Dendrochronological Records of Debris Flow and Avalanche Activity in a Mid-Mountain Forest Zone (Eastern Sudetes — Central Europe)
Dendrochronological methods were used to determine the frequency of debris flow/avalanche events in a forest zone. A debris flow and avalanche track located in the Eastern Sudetes Mountains (Central Europe) was analysed. The length of the youngest debris flow/avalanche track is about 750 m. Three distinct sections of the debris flow can be identified along the longitudinal section: niche, gully and tongue. The dendrochronological study shows that trees started growing on the margins of the debris flow between 1908 and 1963. Hence, debris flow and/or avalanche events occurred on this slope at the turn of the 19th and 20th centuries. All trees collected from the tongue started growing between 1935 and 1964. However, a large debris flow event took place several years before, most probably during an extraordinary rainfall in June 1921. Following this event, several relatively large debris flows have occurred during the growing season, the strongest dendrochronologically confirmed events occurring in 1968, 1971-1972, 1991, 1997 and probably in 1977. Spring debris flow events induced by snow melt and/or avalanches have occurred in 1994 and 2004. The results suggest that with favourable geological conditions, debris flows can occur very frequently within entirely forested slopes.
Dendrochronological methods can be applied to the reconstruction of different types of environmental events such as climate changes, fires, glacier movements, floods, earthquakes, volcano activity. In the field of geomorphology dendrochronology is increasingly frequently used for the absolute dating of different types of mass-movements (rock falls, landslides and debris flows, etc.). Trees growing on slopes transformed by mass-movements are tilted and wounded while their stems and root systems are exposed or buried under sediment. These events are recorded in wood anatomy as eccentric growth, reaction wood, scar overgrowth by callous tissue, changes in cell size or adventitious root production. Dating changes in wood anatomy allows to date and precisely reconstruct the spatial and temporal occurrence of mass-movements with at least one year resolution. The paper provides a review of existing dendrochronological tools used in geomorphology and also an example of the application of eccentric tree-growth to reconstruct landsliding. Using tree-ring eccentricity allows to (1) obtain a dynamic depiction of slopes, (2) study landslide activity, not only contemporary, but also in the last tens of hundreds of years (depending on the stand age).
The study was conducted in two small municipalities in Małopolskie voivodeship in Southern Poland. Both municipalities are located in mountain basins in the Western Beskids mountain range.Cores were taken from trees growing near the centre of Rabka-Zdrój and Sucha Beskidzka in order to analyse the impact of contemporary air pollution on the health of tree stands. Annual tree rings developed during the era of high atmospheric pollution are usually narrower than the others. These municipalities were chosen due to their current air pollution problems despite their relatively small population.Local chronology, skeleton plots and calculated ring reductions were created for the sample trees. Temporal relationships between air pollution and a negative health reaction in trees and in people were also examined. To fulfil this objective the dates of occurrence of tree-ring reductions were compared with the concentration of particulates (PM10) in the atmosphere and also lung disease morbidity in the local population. Two periods of reduced annual tree rings were detected: first from the 1960s to the end of the 1980s (associated with industrial pollution) and more recently the years since 2003. Since 2003 reductions of annual tree rings have increased in parallel with increases in dust pollution. This reaction of trees to dust pollution was immediate. The negative reaction of trees preceded several years of increasing lung disease morbidity. This gives basic evidence to support the argument that tree ring reductions could be used as an early bioindicator for warning against the risk of air pollution. The aim of this work was to determine the periods of reduction in the annual growth of spruce growing near the centre of Rabka-Zdrój and Sucha Beskidzka. In addition, potential associations were sought between the time of occurrence of these periods and changes in air pollution and human disease.
The aim of this study was to present the use of the natural elements of the relief of river valleys such as changes in the width of the valley bottom, landforms occurring in the bottom of the valley, differences in height of the valley terraces as favourable for the location of the dam partitioning the bottom of the valley and creating a water reservoir for the requirements of historic metallurgical centres. The research was carried out based on DEM analysis from LiDAR data. Features were chosen in river basins with a rich metallurgical legacy. Analysis of the location of the former ironworks was carried out using Surfer 12 software. Five centres were selected due to the fact that only these are the only centres suitable for research which have survived to this day. Using the shaded relief models and contour coloured maps absolute differences in height between valley levels and other forms of relief occurring in the valley were analyzed, as well as the distribution of individual terrain forms in the designated part of the valley and changes in the width of the valley bottom were analysed in the context of the location of former metallurgical centres. On the basis of the contours of the former water reservoir visible in the valley relief, and using a surface area measurement tool (Surfer software), the range of the area that the reservoir could cover was measured. On the basis of the results obtained, it can be seen that convenient geomorphological conditions were used for the placement of selected weirs and metallurgical ponds which facilitated the damming of the valley. Natural narrowing of the valley bottom, or dunes and hills directly adjacent to the valley floor, were utilised during the construction of the dam. The rivers on which the furnace ponds were constructed are relatively small watercourses, so the weirs created by the constructors are not impressive. Their height is generally in the range of about 2 to 3 metres and their length is from about 120 to 300 metres. Nevertheless, they were effective in allowing sufficient water retention and the creation of furnace ponds with a measured area of about 4.5 ha to about 25 ha.
The aim of our study was to compare patterns of tree-ring eccentricity developed in Norway spruce trees as a result of landsliding with the one caused by the prevailing wind (in 2 study sites), and with the normal growth of trees (in 2 reference sites). We sampled 20 trees per study site and 10 per reference site. Two cores were taken from each tree (120 cores in total) from the upslope and downslope, windward and leeward sides of stems. Ring widths measured on opposite sides of stems were compared using the method of percent eccentricity index. Graphs of the index obtained for individual trees were analysed. Statistical indicators were calculated for a percent eccentricity index. Disturbance events were dated and the response index was calculated. The results show that the patterns of eccentricity developed as a result of the prevailing winds and due to landsliding differ from one another and from the reference sites. The results suggest that the impact of the prevailing wind on tree growth is more severe than the impact of landsliding. The difference may result from the slow-moving character of the landslide under study. The results, however, indicate that wind impact should be taken into account in dendrogeomorphic research and that the impact of mass movements should be considered in dendroecological studies on wind.
Charcoal was the primary fuel used for iron smelting and processing until the end of the 19th century. It was produced through burning piles of wood called charcoal kilns. The aim of the study was to identify and record traces of charcoal kilns related to past ironworks in the valley of the River Czarna (Małopolska Upland, Central Poland). Detailed analysis was conducted in areas adjacent to historical centres of iron processing in Maleniec, Kołoniec and Machory. A quantitative analysis of the traces of charcoal kilns in the topography was done based on DEM from airborne LiDAR. Soil profiles were analysed at the sites where traces of charcoal kilns were identified from DEM. Radiocarbon dating and palaeobotanical analyses were performed for selected charcoal from kiln remnants. In the study area we identified over 11,500 charcoal kilns. The radiocarbon age of these charcoals indicate that the charcoal kilns under study were used in the 15th, 18th and 19th century. Thus the results suggest that the iron industry in the studied area is c 100 years older than the historical written sources indicate. Palaeobotanical analyses show that coniferous trees were used for charcoal production. The large number of traces of charcoal kilns and their wide spatial distribution indicate that past charcoal production has had a significant impact on the environment and landscape change in the River Czarna valley and adjacent areas.
The aim of the study was to investigate how the emission of pollutants to the atmosphere from the late 19th century until modern times has been recorded in rings of silver fir trees growing in southern Poland. Samples were collected from 24 firs growing in the Beskid Niski Mountains (Western Carpathians). Using a Pressler borer, a single core was collected from each tree. Within the samples, tree-ring widths were measured. On this basis, reductions of tree-ring widths were calculated and subsequently divided into three classes according to their severity. Study results indicate that growth reductions at the site studied were influenced by the pollution emitted from the now-defunct Central Industrial Region, which developed most rapidly from 1920 to 1940, and began to decline after World War II. These emissions were probably responsible for reductions in the trees sampled in the years 1928–1947. On the other hand, reductions of tree-ring widths dating from 1951 to 1989 were caused by the post-war development of heavy industry throughout Poland, and in particular in the Upper Silesian Industrial Region, which developed at its most rapid rate from 1960 to 1990. The results obtained demonstrate that reductions of tree-ring widths in the silver firs studied are related to industrial air pollution in the 20th century. As industrial production declined and environmentally friendly technologies were introduced in the early 1990s, air pollution levels decreased and an increase in tree-ring widths followed in the silver firs studied. Further reductions of tree-ring widths have been observed in recent years (since 2009), which may be caused by air pollution due to low-stack emissions from domestic boilers. The analysis conducted demonstrates that a reduction in tree-ring widths in silver fir is a sensitive bioindicator of air pollution.
We applied dendrochronological methods for dating landslide activity in the study area (3.75 km2), on the slopes of Sucha Mountain (1040 m a.s.l.), in the Beskid Żywiecki Mountains, in the Western Carpathians. 46 sampling sites were distributed throughout the study area. At each site we sampled 1-3 coniferous trees: Norway spruces (Picea abies Karst.) and/or silver firs (Abies alba Mill.). From each tree 2 cores were sampled: one from the upslope and the other from the downslope side of the stem. Based on tree-ring widths measured for opposite sides of stems we have calculated eccentricity index values and dated past landslide events. Mean frequency of landslides was obtained for each sampling site. Finally, the data was interpolated into a map of landslide activity. Inverse Distance Weighting (IDW) interpolation has been applied. For most of the study area we found medium (19 sites) and low (23 sites) levels of landslide activity. The highest level of activity was recorded for the largest landslide slope and for the one small landslide. The study conducted on Sucha Mountain has shown that dendrochronology can be an effective method for analysing landslide activity and may be useful in further studies, including those for landslide hazard and risk assessments.
Large debris flows have destroyed the infrastructure and caused the death of people living in the Moxi Basin (Sichuan Province, Southwestern China). Inhabitants of the Moxi Basin live on the flat surfaces of debris-flow fans, which are also attractive for farming. During the monsoon season debris flows are being formed above the fans. Debris flows can destroy the houses of any people living within the fan surfaces. In order to prevent the adverse effects of flows, people plant alder trees (Alnus nepalensis) at the mouths of debris flow gullies running above debris flow fans. Alders are able to capture the debris transported during flow events. Trees are well adapted to surviving in conditions of environmental stress connected with abrupt transport and deposition of sediment from debris flows. Numerous wounds, tilting and bending of alder trees caused by debris flows only very rarely cause the death of trees. By dating scars and dating the time of alder tilting (through the analysis of annual rings), we have determined the frequency of debris flows occurring at the mouth of the Daozhao valley. In 1980–2012 within the studied debris-flow fan and the Daozhao gully, 2 large debris flow events occurred (1996, 2005) and some smaller events were probably recorded every 2–3 years.