Zofia Rączkowska

Vegetation as a tool in the characterisation of geomorphological forms and processes: an example from the Abisko Mountains

This study addresses the relationships between landforms and vegetation in the sub–Arctic zone around Abisko, and the possibilities for using vegetation in the characterisation of geomorphological forms and processes. It examines the extent to which repeatable linkages can be identified between landforms and diagnostic features of the vegetation as a preliminary step in the development of phytoindicators of geomorphological forms and processes. Sixty sites representative of different landforms were studied in three mountain areas in the alpine belt on both calcareous and crystalline substrates. A series of features characterising the abiotic environment and vegetation was defined. Plant communities were distinguished in line with the ‘Scandinavian–school’ typology. Links were investigated between vegetation and geomorphological processes (deflation, frost sorting, solifluction and nivation) and landforms (thufurs, solifluction lobes, sorted stripes and nival niches). A clear association between vegetation and landforms was noted, though a precise description of the links encountered a number of difficulties, mainly reflecting the indirect nature of the interrelationships between landforms and vegetation (i.e. the fact that they are intermediated by other abiotic factors). A combination of indicative vegetational features capable of characterising the geomorphological processes was established, although those require futher, more detailed analysis. Schematic representations of the links between the different types of landforms and the vegetation growing on them were also developed. There are limits to the applicability of phytoindication in the high–alpine belt and extending into the nival belt, reflecting the unfavourable conditions there for plant growth.

Recent Landform Evolution in the Polish Carpathians

The key drivers of relief transformation in the Polish Carpathians (the best studied region of the Carpathians) have been local downpours, continuous rainfalls, and rapid snowmelt. Threshold values are quickly exceeded during such events and powerful morphological processes are initiated. However, due to human activities, geomorphic processes are often accelerated and intensified with serious consequences. Thus, increased human impact is a key factor in the recent geomorphic evolution of the Polish Carpathians. Over the last two centuries deforestation, intensive agriculture, mining, housing developments on slopes, channelization of streams, and construction of reservoirs all have contributed to changes in the rate of the particular geomorphic processes. The intensity of sheet erosion depends on vegetation cover, land use, and cultivation techniques (terracing, contour tillage, crop rotation, etc.). Slopes bearing poorly constructed infrastructure have become susceptible to mass movements. At higher elevations debris flows, dirty avalanches, and extreme floods are crucial in slope evolution. Over the last 20 years the ratio of agricultural land and the rate of sheet erosion and deflation have decreased, while gully erosion on slopes and the incision of river channels have intensified and the reactivation of shallow landslides has become more common. Increasingly frequent extreme weather events may reverse the stabilizing trend of landform evolution.

Recent Debris Flows in the Tatra Mountains

This chapter results from the interpretation of the data collected by field studies of debris flow events including geomorphological effects, of an Ikonos satellite image from 2004, and the DEM prepared for the entire Tatra massif. Based on about 20-year-long field observations, the rainfall thresholds necessary to trigger debris flows have been identified. Such thresholds, however, vary with lithology and relief. As it is illustrated by the lack of debris flows associated with the extreme weather events in May and June of 2010 in the Tatras, there is no clear relationship between periods of high daily precipitations and the triggering of this type of mass movement. The most spectacular topographic impacts of debris flows are observed in the middle section of the vertical profile of the mountains. Debris flow activity is strongly conditioned by relief (topography and substrate properties) that resulted from Pleistocene glacial and periglacial morphogenesis.

Deglaciation and Impact of Extreme Rainfalls on Recent Relief Transformation of the Upper Pindari Valley: The Kumaun Himalaya, India

The upper Pindari River Valley is situated in the southeast of the Nanda Devi massif in higher reaches of the Kumaun Himalaya. The satellite images were used as the background of the geomorphological mapping during field expeditions in 2012, 2013 and 2014. Particular attention was paid to the glacial relief within the valley floor, relief transformation after glacial retreat and morphogenetic processes responsible for relief transformation. The set of frontal and lateral moraine ridges is identified in the Pindari Valley bottom and their age is evaluated based on morphological features, historical data and relation to other landforms. Glacial landform is well preserved in the uppermost part of valley. In the lower parts it is completely or partly buried under talus cones, fluvioglacial cones and debris flows accumulation. It indicates rather high activity of morphogenetic processes in post glacial period and nowadays. The significant changes in the relief at present are effects of extreme rainfalls, as it occurred in June 2013. They encompass slopes and valley bottom, from the uppermost part up to mouth of the valley. Debris flows and landslides are triggered or rejuvenated on slopes, many new large undercuts occur along river channel, which is completely remodelled.