Directional positive feedback and pattern at an alpine tree line

Alftine, Kathryn J.; Malanson, George P.

doi:10.1658/1100-9233(2004)015[0003:dpfapa]2.0.co;2

Cited by 10 publications

(9 citation statements)

References 30 publications

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“…S1 in the "Electronic supplementary material"). Similar vegetation stripes have been observed in alpine areas with comparable climates, some of which are also believed to be a consequence of either wind (on Xat areas) or wind and slope instability (on slopes) (Alftine and Malanson 2004;Veblen et al 1977). Veblen et al (1977) suggested that such patterns form on scoria slopes as a result of the chance establishment of single plants, which then stabilise scoria enough for other plants to establish.…”

Section: Discussionmentioning

confidence: 52%

“…Investigating the Wne-scale spatial patterns of species associations, speciWcally testing for directionality, can also help to identify which facilitative mechanisms dominate at a site (following, e.g. Alftine and Malanson 2004;Carlsson and Callaghan 1991;Haase 2001). This is useful considering that numerous facilitative mechanisms have been observed in alpine and Arctic areas, which include warmer and less variable temperatures, sheltering from wind, enhanced soil development and stability, and decreased desiccation in the presence of neighbouring plants (Choler et al 2001).…”

Section: Introductionmentioning

confidence: 99%

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Spatial variation in plant interactions across a severity gradient in the sub-Antarctic

Roux

McGeoch

2008

Oecologia

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The stress-gradient hypothesis predicts that the intensity of interspecific positive interactions increases along environmental severity (i.e. stress and disturbance) gradients faster than the intensity of negative interactions. This study is the first to test if the stress-gradient hypothesis is supported for a location in the climatically extreme and species-poor sub-Antarctic. To do so, we investigate the fine-scale spatial distribution of plant species across altitude- and aspect-related abiotic severity gradients on a scoria cone on Marion Island. A clear altitudinal severity gradient was observed across the scoria cone, with lower temperatures, stronger winds and greater soil movement at higher altitudes. The altitudinal severity gradient was matched by stronger interspecific spatial association between the four dominant species at higher altitudes and in areas of lower vegetation cover. This suggests that, relative to the intensity of competition, the intensity of facilitation is greater under more severe conditions, supporting the stress-gradient hypothesis at the community level (i.e. for multiple pairs of species) and corroborating its usefulness for predicting variation in plant interactions at high latitudes and altitudes. Furthermore, the directional intraspecific aggregation and interspecific association plant cover patterns found within the gradient suggest that protection from the prevailing wind and from burial by loose substrate are the dominant facilitative mechanisms. Thus, plants benefit from the presence of neighbours when they provide shelter and substrate stability, and the relative intensity of this positive interaction is greatest at higher altitudes, and varies between species pairs. This study, therefore, not only provides support for the stress-gradient hypothesis in the sub-Antarctic, but also demonstrates fine-scale directional spatial patterns between multiple species nested within the severity gradient.

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Section: Discussionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Spatial variation in plant interactions across a severity gradient in the sub-Antarctic

Roux

McGeoch

2008

Oecologia

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“…Figure 1) are key factors controlling spatial and temporal treeline structures at the landscape and finer scales, (e.g., [4,5,7,[48][49][50][51][52][53][54][55][56]). Microclimates, distribution of soil temperatures and soil moisture, relocation of snow, depth, and duration of the winter snowpack, avalanches, and runoff all depend on microtopography (length and width ≤ 10 m, area 10-100 m 2 ).…”

Section: Treeline At Landscape (Regional) Local and Microscalesmentioning

confidence: 99%

Treelines—Approaches at Different Scales

Holtmeier

Broll

2017

Sustainability

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Scales in treeline research depend on the objectives and must match the underlying natural processes. Factors and processes at one scale may not be as important at another scale. In the global view, the number of factors influencing climatic treeline position can be reduced to the effects of heat deficiency. Emphasis, however, should be laid on differentiation of the treeline by their regionally and locally varying physiognomy, diversity, spatial and temporal features, and heterogeneity. An assessment of the relative importance of the factors shaping regional/local treeline physiognomy, spatial patterns, and dynamics should have priority. This can be achieved only by syndisciplinary research. Such studies are indispensable for assessing treeline response to climate change at the regional and landscape scales.

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“…Deep and persistent snow cover in spring increases water availability in early summer, which in combination with high summer temperatures was found to increase the elevation of treeline in some subalpine forests (Hessl and Baker, 1997) or to favor tree growth in others (Barbour et al, 2002). However, late-laying snow in spring shortens the growing season (Walsh et al, 1994;Alftine and Malanson, 2004), increases the risk of black snow mold (Herpotrichia nigra R. Hartig) infection (Simms, 1967), and may lead to the drowning of seedlings by snow (Wardle, 1968).…”

Section: Introductionmentioning

confidence: 99%