ID33: Life after Ice

Abstract ID 669 | Date: 2022-09-13 16:12 – 16:24 | Type: Oral Presentation | Place: SOWI – Seminar room U1 |

Ramskogler, Katharina (1,2); Knoflach, Bettina (3); Erschbamer, Brigitta (2); Hofmeister, Florentin (4); Müller, Svenja (3); Elsner, Bernhard (3); Heckmann, Tobias (5); Geitner, Clemens (3); Stötter, Johann (3); Tasser, Erich (1)

Due to climate change and the associated glacier retreat, proglacial systems undergo considerable changes. The patterns of proglacial ecosystem dynamics and the adjustment towards non-glacial conditions are highly depending on time since deglaciation, initial site conditions and geomorphic disturbances. Although, several authors emphasize that an interdisciplinary approach is indispensable to develop a holistic understanding of primary succession, investigations that integrate multiple autogenic and allogenic factors are rare.

In the proglacial area of Fürkele-, Zufall-, and Langenferner (Martell Valley/ Eastern Italian Alps), the impact of various geomorphological, climatic, and edaphic parameters on vegetation cover, plant species number, and plant species composition was investigated. A total of 65 plots of 5×2 m was installed to perform vegetation analysis. Community weighted means of the Landolt indicator values (Landolt et al. 2010) were calculated for each plot. Following the geoscientific concept of spheres the effect of atmosphere (temperature, solar radiation, snow free growing degree days), cryosphere (glacier extent, distance to glacier, snow cover duration, snow free freeze thaw days), hydrosphere (topographic wetness index, precipitation), relief-/lithosphere (elevation, inclination, curvature, stream power index, landforms), pedosphere (Landolt indicator values for nutrients, soil organic matter, pH; Landolt et al. 2010; referenced using in situ soil data), and anthroposphere (grazing/trampling) on vegetation cover, species richness, and plant communities were quantified via general additive models.

Patterns in primary succession were highly related to autogenic factors and (micro-)topographic factors. Particularly, temperature variability, controlled by elevation and variability of solar radiation correlated strongly with the spatial patterns of vegetation cover. In addition, the deposition of fine material had a positive effect on it. The species richness was also positively influenced by better nutrient availability, improved water supply, and geomorphic disturbances. The number of species was thereby significantly associated to different landforms, and thus to variations in substrate and process activity.

Abstract ID 691 | Date: 2022-09-13 16:24 – 16:36 | Type: Oral Presentation | Place: SOWI – Seminar room U1 |

Zimmer, Anais

Mountain glaciers are melting worldwide, and their ecosystem services are declining, impoverishing local ecosystems and human communities. The emerging ice-free lands, however, represent an opportunity for novel alpine ecosystems to develop. Previous studies have usually focused on wider areas through satellite imagery or over smaller areas using in situ floristic evaluations. Each approach has strengths and limitations: satellite imagery is recurrent and covers large areas, but it lacks fine resolution, and field data collection has the fine resolution but lacks the breadth and is laborious. Here, we couple field data collection, aerial photogrammetry, and satellite analysis to study the distribution and composition of pioneer alpine communities in glacier forelands. For a total of nine proglacial landscapes distributed between the Alps (France and Switzerland) and the Tropical Andes (Peru) we combined satellite imagery and multispectral UAVs models with ground land cover data using an RGN (Red-Green-Near Infrared) camera and in situ floristic and geomorphologic surveys. We test long-term (1950-2020) primary geo-ecological succession in the context of recent climate change. We use the normalized difference vegetation index (NDVI) to assess vegetation development, predict biomass, and to connect field observed variables i.e., species richness, plant cover, and soil properties, with global ecosystem functioning and services and upscale local patterns to regional processes. We have produced nine high-resolution multispectral orthomosaics (3-5 cm/px^–) and DEMs (6-15cm/pix) and surveyed a total of 620 plots along the 9 chronosequences of deglaciations. This approach allows to couple the space for time substitution approach with geomorphological dynamics and landforms. We found that spatial heterogeneity reflects gradual successional trajectories related to small variations in physical habitat conditions. And abiotic and biotic processes combine to drive the pioneer stages of plant succession after glacier retreat. These mixed geospatial methods allow for high-resolution terrain mapping, ecological modeling, and global upscaling, and provide a robust tool to guide implementation policies and management of proglacial landscapes.

Abstract ID 322 | Date: 2022-09-13 16:36 – 16:48 | Type: Oral Presentation | Place: SOWI – Seminar room U1 |

Zeballos Castellon, Gabriel (1); Mark, Bryan (1); Yager, Karina (2); Meneses, Rosa (3); Guzman Armijo, Kevin (4)

Bofedales, are a type of peat bogs that belong to complex hydro-ecological systems on the Alpine belt of the Andes. Scattered along plateaus and glacier valleys, bofedales are critical water reservoirs that sustain fragile ecosystems and regulate surface and groundwater cycles. The rapid glacier retreat has been shown to affect the number, distribution, and health condition of bofedales but only with an inventory and distribution map would it be possible to understand their vulnerability in the face of climate and land-use changes. To obtain this inventory, we combined extensive fieldwork assessments with the analysis of thousands of Copernicus Sentinel-2 imagery on Google Earth Engine, to determine the current spatial distribution of bofedales in the Subtropical Andes. In addition, we selected 20 bofedales on a latitudinal gradient along the Subtropical Andes (14° to 22° S) to analyze the seasonal and annual trends of bofedales’ vegetation from 1987 to the present. For this, we processed and analyzed monthly NDVI data, from Landsat TM and MODIS sensors. With this long-term set of observations, we obtained a climatology of the NDVI, allowing us to understand the seasonal-to-interannual trends of the vegetation as well as the existing anomalies in their seasonal and annual regime. The information produced in tables and maps will help local and national authorities to determine the next steps towards the conservation of these vulnerable mountain hydro ecosystems in the face of climate change.

Abstract ID 696 | Date: 2022-09-13 16:48 – 17:00 | Type: Oral Presentation | Place: SOWI – Seminar room U1 |

Tamea, Stefania; Camporeale, Carlo; Corte, Elisabetta

Despite the effects of global warming on the cryosphere are well-know and documented, less attention has been devoted to the geomorphological implications of glacial retreat and to the effects of de-glaciation on surface processes in periglacial areas. The water cycle is altered by the changing duration and rate of snow melting and ice ablation, higher frequencies of high-altitude rainfalls which enhance snow melting, increase in average and peak runoff production. These alterations also impact the rate of sediment production, both from glacier areas, where sediments are released by ice melting and bed erosion, and from periglacial areas, where newly exposed sediments are displaced by precipitation and interactions with water flowing enhance sediments mobilization. These modifications impact on and interact with the biological dimension of the high-altitude ecosystem, including vegetation, lichens, microorganisms that adapt to a changing environment.

The goal of our research is the analysis and quantification of the hydrological and morphological dynamics of peri-glacial areas. The presented activity is focused on the Rutor glacier, in the Graie sector of the north-west italian Alps. The Rutor glacier is among the largest glaciers in Italy and its terminus, in the La Thuille valley, reaches an elevation of about 2600 m a.s.l. The area is relatively pristine due to the absence of mechanical lift facilities in the surroundings, although intense fluxes of hikers reach the nearby mountain hut or haunt the climbing and alpine-ski routes in the area. The periglacial area of this fast-retreating glacier (the terminus moved by more than 2 km since the mid-19th century) is characterized by a number of proglacial lakes, the major one being the Seracchi lake, which collects all melt water from the northward slope of the Rutor glacier as well as all the sediments. The research we present results from a multidisciplinary collaboration that involves glaciologists, hydrologists, geophysicists, geomatics and water engineers. The site has been explored and equipped to measure the high-resolution morphology of the area (using drones and airborne surveys), the streamflow and water temperature continuously in time, the lake water balance, the accumulated sediments characterization though radar and the sediment transport at the terminus through the use of geophones. Merging the contributions of different disciplines allows us to gain an advanced quantitative knowledge of the water and sediment budget in the area as well as to investigate the evolution of process defining the landscape at different time scales.

Abstract ID 748 | Date: 2022-09-13 17:00 – 17:12 | Type: Oral Presentation | Place: SOWI – Seminar room U1 |

Llambi C., Luis Daniel (1); Melfo, Alejandra (1); Gamez, Luis E. (1); Pelayo, Roxibel (1); Cárdenas, Mariana (2); Cherry, Rojas (1); Torres, Jesus E. (1); Ramirez, Nerio (3); Huber, Barbara (1); Hernandez, Jesus (4)

Glaciers are receding at unprecedented rates in the alpine tropics, opening-up new areas for ecosystem assembly. However, little is known about the patterns/mechanisms of primary succession during the last stages of glacier retreat in tropical mountains. Our aim was to analyze soil development and vegetation assembly during primary succession, and the role of changing adaptive strategies and facilitative interactions on these processes at the forefront of the last Venezuelan glacier (Humboldt Peak, 4,940 m asl). We established a chronosequence of four sites where the glacier retreated between 1910 and 2009. We compared soil organic matter (SOM), nutrients and temperatures inside vs. outside biological soil crusts (BSCs) at each site, estimated the cover of lichen, bryophyte and vascular plant species present, and analyzed changes in their growth-form abundance and species/functional turnover. We also evaluated local spatial associations between lichens/bryophytes and the dominant ruderal vascular plant (the grass Poa petrosa). We found a progressive increase in SOM during the first century of succession, while BSCs only had a positive buffering effect on superficial soil temperatures. Early seral stages were dominated by lichens and bryophytes, while vascular plant cover remained low during the first six decades, and was almost exclusively represented by wind dispersed/pollinated grasses. There was a general increase in species richness along the chronosequence, but it declined in late succession for lichens. Lichen and bryophyte communities exhibited a higher species turnover than vascular plants, resulting in the loss of some pioneer specialists as succession progressed. Lichen and bryophyte species were positively associated with safe-sites for the colonization of the dominant ruderal grass, suggesting a possible facilitation effect. Our results indicate that lichens and bryophytes play a key role as pioneers in these high tropical alpine environments. The limited initial colonization of vascular plants and the progressive accumulation of species and growth-forms (i.e. direct succession) could be linked to a combination of severe environmental filtering during early seral stages and limitations for zoochoric seed dispersal and entomophylic/ornitophylic pollination. This could potentially result in a slow successional response of these ecosystems to accelerated glacier loss and climate change.