Early human impact (5000–3000 <scp>BC</scp>) affects mountain forest dynamics in the <scp>A</scp>lps

Schwörer, Christoph; Colombaroli, Danièle; Kaltenrieder, Petra; Rey, Fabian; Tinner, Willy

doi:10.1111/1365-2745.12354

Cited by 65 publications

(78 citation statements)

References 88 publications

(128 reference statements)

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“…(Villar, Sesé, & Ferrández, ). Currently, conifers are the most successful taxa forming the tree line in temperate mountain ranges (Körner, ; Schwörer et al, ), including the Pyrenees, and Betula only co‐occurs. At higher latitudes, though, Betula is the main taxon in boreal tree line communities, increasingly admixed with P. sylvestris at lower latitudes (Bjune, ; Körner, ; Lang, ).…”

Section: Discussionmentioning

confidence: 99%

“…(Villar, Sesé, & Ferrández, 1997). Currently, conifers are the most successful taxa forming the tree line in temperate mountain ranges (Körner, 2012;Schwörer et al, 2015), including the Pyrenees, and Betula only co-occurs. At higher latitudes, though,…”

Section: Altitudinal Tree Range Fluctuations At the End Of The Htmmentioning

confidence: 99%

“…Combined pollen and macrofossil evidence from other European mountain ranges have shown that the main changes in Holocene tree line and timberline positions followed major climatic trends. However, land-use intensification has been invoked as the primary cause of late Holocene downward shifts of timberline, with climate playing a primary role for tree line position (Feurdean et al, 2016;Pini et al, 2017;Schwörer, Colombaroli, Kaltenrieder, Rey, & Tinner, 2015;Tinner & Theurillat, 2003). In any case, it remains unclear if this also applies to the Pyrenees, because disentangling the role of climate and human impact is challenging, sometimes provoking controversies, specifically in the Mediterranean realm (e.g., Carrión et al, 2010;González-Sampériz et al, 2017;Samartin et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Ice cave reveals environmental forcing of long‐term Pyrenean tree line dynamics

et al. 2018

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Tree lines are supposed to react sensitively to the current global change. However, the lack of a long‐term (millennial) perspective on tree line shifts in the Pyrenees prevents understanding the underlying ecosystem dynamics and processes. We combine multiproxy palaeoecological analyses (fossil pollen, spores, conifer stomata, plant macrofossils, and ordination) from an outstanding ice cave deposit located in the alpine belt c. 200 m above current tree line (Armeña‐A294 Ice Cave, 2,238 m a.s.l.), to assess for the first time in the Pyrenees, tree line dynamics, and ecosystem resilience to climate changes 5,700–2,200 (cal.) years ago. The tree line ecotone was located at the cave altitude from 5,700 to 4,650 cal year bp, when vegetation consisted of open Pinus uncinata Ramond ex DC and Betula spp. Woodlands and timberline were very close to the site. Subsequently, tree line slightly raised and timberline reached the ice cave altitude, exceeding its today's uppermost limit by c. 300–400 m during more than four centuries (4,650 and 4,200 cal year bp) at the end of the Holocene Thermal Maximum. After 4,200 cal year bp, alpine tundra communities dominated by Dryas octopetala L. expanded while tree line descended, most likely as a consequence of the Neoglacial cooling. Prehistoric livestock raising likely reinforced climate cooling impacts at 3,450–3,250 cal year bp. Finally, a tree line ecotone developed around the cave that was on its turn replaced by alpine communities during the past 2,000 years. Synthesis. The long‐term Pyrenean tree line ecotone sensitivity suggests that rising temperatures will trigger future P. uncinata and Betula expansions to higher elevations, replacing arctic–alpine plant species. Climate change is causing the rapid melting of the cave ice; rescue investigations would be urgently needed to exploit its unique ecological information.

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Section: Discussionmentioning

confidence: 99%

Section: Altitudinal Tree Range Fluctuations At the End Of The Htmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ice cave reveals environmental forcing of long‐term Pyrenean tree line dynamics

et al. 2018

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“…This led to a decline in Abies alba and allowed Picea abies to take over its ecological niche at high altitudes (Schwörer et al, 2015).…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Reconstruction of Holocene vegetation dynamics at Lac de Bretaye, a high-mountain lake in the Swiss Alps

et al. 2015

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Abstract:A deeper understanding of past vegetation dynamics is required to better assess future vegetation responses to global warming in the Alps. Lake sediments from Lac de Bretaye, a small subalpine lake in the Northern Swiss Alps (1780 m a.s.l.), were analysed to reconstruct past vegetation dynamics for the entire Holocene, using pollen, macrofossil and charcoal analyses as main proxies. The results show that timberline reached the lake's catchment area at around 10300 cal. BP, supporting the hypothesis of a delayed postglacial afforestation in the Northern Alps. At the same time, thermophilous trees such as Ulmus, Tilia and Acer established in the lowlands and expanded to the altitude of the lake, forming distinctive boreo-nemoral forests with Betula, Pinus cembra and Larix decidua. From about 5000 to 3500 cal. BP, thermophilous trees declined due to increasing human land use, mainly driven by the mass expansion of Picea abies and severe anthropogenic fire activity. From the Bronze Age onwards (c. 4200-2800BP), grazing indicators and high values for charcoal concentration and influx attest an intensifying human impact, fostering the expansion of Alnus viridis and Picea abies. Hence, biodiversity in alpine meadows increased whereas forest diversity declined, as can be seen in other regional records. We argue that the anticipated climate change and http://mc.manuscriptcentral.com/holocene HOLOCENE F o r P e e r R e v i e w decreasing human impact in the Alps today will not only lead to an upward movement of timberline with consequent loss of area for grasslands, but also to a disruption of Picea abies forests, which may allow the reexpansion of thermophilous tree species. Alnus viridis and Picea abies. Hence, biodiversity in alpine meadows increased whereas forest diversity declined, as can be seen in other regional records. We argue that the anticipated climate change and decreasing human impact in the Alps today will not only lead to an upward movement of timberline with consequent loss of area for grasslands, but also to a disruption of Picea abies forests, which may allow the re-expansion of thermophilous tree species.

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“…Palaeoecological evidence based on micro‐ and macrofossils from natural archives (e.g., lakes, mires, ice, soil) and wood charcoal fragments found in soil profiles confirm widespread human disturbance, even at higher elevations (e.g., Carcaillet & Brun, ; Moe, Fedele, Maude, & Kvamme, ; Talon, ; Tinner, Ammann, & Germann, ). It is commonly thought that logging and pastoralism at high elevations have affected the tree line position (Colombaroli, Henne, Kaltenrieder, Gobet, & Tinner, ; Malanson et al., ; Schwörer, Colombaroli, Kaltenrieder, Rey, & Tinner, ), but for the Apennines, robust evidence is still lacking. Indeed, disentangling the effects of climate from those of human disturbance in the evolutionary dynamics of tree line ecosystems remains a challenge (Batllori, Camarero, & Gutiérrez, ; Malanson et al., ).…”

Section: Introductionmentioning

confidence: 99%

Anthropogenic and environmental factors affect the tree line position of Fagus sylvatica along the Apennines (Italy)

Bonanomi

Rita

Allevato

et al. 2018

Journal of Biogeography

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Aim High‐elevation forest line or tree line is an ecological ecotone representing the upper elevation thermal limit for forest development. The current tree line position is the result of the past human activity interacting with climatic and topographic conditions. In this study, we investigate how climate, local topographic factors and anthropogenic disturbance currently affect tree line distribution. Location Apennine Mountains, 900 km latitudinal gradient along the Italian Peninsula. Methods Overall, 302 mountain peaks were studied, comprising 3,622 km of measured tree lines. The position of the Fagus sylvatica tree line in all peaks was assessed and correlated with 58 selected variables representing climate, topography and human disturbance. Results The mean tree line elevation was 1,589 m a.s.l., with considerable variability among peaks. Contrary to our expectations, the tree line elevation was lower in the warmer southerly exposed slopes compared to north‐facing aspects, where we found the highest tree line (2,141 m a.s.l.). Correlation analysis indicates that both climatic and human density variables are associated with tree line elevation, with the climate having more influence in high elevation mountains, while human impact plays a prominent role in low elevation mountain peaks. Specifically, we found negative correlations between density of the resident population around each peak and tree line elevation at all examined dates (1861, 1921, and 2011), suggesting a pervasive negative impact of human activity on tree lines. As regards climatic variables, tree line elevation showed a stronger negative correlation with winter and spring months temperature than with mean annual temperature. Noteworthy, climatic variables had stronger effect on high elevation peaks (>1,900 m a.s.l.) compared with low elevation ones (<1,900 m a.s.l.). Main Conclusion Our data provide evidence that the current position of the F. sylvatica tree line in the Apennines is heavily depressed as a result of a complex interaction between climatic factors and the past human pressure.

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Early human impact (5000–3000 BC) affects mountain forest dynamics in the Alps

Cited by 65 publications

References 88 publications

Ice cave reveals environmental forcing of long‐term Pyrenean tree line dynamics

Ice cave reveals environmental forcing of long‐term Pyrenean tree line dynamics

Reconstruction of Holocene vegetation dynamics at Lac de Bretaye, a high-mountain lake in the Swiss Alps

Anthropogenic and environmental factors affect the tree line position of Fagus sylvatica along the Apennines (Italy)

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