‘Fading of the temperature‐growth coupling’ in treeline trees reflects a conceptual bias

Körner, Christian

doi:10.1111/gcb.15730

“…The explanatory power of growth variation based on temperature models did not evenly increase with elevation confirming threshold growth responses to temperature at treeline (Paulsen et al, 2000). According to Körner (2021), such variation would be explained by differential growth enhancement by climate warming shifting upwards or polewards. He suggests that once a threshold is surpassed, thermal effects diminish, and this would explain our findings because growth of 20th-century treeline trees will not be any more limited by low temperature since they will not form the "climatic treeline."…”

Section: Tree Growth and Treeline Responses To Temperature: Different Questions And Conceptsmentioning

confidence: 88%

“…In his letter to the editor, Körner (2021) commented on our recent assessment of climate impacts on tree growth at treeline (Camarero et al, 2021). We share some of his opinions such as the nonlinear responses of growth to temperature.…”

Section: Tree Growth and Treeline Responses To Temperature: Different Questions And Conceptsmentioning

confidence: 98%

Tree growth and treeline responses to temperature: Different questions and concepts

Camarero

¹

,

Gazol

²

,

Sánchez-Salguero

³

et al. 2021

Glob. Change Biol.

0

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“…(4) It was noted with surprise, whenever tested, that isolated populations of alpine plant species are genetically very diverse [81,82]. (5) The advance of trees is much slower than the ongoing upslope shift of the isotherm, leaving trees and adjacent alpine terrain behind, and thus, exposed to higher than treeline-temperature [8,83]. As tree recruitment follows the isotherm shift, a new, fragmented, topography-related ecotone will be established at higher than the current elevation.…”

Section: Discussionmentioning

confidence: 99%

Why Is the Alpine Flora Comparatively Robust against Climatic Warming?

Körner¹,

Hiltbrunner²

2021

Self Cite

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The alpine belt hosts the treeless vegetation above the high elevation climatic treeline. The way alpine plants manage to thrive in a climate that prevents tree growth is through small stature, apt seasonal development, and ‘managing’ the microclimate near the ground surface. Nested in a mosaic of micro-environmental conditions, these plants are in a unique position by a close-by neighborhood of strongly diverging microhabitats. The range of adjacent thermal niches that the alpine environment provides is exceeding the worst climate warming scenarios. The provided mountains are high and large enough, these are conditions that cause alpine plant species diversity to be robust against climatic change. However, the areal extent of certain habitat types will shrink as isotherms move upslope, with the potential areal loss by the advance of the treeline by far outranging the gain in new land by glacier retreat globally.

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“…Despite significant research efforts relating to treelines around the world, some uncertainties still remain concerning the nonlinear response of global treelines to recent climate warming. While there is consensus that 20th-century macroclimate warming has played a pivotal role in triggering a recent upward expansion of alpine treelines (e.g., Kullman, 2007;Liang et al, 2016), the feedback of emerging contingent fine-scale factors is still a matter of debate (e.g., Camarero et al, 2021;Körner, 2021a), as are detailed other local mechanisms that may contribute to treeline position or limit the ability of trees to respond to climate change (Harsch & Bader, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Despite significant research efforts relating to treelines around the world, some uncertainties still remain concerning the nonlinear response of global treelines to recent climate warming. While there is consensus that 20th‐century macroclimate warming has played a pivotal role in triggering a recent upward expansion of alpine treelines (e.g., Kullman, 2007 ; Liang et al, 2016 ), the feedback of emerging contingent fine‐scale factors is still a matter of debate (e.g., Camarero et al, 2021 ; Körner, 2021a ), as are detailed other local mechanisms that may contribute to treeline position or limit the ability of trees to respond to climate change (Harsch & Bader, 2011 ). For example, topographical conditions coupled with local (e.g., extreme winds, snow avalanches, rockfall) and anthropogenic (e.g., fires, grazing by livestock) disturbances can significantly depress treeline elevation compared to their climatic potential (Ameztegui et al, 2016 ; Bonanomi et al, 2020 ; Harsch et al, 2012 ; Holtmeier & Broll, 2020 ).…”

Section: Introductionmentioning

confidence: 99%