Quantification of biogeomorphic interactions between small-scale sediment transport and primary succession in the Gepatschferner glacier foreland, Austria

<p>Landscape change is an interplay of abiotic and biotic processes with bi-directional and interwoven relationships. Glacier foreland areas can act as open-air laboratory to observe biogeomorphic interactions. Paraglacial adjustment establishes initial conditions for ecological succession and requires constant feedbacks between plants and landscapes. Frequency and magnitude of geomorphic processes and functional composition and abundance of plants govern these responses. Up to now, biogeomorphic studies have mainly focused on the qualitative description of the relationship between biotic and abiotic processes. However, in order to test biogeomorphic concepts, it is necessary to jointly quantify (i) geomorphic process rates as a function of vegetation and (ii) successional development as a function of geomorphic conditions.</p><p>The proglacial area of the Gepatschferner (Kaunertal) in the crystalline Central Eastern Alps presents a showcase environment to investigate these interactions as the retreating glacier and highly active slope processes provide the ground for different stages of ecological succession and promotes high rates of sediment reworking within the proglacial deposits.</p><p>In this particular study, we investigate small-scale biogeomorphic interactions at 30 test sites of 2*3m size. Experimental plots are established on slopes along an ecological succession gradient that reflect different stages of erosion-vegetation interaction. To cover the abiotic condition for the plot sites morphometric characteristics and edaphic variables were determined. In order to quantify abiotic process rates, we use mechanical measurements (i.e. erosion plots) to determine sediment yield and to measure the effect of vegetation on particle size distribution. Relative Dating, historical image analysis and knowledge of glacial retreat helped to estimate time since last perturbation. A detailed vegetation survey was carried out to capture biotic conditions at the sites. Species distribution and abundance at each site, as well as plant functional types provide information on successional stage and functional diversity.</p><p>This data set provides a vital opportunity to test conceptual models on biogeomorphic succession in glacier forelands and to evaluate the bi-directional influence of primary succession on small-scale sediment transport and vice versa.</p>

Potential of detailed geomorphological mapping for the study of Holocene glacier chronologies: Mueller Glacier, Southern Alps/New Zealand

<p>The investigation of Holocene glacier chronologies has been recognised as a key element of research on mountain glaciations in the light of current global change. They can be utilised as high-resolution palaeoclimatic archives for the immediate and more distant geological past. During the past few decades considerable progress has been achieved, in particular due to substantial improvements of the ability to accurately date glacial landforms such as terminal moraines essential for reconstructing past glacier margins and subsequent analysis in the context of glacier advance/retreat periods. The Southern Alps of New Zealand are among the few suitable study sites for the investigation of Holocene glacier chronologies in the mid-latitudinal Southern Hemisphere that consequently have drawn attention.</p><p>Since early studies of Holocene glacier chronologies in the mid-20th century, mapping of the investigated glacier forelands has been an integrated part of almost all scientific approaches regardless of the individual dating methods that may have been applied. These mapping attempts serve the identification and positioning of certain glacial or glaciofluvial landforms subsequently allowing the reconstruction of former glacier margins. They frequently also provide information about the location of sample sites for the various dating techniques applied. If detailed geomorphological mapping schemes are in use, such maps additionally support the interpretation of any chronological data by identifying the genetic origin of any landform investigated, thus enabling to link the latter to different dynamic stages of the glacier. Additionally, such maps may highlight related uncertainties such as postdepositional disturbance or potentially unclear morphodynamic relationships to the glacier's behaviour.</p><p>Reviewing recent publications it seems, however, that some appraisal of such detailed geomorphological mapping is often traded-off against the impressive progress with up-to-date dating techniques and high-resolution digital elevation models or satellite/aerial imagery. Unfortunately, the latter do neither qualify as geomorphological maps <em>per se</em> or fully serve the abovementioned purposes. The widespread applied common GIS software has, furthermore, limitations with respect to its graphic capabilities and unintentionally entails negligence of established and well-suited signatures or mapping schemes.</p><p>A detailed geomorphological map of the glacier foreland of Mueller Glacier, Southern Alps/New Zealand is presented as a case study. It follows an established geomorphological mapping scheme ("GMK 25") that has been adequately modified to fit both purpose and selected scale. Despite several glacier chronological studies have been conducted on this glacier foreland and the site is considered as a regional key site for related research, this map constitutes the first of its kind. The detailed geomorphological map is utilised to assess discrepancies among existing chronologies by reviewing the morphometric properties and genetic origin of those landforms that have been dated. It reveals that potential postdepositional modification of some landforms investigated had not been appropriately considered with certain previous studies. As a result, the evidence of few glacier advances needs to be classified as weak.  </p><p>Summarising, detailed geomorphological mapping is still essential for the study of Holocene glacier chronologies and should not lose its prominent position or even disappear.</p>

Do carabids (Coleoptera: Carabidae) and chironomids (Diptera: Chironomidae) exhibit similar diversity and distributional patterns along a spatio-temporal gradient on a glacier foreland?

Carabid beetles and chironomid midges are two dominant cold-adapted taxa, respectively on glacier forefiel terrains and in glacial-stream rivers. Although their sensitivity to high altitude climate warming is well known, no studies compare the species assemblages exhibited in glacial systems. Our study compares diversity and distributional patterns of carabids and chironomids in the foreland of the receding Amola glacier in central-eastern Italian Alps. Carabids were sampled by pitfall traps; chironomids by kick sampling in sites located at the same distance from the glacier as the terrestrial ones. The distance from the glacier front was considered as a proxy for time since deglaciation since these variables are positively correlated. We tested if the distance from the glacier front affects: i) the species richness; ii) taxonomic diversity; and iii) species turnover. Carabid species richness and taxonomic diversity increased positively from recently deglaciated sites (those c. 160 m from the glacier front) to sites deglaciated more than 160yrs ago (those located >1300 m from glacier front). Species distributions along the glacier foreland were characterized by mutually exclusive species. Conversely, no pattern in chironomid species richness and turnover was observed. Interestingly, taxonomic diversity increased significantly: closely related species were found near the glacier front, while the most taxonomically diverse species assemblages were found distant from the glacier front. Increasing glacial retreat differently affect epigeic and aquatic insect taxa: carabids respond faster to glacier retreat than do chironomids, at least in species richness and species turnover patterns.