New study: How forestry affects moose – and how moose shape forests

Large herbivores such as moose and reindeer are a natural part of forest landscapes, and their role in the ecosystem is complex. Through browsing, trampling, and nutrient inputs, they influence both vegetation and soil processes – and thereby how forests develop over time. At the same time, where moose choose to spend their time depends on forest structure and conditions.

“We are trying to better understand how large herbivores use different types of forests, and how this in turn interacts with plants, lichens, and fungi,” says Hjalmar Stake, PhD student in the Wallenberg Initiatives in Forest Research programme at the Swedish University of Agricultural Sciences.

In a new research project, he and his colleagues are comparing 36 forests in northern Sweden, half of them managed and half unmanaged by modern forestry. The forests vary in age, from recently harvested stands to forests that have developed over several hundred years.

“Comparisons of managed and unmanaged forests over time have rarely been done at this scale to understand the interactions between animals and other components of forest biodiversity,” says Hjalmar Stake.

Understanding cause and effect

By surveying vegetation and ground flora, measuring browsing pressure, and counting droppings, the researchers can determine how animals use the landscape, which forests they prefer, and when. They will also investigate how the availability of lichens – an important food source for reindeer – is affected by forestry and forest age, and how this in turn influences where reindeer choose to be.

However, studying where animals are found is not enough to understand how they influence, and are influenced by, biodiversity. The field studies are therefore combined with experiments.

In fenced plots, where large herbivores have been excluded for up to 15 years, researchers can compare how vegetation and soil develop with and without the presence of these animals. Soil samples are collected from both fenced and open areas to examine how trampling and nutrient inputs affect soil properties and fungal communities.

By increasing our understanding of how large mammalian herbivores influence forests, this research can contribute to more sustainable decision-making in future forestry.