How biodiversity unfolds

Glaciers are retreating at historically unprecedented rates. While glacial loss poses a serious threat to humanity, it is a unique opportunity for biodiversity research at the same time. How is that possible?

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Melting glaciers - an opportunity for biodiversity research

As glaciers melt, they expose land that has been under ice for centuries. The barren substrate is almost devoid of life but over time, various organisms take up residence in the deglaciated areas and start to form complex ecosystems – a process that is known to ecologists as primary succession. If uninterrupted, a gradient of successional stages emerges that range from species-poor stony habitats to diverse and functional ecosystems. However, these successional seres can only be studied in their full length – from barren substrate to vibrant ecosystem - if there are still glaciers left that continue to melt and leave freshly exposed substrate in their wake. With hindsight to the current pace of glacial retreat, it is a unique opportunity for ecologists to study the establishment of new ecosystems along the gradients of current glacial retreat.

Impression from the Hohe Tauern National Park. Left picture: The forefield of the Ödenwinkel glacier. The whole valley was covered by the glacier until 1850. Right pictures: Sign of the National Park and the terminus of the Ödenwinkel glacier with Robert, the senior author of this study, in the foreground.
Impression from the Hohe Tauern National Park. Left picture: The forefield of the Ödenwinkel glacier. The whole valley was covered by the glacier until 1850. Right pictures: Sign of the National Park (top) and the terminus of the Ödenwinkel glacier with Robert, the senior author of this study, in the foreground (bottom).

Due to rising global temperatures, most glaciers retreat since the late 19th century. Our study system, the Ödenwinkel glacier in the Austrian Alps, lost about 1.7km in length within the last 150 years. I remember well walking down from the glacier´s terminus across the forefield for the first time. You could see all the stages of succession laid out in sequence. In the early stages, recently exposed areas were still uninhabited, whereas in intermediate stages, flower-rich grasslands had already established that were soon to be accompanied by woody plants of the late succession. Certain species became less abundant or disappeared entirely, while others thrived and became dominant. All along the gradient, life interplayed with itself and the physical environment. Some examples were obvious: without plants there would be no pollen-producing flowers and without insects to pollinate there would be no seeds. Others are less obvious – belowground, fungal mycelia and bacteria break down dead plant material and animals and recycle their nutrients. Walking along a succession, you will find countless such interactions. All of them need time to develop and the further you walk, the more interactions you will find until finally, they all mound into a diverse and complex ecosystem.

Ödenwinkel - an alpine  platform for research on ecosystem complexity

Our aim is to achieve a holistic understanding on the processes that drive the emergence of such complex ecosystems. A few years ago, we set up a long-term ecological research and monitoring platform within the Ödenwinkel forefield. Every year our group spent a couple of weeks in the field to measure environmental parameters, collect insects, record plant species, and take microbial samples. For our recent publication, we used this data to calculate multidiversity, a measure of whole ecosystem biodiversity. Previous theoretical work suggested that successions are structured by ecological tipping points. When passing such a tipping-point, the ecosystem is abruptly boosted into a new, more complex developmental stage that is characterized by more and intensified biotic interactions.

To make the long story short: We could identify such a tipping-point and show that the formation of natural ecosystems follows the predicted trajectory of the theoretical framework! We show that structuring mechanisms in the ecosystem completely change before and after the threshold and that this change occurs abruptly within only a few years.  If you´re interested in the whole story, you can find our article here: https://doi.org/10.1038/s42003-022-03372-2

Currently, our glacier is receding another 30 meters every year and is expected to vanish within the next decades. Believe me, it is really frustrating to experience the devastating consequences of human-made climate change up close. Yet, climate change offers us a unique opportunity for fundamental biodiversity research that we should seize. Our group is already planning to set up more observational plots in the feshly exposed areas that the glacier has left over the last years. We will accompany the Ödenwinkel glacier until all the ice has melted and species rich ecosystems have developed instead.

Impression from field work. Left picture: A vegetation survey is performed on one of our observational plots close to the glacier. Right pictures, top: A common plant species in the forefield: Campanula scheuchzeri in flower. Bottom: Collection of soil samples for nutrient analysis (Special thanks to Xie He and Tobias Seifert (both on the picture) for making fieldwork much more pleasant and fun!).
Field work. Left picture: A vegetation survey is performed on one of our observational plots close to the glacier. Right pictures, top: A common plant species in the forefield: Campanula scheuchzeri in flower. Bottom: Collection of soil samples for nutrient analysis (Special thanks to Xie He and Tobias Seifert (both on the picture) for making fieldwork much more pleasant and fun!).

Literature: 

  • Allan, Eric, et al. "Interannual variation in land-use intensity enhances grassland multidiversity." Proceedings of the National Academy of Sciences 111.1 (2014): 308-313.

  • Chang, Cynthia, and Janneke HilleRisLambers. "Integrating succession and community assembly perspectives." F1000Research 5 (2016).

  • Junker, Robert R., et al. "Ödenwinkel: an Alpine platform for observational and experimental research on the emergence of multidiversity and ecosystem complexity." Web Ecology 20.2 (2020): 95-106.

Maximilian Hanusch

PhD-Student, Paris Lodron Universität Salzburg