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Juniper studies on Harris

Two students from Germany have spent their summer studying Dwarf Juniper on the summits of the Harris Hills. Their studies will add to our knowledge of this important plant, helping us conserve its populations on Harris. Below is  Maria and Frauke’s account of their stay.

Frauke (left) and Maria (right)

Our names are Frauke and Maria. We are students of Landscape Ecology at the University of Oldenburg in the north of Germany near the North Sea. After a great trip with the university around the Hebridean Islands last year, we made the decision to come back to Harris. Duncan MacPherson made it possible. With his help we got a masters thesis in our main interests; Botany.

The North Harris Trust is especially interested in baseline data about the Dwarf Juniper (Juniperus communis ssp. nana): Which factors are important to influence or restrict its distribution and what is about the health of dwarf juniper populations on North Harris?

Juniper berries

What we have done?

We have had 3 study sites where Dwarf Juniper is growing. This study sites are on hills around Tabert including Beinn na Teanga, Giolabhal Glas and Tomnabhal. At first we created a datasheet which contained information about the vegetation as well as the whole environment of each plot. We measured, coordinates of each plot, vegetation height, slope direction, grade of slope, geology, soil depth, altitude, land management and animals around the area. We wrote species lists per plot which contained the species´ coverage.  For Juniper we counted its cones and berries, measured its size, age, vitality, disturbance, influence of aninmals (eating), of wind and other plants. Altogether we were looking to find out where Dwarf Juniper is growing and what affects it distribution. Our homework was reading texts about the Juniperus communis and measuring pH- values.

view from Giolabhal Glas

Some results

All together we viewed 133 plots with 73 presence samples and 60 absence samples within 249 dwarf juniper plants (6 seedlings, 108 male plants, 80 female plants and 61 sterile plants). Mostly plants are mature. We found 4 generations of berries and a lot of cones. Influences of sheep, hare, deer and grouse were determined by examining their droppings. The soil is mostly ranker (first generation of soil) with a mean soil depth of 10 cm. Most important is the slope direction – South West. The vitality of all plants we have seen seems to be really good.

With this information and baseline data we were able to determine which factors influence the distribution of juniperus communis ssp. nana in North Harris. Our hypothesis includes depencies on altitude, wind direction, direction of slope (exposure) and on the cover of rocks.

Juniperus communis ssp. nana in North Harris is a big and healthy population with a lot of plants at suitable altitude and exposure. So if you want to see some dwarf juniper, you have to climb up a hill to a minimum altitude of 300 m.

collecting the data

What to do when we will be back in Germany?

We have to write down all our data, hypothesis and results in 2 Masters thesis with the subjects of population ecology and habitat modelling. The statistical analyses will be important to find out the factors which are influencing the Dwarf Juniper. Also we will produce a suitability map for the Dwarf Juniper. And finally we will have Masters in Landscape Ecology.

In total we loved the time on North Harris. We have been here for 3 months. Beautiful landscape, a lot of nature, really nice people and a lot of Scottish culture were finally absolutely amazing.

Finally we’d like to thank the North Harris Trust who made it all possible.


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