Fencing in on climate issues

Fencing in on climate issues

Top image: Counting all plant species in each of the vegetation plots is time consuming and painstaking, but associate professor Elisabeth Cooper (left) and student Allison Bailey get the job done. Photo: Eva Therese Jenssen/UNIS.

Climate change may bring more snow in the winter on Svalbard. Can the plants that thrive in the current harsh Arctic climate survive such a development? UNIS biologist Elisabeth Cooper hopes to find the answer – with the help of snow fences.

12 July 2007
Text: Eva Therese Jenssen

The 12 fences are constructed at the foot of the Mine 7 mountain in Adventdalen, just a few kilometers from Longyearbyen. These are snow fences, an important part of an ongoing research project ”More Arctic Snow”, headed by UNIS associate professor Elisabeth Cooper. The fences were put up last fall to catch snow. The research project is looking at how plants currently thriving in Svalbard, will cope with increased amount of snow in the winter.

Changing Arctic = more snow?
The predictions for climate change in the Arctic are for warmer weather – especially in the winter – and more precipitation. If this falls as snow there could be a deeper and longer lasting snow pack in areas which currently experience only 10-20 cm snow. How will such changing conditions affect the plant species now thriving in Svalbard?

This question will hopefully be answered by the snow fence project, which not only involves Svalbard, but also Alaska, Greenland and Sweden, where scientists are looking at the effects of increased snow precipitation on the Arctic vegetation.

The main winter winds in Adventdalen come from the east, and the fences are constructed so as “catch” the snow which gathers to the west of the fence in larger heaps than in the surrounding area.

Vegetation plots measuring 80 x 80 cm are currently marked off and Cooper together with master students Elke Morgner (Germany), Ditte Strebel (Denmark), Mats Björkman (Sweden), and Fulbright student Allison Bailey (U.S.A) will look closer plant development during the summer and at soil temperatures and gas fluxes year-round in the fence area and nearby controls.

Dark prospects for the Mountain Avens
The two plant species the group is focusing on is the White Arctic Bell-Heather (Cassiope tetragona) and the Mountain Avens (Dryas octopetala).

– We are focusing on these two species in particular because they have opposite requirements for prospering in the high Arctic, Elisabeth Cooper says. – The White Arctic Bell-Heather likes to be buried under snow during winter and we expect it will not be too badly affected if the winters in Svalbard will bring more snow.

– The Mountain Avens, on the other hand, is mostly found on ridges sticking above the snow cover during winter and this plant can tolerate quite cold temperatures, so we expect it will do worse if the future winters will bring more snow, Cooper explains.

Their summer field season started on June 6. The snow cover behind the fences was about 20-30 meters long, whereas there was no snow in the surrounding areas at that date. From then on and until August, Cooper and her students will look at how the plants in the fence areas are developing by looking at how long it takes until the leaves and flower buds develop.

– We can already now see that the later snowmelt behind the fences has led to a greatly delayed plant development for many species, Cooper says. – Behind the fences plants have just started to develop flower buds by early July whereas both Bell-Heather and Mountain Avens are in full bloom in the area outside the snow fences. We are really interested to see if the plants behind the fences will be able to produce mature seeds by the end of August, or whether the later snow melt will have shortened their growing season too much, she says.

Increased CO2 emission
But it is not only plant developments the team will look at in this study that will go on until 2009. In addition, Elke Morgner and Ditte Strebel will measure the carbon dioxide emission from the plants.

-We will measure both the CO2 intake (photosynthesis) and outlet (respiration) in summer to find the net amount of carbon that the plants take up, and compare this with the carbon lost by respiration from the system during winter to see how much the snow affects the CO2 emissions, Cooper says.

Deep snow should act as an insulating layer during winter, enabling warmer plants and microbes to emit more CO2 during their burial under the snow. There are vast areas of tundra and their ability to act as a global carbon source in a warmer future is of worldwide concern at present. In addition Mats Björkman will take out gas samples from the different snow layers to see how gas travels up through the different snow levels. This has of course implication for the amount of CO2 getting to the atmosphere.

How much effect more snow will have on the plants, remains to be seen. However, already after one season with manipulated snow accumulation, it is clear that both the Mountain Avens and White Arctic Bell-Heather are responding to a changed winter climate and a shorter growing season. In the long run it is possible that the plant community will change, some species will disappear and others more suited to a deeper snow pack and shorter growing seasons will turn up.

Certainly future scenarios for climate in the Arctic can be more complicated than just warmer summers, which is what has been studied until now. The changes in temperature and precipitation throughout the year are bound to affect the plants presently on the archipelago, and the new species which will find their way to Svalbard.

Elisabeth Cooper and Allison Bailey in Adventdalen

Associate professor Elisabeth Cooper and Fulbright student Allison Bailey in front of one of the snow fences in Adventdalen. Photo: Eva Therese Jenssen/UNIS.