Recent changes in treeline forest distribution and structure in interior Alaska

Lloyd, Andrea H.; Fastie, Christopher L.

doi:10.1080/11956860.2003.11682765

Cited by 135 publications

(112 citation statements)

References 35 publications

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“…This process is quantitatively paralleled elsewhere in the Northern Hemisphere (Kremenetski et al, 1999;Meshinev et al, 2000;Butler and Dechano, 2001;Munroe, 2003) as a plausible manifestation of broad-scale climate change. Obviously for the same reason, emergence of new stems within the advance zone (between the old and new treelines) is now a conspicuous process in many instances (Butler and Dechano, 2001;Kullman, 2001Kullman, , 2004dLloyd and Fastie, 2003). Notably, however, most sites display upward treeline shifts smaller than those cited above, or no shifts at all (Kullman, 1979(Kullman, , 2001.…”

Section: Introductionmentioning

confidence: 94%

Wind-Conditioned 20th Century Decline of Birch Treeline Vegetation in the Swedish Scandes

Kullman¹

2010

ARCTIC

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ABSTRACT. The study focused on a frequent, although not dominant, mode of treeline change in the Swedish Scandes over the past century. Monitoring of stand density decline in a wind-exposed subalpine birch (Betula pubescens ssp. tortuosa) population was carried out over the past 30 years. The overall result included substantial and unbalanced individual mortality and a drastic reduction in stature of surviving birches. Radiocarbon dating of in situ subfossil birch-tree remains in an adjoining but windier site revealed complete stand demise over the past century or so. It is inferred that the extant and extinct birch populations represent different phases in an unbroken process of stand-level demise, hypothetically initiated in response to reindeer disturbance during the final phase of the Little Ice Age. This process was subsequently communicated more or less autogenically in a leeward direction as a consequence of the exposed and drought-prone nature of the site. Increasing westerly wind circulation and decreasing soil moisture (earlier snowmelt) during the past century may have contributed in this respect, although these aspects require further study. Within strongly wind-exposed terrain, a century of substantial warming has not sufficed to offset the birch decline. The results highlight the conclusion that under certain circumstances, wind and associated ecological and physiological effects are the overriding determinants of treeline position and structure. These are fundamental insights for generating realistic landscape-scale models of treeline change in a hypothetically warmer future.Key words: Betula pubescens ssp. tortuosa, deflation, drought, models, reindeer, retrogression, Swedish Scandes, treeline, warming, wind RÉSUMÉ. Cette étude porte sur un mode fréquent, bien que non dominant, de changement de la limite des arbres dans les Scandes suédoises au cours du siècle précédent. Durant les 30 dernières années, on a suivi le déclin dans la densité d'un peuplement de bouleaux pubescents subalpins (Betula pubescens ssp. tortuosa) qui étaient exposés au vent. Le résultat global comprenait une importante mortalité individuelle non compensée ainsi qu'une baisse radicale dans la taille des bouleaux survivants. La datation au radiocarbone de restes subfossiles de bouleaux trouvés in situ dans un lieu voisin mais plus venteux a révélé qu'un peuplement s'était complètement effondré au cours du siècle dernier ou à peu près. On en déduit que les peuplements de bouleaux existants et disparus représentent différentes phases d'un processus ininterrompu d'effondrement du niveau de peuplement, qui aurait son origine dans la perturbation causée par le renne durant l'ultime phase du petit âge glaciaire. Ce processus s'est ensuite poursuivi de façon plus ou moins autogène dans la direction du vent en raison de la nature du site qui était exposé au vent et à la sécheresse. Un accroissement de la circulation du vent d'ouest et une diminution de l'humidité du sol (fonte des neiges précoce) au cours du siècle dernier pourraient...

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Section: Introductionmentioning

confidence: 94%

Wind-Conditioned 20th Century Decline of Birch Treeline Vegetation in the Swedish Scandes

Kullman¹

2010

ARCTIC

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“…In Canada, an increase in the density of black spruce (Picea mariana) has occurred at the Arctic treeline [42]. In Alaska, an increase in the density and latitudinal position of shrubs and trees such as green alder (Alnus crispa) and white spruce (Picea glauca) has been reported from Arctic treelines [43,44], leading to an estimated expansion of forest across $11 600 km 2 of tundra over the past 50 years [45]. However, despite the theoretical predictions outlined above, reports of latitudinal range retractions remain rare.…”

Section: Glossarymentioning

confidence: 99%

The altitude-for-latitude disparity in the range retractions of woody species

Jump

Mátyás

Peñuelas

2009

Trends in Ecology & Evolution

436

369

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Increasing temperatures are driving rapid upward range shifts of species in mountains. An altitudinal range retreat of 10 m is predicted to translate into a $10-km latitudinal retreat based on the rate at which temperatures decline with increasing altitude and latitude, yet reports of latitudinal range retractions are sparse. Here, we examine potential climatic, biological, anthropogenic and methodological explanations for this disparity. We argue that the lack of reported latitudinal range retractions stems more from a lack of research effort, compounded by methodological difficulties, rather than from their absence. Given the predicted negative impacts of increasing temperatures on wide areas of the latitudinal distributions of species, the investigation of range retractions should become a priority in biogeographical research.Climate change and shifting plant distribution The geographical distribution of plants is strongly influenced by climate [1]. Minimum temperatures are particularly important in limiting the poleward (see Glossary) expansion of plant species, whereas limited water availability interacts with high temperatures to exert a direct climatic limitation on their expansion in the opposite, or equatorial, direction in many regions [1][2][3][4][5][6][7]. Changes in climate are, therefore, predicted to alter the geographic distribution of plant species at global to local scales.Contemporary plant range shifts are most frequently reported from mountain regions, with elevational shifts of the mountain treeline being the most commonly documented response to increasing temperatures [8][9][10][11][12]. The distributions of species in mountain regions are typically restricted to relatively narrow and well-delineated altitudinal bands, in comparison with often broad and poorly defined latitudinal distributions in the lowlands. This strong altitudinal zonation of mountain vegetation, and its climatic sensitivity [13], makes mountains ideal 'natural laboratories' and favoured locations for the study of climate change impacts worldwide [13][14][15].The altitudinal compression of montane vegetation zones is due to a rapid decrease in temperature with increasing elevation ($5-6.5 8C per 1000 m) [3,14], which contrasts with a similar temperature decline occurring over $1000 km of latitude (6.9 8C at 458 N or S) [3]. An implication of this altitude-for-latitude temperature model is that general biogeographical patterns resulting from the climatic limitations imposed on plants in mountains should also be observed in neighbouring lowland regions with similar temperature and moisture regimes. Distributional shifts already observed in mountain plants [8,[16][17][18] should, therefore, be mirrored by lowland range changes occurring over distances that are several orders of magnitude larger (Figure 1).Here, we discuss the implications of the altitude-forlatitude model for shifts in plant distributions and examine why lowland range shifts, particularly range retractions, are rarely reported. We discuss potential climati...

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“…Seedling migration upslope in response to climate change appears to be shifting treelines upward worldwide (Lloyd and Fastie 2003, Lenoir et al 2009, Solár and Janiga 2013. While northward shifts in latitude are occurring in some species (Woodall et al 2009) a contractive rather than expansive distributional pattern dominates in other studies (Zhu et al 2012, Bell et al 2013) indicating a failure of seedlings to migrate northward.…”

Section: Introductionmentioning

confidence: 98%

Demography linked to climate change projections in an ecoregional case study: integrating forecasts and field data

McLaughlin

Morozumi

MacKenzie³

et al. 2014

Ecosphere

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Abstract. Anticipating species movement under climate change is a fundamental concern in 21st century conservation. For blue oak (Quercus douglasii ), an endemic, flagship species in California, we modeled potential responses to future climate, then tested the fit of those projections to empirical field data from natural populations. Specifically, we tested how well species forecasts captured observed recruitment and adult tree mortality, and whether recruitment was structured spatially as a function of fine-scale microtopographic and hydrologic environments. In this ecoregional case study, observed demographic patterns were broadly consistent with theoretical expectations. Adult survivorship was three times lower in areas forecasted to be least suitable as a result of climate change than in areas projected to become suitable. This novel field validation exercise documents patterns of adult tree mortality consistent with model predictions of an emergent shift in distribution. Seedlings and saplings showed evidence of spatial structuring into local refugia in areas projected to contract, suggesting that climate change may reshape how blue oak associates with California landscapes and highlighting the potential importance of micro-environmental diversity in enhancing species resilience to warming.

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Recent changes in treeline forest distribution and structure in interior Alaska

Cited by 135 publications

References 35 publications

Wind-Conditioned 20th Century Decline of Birch Treeline Vegetation in the Swedish Scandes

Wind-Conditioned 20th Century Decline of Birch Treeline Vegetation in the Swedish Scandes

The altitude-for-latitude disparity in the range retractions of woody species

Demography linked to climate change projections in an ecoregional case study: integrating forecasts and field data

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