Coastal dunes near the Baltic Sea are often stabilized by Scots pine forests and are characterized by a mild climate. These ecosystems are affected by water shortages and might be influenced by ...climate extremes. Considering future climate change, utilizing tree rings could help assess the role of climate extremes on coastal forest growth. We used superposed epoch analysis to study Scots pine responses to droughts and cold winters, with focus on frequency, timing, and duration. We measured ring widths (RW) and latewood blue intensity (LBI) on samples extracted from trees growing at dune ridge and bottom microsites at the south Baltic Sea. At the regional scale, we observed some similarities in tree responses to both extremes between RW and LBI within the same microsite type and region. At the local scale, RW and LBI were more frequently influenced by cold winters than droughts. RW and LBI from dune ridges were more frequently influenced by droughts than RW and LBI from dune bottoms. LBI from both microsites was more often influenced by droughts than RW. RW and LBI from both microsites were similarly often influenced by cold winters. At both scales, the response time of RW and LBI after droughts predominantly lagged by one year, while cold winters were recorded in the same year. The typical duration of growth reductions after both extremes was one year for both RW and LBI. Our study indicates that Scots pine from the Baltic Sea region is sensitive to climate extremes, especially cold winters.
Coastal sand dunes near the Baltic Sea are a dynamic environment marking the boundary between land and sea and oftentimes covered by Scots pine (Pinus sylvestris L.) forests. Complex ...climate-environmental interactions characterize these ecosystems and largely determine the productivity and state of these coastal forests. In the face of future climate change, understanding interactions between coastal tree growth and climate variability is important to promote sustainable coastal forests. In this study, we assessed the effect of microsite conditions on tree growth and the temporal and spatial variability of the relationship between climate and Scots pine growth at nine coastal sand dune sites located around the south Baltic Sea. At each site, we studied the growth of Scots pine growing at microsites located at the ridge and bottom of a dune and built a network of 18 ring-width and 18 latewood blue intensity chronologies. Across this network, we found that microsite has a minor influence on ring-width variability, basal area increment, latewood blue intensity, and climate sensitivity. However, at the local scale, microsite effects turned out to be important for growth and climate sensitivity at some sites. Correlation analysis indicated that the strength and direction of climate-growth responses for the ring-width and blue intensity chronologies were similar for climate variables over the 1903–2016 period. A strong and positive relationship between ring-width and latewood blue intensity chronologies with winter-spring temperature was detected at local and regional scales. We identified a relatively strong, positive influence of winter-spring/summer moisture availability on both tree-ring proxies. When climate-growth responses between two intervals (1903–1959, 1960–2016) were compared, the strength of growth responses to temperature and moisture availability for both proxies varied. More specifically, for the ring-width network, we identified decreasing temperature-growth responses, which is in contrast to the latewood blue intensity network, where we documented decreasing and increasing temperature-growth relationships in the north and south respectively. We conclude that coastal Scots pine forests are primarily limited by winter-spring temperature and winter-spring/summer drought despite differing microsite conditions. We detected some spatial and temporal variability in climate-growth relationships that warrant further investigation.
The role of future forests in global biogeochemical cycles will depend on how different tree species respond to climate. Interpreting the response of forest growth to climate change requires an ...understanding of the temporal and spatial patterns of seasonal climatic influences on the growth of common tree species. We constructed a new network of 310 tree‐ring width chronologies from three common tree species (Quercus robur, Pinus sylvestris and Fagus sylvatica) collected for different ecological, management and climate purposes in the south Baltic Sea region at the border of three bioclimatic zones (temperate continental, oceanic, southern boreal). The major climate factors (temperature, precipitation, drought) affecting tree growth at monthly and seasonal scales were identified. Our analysis documents that 20th century Scots pine and deciduous species growth is generally controlled by different climate parameters, and that summer moisture availability is increasingly important for the growth of deciduous species examined. We report changes in the influence of winter climate variables over the last decades, where a decreasing influence of late winter temperature on deciduous tree growth and an increasing influence of winter temperature on Scots pine growth was found. By comparing climate–growth responses for the 1943–1972 and 1973–2002 periods and characterizing site‐level growth response stability, a descriptive application of spatial segregation analysis distinguished sites with stable responses to dominant climate parameters (northeast of the study region), and sites that collectively showed unstable responses to winter climate (southeast of the study region). The findings presented here highlight the temporally unstable and nonuniform responses of tree growth to climate variability, and that there are geographical coherent regions where these changes are similar. Considering continued climate change in the future, our results provide important regional perspectives on recent broad‐scale climate–growth relationships for trees across the temperate to boreal forest transition around the south Baltic Sea.
A tree‐ring network from European beech, Scots pine and oak trees from around the south Baltic Sea was compiled to examine the relationship between tree growth and climate. Our findings indicate tree growth is influenced by warming winter climate and summer moisture availability in northern temperate forests. Furthermore, spatial analysis suggests that there are geographical patterns in similar growth responses to climate and that these responses can be unstable through time.
Growth divergence – i.e. the expression of divergent growth trends of neighboring trees – has certain implications for dendrochronological research, for instance in the context of climate ...reconstructions but also in terms of estimating net ecosystem productivity. Thus, understanding the underlying mechanisms is essential to extend our fundamental dendroecological knowledge. In this context, the Picea genus plays an important role since several of its species were reported to exhibit growth divergence. Here, we investigate a well sampled Norway spruce (Picea abies (L.) Karst) data set for growth divergence comprising ring-width and Blue Intensity measurements from seven sites on Babia Góra Mountain, at the border between Poland and Slovakia. By means of Principal Component Gradient Analysis, inter-series correlations, and climate growth relationships, we are able to show that I) Norway spruce on Babia Góra expressed growth divergence since the 1970s, II) the definition of groups increased the strength of population signals and the stability of climate-growth relationships, and III) Blue Intensity appeared as a more robust proxy for environmental conditions. We discuss soil heterogeneity, genetics, and air pollution as possible underlying mechanisms, thereby indicating further research avenues to obtain a better understanding of growth divergence.
Compression wood is a common tissue present in the trunk, branches and roots of mechanically stressed coniferous trees. Its main role is to increase the mechanical strength and regain the vertical ...orientation of a leaning stem. Compression wood is thought to influence the climate signal in different tree-ring measures. Hence trees containing compression wood are mostly excluded from tree-ring studies reconstructing past climate variability. There is a large gap of systematic work testing the potential effect of compression wood on the strength of the climate signal in different tree-ring parameters, especially stable isotope records. Here we test for the first time the effect of compression wood contained in montane Norway spruce (Picea abies L. Karst) on both δ13C and δ18O tree-ring cellulose records by analyzing compression and opposite wood radii from several disturbed trees together with samples from undisturbed reference trees. We selected four trees tilted by geomorphic processes that were felled by wind, and four undisturbed reference trees in the Tatra Mountains, Poland. We qualitatively classified the strength of compression wood using wood cell anatomical characteristics (tracheid shape, cell wall thickness and presence of intercellular spaces). Then we developed tree-ring width, δ13C and δ18O chronologies from the compression wood radii, the opposite radii of the tilted trees, and from the reference radii. We tested the effect of compression wood on tree-ring cellulose δ13C and δ18O variability and on the climate signal strength. We found only minor differences in the means of δ13C and δ18O compression (δ13C -22.81‰, δ18O: 28.29‰), opposite (δ13C -23.02‰; δ18O: 28.05‰) and reference (δ13C: -22.78‰; δ18O: 27.61‰) radii. The statistical relationships between climate variables, δ13C and δ18O remained consistent among all chronologies. Our findings suggest that moderately tilted trees containing compression wood can be used to reconstruct past geomorphic activity, and for stable-isotope based dendroclimatology.
Annually resolved and absolutely dated Maximum Latewood Density (MXD) and Blue Intensity (BI) measurements are frequently used for reconstructing summer temperature variability over the last ...centuries to millennia. A direct comparison of the outcome of both methods using similar material is needed due to how quickly this method is being adopted. The application of slightly different measuring systems (hardware) and analysis tools (software) in tandem with different wood samples and preparation procedures further challenges any straightforward assessment. Here we process 26 Norway spruce samples from the upper timberline in the Polish Tatra Mountains with the six most frequently used MXD and BI applications. Although offset is found in the raw MXD and BI data (0.04–0.13 g/cm3 and 0.45–1.58 dimensionless blue intensity), interannual and longer-term fluctuations are significantly (p < 0.01) positively correlated between all MXD and BI time-series. Our results emphasize the potential of faster and cheaper, as well as overall more user-friendly techniques to generate reliable MXD surrogates for high-frequency dendroclimatological studies. Although the correlations between MXD and BI were lower than within MXD and BI, the results of growth-climate response performed for both proxies show only marginal differences. The obtained level-offset further questions the suitability of joining different density surrogates for developing long-term composite chronologies to reconstruct low-frequency climate variability.
Himalayan treelines are exposed to above average climate change impact, resulting in complex tree growth–climate relationships for Himalayan Silver Fir (Abies spectabilis (D. Don) Spach) at central ...Himalayan treelines. The majority of recent studies detected current tree growth sensitivity to dry conditions during pre-monsoon seasons. The aim of this study was to analyze growth–climate relationships for more than a century for a treeline ecotone in east-central Nepal and to test for Blue Intensity (BI; used as a surrogate of maximum late wood density) as climate proxy. We determined the relationships of Abies spectabilis radial tree growth and BI to climate by correlating both to temperature, precipitation and drought index data. The results showed a significantly unstable dendroclimatic signal over time. Climate warming-induced moisture deficits during pre-monsoon seasons became a major factor limiting radial tree growth during recent decades. Earlier in time, the dendroclimatic signal was weaker, predominantly reflecting a positive relationship of tree growth and summer temperature. Compared to radial tree growth, BI showed a different but strong climate signal. Temporally unstable correlations may be attributed to increasing effects of above-average rates of climate warming. An extended network of Himalayan tree-ring sites is needed to further analyze cause–effect relationships and to solve this attribution problem.
Floods represent a common process in Tatra Mountain streams and may cause flood risk in the valleys of the Tatra foreland. Dealing with the hazards and risks caused by floods requires a detailed ...analysis of the frequency and magnitude of past and recent events. However, the Polish Tatra region is characterized by a scarcity of data on past floods in general and on systematic peak discharge in particular. In this study, we performed a paleohydrological analyses in four high-gradient mountain streams using scarred trees as paleostage indicators. We couple two-dimensional hydraulic modelling in a highly-resolved topographic environment (LiDAR data) with an important spatiotemporal data set of scars on trees to investigate (i) the magnitude of unrecorded major floods of the twentieth century, (ii) the effect of variability in geomorphic tree positions on the peak discharge reconstruction, and (iii) the impact of reconstructed events on the results of flood frequency analyses. The data set is based on a total of 55 scarred trees and allows peak discharge reconstruction of 16 major floods covering the last 113years. Results suggest that trees growing in straight stream reaches or in the inner side of channel bends would be better candidates for peak discharge reconstructions than trees located on the outer side of channel bends or growing in overbank sections with dense vegetation cover. The largest reconstructed flood is dated to 1903 with an estimated peak discharge of 115.9±59.2m3s−1, and larger-than-today floods are found to have occurred at Strążyska and Łysa Polana in the first half of the twentieth century. The inclusion of our results into the flood frequency analyses suggests that flood hazards might have been underestimated by up to 25.5% in the case of a 100-year flood in Strążyski Stream. In that sense, our findings will be useful for the design of future strategies dealing with flood risks in the foreland of the Polish Tatra Mountains.
•In mountain streams, the scarcity of records hampers the analysis of flood process.•Paleohydrology allows us to estimate peak discharges of past flood events.•We reconstructed past flood events in four streams in the Tatra Mountains.•Larger events have been reconstructed for the first half of the twentieth century.•Our results have implications for flood hazard analysis in the region.
At a global scale, heat deficits during the growing season result in growth limitations, which determine the elevation of natural alpine treelines. Thus, the expected response to global warming is a ...treeline advance to higher elevations. However, empirical studies of diverse mountain ranges have yielded evidence of both advancing alpine treelines as well as rather insignificant responses. Based on an extensive collection of field data, we analysed population structures and regeneration patterns, investigated population density-environment relationships and correlated tree growth with climate in order to assess the sensitivity to climate warming of a near-natural treeline ecotone in east-central Nepal. The presence of an elevational zone dominated by a gnarled growth form of Rhododendron campanulatum physiognomically classifies the treeline as a krummholz treeline. The fraction of juvenile tree individuals reflects prolific regeneration and stand densification. The species-specific variation in adult and juvenile stand density along the treeline ecotone depends not only on temperature but also on soil, topographic, and other microclimatic conditions. Rhododendron campanulatum shows highest competitiveness in the krummholz belt under a constellation of site conditions influenced by this species itself. By contrast, Abies spectabilis (Himalayan Silver Fir) and Betula utilis (Himalayan Birch) have gained predominance under warmer and more nutrient-rich habitat conditions in the closed forest below. The dense krummholz belt effectively controls the potential upslope migration of subalpine forest tree species. Abies spectabilis growth-climate correlations show changing growth limitations in the course of the 20th century, most likely due to intensified climate warming in recent decades, when decreasing moisture availability during the pre-monsoon season has affected Abies spectabilis' radial growth. It is evident from our results that to date the treeline has responded to climate warming in terms of stand densities, seed-based regeneration and growth patterns of trees, the treeline position, however, is rather stable. A treeline shift is to be expected in the mid- to long-term only.
Global betrachtet führt Wärmemangel während der Vegetationsperiode zu Wachstumsbeschränkungen, die die Höhenlage der natürlichen alpinen Waldgrenze bestimmen. Es wird generell angenommen, dass sich alpine Waldgrenzen infolge des Klimawandels in höhere Lagen verschieben. Empirische Untersuchungen in verschiedenen Gebirgszügen haben jedoch Hinweise sowohl auf einen Anstieg alpiner Waldgrenzen als auch auf die Persistenz dieser Höhengrenzen ergeben. Basierend auf umfangreichem Datenmaterial zu Vegetations- und Umweltvariablen konnten Populationsstrukturen und Verjüngungsmuster erfasst, Zusammenhänge zwischen Populationsdichten und Standortfaktoren untersucht und Korrelationen zwischen Baumwachstum und Klima ermittelt werden, um die Empfindlichkeit eines naturnahen Waldgrenzökotons im östlichen Zentral-Nepal gegenüber der Klimaerwärmung zu beurteilen. Aufgrund der Ausbildung einer Höhenstufe, die von Rhododendron campanulatum mit einer krummholzartigen Wuchsform dominiert wird, lässt sich das Ökoton physiognomisch einer Waldgrenze mit einem vorgelagerten Krummholzgürtel zuordnen. Der Jungwuchs aller Arten zeigt eine intensive Verjüngung und Verdichtung der Bestände. Die Variation der Bestandesdichte adulter und juveniler Populations-Kohorten entlang des Höhengradienten hängt in artspezifisch unterschiedlichem Ausmaß nicht nur von der Temperatur, sondern auch von Bodeneigenschaften, topographischen und anderen mikroklimatischen Bedingungen ab. Rhododendron campanulatum weist aufgrund von Standortbedingungen, die von dieser Art selbst stark beeinflusst werden, die höchste Konkurrenzfähigkeit im Krummholzgürtel auf. Auf wärmeren und nährstoffreicheren Standorten des unterhalb gelegenen geschlossenen Waldes dominieren dagegen Abies spectabilis (Himalaya-Tanne) und Betula utilis (Himalaya-Birke). Der dichte Krummholzgürtel verhindert weitgehend die zu erwartende hangaufwärtsgerichtete Wanderung von subalpinen Baumarten. Wachstums-Klima-Korrelationen von Abies spectabilis zeigen im 20. Jahrhundert einen Wechsel der das Wachstum limitierenden klimatischen Einflüsse, was höchstwahrscheinlich auf eine verstärkte Klimaerwärmung in den vergangenen Dekaden zurückzuführen ist. In diesem Zeitraum hat die zunehmende Trockenheit während der Vormonsunsaison das radiale Wachstum von Abies spectabilis begrenzt. Die Ergebnisse zeigen insgesamt, dass die Waldgrenze auf die Klimaerwärmung im Hinblick auf Bestandsdichte, generativer Verjüngung und Zuwachsmuster der Bäume reagiert, dass die Höhenlage der Waldgrenze jedoch relativ stabil ist. Ein Vorrücken der Waldgrenze ist erst in mittel- bis langfristigen Zeiträumen zu erwarten.
The snow avalanche is one of the major processes that shapes the landscape of high mountains. A significant manifestation of its activity is changing the course of the timberline, whose course and ...growth disturbances constitute a good source of information about the history of avalanche activity. The aim of this study was to: i) detail the temporal and spatial reconstruction of snow avalanche events within the three surveyed couloirs in the Rybi Potok Valley, in the High Tatras, ii) analyse of the relationship between the relief of the runout zoneand the course of the avalanches. Dendrogeomorphological, geomorphological and cartographic methods were employed here. Detailed geomorphological maps comprising the runout zone were prepared and use to divide the runout zone into subzones of similar relief. The dendrogeomorphological reconstructions of avalanche events were carried out on two scales, i.e. for the entire runout zone and for the determined subzones. The courses of major avalanche events in the studied couloirs over the past 100 years were reconstructed. A detailed dendrogeomorphological analysis in the subzones allowed the identification of additional local avalanche events whose extent had not covered the entire avalanche path.web URL: https://www.geographiapolonica.pl/article/item/10462.html
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