scholarly journals 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

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.

scholarly journals A 406-year non-growing-season precipitation reconstruction in the southeastern Tibetan Plateau

2021 ◽  
Vol 17 (6) ◽  
pp. 2381-2392
Author(s):  
Maierdang Keyimu ◽  
Zongshan Li ◽  
Bojie Fu ◽  
Guohua Liu ◽  
Fanjiang Zeng ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Tree Growth ◽  
Ring Width ◽  
Growing Season ◽  
Climatic Conditions ◽  
Forest Growth ◽  
Drought Severity ◽  
Precipitation Reconstruction ◽  
Southeastern Tibetan Plateau

Abstract. Trees record climatic conditions during their growth, and tree rings serve as proxy to reveal the features of the historical climate of a region. In this study, we collected tree-ring cores of hemlock forest (Tsuga forrestii) from the northwestern Yunnan area of the southeastern Tibetan Plateau (SETP) and created a residual tree-ring width (TRW) chronology. An analysis of the relationship between tree growth and climate revealed that precipitation during the non-growing season (NGS) (from November of the previous year to February of the current year) was the most important constraining factor on the radial tree growth of hemlock forests in this region. In addition, the influence of NGS precipitation on radial tree growth was relatively uniform over time (1956–2005). Accordingly, we reconstructed the NGS precipitation over the period spanning from 1600–2005. The reconstruction accounted for 28.5 % of the actual variance during the common period of 1956–2005. Based on the reconstruction, NGS was extremely dry during the years 1656, 1694, 1703, 1736, 1897, 1907, 1943, 1982 and 1999. In contrast, the NGS was extremely wet during the years 1627, 1638, 1654, 1832, 1834–1835 and 1992. Similar variations of the NGS precipitation reconstruction series and Palmer Drought Severity Index (PDSI) reconstructions of early growing season from surrounding regions indicated the reliability of the present reconstruction. A comparison of the reconstruction with Climate Research Unit (CRU) gridded data revealed that our reconstruction was representative of the NGS precipitation variability of a large region in the SETP. Our study provides the first historical NGS precipitation reconstruction in the SETP which enriches the understanding of the long-term climate variability of this region. The NGS precipitation showed slightly increasing trend during the last decade which might accelerate regional hemlock forest growth.

scholarly journals From Dendrochronology to Allometry

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 146 ◽  
Author(s):  
Franco Biondi
Keyword(s):  
Tree Ring ◽  
Tree Rings ◽  
Tree Growth ◽  
Scientific Inquiry ◽  
Population Biology ◽  
Wood Formation ◽  
Allometric Relationships ◽  
Growth Study ◽  
Accurate Identification ◽  
Ring Analysis

The contribution of tree-ring analysis to other fields of scientific inquiry with overlapping interests, such as forestry and plant population biology, is often hampered by the different parameters and methods that are used for measuring growth. Here I present relatively simple graphical, numerical, and mathematical considerations aimed at bridging these fields, highlighting the value of crossdating. Lack of temporal control prevents accurate identification of factors that drive wood formation, thus crossdating becomes crucial for any type of tree growth study at inter-annual and longer time scales. In particular, exactly dated tree rings, and their measurements, are crucial contributors to the testing and betterment of allometric relationships.

Cutting time slices of tree rings —How intra-annual dynamics of wood formation help to decipher space for time conversion in tree-ring sciences

2020 ◽  
Author(s):  
Gonzalo Peres-De-Lis ◽  
Cyrille Rathgeber ◽  
Stéphane Ponton
Keyword(s):  
Cell Differentiation ◽  
Tree Ring ◽  
Isotope Composition ◽  
Growing Season ◽  
Wood Formation ◽  
Tree Level ◽  
Wall Thickening ◽  
North East ◽  
Common Signal ◽  
Kinetics Of

<p>Despite a long-standing interest in retrieving intra-annual environmental information from tree-ring features, none of the approaches developed so far for accurately dating intra-ring sector has been validated on observations. Here, we investigated space-for-time association across regular intra-ring sectors for which we estimated the timing of formation. For this purpose, a unique dataset containing quantitative wood anatomy measurements and kinetics of tracheid differentiation was compiled for 45 trees grown in North-East France (three years of wood formation monitoring, for five trees, from three different conifer species). Tracheid dimensions were measured directly on the best anatomical sections at the end of the growing season, while the kinetics of xylem cell differentiation were provided at tree-level by an empirical model of wood formation dynamics. Our results confirmed that the time taken to form sectors of the same width increased from earlywood (composed of wide thin-walled tracheids) to latewood (composed of narrow thick-walled tracheids). This mainly reflected the increase of the duration of cell wall deposition through the growing season, and, to a lesser extent, the augmentation of the number of tracheids per sectors. However, our results also show that regular intra-ring sectors, which were well separated in space, overlapped in time. The overlapping culminated during the summer period, reaching 40 % for 10 sectors. It could be reduced to approx. 30 % by increasing the number of sectors (from 10 to 25, for example), but it cannot be removed. Therefore, successive intra-ring sectors could not be attributed to a succession of separated time intervals by simply using their relative position along the ring. However, the formation of sectors of equivalent ranks were noticeably synchronous between the different trees and years, reaching 80 % of synchronicity for the process of wall thickening. This suggest that data from regular intra-ring sectors could be reliably used to build mean chronologies expressing the common signal of tree populations. Our results show the limits that the xylogenesis process itself imposes on the dating of intra-ring features. They also argue for an in-depth understanding of the association between cell differentiation processes (enlargement, wall thickening and lignification) and wood characteristics (density, anatomy, stable isotope composition).</p>

scholarly journals Tree growth and its climate signal along latitudinal and altitudinal gradients: comparison of tree rings between Finland and Tibetan Plateau

2017 ◽  
Author(s):  
Lixin Lyu ◽  
Susanne Suvanto ◽  
Pekka Nöjd ◽  
Helena M. Henttonen ◽  
Harri Mäkinen ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Tree Growth ◽  
Latitudinal Gradient ◽  
Ring Width ◽  
Growing Season ◽  
Climate Variables ◽  
Climate Data ◽  
Altitudinal Gradients ◽  
Summer Temperatures

Abstract. Latitudinal and altitudinal gradients can be utilized to forecast the impacts of climate changes on forests. To improve the understanding of forest dynamics on these gradients, we tested two hypotheses: (1) the change in the tree growth-climate relationship is similar along both latitudinal and altitudinal gradients, and (2) the time periods during which climate affects growth the most occur later towards higher latitudes and altitudes. We used tree-ring data from a latitudinal gradient in Finland and two altitudinal gradients on the Tibetan Plateau. We analysed the latitudinal and altitudinal growth patterns in tree-rings and investigated the growth-climate relationships of trees by correlating ring-width index chronologies with climate variables calculated with flexible time-windows, using daily-resolution climate data. The high latitude and altitude plots showed higher correlations between the tree-ring chronologies and growing season temperature. However, the effects of winter temperature showed differing patterns for the gradients. The timing of highest correlation with summer temperatures in southern sites was approximately one month ahead of the northern sites in the latitudinal gradient. In one out of the two altitudinal gradients the timing of strongest negative correlation with summer temperatures at low altitude sites was ahead of the treeline sites, possibly due to differences in moisture limitation. Mean values and the standard deviation of tree-ring width was found to increase with increasing mean summer temperatures on both types of gradients. Our results showed similarities of tree growth responses to growing season temperature between latitudinal and altitudinal gradients. However, differences in climate-growth relationships were also found between the gradients, due to differences in other factors, such as moisture conditions. Changes in the timing of the most critical climate variables demonstrated the need to use daily resolution climate data in studies on environmental gradients.

Intra-annual climatic signal in tree rings of Larix sp. based on the Vaganov-Shashkin model output

2021 ◽  
Author(s):  
Marina Fonti ◽  
Olga Churakova (Sidorova) ◽  
Ivan Tychkov
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Climatic Factors ◽  
Ring Width ◽  
Growing Season ◽  
Climatic Conditions ◽  
Limiting Factor ◽  
Precipitation Regime ◽  
The North ◽  
Temperature And Precipitation

<p>Air temperature increase and change in precipitation regime have a significant impact on northern forests leading to the ambiguous consequences due to the complex interaction between the ecosystem plant components and permafrost. One of the major interests in such circumstances is to understand how tree growth of the main forest species of the Siberian North will change under altering climatic conditions. In this work, we applied the process-based Vaganov-Shashkin model (VS - model) of tree growth in order to estimate the daily impact of climatic conditions on tree-ring width of larch trees in northeastern Yakutia (Larix cajanderi Mayr.) and eastern Taimyr (Larix gmelinii Rupr. (Rupr.) for the period 1956-2003, and to determine the extent to which the interaction of climatic factors (temperature and precipitation) is reflected in the tree-ring anatomical structure. Despite the location of the study sites in the harsh conditions of the north, and temperature as the main limiting factor, it was possible to identify a period during the growing season when tree growth was limited by lack of soil moisture. The application of the VS-model for the studied regions allowed establishing in which period of the growing season the water stress is most often manifest itself, and how phenological phases (beginning, cessation, and duration of larch growth) vary among the years.</p><p>The research was funded by RFBR, Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science, project number 20-44-240001 and by the Russian Ministry of Science and Higher Education (projects FSRZ-2020-0010).</p>

scholarly journals Stable Isotopes in Tree Rings of Pinus heldreichii Can Indicate Climate Variability over the Eastern Mediterranean Region

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 350
Author(s):  
Ljubica Lukač ◽  
Stjepan Mikac ◽  
Otmar Urban ◽  
Tomáš Kolář ◽  
Michal Rybníček ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Climate Variability ◽  
Tree Ring ◽  
Mediterranean Region ◽  
Eastern Mediterranean ◽  
Climatic Variability ◽  
Eastern Mediterranean Region ◽  
Balkan Peninsula ◽  
Past Climate ◽  
Δ13c And Δ18o

A long-term context is important for understanding past climatic variability. Although tree-ring widths (TRWs) are widely used as a proxy for reconstructing past climate, the use of annually-resolved values of δ13C and δ18O tree-ring stable isotopes (TRSIs) is increasing and may provide further valuable information. Here, we present a 487-year-long TRW chronology and 240-year-long TRSI chronology for Bosnian pine (Pinus heldreichii H. Christ) and compare them to each other. We demonstrate that both δ13C and δ18O values are better proxies for temperature, precipitation, and drought than TRW. The correlations between these climate parameters and TRSIs are strongest for the combined summer (JJA) period. The results of temporal and spatial field correlation indicate that TRSI chronologies are stable, reliable proxies for JJA precipitation reconstruction over the whole Balkan Peninsula and surrounding eastern Mediterranean region. However, the stability of the temperature signal of the both δ13C and δ18O chronologies declines after the 1950s. Our work supports the emerging evidence that TRSI data track climate variability more accurately than a conventional TRW approach and can be subsequently used for the reconstruction of past climate.

scholarly journals Tree growth and its climate signal along latitudinal and altitudinal gradients: comparison of tree rings between Finland and the Tibetan Plateau

2017 ◽  
Vol 14 (12) ◽  
pp. 3083-3095 ◽  
Author(s):  
Lixin Lyu ◽  
Susanne Suvanto ◽  
Pekka Nöjd ◽  
Helena M. Henttonen ◽  
Harri Mäkinen ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Tree Ring ◽  
Tree Growth ◽  
Latitudinal Gradient ◽  
Ring Width ◽  
Growing Season ◽  
The Tibetan Plateau ◽  
Climate Variables ◽  
Climate Data ◽  
Altitudinal Gradients

Abstract. Latitudinal and altitudinal gradients can be utilized to forecast the impact of climate change on forests. To improve the understanding of how these gradients impact forest dynamics, we tested two hypotheses: (1) the change of the tree growth–climate relationship is similar along both latitudinal and altitudinal gradients, and (2) the time periods during which climate affects growth the most occur later towards higher latitudes and altitudes. To address this, we utilized tree-ring data from a latitudinal gradient in Finland and from two altitudinal gradients on the Tibetan Plateau. We analysed the latitudinal and altitudinal growth patterns in tree rings and investigated the growth–climate relationship of trees by correlating ring-width index chronologies with climate variables, calculating with flexible time windows, and using daily-resolution climate data. High latitude and altitude plots showed higher correlations between tree-ring chronologies and growing season temperature. However, the effects of winter temperature showed contrasting patterns for the gradients. The timing of the highest correlation with temperatures during the growing season at southern sites was approximately 1 month ahead of that at northern sites in the latitudinal gradient. In one out of two altitudinal gradients, the timing for the strongest negative correlation with temperature at low-altitude sites was ahead of treeline sites during the growing season, possibly due to differences in moisture limitation. Mean values and the standard deviation of tree-ring width increased with increasing mean July temperatures on both types of gradients. Our results showed similarities of tree growth responses to increasing seasonal temperature between latitudinal and altitudinal gradients. However, differences in climate–growth relationships were also found between gradients due to differences in other factors such as moisture conditions. Changes in the timing of the most critical climate variables demonstrated the necessity for the use of daily-resolution climate data in environmental gradient studies.

scholarly journals Vegetation greenness and land carbon-flux anomalies associated with climate variations: a focus on the year 2015

2017 ◽  
Vol 17 (22) ◽  
pp. 13903-13919 ◽  
Author(s):  
Chao Yue ◽  
Philippe Ciais ◽  
Ana Bastos ◽  
Frederic Chevallier ◽  
Yi Yin ◽  
...  
Keyword(s):  
Carbon Source ◽  
El Niño ◽  
El Nino ◽  
Carbon Sink ◽  
Growing Season ◽  
Satellite Observations ◽  
Carbon Uptake ◽  
Climate Variations ◽  
Strong Transition ◽  
The Tropics

Abstract. Understanding the variations in global land carbon uptake, and their driving mechanisms, is essential if we are to predict future carbon-cycle feedbacks on global environmental changes. Satellite observations of vegetation greenness have shown consistent greening across the globe over the past three decades. Such greening has driven the increasing land carbon sink, especially over the growing season in northern latitudes. On the other hand, interannual variations in land carbon uptake are strongly influenced by El Niño–Southern Oscillation (ENSO) climate variations. Marked reductions in land uptake and strong positive anomalies in the atmospheric CO2 growth rates occur during El Niño events. Here we use the year 2015 as a natural experiment to examine the possible response of land ecosystems to a combination of vegetation greening and an El Niño event. The year 2015 was the greenest year since 2000 according to satellite observations, but a record atmospheric CO2 growth rate also occurred due to a weaker than usual land carbon sink. Two atmospheric inversions indicate that the year 2015 had a higher than usual northern land carbon uptake in boreal spring and summer, consistent with the positive greening anomaly and strong warming. This strong uptake was, however, followed by a larger source of CO2 in the autumn. For the year 2015, enhanced autumn carbon release clearly offset the extra uptake associated with greening during the summer. This finding leads us to speculate that a long-term greening trend may foster more uptakes during the growing season, but no large increase in annual carbon sequestration. For the tropics and Southern Hemisphere, a strong transition towards a large carbon source for the last 3 months of 2015 is discovered, concomitant with El Niño development. This transition of terrestrial tropical CO2 fluxes between two consecutive seasons is the largest ever found in the inversion records. The strong transition to a carbon source in the tropics with the peak of El Niño is consistent with historical observations, but the detailed mechanisms underlying such an extreme transition remain to be elucidated.

Climatic response of tree-ring densitometric records in a semiarid site of China

2020 ◽  
Author(s):  
Huiming Song ◽  
Yu Liu
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Monsoon Season ◽  
Growing Season ◽  
Moisture Stress ◽  
Maximum Density ◽  
Semiarid Region ◽  
Summer Temperatures ◽  
Positive Correlations ◽  
Fall Temperature

<p>The tree-ring densitometric studies conducted in the semiarid regions are rare, among them, minimum earlywood density (MND) records the strongest climate signals than other density parameters. In contrast, maximum density of latewood (MXD) in cold and humid regions usually shows the most significant association with summer temperatures. Density parameters of Purplecone Spruce (Picea purpurea Mast.) in Mt. Shouyang, northwestern China, a typical semiarid region were obtained to test the density-climate relationships. It is showed that MXD has strong positive correlations with temperatures and a negative correlation with precipitation in the late growing season from July to September. MND is significantly positively correlated with temperature and positively correlated with precipitation during the early growing season. During early growing season, spring droughts always occur due to low precipitation. A narrow ring is built under moisture stress, since tree growth is inhibited by decreasing cell division and cell enlargement. With the intensification of monsoon, more precipitation is available, which can basically meet the needs of tree growth. During strong monsoon season with humid conditions, trees are less affected by moisture stress. In this case, high temperature could increase cell wall thickness in the latewood which strongly affects the tree-ring maximum density. It could explain why there is a significant positive correlation between MXD and summer-fall temperature.</p>

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