Age-dependency, climate, and environmental controls of recent tree growth trends at subarctic and alpine treelines

Mamet, Steven D.; Kershaw, G. Peter

doi:10.1016/j.dendro.2012.08.002

Cited by 21 publications

(16 citation statements)

References 42 publications

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“…While the objective of this study was not to elucidate mechanisms driving any agerelated changes in tree growth, our analyses do indicate that age effects should be considered in similar analyses to control for confounding trends that are inherent in temporal series of RG measurements. Additionally, age-related differences in tree growth responses to climate have been detected in some previous studies (Carrer & Urbinati 2004;Mamet & Kershaw 2013). Age effects, where significant, may interact with other site level effects, including locally differentiated growth processes, to further modify or amplify differences between disjunct populations in their responses to climate change.…”

Section: Discussionmentioning

confidence: 84%

Climate and competition effects on tree growth in Rocky Mountain forests

2017

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Summary Climate is widely assumed to influence physiological and demographic processes in trees, and hence forest composition, biomass and range limits. Growth in trees is an important barometer of climate change impacts on forests as growth is highly correlated with other demographic processes including tree mortality and fecundity. We investigated the main drivers of diameter growth for five common tree species occurring in the Rocky Mountains of the western United States using nonlinear regression methods. We quantified growth at the individual tree level from tree core samples collected across broad environmental gradients. We estimated the effects of both climate variation and biotic interactions on growth processes and tested for evidence that disjunct populations of a species respond differentially to climate. Relationships between tree growth and climate varied by species and location. Growth in all species responded positively to increases in annual moisture up to a threshold level. Modest linear responses to temperature, both positive and negative, were observed at many sites. However, model results also revealed evidence for differentiated responses to local site conditions in all species. In severe environments in particular, growth responses varied nonlinearly with temperature. For example, in northerly cold locations pronounced positive growth responses to increasing temperatures were observed. In warmer southerly climates, growth responses were unimodal, declining markedly above a threshold temperature level. Net effects from biotic interactions on diameter growth were negative for all study species. Evidence for facilitative effects was not detected. For some species, competitive effects more strongly influenced growth performance than climate. Competitive interactions also modified growth responses to climate to some degree. Synthesis. These analyses suggest that climate change will have complex, species‐specific effects on tree growth in the Rocky Mountains due to nonlinear responses to climate, differentiated growth processes that vary by location and complex species interactions that impact growth and potentially modify responses to climate. Thus, robust model simulations of future growth responses to climate trends may need to integrate realistic scenarios of neighbourhood effects as well as variability in tree performance attributed to differentiated populations.

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Section: Discussionmentioning

confidence: 84%

Climate and competition effects on tree growth in Rocky Mountain forests

2017

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“…These palsas have persisted since the eruption of the Bona‐Churchill massif approximately 1200 years ago, while other palsas in the region have disappeared completely (Skaret, ; Kershaw, ). The climatic change in the Canol region, on‐going since the early 1990s, continues a warming initiated in the early 1930s (Liang and Kershaw, ), as suggested by enhanced growth and recruitment of Canol tree populations during that period – particularly since the 1980s (Mamet and Kershaw, , ). Palsa response to climate is complex, incorporating the influence of environmental forcings at seasonal, annual, and probably decadal to centennial scales ( sensu Hugenholtz and Wolfe, ).…”

Section: Discussionmentioning

confidence: 99%

Recent Increases in Permafrost Thaw Rates and Areal Loss of Palsas in the Western Northwest Territories, Canada

Mamet

Chun

Kershaw

et al. 2017

Permafrost & Periglacial

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Decay of palsas can indicate permafrost status, particularly in regions where air temperatures have increased rapidly in recent decades. Using weather data, annual surveys of active‐layer thickness, and analyses of high‐resolution aerial imagery from the eastern Selwyn/western Mackenzie Mountains, NT, Canada, we show that permafrost temperatures have increased, active layers have deepened, and palsa areal extents have decreased considerably since the 1940s. High‐altitude palsas thawed quickly from the 1940s to the 1980s, although some low‐altitude palsas have recently decreased rapidly in areal extent due to peat‐block calving. The linear rate of increasing active‐layer thickness may not be congruent with the non‐linear rate of areal loss of palsas. The rapid and episodic collapse of palsas at some sites highlights the necessity to consider hydrology, vegetation cover, landscape position, and morphology in palsa dynamics in addition to a warming climate. Copyright © 2017 John Wiley & Sons, Ltd.

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“…The fact that tree physiology undergoes changes in sensitivity to climate with age is also supported by tree-ring studies (e.g. Rozas et al 2009;Vieira et al 2009;Wang et al 2009;Copenheaver et al 2011;Linares et al 2013;Mamet and Kershaw 2013;Wu et al 2013). These contributions suggest that trees experience age-related changes in climate sensitivity, but not always in the same direction.…”

Section: Introductionmentioning

confidence: 90%

Age effects on the climatic signal inAraucaria araucanafrom xeric sites in Patagonia, Argentina

Hadad

Roig

Boninsegna

et al. 2014

Plant Ecology & Diversity

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Background: At different cambial ages, trees experience changes in their structure and interactions with environmental conditions. Reciprocal mechanisms between tree age and physical resources, photosynthetic rates, and xylem production may influence hydraulic resistance and plant water stress. However, it is yet uncertain how these mechanisms are associated with changes in growth sensitivity to biophysical drivers, especially climate. Aim: To establish age-associated climate -growth relationships in growth rings of Araucaria araucana trees from the temperate xeric zones of northern Patagonia, Argentina. Methods: We analysed the growth in 211 A. araucana trees from four sampling sites, in three age classes: young (≤120 years), mature (121-275 years), and old (≥276 years). We explored the correlations between the signal strength of tree growth and climate, based on comparisons between each age-class chronology and monthly mean surface air temperature, total precipitation, and the Southern Annular Mode (SAM) index. Results: The young trees showed higher correlations when their growth was compared with precipitation, air temperature, and the SAM index during austral spring and summer months of the same year. In contrast, growth in mature and old trees showed higher correlations with summer temperatures of the previous growing season. Conclusions: The sensitivity of the radial-growth response of A. araucana to climate varies with age and is strongest in the rings of young trees.

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Age-dependency, climate, and environmental controls of recent tree growth trends at subarctic and alpine treelines

Cited by 21 publications

References 42 publications

Climate and competition effects on tree growth in Rocky Mountain forests

Climate and competition effects on tree growth in Rocky Mountain forests

Recent Increases in Permafrost Thaw Rates and Areal Loss of Palsas in the Western Northwest Territories, Canada

Age effects on the climatic signal inAraucaria araucanafrom xeric sites in Patagonia, Argentina

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