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.
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).
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.
We found ubiquitous evidence of ongoing slope instability by analysing the variability of tree-ring eccentricity index in trees growing on three apparently relict landslide slopes in the Sudetes (Poland, Central Europe). Slow movement of these landslide bodies occurs in the present-day conditions and is recorded almost every year, although with variable intensity. Correlation of dendrochronological record with the rainfall record from a nearby station in Mieroszów for the 1977–2007 period is very poor for two deep-seated rotational slides at Mt Suchawa and Mt Turzyna but considerably better for a shallow flowslide at Mt Garbatka. While this may reflect higher permeability of heavily jointed rocks involved in deep-seated sliding this could be linked with imperfections in the rainfall record. Dendrochronology proved capable of detecting minor displacements within landslides which otherwise show no geomorphic evidence of recent activity. Therefore, claims for the entirely relict nature of the landslides are not substantiated.
Most landslide hazard maps are developed on the basis of an area’s susceptibility to a landslide occurrence, but dendrochronological techniques allows one to develop maps based on past landslide activity. The aim of the study was to use dendrochronological techniques to develop a landslide hazard map for a large area, covering 3.75 km2. We collected cores from 131 trees growing on 46 sampling sites, measured tree-ring width, and dated growth eccentricity events (which occur when tree rings of different widths are formed on opposite sides of a trunk), recording the landslide events which had occurred over the previous several dozen years. Then, the number of landslide events per decade was calculated at every sampling site. We interpolated the values obtained, added layers with houses and roads, and developed a landslide hazard map. The map highlights areas which are potentially safe for existing buildings, roads and future development. The main advantage of a landslide hazard map developed on the basis of dendrochronological data is the possibility of acquiring long series of data on landslide activity over large areas at a relatively low cost. The main disadvantage is that the results obtained relate to the measurement of anatomical changes and the macroscopic characteristics of the ring structure occurring in the wood of tilted trees, and these factors merely provide indirect information about the time of the landslide event occurrence.
Channels of Czadeczka and Krężelka rivers (Beskidzie Śląski Mts) are at present subjected to regulation because of which these rivers have lost their natural character, partially still preserved. The reasons for the river regulation have been analysed. Using archival maps, the buildings erection time has been analysed on valley floors, in the immediate vicinity of river channels for the period 1790-2012. Next, the distribution of existing buildings has been compared with hydraulic structures in the channels developed in order to regulate the Czadeczka and the Krężelka reaches, such as: concrete and stone embankments reinforcing the channel banks, check dams on channel bottoms. Results indicate a strong correlation between the number of buildings on valley floors in the 20th century and channel regulation. The mechanism of destroying rare, preserved natural river reaches is based on irrational permission allowing construction of buildings in areas threatened by floods and lateral erosion of rivers. Consequently, the inhabitants, in fear of floods and erosion of land or house foundations, seek river regulation that gives them a false sense of security. Natural river reaches are destroyed though efficient protection against floods and lateral erosion is still not provided and the range of possible losses increases even more due to continued building erection.