What is the impact of deer on the forests and meadows of Aubrac? Studies to measure it

What impacts do deer have on meadows and forests? Since 2029, the Aubrac Regional Natural Park has been carrying out work to measure the quantity of grass grazed by deer. Around thirty exclosures are installed in meadows in the valleys of Saint-Chély-d'Aubrac, Castelnau-de-Mandailles and Prades-d'Aubrac.

These very simple installations, four construction site grids arranged in a square in the middle of plots which are not grazed by cattle, make it possible to measure the quantity of grass which grows inside and to compare it to that which grows around it, grazed by deer.

30% loss of fodder

“Now that we have hindsight over five years of measurements, we can affirm that the data collected is significant, explains Marieke Paardekooper, forest mission manager at the Park. The main information we draw from this work is that the loss of forage due to deer averages nearly 30%, a result which is relatively stable from one year to the next..”

These results were presented to partners in this sector, hunters, farmers, mayors as well as to the general secretariat of the prefecture which is leading consultation on this subject.

The impact on forests

But forests can also suffer from too many deer.

A second action program carried out by the Park made it possible to monitor around ten exclosures located in forests, both in Aveyron, Cantal and Lozère. Installed since 2021, we had to wait four years to give the vegetation time to properly evolve before being able to conduct a very first observation protocol. “Our data is not yet significant. However, a trend seems to be emerging: it would be the shrubs (between 0.5 and 3 m high) which would be most impacted. Does, stags and roe deer love tender buds, rubbing their antlers on young trunks until they break…“

A definite impact for forestry operators who find that forests are more difficult to regenerate and that their plantations have difficulty developing properly.

Balance

“The action of the Park is essentialexplains Christian Malavieille, president of the Association of Forest Communes of Lozère.The Park first makes it possible to produce objective and localized measurements to better understand the problem. It also monitors this deer-forest balance over time. But above all, on a subject that is usually very passionate, it makes it possible to initiate a dialogue between foresters, farmers and hunters on an objective basis.“

These observations will be repeated every four years, before producing consolidated results.