Monitoring lichens and mosses in Dronning Maud Land
Introduction
The terrestrial vegetation of Dronning Maud Land is sparse and consists of lichens, mosses and algae. The growth rates of Antarctic lichens at continental localities have been measured to 0.1 mm per year. This means that the development of lichen communities is a slow process, sensitive to human disturbance. According to the Protocol on Environ-mental Protection to the Antarctic Treaty, “procedures shall be put in place, including appropriate monitoring of key environmental indicators” (Antarctic Treaty, Annex I, Article 5). In Antarctica the lichens and mosses are such key environmental indicators and consequently monitoring the lichen and moss vegetation is part of the Environmental Project run by SWEDARP since 1991/92 (Modig, 1999).
In the austral summer season of 2001/02 I participated in the SWEDARP expedition to Dronning Maud Land and my mission was to survey the lichens and mosses in the permanent sample plots that were established by Göran Thor (Thor, 1997) around the Wasa and Svea research stations in 1991/92. The main objective with this survey was to evaluate whether there have been any changes in species richness and abundance during the last ten years and if so, whether these changes differ between the sites close to the research stations and the reference sites.
Hithertho there have been very few published studies on long-term monitoring of the lichen communites in Antarctica, and none have aimed at evaluating the human impact on species richness and abundance. Existing studies have primarily focused on growth and colonization rates (Kanda and Inoue, 1994, Smith, 1995). Besides evaluating the possible impact of human activities, the sample plots around Wasa and Svea stations may also be used to indicate vegetation changes caused by other factors. In a long-term monitoring study of the only two native vascular plants of Antarctica, Colobanthus quitensis and Deschampsia antarctica, Smith (1994) found an increase in abundance of these species to correlate with increased mean austral summer temperatures in maritime Antarctica. Barbraud and Weimerskirch (2001) reported a drastic decline in the Emperor penguin population in Terre Adelie, as a possible effect of reduced sea-ice extent. These results indicate that climate change may have significant impact on the Antarctic ecosystems. Further, the increased UV-B radiation due to the depletion of stratospheric ozone above Antarctica may be expected to affect the vegetation, since UV-B radiation has been found to damage plant DNA (see Rozema et al., 2001). However, there are so far no unequivocal responses in plants and lichens performance after experimentally altered UV-B radiation (e.g. Lud et al., 2001, Rozema et al., 2001).
The fieldwork
The field work was carried out between 14 December 2001 and 20 January 2002. I found no difficulty in repeating the methods described by Thor (1997) and it was fairly easy to find the transects and sample plots again. The major obstacle was the weather, and due to extensive snow cover during this austral summer period I had to exclude some of the plots. Especially the field work at Svea in Heimefrontfjella was a struggle against the weather. We arrived there on 3 January and the next day around 20 cm of snow fell and covered the ground, beautiful but annoying! At the time this snow had melted away a severe storm struck us with wind speeds up to 40 m/s, blowing lots of snow into the sample plots again. However the storm calmed down, the snow melted and during the final days at Svea I managed to complete a good enough number of sample plots to allow analyses of both changes in species richness and abundance for most of the transects. In all, I could finally survey 81 of the initial 120 plots and only one of the original transects had to be excluded in the subsequent analyses.
Preliminary results
I found in all 23 lichen species compared with 20 in 1991/92 for the corresponding 81 plots. The result suggests an increase in both mean species number and abundance per sample plot and the preliminary analyses also support such an overall increase. The lichen cover in the sample plots was generally very low, which reflects the harsh conditions of continental Antarctica. For example the maximum lichen cover, recorded in transect 5 at Heimefrontfjella, was only 3.5% of the sample plot area.
Most transects showed a high consistency over the 10 years. Some plots in transect 7, which is located just behind the Wasa station, were affected by driving with track vehicles and some plots in transect 4, which is located at the same small hill as the Svea station, had clearly been affected by activities from maintaining the station and keeping gear on the ground.
There are very few long-term studies of the vegetation in Antarctica, especially at continental sites. The sample plots in the Wasa and Svea areas cover all lichen species and the number, 120 plots, is fairly high. This makes them unique and very valuable not only for monitoring the human impact but also for detecting overall environmental changes in Antarctica. The results from these plots may also suggest future detailed research on key species and processes.
Lichen investigations at the summit of Plogen
While waiting for the snow to melt away from the transects I had time to explore the lichen vegetation in other areas at Basen and Heimefrontfjella in order tomake notes complementary to the surveys by Göran Thor in 1991/92. At the end of the season I also had the opportunity to visit the summit of Plogen, almost 900 m.a.s.l. Plogen is one of the few localities in the area that was not visited by Thor in 1991. This visit was very rewarding since the summit of Plogen showed a remarkable species richness.
Dates
14 December 2001–20 January 2002
Participants
Principal investigator
Per Johansson
Department of Conservation Biology, Swedish University of Agricultural Sciences
Uppsala, Sweden
References
Barbraud, C. and Weimerskirch, H. 2001. Emperor penguins and climate change. Nature 411, 183–186
Kanda, H. and Inoue, M. 1994. Ecological monitoring of moss and lichen vegetation in the Syowa station area, Antarctica. Proceedings of the NIPR Symposium on Polar Biology 7, 221– 231
Lud, D., Huiskes, A.H.L., Moerdijk, T.C.W. and Rozema, J. 2001. The effects of altered UV-B radiation on an Antarctic grass and lichen. Plant Ecology 154, 89– 99
Modig, A. 1999. Environmental project – SWEDARP 1997/98. In: Polarforskningssekretariatets årsbok 1998. Grönlund, E. (ed.). Polarforskningssekretariatet, Stockholm, 52
Rozema, J., Broekman, R., Lud, D., Huiskes, A.H.L., Moerdijk, T., de Bakker, N., Meijkamp, B. and van Beem, A. 2001. Consequences of depletion of stratospheric ozone for terrestrial Antarctic ecosystems: the response of Deschampsia antarctica to enhanced UV-B radiation in a controlled environment. Plant Ecology 154, 103–115
Smith, R.I. Lewis. 1994. Vascular plants as bioindicators of regional warming in Antarctica. Oecologia 99, 322–328
Smith, R.I. Lewis. 1995. Colonization by lichens and the development of lichen-dominated communities in the maritime Antarctic. Lichenologist 27, 473–483
Thor, G. 1997. Establishment of permanent plots with lichens and mosses for monitoring local human impact on environment in Heimefrontfjella and Vestfjella, Dronning Maud Land, Antarctica. Antarctic Record 41, 652–672