Leif Kullman

Umeå University | UMU · Department of Ecology and Environmental Science

Treeline dynamics, climate change

A megafossil wood remnant of Norway spruce (Picea abies (L.) Karst.) was retrieved from a high-elevation nunatak in the southern Swedish Scandes. The site was nearly 600 m higher than the present-day treeline. These circumstances comply with analogous earlier recoveries, indicating presence of spruce at high elevations in the Scandes, several thous...

In the context of post-Little Ice Age climate change, regional forest-limit (strictly defined) adjustment was studied over the period 1915 to 1975. The study comprised nearly 200 sites, in the form of systematically distributed belt transects. Forest-limit positions (m a.s.l.) were reconstructed for the years around 1915 and compared to the situati...

Positional and population change of the alpine treeline ecotone were studied at a site (isolated low-fell) in the Swedish Scandes. Methods included early-20th century records and subsequent re-visitations, including repeat photography, up to 2021. Substantial temperature rise (summer and winter) during the past 100 years, has left the elevational f...

This study focuses on structural change of a praealpine stand of Norway spruce (Picea abies), in a context of centennial climate warming, in the Swedish Scandes. Progressive stand building followed on the end of the Little Ice Age by the late 19th century. A distinct hiatus of this process occurred during the 1980s, as a consequence of exceptionall...

Climate change and response if Picea abies in the treeline ecotone

This study reports a case of climate-mediated transformation and physiognomic progression of the Norway spruce (Picea abies) treeline ecotone since the mid-1990s in the Swedish Scandes. The methods include repeat photography and foliation estimates of old-established clonal spruces. An air and soil temperature nadir by the 1980s had caused extensiv...

Ecological change in the Swedish Scandes ant its relationship to climate change

Treeline advance during the past 100 years was assessed by repeat in situ measurement at 14 locations distributed along the entire Swedish Scandes, c. 800 km from south to north. Concerned species were mountain birch (Betula pubescens ssp. czerepanovii), Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and rowan (Sorbus aucuparia). Treeli...

In a context of recent climate change, the conversion of a restricted area of treeless alpine/subalpine tundra to mountain birch forest (Betula pubescens ssp. czerepanovii) was studied by repeat photography, demographic analysis in combination with tree growth surveillance in permanent plots. In addition, flora change was recorded within the emergi...

This study addresses the issue of climate control of the elevational treeline, foremost the role of soil temperatures. During the period 1999 to 2020, soil temperatures were recorded over the year at a depth of 10 cm in a sparse stand (Betula pubescens ssp. czerepanovii) within the upper treeline ecotone of the Swedish Scandes. Over the years 2010...

Treeline change during past 100 years

fauna&flora 2 Främmande trädarter sprids till svenska fjällbjörkskogar Inhemska värmekrävande lövträd som ek och klibbal etablerar sig i fjällnära natur, men också främmande arter som contorta-tall, sibirisk cembratall och sibirisk lärk, har börjat självsprida sig.

This paper reports recently discovered specimens of relatively warmth-requiring Black alder (Alnus glutinosa (L.) Gaertn.), growing far to the west and at a much higher elevation than previously known in northern Sweden. The uppermost young tree has become established in the subalpine birch forest belt (Betula pubescens ssp. czerepanovii), where Al...

Adds detail to early Holocene tree exclaves in ice-empty glacier niches

This paper concens the performance performance o krummholz specimens at the treeline in Sweden

Performance of krummholz pines

The article describes a recent spectacular upswing of pine (Pinus sylvestris) reproduction in the treeline ecotone of the Swedish Scandes.

Vegetation history of northern Fennoscandia has for more than a century revolved around pollen analysis. A major problem and shortcoming with this approach is the interpretation of very small pollen counts or the total absence of pollen at certain positions in the strati-graphies. This complication has been emphatically highlighted with some recent...

Treeline advance during the past 100 years was assessed by repeat in situ measurement at 14 locations distributed along the Swedish Scandes, c. 800 km from south to north. Concerned species were mountain birch (Betula pubescens ssp. czerepanovii), Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and rowan (Sorbus aucuparia). Treeline was...

Positional treeline change since the early 20th century and up to 2017 was assessed along three elevational transects on Mt. Getryggen in the southern Swedish Scandes. Baseline data, representing the year 1915, were compared with later intermittent records up to 2017. Concerned species were Betula pubescens ssp. czerepanowii, Picea abies,Pinus sylv...

With a climate-change perspective, this study focuses on the recent history and performance of the much separated pine (Pinus sylvestris L.) tree and forest lines in a mountain valley in the southern Swedish Scandes. Historical records define quite accurately these "lines" by the early 20th century and mid-1970s. Their subsequent dynamic performanc...

Elevational treeline change for different subalpine species over the past 100 years was assessed in the Kebnekaise pubescens (Prunus reliability by tree ring analyses, and compared with present at the same locations maximum advances by 200 m in elevation, with smaller d common pattern for all the concerned species was that treeline advance was achi...

In a context of recent climate change, the conversion of treeless alpine tundra to mountain birch (Betula pubescens ssp. czerepanovii) forest was studied by repeat photography, demographic and growth surveillance in permanent plots. In addition, flora change was recorded within the emerging birch forest stand. The study was initiated in 1980, when...

Climate warming and associated post-Little Ice Age recession of glacier ice and permanent snow in high mountains of the Swedish Scandes have opened a new view for alpine palaeoecology. Receding glaciers and snow/ice patches, high above current tree-lines of all boreal tree species, have exposed forefields with a plethora of megafossil tree remnants...

The present paper reports results from an extensive project aiming at improved understanding of postglacial subalpine/alpine vegetation, treeline, glacier and climate history in the Scandes of northern Sweden. The main methodology is analyses of mega fossil tree remnants, i.e. trunks, roots and cones, recently exposed at the fringe of receding glac...

Peripheral populations of cold-marginal tree species are often supposed to serve as dispersal nodes in relation to rapid climate warming. The history and evolution of a discrete outlying subarctic stand of Norway spruce (Picea abies (L.) Karst.), growing in northern Swedish Lapland, was investigated. Accordingly, it was hypothesized that climate ch...

Elevational treeline change for different subalpine species over the past 100 years was assessed in the Kebnekaise pubescens (Prunus reliability by tree ring analyses, and compared with present at the same locations maximum advances by 200 m in elevation, with smaller d common pattern for all the concerned species was that treeline advance was achi...

Pine (Pinus sylvestris L.) Penetration towards the Head of the Handolan Valley: Recent Reversal of Long- Term Retrogressional Trend-Contrasting Responses to Climate Change of Tree-and Forest Line With a climate-change perspective, this study focuses on the recent history and performance of the much separated pine (Pinus sylvestris L.) tree and for...

Recent recession of high-mountain glacier ice and perennial snow and ice patches has exposed megafossil and macrofossil tree remnants and peat, offering a new source of Holocene high alpine vegetation history in the Scandes. Radiocarbon dates of 90 tree megafossils from Swedish Lapland, 29 of which had not previously been published, range from 11 9...

The upper treeline of Scots pine (Pinus sylvestris L.) is renowned as a sensitive indicator of climate change and variability. By use of megafossil tree remains, preserved exposed on the ground surface, treeline shift over the past millennium was investigated at multiple sites along the Scandes in northern Sweden. Difference in thermal level betwee...

For about a century, Abisko Scientific Research Station in northern Swedish Lapland has served as a logistic base for high-quality geoecological research in subalpine/subarctic environments. In recent years, and driven by the prospect of alleged man-made global warming, much of the scientific focus has been on dynamics of the treeline ecotone. In t...

Changes in plant species richness on alpine summits in the southern Swedish Scandes were analyzed between 2004/2006 and 2012. This period experienced consistent summer and winter cooling and finalized with a cold and snow rich summer 2012. Re-surveys of these summits had previously documented substantial increases in species numbers in concordance...

The article reports the outcome of long-term demographic monitoring of elevational treeline ecotonal stands of Scots pine (Pinus sylvestris L.) in the southern Swedish Scandes. Annual censuses were undertaken of recruitment, mortality, growth, seed viability, and causes of mortality during the period 1973–2012 in a set of 18 permanent plots. A net...

The postglacial tree line and climate history in the Swedish Scandes have been inferred from megafossil tree remains. Investigated species are mountain birch (Betula pubescens ssp. czerepanovii), Scots pine (Pinus sylvestris) and grey alder (Alnus incana). Betula and Pinus first appeared on early deglaciated nunataks during the Lateglacial. Their t...

Alpine (altitudinal) treeline ecotones are elusive, spatially heterogeneous and dynamic transitional zones between closed mountain forest and treeless alpine tundra. From a distance the may look sharp, but a closer view usually reveals a highly complex structural pattern (Kullman 1979). Thermal growth limitation is considered as the fundamental par...

Positional treeline shift is a fundamental aspect and indicator of high-mountain vegetation response to climate change. This study analyses treeline performance during the period 2005/2007-2010/2011 in the Swedish Scandes. Focus is on mountain birch (Betula pubescens ssp. czerepanovii) along a regional climatic maritimity-continentality gradient. T...

Climate warming during the past century has imposed recession of glaciers and perennial snow/ice patches along the entire Swedish Scandes. On the newly exposed forefields, subfossil wood remnants are being outwashed from beneath ice and snow bodies. In Scandinavia, this kind of detrital wood is a previously unused source of postglacial vegetation a...

This study addresses the long-standing issue of postglacial immigration of Picea abies (Norway spruce) into Scandinavia. The main methodological focus is on using megafossil tree remains (wood and cones) of spruce and other species retrieved from the treeline ecotone of the Swedish Scandes as a tool for vegetation reconstruction. The core data come...

The recent history of Piceaabies (L.) Karst. at its altitudinal tree limit has been studied in the southern Swedish Scandes. Altitudinal transects (131) were evenly distributed over a tract of mountains of ca. 40 × 200 km. The age of spruces growing at the tree limit and downhill were estimated by annual ring counts. The spruce tree limit had risen...

The age structure was studied of two stands of Pinus sylvestris L. and Picea abies (L.) Karst. growing on "fire-safe," opposing (north- and south-facing, respectively) slopes at the forest limit in the Scandes Mountains, in central Sweden. It is suggested that the spatial species segregation is due to different microclimatic demands during seedling...

Reports about changes of alpine plant species richness over the past 60 years in the Swedish Scandes are reviewed, synthesized and updated with data from recent reinventories. Methodologically, this endeavour is based on resurveys of the floristic composition on the uppermost 20 m of four high-mountain summits. The key finding is that the species p...

This paper elaborates and visualizes processes recorded in a recent regional and multi-site study of elevational treeline dynamics during the period 1915 to 2007 in the Swedish Scandes. The purpose is to give a concrete face of the landscape transformation which is associated with the recorded treeline shifts. The main focus is on stand-level struc...

Summary • Elevational tree line change in the southern Swedish Scandes was quantified for the period 1915–2007 and for two sub-periods 1915–1975 and 1975–2007. The study focused on Betula pubescens ssp. czerepanovii, Picea abies and Pinus sylvestris at a large number of sites distributed over an 8000-km2 area. The basic approach included revisitati...

Exceptionally old spruces Picea abies have been recovered at several locations along the Scandes of northern Sweden. The main method of scientific inquiry, megafossil analysis, implies that large tree remnants (trunks, roots and cones) are searched for and extracted from different "natural archives". These comprise peat deposits, lake sediments, ra...

This paper reviews megafossil evidence for the first postglacial records of different tree species in northern Scandinavia. Betula pubescens coll. appeared at the Arctic coast of northern Norway by 16, 900yrBP. In addition, Betula pubescens (14, 000yrBP), Pinus sylvestris (11, 700yrBP) and Picea abies (11, 000yrBP) existed on early ice- free mounta...

Wood samples from above the present-day pine limit were collected from within a limited area in central Sweden. New dates from an intensively investigated part of that area all fall within the period 8550 ± 110 to 4270 ± 90 14C years B. P. No evidence at present exists to suggest that any drastic change, or fluctuations, in the pine tree-limit, too...

Analyses of subfossil tree remains in peats and raw humus soils account for the immigration and spread of Picea abies (Norway spruce) into Sweden and the evolution of the alpine tree-limit ecotone. Picea abies is recorded for the first time about 11 000 BP, on an early emerging nunatak in the southern Swedish Scandes. Prior to c. 8 000 BP, Picea wa...

This article focuses on the Holocene tree line (Pinus sylvestris) and climate change in the Swedish Scandes. A composite of three previously independently published data sets of megafossil tree remains (trunks, stumps and roots) from sites above today's tree line is analysed. Calibration of ages, adjustment for glacio-isostatic land uplift and a la...

Consistent with general predictions and earlier empirical studies, it appears that recent climate warming has started to affect large-scale biogeographical patterns in northern Sweden. Long-term, systematic monitoring in permanent altitudinal belt transects reveals spread of broadleaved thermophilic tree species with quite different life histories...

Radiocarbon dates of subfossil pines found on dry ground above the present-day tree-limit are reported from northern Sweden. The uppermost and oldest specimen germinated c. AD 300–600. During some shorter part of this interval the tree-limit might have been 235 m higher than it was at the turn of the last century. Based on a current adiabatic lapse...

Early-Holocene occurrences of broad-leaved temperate tree species at a site now within the subalpine belt of the Swedish Scandes are reported and analysed. Macrofossil remains (fruits and leaves) of Alnus glutinosa, Corylus avellana, Quercus robur and Ulmu.s glahra were recovered in a peat deposit far beyond and above their modern distributional li...

Kullman, Leif 1987 03 01: Sequences of Holocene forest history in the Scandes, inferred from megafossil Pinus sylvestris. Boreas, Vol. 16, pp. 21–26. Oslo. ISSN 0300–9483. Altogether 54 14C-datings of megafossil Pinus sylvestris L. from above the present tree-limit in the southern Swedish Scandes were evaluated. The samples were discussed in relati...

1Demographic trends of Pinus sylvestris L. (Scots pine) tree line populations are reported for a 32-year monitoring period (1973–2005). Functional and projective aspects of tree line performance were analysed by relating temporal variability and change of vital population parameters, such as natality/mortality, vigour, injuries, height growth and s...

Saplings of mountain birch Betula pubescens Ehrh. ssp. tortuosa (Ledeb.) Nyman, three years old, were transplanted into three contrasting habitats, viz. moderate and extreme snow-bed and windswept crest. The experimental sites were situated just below the present local tree-limit of birch. During 1978–1983 mortality and height increment were monito...

summaryRepeat photography and tree ring analyses were used to investigate structural change, 1938–88, of an old growth and high elevation Picea abies (L.) Karst. forest in northern Sweden. The forest, initially moribund, senescent and top-broken, regenerated broken tops and apparently gained in vigour. Up to the 1930s this progressive change was pr...

summaryElevational distribution, site characteristics and regeneration patterns of grey alder [Alnus incana (L.) Moench] have been studied in subalpine forest of the southern Swedish Scandes, mainly as a basis for paleoecological inferences. Alder occurs very sparsely in the mountain birch forest and is strictly confined to sites with fresh finegra...

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 mort...

Kullman, L. 2005: Pine (Pinus sylvestris) treeline dynamics during the past millennium — a popu-lation study in west-central Sweden. — Ann. Bot. Fennici 42: 95–106. Dynamics of a pristine and fire-free treeline population of Scots pine (Pinus sylvestris) over the past millennium was reconstructed at a site in the southern Swedish Scandes. At the br...

A new national park, Fulufjället, was established in 2002. The main intention is to preserve distinctive and pristine alpine tundra and adjacent mountain taiga in the southern Swedish Scandes. Quite uniquely, this area has never harboured semi-domestic reindeer herds. Therefore this is an ideal target for pure studies of vegetational responses to p...

In the context of projected future human-caused climate warming, the present study reports and analyses the performance of subalpine/alpine plants, vegetation and phytogeographical patterns during the past century of about 1 °C temperature rise. Historical baseline data of altitudinal limits of woody and non-woody plants in the southern Scandes of...

Megafossil wood remnants (trunks and roots) of mountain birch (Betula pubescens ssp. tortuosa) were retrieved from the alpine tundra of the southern Swedish Scandes (the Sylarna Mountains). The samples have recently become exposed by rapid recession of glaciers and snow patches at three sites located 630 to 350 m higher than the present-day birch t...

Tree-limit and climate evolution at the southern extremity of the Swedish Scandes have been reconstructed for the entire Holocene and for the past century. The main objective was to test the reproducibility of a similar study further north in the Swedish Scandes. The long-term history relies mainly on radiocarbondated megafossil tree remains preser...

The paper focuses on early Holocene tree growth and alpine tree-limits in the northernmost Swedish Scandes (Lapland). Megafossil wood remnants in peats and lakes were searched for over a large area at elevations high above the modern tree-limits. Wood of Pinus sylvestris, Betula pubescens spp. tortuosa and Alnus incana was discovered near the shore...

The paper reviews various kinds of geoecological change in the tree-limit ecotone of the Scandes Mountains during the period 1970–95. The focus of the study is a part of a regional network of sites intended for long-term tree-limit monitoring, with special stress on effects of climatic variability. The elevational tree-limits of Betula pubescens sp...

An intensive study reconstructs the local late-Holocene tree-limit history (Betula pubescens ssp. tortuosa) in the southern Swedish Scandes, as a proxy palaeoclimatic indicator. Elevational tree-limit rise by 75 m, in accordance with instrumentally recorded summer warming, took place over the past century as evidenced by a combination of historical...

Films of Ni and Cr oxide were made by reactive DC magnetron sputtering. Ozone exposure, obtained by ultraviolet irradiation in the presence of oxygen, gradually induced coloration in the initially transparent films. Electrochemical measurements correlated the optical absorption with a charge deficiency in the film. Our results demonstrate a conveni...

Elevational limits of some vascular plants in the southern Swedish Scandes have risen significantly in response to slightly less than 1°C climate warming over the past century and, in particular, warmer winters since 1988. Present-day elevational limits are compared with historical records from the 1950s. The reality of the advance is confirmed by...

The tree-limit altitudes of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) from 180 sites (within an area of 95 km × 165 km) in the southern Scandes were correlated with the geographical variables latitude, longitude and distance to the sea. The results were compared with a similar investigation of the tree-limit of mountain birch (B...

AimThis paper seeks to elucidate the first post-glacial arrival of tree species to high elevations in the Scandes. This enables testing of general theories concerning glacial refugia, immigration routes and palaeoclimate.LocationThe study site, 1360 m a.s.l., was close to the summit of Mt Åreskutan in the alpine region of the southern Swedish Scand...