Delta evolution in Greenland

Two weeks ago, I had the great fortune to publish a paper in nature together with a team of amazing cryosphere scientists.

The study system during the last two years. The delta plain, the hinterlands and the surrounding ocean @Nikolaj Krog Larsen.

The paper is freely available here

In the study, we show that deltas in the southern half of Greenland have grown over the past few decades, following a period of stability in the mid-twentieth century. Furthermore, we tie these delta expansions to periods of reduced sea ice and increased melt from the Greenland Ice Sheet. Throughout the Arctic, coasts have shown erosional trends, and deltas in particular, are known to drown all over the globe – Our results are interestingly showing, that as a consequence of climate change and increased run-off from the glaciers and ice sheet, Greenlandic deltas are growing.

The study started as dinner conversations between Mette and I where we discussed some of Mette’s recent delta work on the island of Disko at the west coast of Greenland (Bendixen & Kroon 2017 ESPL). In the beginning, it was most about potential fun applications of different non-parametric models but quickly turned into the ambition of upscaling the study from Disko.

Crucial was the realization that open sources images from Google Earth could be binned to an archive of historical aerial images from the 1980s. Images stored in a large archive at the Geo-data agency in Copenhagen together with other image archives from the 1940s and 1960s. From thereof the project did grow step by step and thanks to the incredible hard work of Mette and the other co-authors we have been able to place rapid changes of the Greenlandic landscape in the global spotlight

Working on the first resubmission.

Second resubmission.

Personally, the project has been a first encounter with arctic research. Although I’m not a geologist, nor will I ever be, it’s been extremely rewarding to work with strict landscape patterns (no ecology...). Of course, the project has produced more questions than answers and a cascade of interesting spinoffs is now emerging. So, more exiting arctic research to come!

Atlas of the European dragonflies and damselflies

During the past decade over fifty European odonatologist have been co-operating to bring together all published and unpublished distribution records of the 143 European species of dragonflies and damselflies. The results of this endeavor will appear December 2015 in the Atlas European dragonflies and damselflies.

This is the first detailed and complete overview of the distribution of the dragonflies and damselflies of Europe. The book includes over 200 distribution maps showing both the European and global distribution of the species. Further included is information on taxonomy, range, population trends, flights season-, habitat, photos of nearly all species and for each country an overview of the history of odonatological studies.

The work was coordinated by Jean-Pierre Boudot and Vincent Kalkman and together with Erland Refling Nielsen, I contributed with the Danish database and supported some of the chapters in the book. The main part of the data collection was done way back in 2009 when I was still a BSc student. It’s really great to finally see the result of all the hours spend in the museum collections in print.  

Dragonlife

Following the recently finished EU LIFE project DROGONLIFE colleagues and I have published a study on the Yellow-spotted Whiteface Leucorrhinia pectoralis in Estonia. In the paper we show that the mikrohabitat niches of L. pectoralis derived directly from local distributions are significantly constrained by the land use history of a given landscape.
We recorded the presence/absence of L. pectoralis and measured 7 habitat variables for 140 lakes and ponds located in one restored and three un-restored landscapes in Estonia. Lake size and proportion of short riparian vegetation were significantly positive parameters determining the presence of L. pectoralis across landscape types. However, the species was much more habitat specific in the restored landscape, with larger influence of other habitat parameters. Our data suggest that the realized niche of the species in the un-restored landscapes was constrained by the present-day habitats.
The study demonstrate that if a species realized niche is derived from local species distributions without incorporating landscape history it can lead to an erroneous niche definition. We show that landscape restorations can provide knowledge on the species’ habitat dependencies before habitat degradations occurred, provided that restoration mitigation reflects the former landscape characteristics.

Independent contributions (percentage of the total independent explained variance) of habitat predictor variables of the restored landscape (white bars) and un-restored landscapes (black bars)

Iversen L.L., Rannap R., Briggs L. & Sand-Jensen K. (2015): Variable history of land use reduces the relationship to specific habitat requirements of a threatened aquatic insect. Population Ecology DOI: 10.1007/s10144-015-0516-z pdf pdf