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Aim
Open woodlands are biologically highly diverse habitats, and veteran (i.e., old, senescent) trees are key structures supporting their biodiversity. Open canopy structure had been maintained by both natural‐ and human‐induced disturbances. In the past two centuries, suppression of such disturbances, together with forestry intensification, has turned most lowland woodlands into closed‐canopy forests. We investigated the effect of increased canopy closure on veteran trees and several threatened beetles associated with them.
Location
Floodplain woodlands along the lower Dyje and Morava rivers, Czech Republic.
Methods
We used an approach combining the study of aerial photographs with on‐ground survey of veteran trees and associated endangered beetles. The aerial images were used to obtain the information on historical (1938) and recent (2009) canopy closure in the area of 146 km ² , where we mapped large oaks (d.b.h. >70 cm), hollow trees and three associated beetles including the hermit beetle ( Osmoderma barnabita ), the great capricorn beetle ( Cerambyx cerdo ) and the jewel beetle Eurythyrea quercus .
Results
The presence of large oaks, hollow trees and their associated beetle species are negatively related to recent high canopy closure, and the historical level of canopy closure matters, as in nowadays closed‐canopy stands, the beetles and veteran trees are more common in places that were rather open in 1938 than in the places with closed canopy already in 1938. Moreover, the health state of veteran trees highly depends on the canopy closure.
Main conclusion
The negative effect of canopy closure on veteran trees and their endangered inhabitants is several decades delayed and may thus often go undetected. In the forests, however, large and hollow trees and their associated biodiversity are relics of the past, more open conditions. The restoration of open woodlands is therefore vital for preventing their further decline. Conservation management planning needs to take this into account wherever, veteran trees and associated biota are concerned.
Natural conditions that explain the triggering of snow avalanches are becoming better-known, but our understanding of how socio-environmental changes can influence the occurrence of damaging avalanches is still limited. This study analyses the evolution of snow avalanche damage in the Asturian Massif (NW Spain) between 1800 and 2015, paying special attention to changes in land-use and land-cover patterns. A damage index has been performed using historical sources, photointerpretation and fieldwork-based data, which were introduced in a GIS and processed by means of statistical analysis. Mapping allowed connecting spatiotemporal variations of damage and changes in human-environment interactions. The total number of victims was 342 (192 dead and 150 injured). Results show stability in the number of avalanches during the study period, but a progressive decrease in the damage per avalanche. Changes in land use explain the evolution of damage and its spatial/temporal behaviour. The role played by vegetation cover is at the root of this process: damage was the highest during the late 19th and early 20th centuries, when a massive deforestation process affected the protective forest. This deforestation was the result of demographic growth and intensive grazing, disentailment laws and emerging coal mining. Since the mid-20th century, the transformation of a traditional land-management system based on overexploitation into a system based on land marginalization and reforestation, together with the decline of deforestation due to industrial and legal causes, resulted in the decrease of avalanches that affected settlements (mostly those released below the potential timberline). The decrease of damage has been sharper in the western sector of the Asturian Massif, where oak deforestation was very intense in the past and where lithology allows for a more successful ecological succession at present. Taking into account that reforestation can be observed in mountain environments of developed countries worldwide, and considering present initiatives conducted to counteract its negative cultural effects by means of grazing and clearing operations, planning is imperative, and this research provides useful information for environmental management policies and risk mitigation in avalanche prone areas.
The present cultural landscape is a result of development which has been carried out for several thousand years. The land -use changes, driving forces, threats and trends relating to agricultural landscape mosaics in Slovakia were studied using examples of model areas with preserved landscape mosaics: the villages Zuberec -Habovka, Liptovská Teplička, Osturňa and the town of Svätý Jur. The primary land cover of the Slovak republic was mostly forest. The outstanding feature of the landscape, as a result of settlement, deforestation and colonisation, was a landscape characterised by a high biodiversity and cultural mosaic because of the heterogeneity of land forms and cover, relief segmentation, and a variety of farming products. The most important interventions in the landscape started in the second half of the 20 th century. Intensification of agriculture was linked with collectivisation and removal of hedges and riparian vegetation, decreasing the mosaic of arable fields, grasslands and woods. Landscape mosaics were transformed into large fields. Only in less accessible, less fertile localities was the original agricultural landscape partially preserved, and did not lose the shape of a cultural-historical countryside. At the same time, partial abandonment and reforestation has started as a consequence of changes in employment patterns and the decline of populations. After 1990 the landscape was partly retrospectively diversified by virtue of land restitution. Although the decline of the traditional use of farmland is noticeable in Slovakia, in some regions local inhabitants are strongly linked to traditional land use. In less accessible, less fertile localities, abandonment of traditional agriculture and succession dominance of forest continues. The challenge to maintain the original agrarian landscape could be supported by agro-environmental schemes. However, localities with beneficial geographical positions are threatened. The town of Svätý Jur faces non-regulated urbanisation, old vineyards are being replaced by new villas and houses for recreation. The villages of Zuberec -Habovka face non regulated tourism. The marginal sites, Osturňa, Liptovská Teplička are threatened by abandonment and the subsequent overgrowth by woody vegetation.
A study of the forest lines, tree lines and the structures of the sub-alpine forest was performed in Vallone Vallanta and in Aleve forest in the Varaita Valley (Cottian Alps, Piedmont, Italy). Forest- and tree lines were analysed over 1728 ha while forest structures were studied on six 3000-m(2) plots located at the tree line (2), at the forest line (2) and inside the sub-alpine forest (2). Dendro-ecological analysis of living plants and stumps showed that Larix decidua was more abundant in the past than today and that Pinus cembra has expanded, both upwards and within sub-alpine forests. Age structure analysis revealed that the current sub-alpine forest stands were established 200-220 yr ago, probably following a clearcut. At the forest lines the tree density decreases, and some trees are more than 500 yr old, whereas at the tree lines most of the trees (almost exclusively Pinus cembra) are younger than 100 yr. Growth dynamics were investigated both by observing Basal Area Increment (BAI) in the old and dominant trees, and by comparing the BAIs of classes of trees with a given cambial age range in different time periods. The results showed that the growth rates of mature Pinus cembra and Larix decidua had increased. These increments are more substantial for Pinus than for Larix. The growth rate of young trees (< 100 yr) of both species has decreased over recent decades. This could be due to competition caused by increased tree densities that have resulted from a decrease in grazing.
The reversal from deforestation to forest increase is named forest transition. It combines factors related to social and economic development or policies attempting to overcome the possible scarcity of timber. This study focuses on forest transition in the northern Carpathians, stretching across four countries (Czech Republic, Poland, Slovakia and Ukraine) with complex history and variability with respect to present-day economical development. Forest maps were computed for the 1930s and 1990s on the basis of available topographical and satellite data. Forest cover changes were then analysed and discussed in the context of population change and environmental conditions of the area.Between the 1930s and the 1990s net forest cover change was between 5% and 31%. The highest values (>20%) were recorded in areas which suffered post-war re-settlement and depopulation. Medium values (10–15%) were found in areas affected by the post-war gradual marginalization and depopulation. The lowest values (
Summary • Part of the forest reserve established in Paneveggio Forest (Trento, Italy) in 1992 has been allowed to evolve without human intervention. Inside this reserve, two 1-ha long-term monitoring plots were established in subalpine multi-layered forest stands. • To investigate the origin, spatio-temporal development and disturbance history of these plots, the present study combined dendroecological tree ring analysis with historical evidence. • One stand (VB3) had an uneven-aged population in which the oldest trees were more than 400 years old. Regeneration has been continuous both in time and space over the last three centuries, during which time the stand has been affected regularly by disturbances. This supports the information from historical documents, suggesting that a selection system was carried out in this area. • The second stand (BDO) also had an uneven-aged population, with trees up to 397 years old. Although this plot too had been affected quite regularly by disturbances, massive regeneration occurred only after 1920, suggesting that the land might previously have been exploited as pasture. • Despite their relatively similar structures, the two plots developed in entirely different ways. Our study confirmed that biological data can be used to identify the occurrence and intensity of prior localized disturbances in forest stands, but the precise causes of the disturbances can be determined only by comparing biological data and historical records.
Landsliding is a natural process influencing montane ecosystems, particularly in areas with elevated rainfall and seismic activity. Yet, to date, little effort has been made to quantify the contribution of this process to land-cover change. Focusing on the mountains of Mexico and Central America (M-CA), we estimated the contribution of landsliding to land-cover change at two scales. At the scale of M-CA, we classified the terrain into major landforms and entered in a GIS historical data on earthquake- and rainfall-triggered landslides. At the scale of the Sierra de Las Minas of Guatemala, we investigated Landsat TM data to map rainfall-triggered landslides. During the past 110 yr, > 136,200 ha of land in the mountains of M-CA have been affected by landslides, which translates into disturbance rates exceeding 0.317 percent/century. In Sierra de Las Minas, rainfall associated with hurricane Mitch affected 1765 ha of forest, or equivalently, landslides triggered by storms of this magnitude transformed between 0.196 (return time of 500 yr) and 1.290 (return time of 75 yr) percent of forest/century. Although landsliding results in smaller rates of land-cover change than deforestation, we hypothesize that it has a stronger impact on ecosystems, both in qualitative and quantitative terms, given its influence on vegetation and soil. Moreover, interactions between landsliding and deforestation may be altering the expression of this complex process such that the few protected areas in the mountains of M-CA may represent the only possibility for the conservation of this process.
In 2000, the Task Force on Forests in Sustainable Mountain Development of the International Union of Forestry Research Organizations (IUFRO) published a state-of-knowledge report (Price and Butt 2000). The terms of reference for the Task Force recognized the need for such a report, deriving from four linked trends:
a widespread shift in the science and practice of forestry, from an emphasis on the production of wood towards integrated management recognizing that forests serve multiple functions and produce a wide range of goods;
changing expectations regarding the roles of mountain forests among populations around the world, in an increasingly urbanized global society;
rapid rates of change, both perceived and measured, in the cover and uses of forests and adjacent ecosystems in mountain regions around the world;
the growing recognition of the global importance of mountain ecosystems and their inhabitants.
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