la presqu'île de Kola. Depuis ces années, ces régions ont fait partie de l'Union soviétique ou de la Russie. Svalbard, Terre-Neuve et le Labrador ont été étudiés à plusieurs reprises aussi, Svalbard depuis les années 1860 et Terre-Neuve et le Labrador depuis les années 1930. Cet article porte sur les collections finlandaises. Celles-ci sont dépo-sées dans les herbiers des universités de Helsinki, de Turku et d'Oulu, sauf le matériel des expéditions Nordenskiöld qui a été principalement déposé à Stockholm. En ce qui concerne la presqu'île de Kola, les collections à Helsinki sont les plus vastes. On ne connaît pas le nombre exact de spécimens, mais par l'estimation approximative le nombre est environ 60 000, avec 110 000 observations supplémentaires comprises dans la base de données. Ces expéditions ont fourni le matériel qui a servi à décrire 305 nouveaux taxa pour la science, à savoir 47 algues, 78 bryophytes, 25 champignons, 136 lichens et 19 plantes vasculaires. Ce nombre est une sous-estimation, puisque de nombreuses nouvelles espèces ont été décrites dans plusieurs articles taxonomiques. Au moins 63 personnes ont contribué à la création de ces collections aux herbiers finlandais. De ce nombre 52 sont de nationalité finlandaise.

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Section: Arctic Siberiamentioning

confidence: 99%

Finnish botanists and mycologists in the Arctic

Väre

2017

Arctic Science

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“…Building on previous work by Dullinger et al (2004) and Körner (2003), Cairns and colleagues argued that hypotheses regarding climatic influences on treeline dynamics in Fennoscandia failed to consider the influence of herbivory (Cairns and Moen, 2004;Cairns et al, 2007;Moen et al, 2008). Pajunen (2009) collected measurements of S. glauca and S. lanata on the Yamal Peninsula and counts of reindeer feces as a proxy for grazing intensity, and discovered that Salix growth was positively associated with mean summer temperatures, and negatively associated with reindeer grazing. This suggests that reindeer grazing can partially counteract the effect of increasing temperatures on Arctic shrubs.…”

Section: The Arcticmentioning

confidence: 99%

“…Studies of herbivory suggest that such activities counteract the effect of climatic warming on shrub growth (e.g. Pajunen, 2009). …”

Section: Processesmentioning

confidence: 99%

Patterns and processes of global shrub expansion

Naito

Cairns

2011

Progress in Physical Geography: Earth and Environment

193

136

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Shrub expansion is a global phenomenon that is occurring on savannas, rangelands, and grasslands. In addition, this is an increasingly documented occurrence in the Arctic. Numerous recent studies have strived to pinpoint the drivers of this phenomenon, quantify the changes, and understand their implications for regional and global land use, disturbance regimes, and nutrient cycling. Inquiry into these topics has been facilitated by recent technological developments in satellite remote sensing, aerial photograph analysis, and computer simulation modeling. We provide a new review that accounts for more recent studies in these regions, Arctic shrub expansion, and technological and analytical developments. This four-part discussion focuses on observed patterns of shrub expansion in three rangeland types (desert grasslands, mesic grasslands, savannas) and the Arctic tundra, the primary causes of this expansion, critical comparisons and contrasts between these land types, and recommendations for future avenues of research. These new avenues can inform the development of future land management policies, as well as ongoing investigations to understand and mitigate the effects of climate change.

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“…Willows (Salix spp.) usually grow along rivers or on slopes and are often the tallest plants in the tundra landscape (Pajunen 2009, Pajunen et al 2010. The thickets represent a major structural element and are highly productive habitats compared to the surrounding low-statured tundra vegetation.…”

mentioning

confidence: 99%

The Importance of Willow Thickets for Willow Ptarmigan in Shrub Tundra: The More the Better?

Ehrich¹

2011

Gyrfalcons and Ptarmigan in a Changing World

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ABSTRACT.-In patchy habitats, the relationship between animal abundance and cover of a preferred habitat may change with the availability of that habitat, resulting in a functional response in habitat use. Here, we investigate the relationship of two specialized herbivores, Willow Ptarmigan (Lagopus lagopus) and Mountain Hare (Lepus timidus), to willows (Salix spp.) in three regions of the shrub tundra zone-northern Norway, northern European Russia and western Siberia. Shrub tundra is a naturally patchy habitat where willow thickets represent a major structural element and are important for herbivores both as food and shelter. Habitat use was quantified using feces counts in a hierarchical spatial design and related to several measures of willow thicket configuration. We document a functional response in the use of willow thickets by ptarmigan, but not by hares. For hares, whose range extends into forested regions, occurrence increased overall with willow cover. The occurrence of Willow Ptarmigan showed a strong positive relationship to willow cover and a negative relationship to thicket fragmentation in the region with lowest willow cover at landscape scale, where willow growth may be limited by Reindeer (Rangifer tarandus) browsing. In regions with higher cover, in contrast, such relationships were not observed. Differences in predator communities among the regions may contribute to the observed pattern, enhancing the need for cover where willow thickets are scarce. Such region-specific relationships reflecting regional characteristics of the ecosystem highlight the importance of large-scale investigations to understand the relationships of habitat availability and use, which is a critical issue 125

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Environmental and Biotic Determinants of Growth and Height of Arctic Willow Shrubs along a Latitudinal Gradient

Cited by 34 publications

References 66 publications

Finnish botanists and mycologists in the Arctic

Finnish botanists and mycologists in the Arctic

Patterns and processes of global shrub expansion

The Importance of Willow Thickets for Willow Ptarmigan in Shrub Tundra: The More the Better?

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