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Computer-Assisted Quality Control in Tree-Ring Dating and Measurement
... The samples were pre-processed and visually compared under a microscope for cross-dating. The width of the tree rings was measured with the German LINTAB6 instrument, accurate to 0.001 mm [32]. The measurements were cross-dated using the COFECHA software [33] to sequences with low correlations with the main sequence due to anisotropic growth and many outliers. ...
... The results show that the temperature changed significantly in 1989. 0.001 mm [32]. The measurements were cross-dated using the COFECHA software [33] to sequences with low correlations with the main sequence due to anisotropic growth and many outliers. ...
We developed a tree ring width chronology from 1797 to 2020 (224 years) for the northwestern foothills of the Greater Khingan Mountains (GKMs) in northeastern China using 51 tree ring sample cores from 24 Pinus sylvestris var. mongolica (PSM). Pearson’s correlation analysis was used to analyze the relationship between tree ring width and regional climate factors. The standardized chronology was positively associated with the minimum temperature (Tmin) in the previous May (r = 0.721, p < 0.01), indicating that this parameter was the main climatic factor limiting PSM growth in the region. We established a secure reconstruction equation for the May Tmin from 1797 to 2020. There were 31 warm and 43 cold years in the 224-year reconstructed temperature series, accounting for 13.8% and 19.2% of the total years, respectively. Warm periods were observed in 1820–1829, 1877–1898, 1947–1958, and 1991–2020, whereas cold periods occurred in 1820, 1829–1870, 1899–1927, 1934–1947, and 1960–1988. The observed temperature sequence was highly consistent with the reconstructed sequence from the tree rings, which verified the reliability of the reconstructed results. The spatial correlation analysis indicated that the reconstructed temperature sequence accurately represented the temperature changes in the northwestern foothills of the GKM and surrounding areas. Multi-window spectral analysis and wavelet analysis revealed significant periodic fluctuations from 2 to 6 years, 21.2 years, 48.5 years, and 102.2 years. These periodic variations may be related to the El Niño–Southern Oscillation (ENSO), the Atlantic Multi-Year Intergenerational Oscillation (AMO), the Pacific Decadal Oscillation (PDO), and solar activity. This study expands the existing climate records in the region and provides valuable data support for understanding climate change patterns in the GKM and the scientific predictions of future climate changes.
... This program statistically compares the dating of each sample through the measurement files of each tree-ring width series by successively correlating segments of 50 years with an overlap of 25 years. COFECHA identifies segments of the tree-ring width series that are poorly correlated with the master chronology series, for which it shows dating errors, measurement errors, or growth problems; this process allows the assignment of the exact date to each of the tree rings (Grissino-Mayer, 2001;Holmes, 1983). ...
... Este programa compara estadísticamente el fechado de cada muestra a través de los archivos de medición de cada serie de crecimiento, al correlacionar sucesivamente segmentos de 50 años con traslapes de 25. COFECHA identifica segmentos de la serie de anillos poco correlacionados con la serie maestra de la cronología, para los cuales muestra los errores de fechado, de medición, o bien problemas de crecimiento; este proceso permite la asignación de la fecha exacta a cada uno de los anillos (Grissino-Mayer, 2001;Holmes, 1983). ...
Introducción. El potencial dendrocronológico de una especie revela su capacidad para desarrollar anillos de crecimiento anuales con una fuerte señal climática. Objetivo. Evaluar el potencial dendrocronológico de Pinus pinceana Gordon para registrar la variabilidad climática en sus anillos de crecimiento. Materiales y métodos. Se extrajeron núcleos de crecimiento de P. pinceana en un matorral submontano en Tamaulipas, México. Se usaron programas dendrocronológicos para la medición del ancho anual de los anillos, su fechado y su transformación a índices de crecimiento. Estos índices se relacionaron con datos de precipitación y de temperatura. Resultados y discusión. La correlación entre series fue r = 0.54 (p < 0.001) y la sensibilidad media de 0.31. Estos valores son más bajos que lo documentado para la especie; sin embargo, indican que esta es sensible a los factores climáticos y capaz de registrar su variabilidad a través del grosor de los anillos de crecimiento. Se generó una cronología de 153 años (1867-2019) con potencial para detectar la variabilidad de la precipitación promedio acumulada septiembre-mayo (r = 0.71; p < 0.001) y de temperatura máxima promedio septiembre-junio (r = -0.64; p < 0.001). El piñonero llorón en Tamaulipas supera la sensibilidad a la precipitación que la especie presenta en otras poblaciones del centro y norte de México. Conclusiones. P. pinceana en Tamaulipas tiene un buen potencial dendrocronológico por la capacidad de registrar, en sus anillos de crecimiento, la variabilidad climática de la región, particularmente la precipitación.
... Tree rings were visually cross-dated and measured to the nearest 0.01 mm, using the semi-automatic LINTAB device with the TSAP-Win software (RINNTECH, Heidelberg, Germany), obtaining two tree-ring width (TRW) series for each tree. Cross-dating was further verified with the COFECHA program (Holmes, 1983). In addition, sapwood length was also measured directly on the dry cores with a ruler. ...
... Q. faginea showed in Monfragüe a lower number of pointer years (7 against 12 for Q. suber). The years that met the criteria to be considered a dry year (less than -1.25 in the June SPEI12; see Fig. S4) were 1954, 1965, in Cabañeros, and 1955, 1976, 1981, 1983 Monfragüe. Some of these droughts produced drops in growth, being 1995 and 2012 pointer years in Cabañeros, and 1976Cabañeros, and , 1981Cabañeros, and , 1982Cabañeros, and , 1992 and 2012 pointer years in ...
... Cores were either scanned at a resolution of 2400 dpi with an Epson Expression 10000XL scanner and ring widths were measured with CooRecorder 9.4 (Larsson, 2020), or measured with a LINTAB digital positioning table using the software TSAP-Win (version 4.81j, RINNTECH, Germany). Cross-dating was done both visually with TSAP-Win and statistically using COFECHA (Holmes, 1983, Grissino-Mayer, 2001. Before further processing, the individual times series were detrended to eliminate age and management related trends (Fritts, 1976, Cook et al., 1990. ...
... Ring widths were measured to an accuracy of 0.001 mm under a binocular microscope using the Lintab measurement system, which was interfaced with the Time Series Analysis Program (Frank Rinntech, Heidelberg, Germany). Cross-dating accuracy was visually confirmed and further validated using the COFECHA (version 6.02P) program [20]. ...
Understanding how forest ecosystems respond to climate variability is critical for predicting the impacts of climate change on semi-arid and temperate regions. This study examines the climatic drivers of radial growth in Larix sibirica Ledeb in the Kanas Lake region, northern Xinjiang, China, to explore how climate change may alter forest growth patterns. Using tree-ring chronologies, we examine the relationships between temperature, precipitation, and drought conditions, as well as the influence of large-scale atmospheric circulation patterns on growth. Results indicate that high summer temperatures negatively affect tree growth, while adequate precipitation plays a crucial role in mitigating water stress, especially during key growth periods. Positive correlations with the Palmer Drought Severity Index further underscore the importance of long-term moisture availability. Moreover, the study highlights the role of the El Niño-Southern Oscillation in influencing moisture transport, with significant correlations between sea surface temperatures in the Niño 4 region and tree-ring growth. Future growth simulations under two climate scenarios suggest that moderate warming (SSP 2–4.5) may enhance growth, while more extreme warming (SSP 5–8.5) introduces greater uncertainty and potential growth instability. These findings provide critical guidance for forest management strategies in the face of climate change.
... Each core was visually crossdated against preexisting chronologies from each site, and a second analyst confirmed the correct dating of each sample. We then recorded ring widths using a measuring stage (Velmex, Bloomfield, NY) and Measure J2X software (VoorTech Consulting, Holderness, NH) and verified crossdating using COFECHA (Holmes, 1983). Mean inter-series correlations (Pearson's r) ranged from 0.65 to 0.82 across sites. ...
The frequency and severity of drought events are predicted to increase due to anthropogenic climate change, with cascading effects across forested ecosystems. Management activities such as forest thinning and prescribed burning, which are often intended to mitigate fire hazard and restore ecosystem processes, may also help promote tree resistance to drought. However, it is unclear whether these treatments remain effective during the most severe drought conditions or whether their impacts differ across environmental gradients. We used tree‐ring data from a system of replicated, long‐term (>20 years) experiments in the southwestern United States to evaluate the effects of forest restoration treatments (i.e., evidence‐based thinning and burning) on annual growth rates (i.e., basal area increment; BAI) of ponderosa pine (Pinus ponderosa), a broadly distributed and heavily managed species in western North America. The study sites were established at the onset of the most extreme drought event in at least 1200 years and span much of the climatic niche of Rocky Mountain ponderosa pine. Across sites, tree‐level BAI increased due to treatment, where trees in treated units grew 133.1% faster than trees in paired, untreated units. Likewise, trees in treated units grew an average of 85.6% faster than their pre‐treatment baseline levels (1985 to ca. 2000), despite warm, dry conditions in the post‐treatment period (ca. 2000–2018). Variation in the local competitive environment promoted variation in BAI, and larger trees were the fastest‐growing individuals, irrespective of treatment. Tree thinning and prescribed fire altered the climatic constraints on growth, decreasing the effects of belowground moisture availability and increasing the effects of atmospheric evaporative demand over multi‐year timescales. Our results illustrate that restoration treatments can enhance tree‐level growth across sites spanning ponderosa pine's climatic niche, even during recent, extreme drought events. However, shifting climatic constraints, combined with predicted increases in evaporative demand in the southwestern United States, suggest that the beneficial effects of such treatments on tree growth may wane over the upcoming decades.
... The tree-ring samples were processed by fixation, polishing, and cross-dating sequentially. Each ring width was measured at a 0.01 mm resolution, and the accuracy of the results were checked by the COFFCHA program, which can also be used for cross-dating (Holmes 1983). It is believed that the negative exponential curve detrending method is suitable for arid and semi-arid regions (Fritts 1976;Li et al. 2011). ...
Clarifying the climate change effects on the radial growth of trees has implications for sustainable forest management, especially under global warming. To investigate tree growth responses to regional climate change of Xiaowutai Mountain, four Chinese pine (Pinus tabulaeformis) ring-width index chronologies were established at different elevations (1290–1600 m). Species growth trends were estimated using climate change projections derived from global climate models. The results show: (1) the four ring-width chronologies exhibited strong statistical characteristics, making them suitable for dendroclimatology studies. Radial growth-climate relationships were highly consistent, showing a negative correlation with previous September temperatures and current May–June temperatures, as well as a positively correlated with precipitation and Palmer Drought Severity Index during the corresponding period; and (2) climate change scenarios revealed that temperature will gradually increase on the Xiaowutai Mountain, and only a slight variation in precipitation is expected. Chinese pine radial growth may show a decline under future climate change.
... All samples were visually cross-dated and the earlywood (EW), latewood (LW) and tree-ring (TRW) widths were measured on a measuring device (LINTAB 6, Rinntech, Heidelberg, Germany) with a resolution of 0.001 mm. Subsequently, the COFECHA program was employed to assure that each tree-ring was assigned to a particular year without error (Holmes 1983). To reduce the non-climatic variability in tree-ring series and preserve the high-frequency variability of growth possibly related to climate, each radial growth series was detrended using a negative exponential function and a spline function with a 50% frequency response. ...
To understand and manage Mediterranean forested ecosystems under a changing climate, forest managers require improved knowledge of forest plantations ability to adaptat to drought stress. This paper analyses the radial growth dynamics (earlywood width, EW; latewood width, LW; tree-ring width, TRW; basal area increment, BAI) and vegetation activity (normalized difference vegetation index, NDVI; enhanced vegetation index, EVI) of Pinus nigra plantations growing on two sites (lower, upper) with contrasting edaphic conditions, in eastern Albania, and evaluates the growth responses to climate (temperature and precipitation) and drought (standardized precipitation index, SPI; standardized precipitation evaporation index, SPEI). P. nigra plantations showed pronounced differences in growth and response to climate (drought) and soil variations between sites. Trees at the lower site, located on poor soils, showed lower growth rates and higher response to June-July precipitation, August temperatures and drought index SPI (< 8 months) in summer as compared to trees at the upper site distributed on rich soils which remained more buffered. At the upper site, the high vegetation activity in July (EVI) and August (NDVI) affected considerably the radial growth rate, whereas at the lower site, only July EVI showed significant relationship with EW, LW and TRW. Vegetation indices at the lower site showed the strongest association with drought. We conclude that future management of P. nigra plantations should be properly adapted to modulate variations in climate and to sustain tree growth and productivity, triggered by local site conditions.
... The width of each annual ring of the strips was remeasured by the use of WinDendro software (Regent Instruments Canada Inc 2012). Each individual timeseries (radius) of tree-ring widths measured by WinDendro and SilviScan was visually cross-dated based on a master tree-ring chronology of 36 F. sylvatica trees from the same study site and a nearby area (Huang et al. 2017), and dating was verified using the COFECHA software (Holmes 1983). ...
Tree-ring width chronologies of Fagus sylvatica L. have been studied to understand the growth–climate relationship in Denmark, but there is little evidence of a clear climate signal in such tree-ring width data. In this study, tree-ring width chronologies of F. sylvatica trees growing in an even-aged stand in Denmark over the period 1972–2012 were supplemented with wood density and quantitative wood anatomy variables using the SilviScan-3 combined set-up. The effects of moisture availability and temperature variations on xylem features were investigated. Some xylem features showed stronger associations with drought index (DI) and temperature than ring width. Specifically, the September drought was associated with an increased mean area of the individual fibers in the ring formed the following year. Drought
in October resulted in a higher density the following year, probably via increased fiber wall thickness and decreased areas of individual vessels. Further, late summer and early autumn warming increased the vessel density in the following year, but drought reduced their cross-sectional area. By dividing tree rings into ten segments, relationships between wood density and DI could be evaluated at the intra-annual level. In the third segment, wood density decreased with previous year December drought, while the April drought increased the wood density of this segment. Together, the results indicated that xylem formation and anatomy in F. sylvatica seem to be linked to moisture availability and temperature, and that dry and warm conditions affect xylem features differently depending on when they occur relative to wood formation.
... Ring widths were measured with a 0.001 mm resolution using scanned images and the CooRecorder-CDendro software (Maxwell & Larsson, 2021). The quality of cross-dating was checked using the COFECHA software which calculates moving correlations between individual series of ring-width values and the mean sites series (Holmes, 1983). 140 ...
Changing snow regimes and warmer growing seasons are some climate factors influencing productivity and growth of high-elevation forests and alpine treelines. In low-latitude mountain regions with seasonal snow and drought regimes such as the Pyrenees, these climate factors could negatively impact forest productivity. To address this issue, we assessed the relationships between climate, snow, and inter- and intra-annual radial growth and stem increment data in an alpine Pinus uncinata treeline ecotone located in the central Spanish Pyrenees. First, we developed tree-ring width chronologies of the study site to quantify climate-growth relationships. Second, radial growth, tree water deficit, and shrinking/swelling cycles were quantified and identified at monthly to daily scales using fine-resolution dendrometer data. These variables were extracted for three climatically different years, including one of the hottest summers on record in Spain (2022), and were related to soil water content, soil and air temperature, and the dates of snow duration across the treeline ecotone. Warmer February and May temperatures enhanced tree radial growth, probably because of an earlier snow melt-out and start of the growing season and higher growth rates in spring, respectively. The characteristic circadian cycle of stem increment, defined by night swelling and day shrinking, was detected in summer and autumn. However, this pattern inverted during the snow season from November through April, suggesting a transition phase characterized by wet soils and swollen stems preceding the spring onset of growth. Air temperature, soil temperature and moisture, and the presence of snow are strong indicators of how much and for how long mountain trees can grow. Shifts in daily stem increment patterns reveal changes in early growth phenology linked to snow melting.
... Ring widths were measured to the nearest 0.01 mm using Windendro 1 (Regent Instruments, Blaine, Quebec). COFECHA (Holmes 1983) was used to help correct dating errors. For incomplete cores, the total age at coring height was estimated using the protocol of Frelich and Reich (1995). ...
For wet sub-boreal sprucefir forests (white spruce (Picea glauca (Moench) Voss) Engelmann spruce (Picea engelmannii Parry ex Engelm.) subalpine fir (Abies lasiocarpa (Hook.) Nutt.)) in east-central British Columbia, we asked (i) do compositional and structural dynamics differ for unmanaged (UN) and partial-cut (PC) (50% removal 45years before measurement) forests and (ii) how does Inonotus tomentosus Fr. (Teng) affect these dynamics? Inonotus tomentosus infected stands had 17% less spruce basal area (P = 0.059) than uninfected stands, but PC did not exacerbate I. tomentosus effects. PC and UN had similar live tree density, but UN had lower dead tree density. In all stands, snag longevity was typically<32years, and ~40years was required for dead wood to reach decay stage 3 or greater. UN was characterized by variable severity disturbances averaging ~8% of the canopy per decade. Management implications include the following: (i) harvest systems designed to emulate small-scale disturbance could remove trees at 8% of the canopy per decade, varied spatiotemporally, (ii) emulating dead wood abundance with partial cutting may be difficult given the impacts of partial cutting on dead wood abundance, and (iii) forests with moderate levels of I. tomentosus should not respond differently to harvesting than uninfected forests and thus require no special management.
... Tree-ring widths (TRW) were measured to the nearest 0.01 mm using a digital LINTAB positioning table connected to an Olympus stereomicroscope and TSAPWin Scientific software (Rinn 2003). Prior to further estimates based on the TRW data, all data series were cross dated for missing rings and dating errors using COFECHA (Holmes 1983;Cook and Holmes 1984). Each observation in the dataset represents an annual ring size measurement from individual trees, a certain species, and located at specific sites. ...
... For cores with rings that were difficult to see in the digitally scanned image, a stage micrometer (Velmex: Bloomfield, NY, USA) was also used for tree ring measurement. We also used the program COFECHA (Version 6.06P) as a statistical quality control tool to verify the cross-dating accuracy [28]. ...
The overall objective of our study was to examine the influence of climatic factors and tree-based competition on the radial growth of jack pine (Pinus banksiana) forests affected by the fungal pathogen, Diplodia pinea. Our study utilized dendroclimatic techniques to examine how past annual diameter growth can be influenced by the historical climate of the region. Twenty jack pine sites were sampled in Michigan within the Upper Peninsula (UP) and the Lower Peninsula (LP) region. Furthermore, two condition levels of forest health (D. pinea-affected vs. healthy reference stands) were considered between two levels of stand density (i.e., high vs. low density). The relationships between radial growth and climate identified in this study indicated that jack pine radial growth was typically affected by the climatic moisture index, whereas the response to temperature variables was weak to non-existent. In the Upper Peninsula region, crown damage likely sustained during harsh winters could have made jack pine stands prone to D. pinea by facilitating a point of entry for infection; furthermore, higher-density stands infected by D. pinea were influenced by moisture stress that occurred during the summer of the prior year. In the LP region, regardless of stand density, D. pinea was sensitive to moisture stress in the summer of the prior growing season; furthermore, negative relationships with precipitation in the spring may have improved spore dispersion in D. pinea-affected stands. Overall, our study provides improved understanding of the interactive role of climatic stress and forest pathogens on jack pine productivity.
... We delineated ring boundaries and measured annual ring width with 0.001 mm precision. Next, we visually crossdated our samples by species and plots, which we then statistically veri ed using COFECHA (Holmes 1983). Annual basal area increments (BAI, cm 2 yr − 1 ) were calculated from ring width and eld-measured DBH as: BAIt = π(R t 2 -R t−1 2 ) where R t and R t−1 are the radius of a tree at year t and t-1, respectively. ...
Context Floodplain forests along the Upper Mississippi River System (UMRS) are highly influenced by the human-altered river flow regime. More intense and frequent floods are inducing decline in less flood-tolerant tree species. Of special concern is the situation of northern pecan tree (Carya illinoinensis (Wangenh. K.Koch)), which shows clear symptoms of decline ( i.e. defoliation, mortality) and a lack of regeneration. Objective We attempt to investigate changes in C. illinoinensis decline and health and determine the biometric factors that lead to these differences. Methods We established 15 plots along the UMRS floodplain and within each plot, we recorded species composition, health status, diameter at breast height and tree location. Additionally, we collected increment cores to study the disturbance regime, and the effects of climate and river flow on radial growth. We applied a principal component analysis and a mixed effect regression model to determine the factors related to pecan health at site and individual level, respectively. Results Two major disturbance events occurred during the 20th century: in 1965 and 1993. Both events are related to extraordinary flow discharges in the river that led to significant tree mortality in the overstory. Pecans exhibited growth release after the disturbances, however, the incidence of recruitment for this species was very scarce during the 20th century. Our analysis revealed that plots with a higher proportion of healthy pecans are located in the southmost area, which is characterized by less frequent extraordinary floods and less stand competition. Conclusions We conclude that without oriented management efforts, pecans will eventually disappear from the northern extent of the species range soon, leading to a loss in tree diversity in the UMRS.
... 29.03°-30.13°N) is located on Haizi mountain, southeastern TP, China, with the average elevation of 4500 m (Fig. 1). The Eastern Asian monsoon, Indian monsoon, and the continental westerlies play an active role in driving the regional climate patterns of this region 74 . According to the record from 1958-2017 at the Daocheng meteorological station (29.03°N, 100.18°E, 3728 m a.s.l.), the mean annual temperature is about 4.58℃, with the warmest and coldest months being June (12.3℃) ...
Precisely dated paleoclimatic records are essential for understanding natural and anthropogenic climate influences. Here, an annually resolved absolutely dated Juniperus saltuaria tree ring width chronology from the Haizi mountain, southeastern Tibetan Plateau (TP) was developed. The chronology shows the annual- to decadal-scale paleoclimatic variability of the southeastern TP over the past 903 years (1115–2017 CE). The tree ring widths correlate significantly with mean annual temperature (Tmean). A linear regression model between ring width and Tmean, accounting for 57% of the variance in temperature from 1959 to 2017 CE, was used to reconstruct the past 903 years of Tmean variation in the southeastern TP. The chronology aligns with other temperature records from the TP, Asia, and the Northern Hemisphere (NH), indicating a marked temperature increase since the late twentieth century, with 1998–2017 CE identified as the warmest period. The coldest thirty years occurred in 1115–1145 CE. Solar activity and the Atlantic Multidecadal Oscillation exert notable influences on temperature fluctuations in this region. Superposed epoch analysis indicates that volcanic eruptions had significantly impacted southeastern TP temperatures, causing dramatic cooling for 2–4 years. Our study presents the longest width chronology developed by Juniperus saltuaria to date, offering a long-term perspective on recent climatic shifts across the southeastern TP. This work enhances understanding of historical climate variability, providing critical insights to refine projections of future climate variability.
... Both methods provided accurate and comparable measurements. Tree-ring widths were visually crossdated with the measuring software and statistically checked with the software COFECHA (Holmes 1983). For crossdating, a total of 20 trees per site and species that were sampled in Charlet de Sauvage et al. (2023) were used. ...
Oxygen ( δ ¹⁸ O) and hydrogen ( δ ² H) stable isotope ratios are tightly coupled in precipitation and, albeit damped, in leaf water, but are often decoupled in tree‐ring cellulose. The environmental and physiological conditions in which this decoupling occurs are not yet well understood. We investigated the relationships between δ ¹⁸ O and δ ² H and tree‐ring width (TRW), tree crown volume, tree age and climate in silver fir and Douglas‐fir and found substantial differences between δ ¹⁸ O and δ ² H. Overall, δ ¹⁸ O– δ ² H correlations were weak to absent but became significantly negative under high summer vapour pressure deficit (VPD). δ ¹⁸ O and δ ² H had positive and negative nonlinear relationships with TRW, respectively, with clear relationships at the site and tree levels for silver fir and, to a lesser extent, for Douglas‐fir. Age trends for silver fir were weakly negative in δ ¹⁸ O but positive in δ ² H. Tree crown volume and δ ¹⁸ O or δ ² H had no significant relationships. Most strikingly, δ ¹⁸ O strongly depended on spring climate (precipitation and VPD), whereas δ ² H depended on summer climate (temperature and VPD) for both species. Our study shows that the δ ¹⁸ O– δ ² H decoupling in tree‐ring cellulose in two temperate conifer species could be highlighted by their contrasting relationships to climate and tree intrinsic variables (TRW, age).
... The tree ring series were dated using t-values of correlation coefficients [45] and Gleichläufigkeit coefficients [46]. The quality of the dated series was checked using the COFECHA software (version 6.06P) [47]. Finally, the well-dated individual tree ring series were averaged for each tree (TRWt). ...
The mountain forests in Europe, especially the ecosystems dominated by Norway spruce [Picea abies (L.) Karst], are facing major challenges due to climate change. Climatic stress factors such as increased temperatures and drought contribute to reduced growth and increased mortality, especially at lower altitudes. In this study, which was conducted in the northern Velebit region, the growth dynamics and climate sensitivity of Norway spruce were analyzed using standard dendrochronological methods. The focus was on samples collected at altitudes between 1135 and 1545 m. The results show two different growth trends: a positive trend from 1950 to 1977, followed by a negative trend from 1977 to 2013. Precipitation proved to be a key factor for the stability of spruce growth, while the high summer temperatures of the previous year correlated negatively with growth increment. In addition, trees at higher altitudes showed greater resistance to climatic stress. These results underline the crucial role of precipitation and site-specific conditions in maintaining the vitality of spruce forests in mountainous regions, and suggest that climate change could further destabilize spruce ecosystems in the Dinaric Alps.
... We mounted increment cores and sanded them with increasing fine-grit sandpaper (80 grit-15 μm grit). We visually cross-dated (Speer, 2010) and measured cores to a 0.001-mm resolution using a Velmex measuring system (Velmex Inc.; Bloomfield, NY) and verified our dating using the COFECHA 6.06P program (Holmes, 1983). ...
Warming and more variable climates threaten to upend historical tree ranges, climatic sensitivity, and vigor. In western North America, the species Picea engelmannii var. engelmannii Parry ex Engelmann (Engelmann spruce) and Picea pungens Engelmann (Colorado blue spruce) are widespread spruce that act as foundational species in their montane to subalpine habitats. However, there is currently a lack of knowledge on P. pungens climatic responses, and how it differs from P. engelmannii. To address this gap, we assessed the climatic sensitivity and correlates of tree growth in a co‐occurring old‐growth stand of P. engelmannii and P. pungens, at high elevation in southern Utah, USA. We report the putative oldest cross‐dated P. pungens, with 457 rings, and sampled multiple P. pungens >400 years old. Both Picea populations had strongly positive growth responses to May–July precipitation and negative responses to maximum May–July temperature. Notably, October in the previous year had the strongest correlation with growth for both Picea species. Neither population exhibited signs of directional changes in climate–growth responses. Spectral analysis identified peaks associated with El Niño–Southern Oscillation at 3–4 years and quasi‐decadal oscillations (18–20 years) in both species. Cumulatively, our results highlight the growth–climate relationships of two frequently understudied subalpine tree species. In particular, P. pungens may warrant further study across its range and identification of other ancient populations.
... Individual series of TRW measured using the LINTAB 5 device and the TSAP program v.4.67 [30] were cross-dated, and the dating was checked in the COFECHA program v.6.06p [31]. Using the ARSTAN program v.41d [32], age trends described by a 67% spline and the autocorrelation component were removed from the original series to highlight high-frequency fluctuations (including the climate signal). ...
A joint analysis of dendrochronological and genomic data was performed to identify genetic mechanisms of adaptation and assess the adaptive genetic potential of Siberian stone pine (Pinus sibirica Du Tour) populations. The data obtained are necessary for predicting the effect of climate change and mitigating its negative consequences. Presented are the results of an association analysis of the variation of 84,853 genetic markers (single nucleotide polymorphisms—SNPs) obtained by double digest restriction-site associated DNA sequencing (ddRADseq) and 110 individual phenotypic traits, including dendrophenotypes based on the dynamics of tree-ring widths (TRWs) of 234 individual trees in six natural populations of Siberian stone pine, which have a history of extreme climatic stresses (e.g., droughts) and outbreaks of defoliators (e.g., pine sawfly [Neodiprion sertifer Geoff.]). The genetic structure of studied populations was relatively weak; samples are poorly differentiated and belong to genetically similar populations. Genotype–dendrophenotype associations were analyzed using three different approaches and corresponding models: General Linear Model (GLM), Bayesian Sparse Linear Mixed Model (BSLMM), and Bayesian-information and Linkage-disequilibrium Iteratively Nested Keyway (BLINK), respectively. Thirty SNPs were detected by at least two different approaches, and two SNPs by all three. In addition, three SNPs associated with mean values of recovery dendrophenotype (Rc) averaged across multiple years of climatic stresses were also found by all three methods. The sequences containing these SNPs were annotated using genome annotation of a very closely related species, whitebark pine (P. albicaulis Engelm.). We found that most of the SNPs with supposedly adaptive variation were located in intergenic regions. Three dendrophenotype-associated SNPs were located within the 10 Kbp regions and one in the intron of the genes encoding proteins that play a crucial role in ensuring the integrity of the plant’s genetic information, particularly under environmental stress conditions that can induce DNA damage. In addition, we found a correlation of individual heterozygosity with some dendrophenotypes. Heterosis was observed in most of these statistically significant cases; signs of homeostasis were also detected. Although most of the identified SNPs were not assigned to a particular gene, their high polymorphism and association with adaptive traits likely indicate high adaptive potential that can facilitate adaptation of Siberian stone pine populations to the climatic stresses and climate change.
... 9.8.1, Saltsjöbaden, Sweden) [23]. The visual crossdating was statistically checked using the COFECHA software, which calculates moving correlations between individual series of indexed ring-width values and the mean site series of each species [24]. The age at 1.3 m of sampled individuals was estimated by counting the number of rings along the two radii, from the bark to the pith, and keeping the maximum value. ...
Fires affect forest dynamics in seasonally dry regions such as the Mediterranean Basin. There, fire impacts on tree growth have been widely characterized in conifers, particularly pine species, but we lack information on broadleaf tree species that sprout after fires. We investigated post-fire radial growth responses in two coexisting Mediterranean hardwood species (the evergreen Quercus ilex, the deciduous Celtis australis) using tree-ring width data. We compared growth data from burnt and unburnt stands of each species subjected to similar climatic, soil and management conditions. We also calculated climate–growth relationships to assess if burnt stands were also negatively impacted by water shortage, which could hinder growth recovery. Tree-ring data of both species allowed us to quantify post-fire growth enhancements of +39.5% and +48.9% in Q. ilex and C. australis, respectively, one year after the fire. Dry spring climate conditions reduced growth, regardless of the fire impact, but high precipitation in the previous winter enhanced growth. High June radiation was negatively related to the growth of unburnt Q. ilex and burnt C. australis stands, respectively. Post-fire growth enhancement lasted for five years after the fire and it was a transitory effect because the growth rates of burnt and unburnt stands were similar afterwards.
... The ring widths on the transverse surfaces were measured using the VIAS TimeTable (model TT-60-O-100/5) with the precision to the nearest 0.01 mm. The computer program COFECHA was used for testing the crossdating quality of the ring-width measurements (Holmes, 1983;Grissino-Mayer, 2001). Treering series were standardized by fitting a linear or negative exponential regression equation. ...
Scots pine is geographically the most widespread pine species in the world, and it shows different growth responses to climate and environmental factors in diverse ecological sites. We studied both the stand dynamics and climate-growth relationships of scots pine in isolated coastal stand (recently found) in the Western Black Sea Region of Turkey. The homogeneity index of this stand has varied between 1.92–3.56. In growth-ring analyses, after cross-dating of individual chronologies, COFECHA and ARSTAN software were used respectively for chronology quality control and standardization (detrend). In this way, a 58-year-long chronology (1959-2016) of scots pine was constructed. In addition, DENDROCLIM software was used for investigating scots pine’s radial growth-climate relationships. Mean sensitivity changed from 0.163 to 0.331, with a mean of 0.183. Mean correlation among trees and signal to noise ratio were 0.389 and 7.012 respectively. In terms of the effect of precipitation on the radial growth of scots pine in this site, the correlation coefficients were 0.43 (p<0.05) for December of the previous year and 0.41 (p<0.05) for July of the current year. For all the other months, precipitation had a non-significant effect. As for the maximum and mean air temperature, the correlation coefficients were 0.36 (p<0.05) and 0.40 (p<0.05) for February, and 0.40 (p<0.05) and 0.42 (p<0.05) for March, respectively. However, on the radial growth, while the maximum temperature in August had a negative effect (r= -0.26; p<0.05), minimum temperatures in February, March and July had a positive effect (r= 0.39, 0.40 and 0.34 respectively; p<0.05).
... The precisely cross-dated samples were measured using LINTAB measuring machine with 0.01 mm resolution attached to a computer [49]. The quality control program COFECHA [50] was used to check the accuracy of dated samples. Program ARSTAN [51] was used to standardize raw ring-width measurement series and to remove non-climatic age growth effects. ...
The Himalayan cedar forests in the temperate regions of the Himalaya are crucial for providing ecosystem services such
as carbon storage and nutrient maintenance, playing a vital role in combating climate change. This study employs a
Dendrochronological approach to examine the impact of Himalayan cedar forest stands on soil properties across fve
distinct sites in the Kumaun Himalaya. Soil samples were collected from a depth of 0–15 cm and analyzed for total nitrogen (TN), total phosphorus (TP), soil organic carbon (SOC), pH, and C:N ratios. Tree-ring samples were also collected taken
from the same sites. Our analysis revealed a positive correlation between tree age and SOC content. Notably, the oldest
forests at Jageshwar Dham (480 years) and Hatkalika (413 years) exhibited the highest levels of SOC, TP, and TN, while
the youngest forests at Naudunga (135 years) and Patal Bhuwaneshwar (134 years) showed the lowest values. Signifcant
diferences in all soil parameters were confrmed through a Tukey post hoc test. Additionally, the relationship between
climate and tree growth was analyzed using tree-ring chronologies and meteorological records, indicating that cool and
moist spring conditions (February-May) enhance tree growth by increasing soil microbial activity. Our fndings emphasize
that conserving older natural forests, particularly mature Himalayan cedar forests, is crucial for maintaining soil characteristics, including carbon storage and nutrient levels, to support sustainable soil health and climate change mitigation.
... The tree-ring samples were firstly visually cross-dated under a microscope and then measured using a LINTAB measuring device (LINTAB™ 6; Rinntech) with a precision of 0.001 mm. To ensure the accuracy of cross-dating, the quality of the process was rigorously assessed using the COFECHA program (Holmes, 1983), guaranteeing that each ring was correctly assigned to its corresponding year of formation (Schweingruber, 1990). ...
Tree‐growth stability is crucial in upholding forest ecosystem services. Despite extensive research on the correlation between tree growth and climate, the influence of forest understorey on tree‐growth stability remains understudied.
We surveyed forest plots and collected tree‐ring samples along two elevational gradients, ranging from 3600 to 4400 m a.s.l., in the southeastern Tibetan Plateau. An index was developed to quantify individualistic growth stability of trees, and its linkage with the complexity of forest understorey structure was examined.
We found that tree‐growth stability is more pronounced in complex forest communities. In forests with higher understorey complexity, the proportion of trees experiencing growth release increased during wet years, while those with growth suppression augmented during dry years. Interestingly, a subset of trees exhibits abnormal growth increases even during the driest years, whereas another subset shows abnormal growth reductions during the wettest years. Furthermore, forests with more complex understorey structures exhibited a higher proportion of trees showcasing these two types of ‘anti‐phase’ growth statuses.
Synthesis. Our study underscores the linkage between individualistic growth stability of trees and the complexity of understorey structures. The growth stability of the overstorey layer is conveyed at the expense of individual‐level growth stability and synchrony in forests with complex understorey structures. These findings emphasize the necessity for attention to the interplay between tree growth and understorey community structures when assessing the impacts of future climate change on forest dynamics.
... 9.8.1, Saltsjöbaden, Sweden) [23]. The visual cross-dating was statistically checked using the COFECHA software, which calculates moving correlations between individual series of indexed ring-width values and the mean site series of each species [24]. The age at 1.3 m was estimated by counting the number of rings and by estimating the missing innermost rings (see [9]). ...
Pollarding has historically been used in broadleaf tree species across European woodlands. However, despite pollarding enhances vigor growth in the short term, it is still unclear how long this effect lasts and whether it can alleviate drought stress in seasonally dry regions. We compared the radial growth and wood δ13C (13C/12C), a proxy of intrinsic water-use efficiency (iWUE), of trees pollarded 10 and 20 years ago in two black poplar (Populus nigra L.) riparian stands located in North Eastern Spain and subjected to different ecohydrological conditions. We also assessed if pollarded trees showed different leaf phenology as compared with uncut trees of coexisting white poplar (Populus alba L.) trees. The relationships between growth, climate variables, drought severity and river flow were quantified. Pollarded and uncut trees showed a similar leaf phenology with a trend towards earlier leaf unfolding as springs become warmer. Pollarding increased growth rates by 54% (ratio between trees pollarded 10 and 20 years ago, respectively), but this enhancement was transitory and lasted ca. 10 years, whereas wood δ13C decreased −5%. The growth of black poplar increased in response to high precipitation in the previous winter, cool wet conditions, and a higher river flow in summer. Pollarding improves growth and relieves drought stress.
... In the laboratory, all core samples were fixed, air-dried, sanded, measured for width, and cross-dated according to the methods of Stokes ma Smiley-TL (1968) and others in the ITRDB. The crossdating results were corrected using the COFECHA program (Holmes, 1983), and any missing or false tree rings in the samples were corrected and quality controlled. Samples with low consistency with the main sequence were excluded. ...
Based on the need to protect previous ancient trees and the development of dendroclimatology, the use of non-destructive technologies in tree-ring research has gained increasing attention. This study focuses on the ancient Pinus tabulaeformis in Yu Xiang Forest Farm in Henan Province. Firstly, samples were collected using the traditional Increment borers and the Resistograph, a non-destructive method. Subsequently, the peak-valley analysis was used to filter the data obtained by the Resistograph to extract the tree ring width sequence, and the data’s accuracy was verified by correlation analysis with tree ring width sequence by the Increment borers. Then, the optimal filtering method and an appropriate comprehensive threshold were determined, and tree ring width and density sequences were successfully extracted. Following that, the growth trend and residual resistance in the measurement process were corrected using linear fitting and Ensemble Empirical Mode Decomposition (EEMD) technology, thereby establishing the tree-ring width and density index series, which were further validated through correlation analysis and t-tests. Finally, analysis of the correlation with climatic factors, identified the main limiting factors for tree growth, and the accuracy of the tree-ring information extracted by the Resistograph was further verified. The results showed that spite of certain differences between the tree-ring width indices extracted by the Resistograph and the Increment borer, they were generally reliable. The radial growth of the ancient P.tabulaeformis in Yu Xiang Forest Farm is primarily influenced by temperature, with the maximum density of the tree rings responding more significantly to the mean maximum temperature, while the minimum density of the tree rings responded more significantly to the mean minimum temperature. These results not only provide a scientific and accurate age for the protection of ancient trees and verify the reliability of the data obtained by the Resistograph, but also facilitate the use of non-destructive technology for in-depth study of ancient trees, therefore enhancing our understanding of how climate change affects tree growth and provide valuable insights for the future protection and management of these ancient trees.
... Tree-ring counts for Dahurian larch and Mongolian oak were measured using a LINTAB 5.0 system (RINNTECH, Heidelberg, Germany). The dating of tree-rings was performed and corrected using COFECHA software [ 48 ]. The average tree-ring counts for the eight larch trees in each plot were used to estimate stand age. ...
... All trees were crossdated using anatomical features, long-term growth patterns, and statistical verification. Crossdating accuracy was quantitatively assessed using COFECHA (Holmes, 1983;Grissino-Mayer, 2001). Crossdated ring widths for J o u r n a l P r e -p r o o f the same tree (two cores per tree) were averaged for each calendar year. ...
Climate warming can alleviate temperature and nutrient constraints on tree growth in boreal regions, potentially enhancing boreal productivity. However, in permafrost environments, warming also disrupts the physical foundation on which trees grow, leading to leaning trees or “drunken” forests. Tree leaning might reduce radial growth, undermining potential benefits of warming. Here, we found widespread radial growth reductions in southern latitude boreal forests since the 1980s. At mid latitudes, radial growth increased from ~1980 to ~2000 but showed recent signs of decline afterward. Increased growth was evident since the 1980 s at higher latitudes, where radial growth appears to be temperature limited. However, recent changes in permafrost stability, and the associated increased frequency of tree leaning events, emerged as a significant stressor, leading to reduced radial growth in boreal trees at the highest latitudes, where permafrost is extensive. We showed that trees growing in unstable permafrost sites allocated more nonstructural carbohydrate reserves to offset leaning which compromised radial growth and potential carbon uptake benefits of warming. This higher allocation of resources in drunken trees is needed to build the high-density reaction wood, rich in lignin, that is required to maintain a vertical position. With continued climate warming, we anticipate widespread reductions in radial growth in boreal forests, leading to lower carbon sequestration. These findings enhance our understanding of how climate warming and indirect effects, such as ground instability caused by warming permafrost, will affect boreal forest productivity in the future.
Annual tree rings are widely recognized as valuable tools for quantifying and reconstructing historical forest disturbances. However, the influence of climate can complicate the detection of disturbance signals, leading to limited accuracy in existing methods. In this study, we propose a random under-sampling boosting (RUB) classifier that integrates both tree-ring and climate variables to enhance the detection of forest insect outbreaks. The study focused on 32 sites in Alberta, Canada, which documented insect outbreaks from 1939 to 2010. Through thorough feature engineering, model development, and tenfold cross-validation, multiple machine learning (ML) models were constructed. These models used ring width indices (RWIs) and climate variables within an 11-year window as input features, with outbreak and non-outbreak occurrences as the corresponding output variables. Our results reveal that the RUB model consistently demonstrated superior overall performance and stability, with an accuracy of 88.1%, which surpassed that of the other ML models. In addition, the relative importance of the feature variables followed the order RWIs > mean maximum temperature (Tmax) from May to July > mean total precipitation (Pmean) in July > mean minimum temperature (Tmin) in October. More importantly, the dfoliatR (an R package for detecting insect defoliation) and curve intervention detection methods were inferior to the RUB model. Our findings underscore that integrating tree-ring width and climate variables as predictors in machine learning offers a promising avenue for enhancing the accuracy of detecting forest insect outbreaks.
Minimum temperatures have remarkable impacts on tree growth at high-elevation sites on the Tibetan Plateau, but the shortage of long-term and high-resolution paleoclimate records inhibits understanding of recent minimum temperature anomalies. In this study, a warm season (April–September) reconstruction is presented for the past 467 years (1550–2016) based on Sabina tibetica ring-width chronology on the Lianbaoyeze Mountain of the central eastern Tibetan Plateau. Eight warm periods and eight cold periods were identified. Long-term minimum temperature variations revealed a high degree of coherence with nearby reconstructions. Spatial correlations between our reconstruction and global sea surface temperatures suggest that warm season minimum temperature anomalies in the central eastern Tibetan Plateau were strongly influenced by large-scale ocean atmospheric circulations, such as the El Niño-Southern Oscillation and the Atlantic Multidecadal Oscillation.
Although creep is a relatively slow slope movement, it can precede catastrophic events, and therefore information on its past occurrence is crucial to assessing the extent of natural hazards. Dendrogeomorphic methods are very effective tools for analyzing different types of slope processes, but their use in creep studies is still very limited. In doing so, it can be a unique source of information that cannot be ascertained in any other way. Thus, this study focused on validating the potential of tree-ring-based methods in the analysis of spatio-temporal creep activity. For the research, 420 tree-ring series from 210 individuals of common spruce (Picea abies (L.) Karst.) evenly distributed on the study slope were analyzed. The methodological apparatus used had to be adapted to the needs of the specific behavior of creep compared to other types of slope processes. These included the determination of a high minimum number of trees defining the relevant part of the chronology, specific sampling, or the absence of a threshold value for the event-response index. This resulted in two chronologies, the first of which was constructed from average annual values of tree-ring eccentricity and characterized a rather continuous creep that showed signs of a steady decline in its activity. The second chronology was constructed from the occurrence of compression wood and abrupt growth suppression, i.e., growth responses following major slope movements. This chronology reflected more of an acceleration phase of seasonal creep. The spatial reconstruction of creep showed high variability of tree-ring-based signals with no tendency to cluster. This study not only provided new insights into the possibility of using dendrogeomorphic analysis in creep research but also indicated a further direction in this field, which may include in particular the analysis of age-dependency of P. abies to form asymmetric growth or the effect of tree size on local acceleration of creep.
Recent changes in climate have triggered widespread mortality events in oak forests worldwide. Despite the ecological importance of these ecosystems, limited information exists on the long-term resilience of oak forests in response to extreme climate events. Quercus canariensis , a semi-deciduous oak sensitive to summer drought characteristic of the Mediterranean climate, is currently showing defoliation and mortality episodes in the drier areas of its natural range. Here, we investigated the long-term impacts of climate on the radial growth of Q. canariensis and assessed changes in resilience to extreme droughts across eight populations in S Spain following an environmental gradient. We observed a clear latitudinal gradient in growth performance, as reflected by resilience indices across populations. Since 1970, Q. canariensis has shown a marked decline in resilience to extreme drought events at the wettest region, resulting in a diminished capacity to recover pre-drought growth levels. This trend has preceded growth declines in certain populations, suggesting increased vulnerability to the increasing frequency of extreme climatic events. Through growth analyses, we identified early-warning signals of forest decline in this Mediterranean oak species, highlighting the most sensitive populations and its high susceptibility to extreme droughts impacts.
Against the background of climate warming and humidification, the so-called ‘divergence problem’ reduces the stability of tree rings in response to climate, and affects the reliability of tree-ring reconstruction. Investigation of the divergence problem is crucial to improve our understanding of the response patterns of trees to climate warming, and provide a scientific basis for accurate climate reconstruction. Based on tree-ring width data for Siberian larch (Larix sibirica Ledeb.) growing at low elevations in the eastern Altay Mountains, we analyzed the relationship between radial growth of trees and climatic factors in the context of abrupt climate change in this region. We calculated the proportional contribution of five climatic factors to the radial growth of trees, and discussed the response mechanism of radial growth of L. sibirica in combination with large-scale atmospheric circulation patterns. The radial growth of L. sibirica was mainly constrained by water availability. Before climate warming (1961–1990), the radial growth of L. sibirica was mainly limited by temperature in the previous June. After abrupt climate warming (1991–2020), there was a significant positive correlation between growth and soil moisture in the previous winter, suggesting that high temperatures in the following spring would limit tree radial growth if water availability was low. The attribution analysis results revealed that, before 1990, the proportional of relative contribution of temperature to radial growth of trees exceeded 60%. Since 1990, the proportional of relative contribution of water (precipitation and volumetric soil water) to growth of L. sibirica increased. This might reflect the combined effects of local climatic conditions and changes in large-scale atmospheric circulation.
Detection of early warning signals (EWSs) for forest declines is a critical yet challenging in forest ecology and management. Although the EWSs have been investigated from the perspective of external stresses, changes in tree resistance in stresses before forest declines have received much less attention. In this study, we utilized tree ring-width data from 346 juniper trees in the Qilian Mountains to calculate tree resistance in stresses during non-decline period of forest and to explore the temporal relationships between the occurrence of forest declines and changes in resistance of trees. The forest declines, characterized by sustained slow growth rates, were identified independently. The results showed that, there was a decrease in tree resistance during the 12 years before forest declines. This phenomenon was particularly common at the study sites. Resistance of trees before forest declines was positively correlated with tree growth during forest declines, which implying that lower pre-decline resistance was associated with more severe forest decline. These observations suggest that decreasing resistance can be used as an EWS of forest declines. Our results provide insights into the relationships between changes in ecological resilience and forest stability and are useful for monitoring or predicting changes in forest health under future climate change.
Doğal afetler, süreç içerisinde belirli aralıklarla tekrarlayan hareketlerdir. Doğal
tehlikelerin gerçekleşme sıklığı, hareket zamanı ve büyüklüğünün doğru
tanımlanabilmesi için bu tehlikelerin paleoçevresel ortam koşullarında gelişim
süreçlerinin incelenmesi ve ortaya çıkan bulguların analiz edilmesi gerekmektedir.
Tez çalışmasının konu kapsamını dendrokronolojinin bir alt dalı olan
dendrojeomorfoloji oluşturmaktadır. Yapılan bu çalışmayla doğal afet araştırmalarında kullanılan yöntemlerden biri olan dendrojeomorfolojinin coğrafya bilim literatürüne katkı vermesi amaçlanmıştır. Araştırmada yöntem olarak betimsel tarama modeli kullanılmıştır. Araştırmanın içeriğini dendrokronolojinin ve dendrojeomorfolojinin tarihsel gelişimi, prensipleri, uygulama alanları ve yöntemleri hakkında bilgiler oluşturmaktadır. Bu çalışmayla dendrojeomorfoloji alanında yapılmış güncel araştırmalara yer verilerek doğal afet araştırmalarında kullanımı değerlendirilmiştir. Tezin beklentisi araştırmacılara dendrojeomorfoloji konusunda hazırlanmış ve uygulama örneklerini içeren bilgilerin yer aldığı temel düzeyde toplu bir kaynak oluşturmasıdır. //
Natural disasters are prcesses of repetitive movements at regular intervals. In
order to accurately identify the frequency, time and magnitude of the occurrence of
natural hazards, the developmental processes of these hazards in paleoenvironmental conditions need to be examined and analyzed the findings of result. The subject of the thesis is dendrogeomorphology which is a sub-branch of
dendrochronology. In this study, dendrogeomorphology, which is one of the methods used in natural disaster research, is aimed to contribute to geography science literature. Descriptive scanning model was used as the method in the research.
The content of the research consists of information about the historical
development, principles, application areas and methods of dendrochronology and
dendrogeomorphology. In this study, current researches in the field of
dendrogeomorphology have been evaluated and their use in natural disaster researches
has been evaluated. The expectation of the thesis is to provide the researchers with a
basic level of information on dendrogeomorphology, which includes the application
examples.
Hydrologic stress is increasing in Fremont cottonwood ( Populus fremontii ) forests across the southwestern United States because of increased temperature and streamflow diversion. The spatial variability of this stress is large yet poorly understood. Along the Yampa and Green Rivers in Colorado and Utah, vapour pressure deficit and flow diversions increase downstream. To investigate effects of this gradient on cottonwoods, we measured the percent live canopy and height of randomly selected trees at three sites: Deerlodge Park on the Yampa River (DLP), Island Park on the upper Green (ILP) and Canyonlands National Park on the lower Green (CAN). From these same trees, we took increment cores to understand differences in tree growth in each forest over time. We then related tree metrics to local water availability, streamflow and climatic data. Cottonwoods at CAN were shorter and had lower percent live canopy and growth rate than similarly aged trees upstream. CAN trees that grew higher above the water surface also tended to have lower tree growth, height and live canopy percentage. Furthermore, the correlation between tree growth and maximum vapour pressure deficit showed a much stronger negative shift since 1990 at CAN than at the other sites. All of these differences suggest higher hydrologic stress at CAN, which we attribute to the combined effects of peak flow declines from Flaming Gorge Reservoir, flow diversion and the higher and increasing vapour pressure deficit at CAN. Further research on the variability of hydrologic stress on cottonwoods could help managers anticipate and mitigate the effects of drought stress in these iconic forests.
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