Soil mapping exercise and field work in New Island

By iLaria Marengo

New Island is one of the western islands of the Falkland Islands archipelago. Its western coastline is characterised by sheer cliffs (mainly sandstone) which are the nesting (breeding) ground of black-browed albatrosses, king cormorants and rockhopper penguins. The cliffs are a distinctive character of the island and the most scenic and spectacular landscape that people can enjoy along with several white sandy beaches scattered all over. A field research station built in the 1970s has been offering a great support to researchers coming to study what nature shows at its best in this place. The mix between the natural beauty, the self-contained and small environment, and the research facilities provided by New Island, made the location the perfect ground for attempting the first ground truthing of the Falkland Islands interpreted soil map.

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The map (see May blog) is one of outcomes of the TEFRA (Terrestrial Ecosystems of the Falklands – a Climate Change Risk Assessment) project and it is a very valuable dataset considering that there are very few studies of the soils of the Falklands and the most prominent goes back to the 1970’s. The interpretation was by Rodney Burton, a soil specialist who has worked previously in the Falklands, on the basis of the superficial deposits described in the geological map drawn up by the British Geological Survey. In late May Rodney came to Stanley and delivered a two week soil course funded by the TEFRA project and the result was a familiarisation with the identification of types of soils and above all a new interest in an element of the landscape that generally is not eye-catching, except in eroded areas.

The ground truthing work ended in coring locations across 80% of the island (the southernmost area and Sabina point were not visited) resulting in a total of 160 cores and describing the soil characteristic of each core such as depth, colour, texture, stoniness, structure and mottling. Dutch and gouge augers were the tools used to extract the cores; the latter was preferred in the case of peat or very peaty soils (figures below). According to the landscape and the interpreted soil map, the cores were taken along transects perpendicular to slope and longitudinal to the valleys in order to have a good representation of changes in soil types if these occurred.

nisoilsurvey IMG_0341 IMG_0393 IMG_0332 IMG_0049The data and description of the soils cored to different depth have been entered in a postgres database and mapped in QGIS. The last part of the work, currently in progress, is to match the soil descriptions with the soil type classification scheme adopted by the World Reference Base for Soil Resources (WRB). A simplified illustrated legend of soil types with related pictures was presented by Rodney in May and it will provide a valuable visual aid. WRB methodology for soil classification can be summarised in three steps: determining diagnostic horizons, properties and materials; allocating the soil to a Reference Soil Group; allocating principal and supplementary qualifiers. The principal qualifier are ranked from right to left in order of importance and differentiate the RSG according to the primary pedogenetic process (soil-forming factors or processes that most clearly condition the soil) that characterise soil features. The supplementary qualifiers, used in alphabetical order, are added in brackets. The two tables below offer example of a simplified guide to the WRB RGS and the classes of soils identified in the Falklands.

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Scale is the factor to be taken into account after the soil identification at each sample point has been completed. In fact there is a discrepancy between the scale of the interpreted map, which is at 1:250,000, and the level of detail provided by the ground truthing, which is in the order of 300-500 metres (where the coring took place the samples were taken on average at 300-500 metres). A full report will be available in early 2016 and the hope is that the results can be useful to refine the interpreted map; the methodology could be applied to other small islands; conservationists can refer to the outcomes for planning habitat restoration projects and other researchers can be inspired to carry out further investigations. We would like to thank the New Island Conservation Trust to give us the opportunity to carry out the field works and to offer the Field station facilities as base camp. Thank you to the wardens of New Island for their kindness and hospitality.

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Learning how to identify soils in the Falklands Islands

By iLaria Marengo

Soil is a natural, unique and multifunctional resource that provides and supports a range of ecosystem services, in the form of food and as a host for organisms and material that are important for human life. However, much we know about what we are standing on? How much are we aware of soils, their characteristics and properties? Can we use the soil in a more advantageous way for our activities without damaging them?

The Falklands Islands are an archipelago that spread across a bit more than 12,000 square kilometres and we know only approximately and generically about the soils within the islands. In order to start addressing this, a two week course in soil identification was funded as part of an EU BEST project, the Terrestrial Ecosystems of the Falklands – A climate change risk assessment (TEFRA), led by Dr Rebecca Upson and Prof Jim McAdam.

Rodney Burton, with 45 year of experience in soil survey, has travelled all the way south to train and enthuse representatives of Falklands Conservation (FC), Department of Agriculture (DOA), landowners and SAERI about soils. The aim of the course was to provide information and stimulus for the participants in understanding the basics of soil, its properties and processes, and how to apply that understanding to their everyday work and own specific needs.

The lack of a soil map is a noticeable and important gap in the baseline spatial information of the Falkland Islands. Hence, the main objective in learning about soils is to enable the participants to gather soil information (through description, interpretation and recording) to improve the first draft of the TEFRA project soil map. This map is an interpretation that Rodney Burton has produced based on the solid and superficial deposits geological maps.

 

The new skills acquired during the course are going to be applied to the identification and description of soil profiles for the main soil types derived from the TEFRA soil map. The idea is to do surveys at specific study areas chosen by Dr Stuart Smith, leader of the habitat restoration project at FC, add some opportunistic auger holes at farms where DOA is taking already soil samples for lab analyses and wherever leisure walks take iLaria Marengo in her attempt to walk each 1 km2 cell of the OS map.

The course was fascinating and enjoyable. It comprised of two days in the classroom, where Rodney gave a general introduction on soil genesis, classification, sampling, interpretation and a description of the soil survey field handbook. This was followed by a week spent in the field finding spots for the description and interpretation of soil profiles.

Each day in the field revealed something new. We went from some extreme conditions, such as snow and freezing strong winds, to a more “balmy” temperature of 8 degrees and absence of wind. We found that the soils are largely shallow, except in areas where peat accumulates. In Cape Pembroke we dug through almost 4 metres of peat but in the other locations we didn’t manage to dig more than 40 cm because the bottom (clay) was too hard.

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Interesting periglacial polygonal features were spotted in all the location and in Saladero ventifacts were scattered across some bare land. Both features thrilled an already enthusiastic Rodney and were evidence that the geomorphology of the Falkland Islands is extremely rich in fascinating and puzzling features which are worth further investigation.

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We would like to thank Rodney for the way he taught us soils, for his passion and the clarity of his explanations. Another thank is for the TEFRA project which made possible this course. We hope that as participants we can use the new skills efficiently and in a useful way.

 

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