Tree‐ring stable isotopes and radiocarbon reveal pre‐ and post‐eruption effects of volcanic processes on trees on Mt. Etna (Sicily, Italy)

Abstract Purpose of Review Society is concerned about the long-term condition of the forests. Although a clear definition of forest health is still missing, to evaluate forest health, monitoring efforts in the past 40 years have concentrated on the assessment of tree vitality, trying to estimate tree photosynthesis rates and productivity. Used in monitoring forest decline in Central Europe since the 1980s, crown foliage transparency has been commonly believed to be the best indicator of tree condition in relation to air pollution, although annual variations appear more closely related to water stress. Although crown transparency is not a good indicator of tree photosynthesis rates, defoliation is still one of the most used indicators of tree vitality. Tree rings have been often used as indicators of past productivity. However, long-term tree growth trends are difficult to interpret because of sampling bias, and ring width patterns do not provide any information about tree physiological processes. Recent Findings In the past two decades, tree-ring stable isotopes have been used not only to reconstruct the impact of past climatic events, such as drought, but also in the study of forest decline induced by air pollution episodes, and other natural disturbances and environmental stress, such as pest outbreaks and wildfires. They have proven to be useful tools for understanding physiological processes and tree response to such stress factors. Summary Tree-ring stable isotopes integrate crown transpiration rates and photosynthesis rates and may enhance our understanding of tree vitality. They are promising indicators of tree vitality. We call for the use of tree-ring stable isotopes in future monitoring programmes.

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Different climate sensitivity for radial growth, but uniform for tree-ring stable isotopes along an aridity gradient in Polylepis tarapacana, the world’s highest elevation tree-species

Tree Physiology ◽

10.1093/treephys/tpab021 ◽

2021 ◽

Author(s):

Milagros Rodriguez-Caton ◽

Laia Andreu-Hayles ◽

Mariano S Morales ◽

Valérie Daux ◽

Duncan A Christie ◽

...

Keyword(s):

Stable Isotopes ◽

Carbon Source ◽

Tree Ring ◽

Tree Growth ◽

Carbon Sink ◽

Growing Season ◽

Wood Formation ◽

Aridity Gradient ◽

Leaf Level ◽

Δ13c And Δ18o

Abstract Tree growth is generally considered to be temperature-limited at upper elevation treelines. Yet, climate factors controlling tree growth at semiarid treelines are poorly understood. We explored the influence of climate on stem growth and stable isotopes for Polyepis tarapacana, the world’s highest elevation tree-species found only in the South American Altiplano. We developed tree-ring width index (RWI), oxygen (δ18O) and carbon (δ13C) chronologies for the last 60 years at four P. tarapacana stands located above 4,400 meters in elevation, along a 500-km latitude-aridity gradient. Total annual precipitation decreased from 300 to 200 mm from the northern to the southern sites. We used RWI as a proxy of wood formation (carbon sink) and isotopic tree-ring signatures as proxies of leaf-level gas exchange processes (carbon source). We found distinct climatic conditions regulating carbon-sink processes along the gradient. Current-growing season temperature regulated RWI at wetter-northern sites, while prior-growing season precipitation determined RWI at arid-southern sites. This suggests that the relative importance of temperature to precipitation in regulating tree growth is driven by site-water availability. In contrast, warm and dry growing-seasons resulted in enriched tree-ring δ13C and δ18O at all study sites, suggesting that similar climate conditions control carbon-source processes. Site-level δ13C and δ18O chronologies were significantly and positively related at all sites, with the strongest relationships among the southern-drier stands. This indicates an overall regulation of intercellular carbon dioxide via stomatal conductance for the entire P. tarapacana network, with greater stomatal control when aridity increases. The manuscript also highlights a coupling and decoupling of physiological processes at leaf level versus wood formation depending on their respectively uniform and distinct sensitivity to climate. This study contributes to better understand and predict the response of high-elevation Polylepis woodlands to rapid climate changes and projected drying in the Altiplano.

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Beyond tree-ring widths: stable isotopes sharpen the focus on climate responses of temperate forest trees

Tree Physiology ◽

10.1093/treephys/tpu115 ◽

2015 ◽

Vol 35 (1) ◽

pp. 1-3 ◽

Cited By ~ 22

Author(s):

L. A. Cernusak ◽

N. B. English

Keyword(s):

Stable Isotopes ◽

Tree Ring ◽

Temperate Forest ◽

Forest Trees ◽

Climate Responses

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Stable isotope paleoclimatology of the earliest Eocene using kimberlite-hosted mummified wood from the Canadian Subarctic

Biogeosciences ◽

10.5194/bg-12-5899-2015 ◽

2015 ◽

Vol 12 (20) ◽

pp. 5899-5914 ◽

Cited By ~ 3

Author(s):

B. A. Hook ◽

J. Halfar ◽

Z. Gedalof ◽

J. Bollmann ◽

D. J. Schulze

Keyword(s):

Stable Isotopes ◽

Tree Ring ◽

Transfer Functions ◽

Ring Width ◽

Growth Patterns ◽

The Arctic ◽

Mean Annual Temperature ◽

Leaf Margin ◽

Early Eocene ◽

Intrinsic Water Use Efficiency

Abstract. The recent discovery of well-preserved mummified wood buried within a subarctic kimberlite diamond mine prompted a paleoclimatic study of the early Eocene "hothouse" (ca. 53.3 Ma). At the time of kimberlite eruption, the Subarctic was warm and humid producing a temperate rainforest biome well north of the Arctic Circle. Previous studies have estimated that mean annual temperatures in this region were 4–20 °C in the early Eocene, using a variety of proxies including leaf margin analysis and stable isotopes (δ13C and δ18O) of fossil cellulose. Here, we examine stable isotopes of tree-ring cellulose at subannual- to annual-scale resolution, using the oldest viable cellulose found to date. We use mechanistic models and transfer functions to estimate earliest Eocene temperatures using mummified cellulose, which was well preserved in the kimberlite. Multiple samples of Piceoxylon wood within the kimberlite were crossdated by tree-ring width. Multiple proxies are used in combination to tease apart likely environmental factors influencing the tree physiology and growth in the unique extinct ecosystem of the Polar rainforest. Calculations of interannual variation in temperature over a multidecadal time-slice in the early Eocene are presented, with a mean annual temperature (MAT) estimate of 11.4 °C (1 σ = 1.8 °C) based on δ18O, which is 16 °C warmer than the current MAT of the area (−4.6 °C). Early Eocene atmospheric δ13C (δ13Catm) estimates were −5.5 (±0.7) ‰. Isotopic discrimination (Δ) and leaf intercellular pCO2 ratio (ci/ca) were similar to modern values (Δ = 18.7 ± 0.8 ‰; ci/ca = 0.63 ± 0.03 %), but intrinsic water use efficiency (Early Eocene iWUE = 211 ± 20 μmol mol−1) was over twice the level found in modern high-latitude trees. Dual-isotope spectral analysis suggests that multidecadal climate cycles somewhat similar to the modern Pacific Decadal Oscillation likely drove temperature and cloudiness trends on 20–30-year timescales, influencing photosynthetic productivity and tree growth patterns.

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Disentangling seasonal and interannual legacies from inferred patterns of forest water and carbon cycling using tree-ring stable isotopes

Global Change Biology ◽

10.1111/gcb.14395 ◽

2018 ◽

Vol 24 (11) ◽

pp. 5332-5347 ◽

Cited By ~ 13

Author(s):

Paul Szejner ◽

William E. Wright ◽

Soumaya Belmecheri ◽

David Meko ◽

Steven W. Leavitt ◽

...

Keyword(s):

Stable Isotopes ◽

Carbon Cycling ◽

Tree Ring

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Chapter 9 Air Quality Changes in an Urban Region as Inferred from Tree-Ring Stable Isotopes

Air Quality and Ecological Impacts: Relating Sources to Effects - Developments in Environmental Science ◽

10.1016/s1474-8177(08)00209-x ◽

2009 ◽

pp. 229-245 ◽

Cited By ~ 4

Author(s):

Martine M. Savard ◽

Christian Bégin ◽

Joëlle Marion ◽

Jean-Christophe Aznar ◽

Anna Smirnoff

Keyword(s):

Stable Isotopes ◽

Air Quality ◽

Tree Ring ◽

Urban Region ◽

Quality Changes

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Tree-Ring Width and Carbon Isotope Chronologies Track Temperature, Humidity, and Baseflow in the Tianshan Mountains, Central Asia

Forests ◽

10.3390/f11121308 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1308

Author(s):

Yuting Fan ◽

Huaming Shang ◽

Ye Wu ◽

Qian Li

Keyword(s):

Stable Isotopes ◽

Tree Ring ◽

Ring Width ◽

River Basins ◽

Tianshan Mountains ◽

Limiting Factor ◽

Source Water ◽

Tree Ring Width ◽

The North ◽

Temperature And Precipitation

Concerns have been raised about the negative impacts of global warming on the hydrological climate change and ecosystems of Asia. Research on the high-altitude mountainous regions of Asia with relatively short meteorological and hydrological records relies on paleoclimate proxy data with long time scales. The stable isotopes of tree-rings are insightful agents that provide information on pre-instrumental climatic and hydrological fluctuations, yet the variability of these data from different regions along the Tianshan Mountains has not been fully explored. Herein, we related climate data with tree-ring width (TRW) chronologies and δ13C (stable carbon isotope discrimination) series to discern if the Picea schrenkiana in the Ili and Manas River Basins are sensitive to climatic factors and baseflow (BF). The results show significant correlations between temperature and TRW chronologies, temperature and δ13C, relative humidity and TRW chronologies, and BF and δ13C. Temperature, particularly the mean late summer to early winter temperature, is a pronounced limiting factor for the tree-ring and the δ13C series in the Manas River Basin, located in the middle of the North Tianshan Mountains. Meanwhile, mean early spring to early autumn temperature is a limiting factor for that of the Ili River Basin, located on the southern slope of the North Tianshan Mountains. We conclude that different seasonal variations in temperature and precipitation of the two river basins exerted significant control on tree growth dynamics. Tree-ring width and tree-ring δ13C differ in their sensitivity to climate and hydrological parameters to which tree-ring δ13C is more sensitive. δ13C showed significant lag with precipitation, and the lag correlation showed that BF, temperature, and precipitation were the most affected factors that are often associated with source water environments. δ13C series correlated positively to winter precipitation, suggesting baseflow was controlling the length of the growing season. The tree-ring δ13C provided information that coincided with TRW chronologies, and supplied some indications that were different from TRW chronologies. The carbon stable isotopes of tree-rings have proven to be powerful evidence of climatic signals and source water variations.

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