Red deer's eating habits change the forest ecosystem


Northern European red deer population numbers are today at a historically high level. In Norway, the species’ highest population densities occur in the areas of western Norway, but geographically it is expanding. As a result, red deer are increasingly hunted in the south, east and north of Norway.

Management challenge
"The red deer expansion creates new challenges for wildlife managers," PhD candidate Marte Synnøve Lilleeng says.
“In some regions it is in all practical terms a new species. What effects will it have on the environment around it?”
She further explains that in order to predict and understand the consequences of the deer's expansion, we need knowledge about how the deer can directly and indirectly change the ecosystems in which it lives.
“Then we can set better management goals.”

Ph.d.-kandidat Marte S. Lilleeng har studert effekten av hjortens beiting på den boreale skogens plante- og insektsamfunn.


Plants and insects
In her doctorate thesis, Lilleeng has focused on improving our knowledge of how the deer affects the boreal forest. She has studied the effect of the deer on both the plant and insect communities on the forest floor. Location has been on Svanøy outside Florø in west-Norway.

Different effects
Lilleeng's research shows that the deer affects the plant and insect communities differently.
"It increases the general species diversity of plants, but trees and heather plants are limited, so that the forest floor becomes more herbaceous where the deer browse," says Lilleeng. This may be beneficial to pollinators, for example.
The deer's eating habits makes forest floor’s plant distribution more homogenous, whereas the opposite happens to the beetles:
"In areas with deer browsing, beetle diversity differ more among sites," she says.

Some win, others lose
Even beetles that are not usually associated with large mammals are affected by deer densities. Some species win where the deer is present, other species lose. Lilleeng also found that the red deer limits leaf-eating insect larvae.
"These larvae are an important part of the diet of many other animals and birds," she says.
Consequently, the deer's feeding habits can have so-called cascading effects on the ecosystem.
“Thus, other species than those that immediately spring to mind can be influenced and dependent on red deer management goals.”

Ph.d.-kandidat Marte S. Lilleeng (MINA) i felt.



Must be included in the calculation
The results from Lilleeng's PhD project point out that it is important to include the density of deer species in the assessments for the management of vulnerable species or natural habitats.
“Which animal density that is the optimal number will vary with area, and the protection status of the given area,” she adds.

New era?
Is there a new era in Europe's wildlife management? While red deer numbers are increasing, it is not necessarily true that this growth will continue. Recently, the Chronic wasting disease (CWD) was discovered in wild ungulates in Norway. First in wild reindeer, then in deer and moose. It can be very contagious and is always deadly. This is the first time this serious prion disease has been detected in Europe.
The findings from Lilleeng's research show that major changes in Norway's deer wildlife stocks, both reduction and increases, can dramatically change the way forests will look and function in the future.

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26 Oct - Marte Synnøve Lilleeng (MINA)

26 Oct - Marte Synnøve Lilleeng (MINA)

Marte Synnøve Lilleeng, Faculty of Environmental Sciences and Natural Resource Management (MINA), will defend her PhD thesis "Ecological impacts of red deer browsing in boreal forest", on October 26 2018. 

Published 24. October 2018 - 17:02 - Updated 25. October 2018 - 16:32