Wild boar are heading to the fields

Late frost and drought also took their toll on forests in 2017.

With acorn and beechnut yields also poor that year, wild boar are now finding less food in the forest during winter.

After oak trees bore an abundant crop in many parts of Switzerland in 2016, this year’s harvest was weak — as is typical of the cycle. Beechnuts were also very scarce across the country in 2017, as the Forest Dynamics research unit of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) confirms.

Due to the limited winter food supply in the forest, wild boar can be expected to forage more in open areas, according to the Forest Office of both Basel cantons. Indeed, the Baselland hunting authority has already been observing more wild boar in fields and at «kirrungen» (feeding stations maintained by recreational hunters).

A recreational hunter from the Sissach BL area has also observed since the cold spell began in November that wild boar have been very active, rooting through piles of leaves and loose soil in search of food. But as far as food is concerned, the forest this year is essentially “empty,” which explains the already “enormous damage” to fields and crops.

Crop damage

Whereas damage reports in the canton of Baselland totalled 210’000 francs over the entire previous hunting year, the figure had already reached nearly 180’000 francs before New Year’s Eve — with a full three months of the hunting year still to go. On the upside, the animals are easier to target when they are outside the forest.

Because 2016 had been a so-called «mast year» with abundant acorns, but hardly any can be found in 2017, damage and culling are likely to increase significantly nationwide. Years with many acorns in the forest are called «mast years,» incidentally, because farmers used to bring their pigs into the forest to feed. Wild boar are now making the reverse journey. The fact that recreational hunting fails as population control is particularly evident in the case of wild boar.

Frost damage

In addition, the late frost in April, which had caused extensive damage in various orchards across the country, also harmed tree species that bud early. While the relatively late-budding beeches were largely spared according to the WSL, the early foliage of oaks was partially killed by frost. Affected trees produced new shoots once temperatures rose again.

However, valuable time in the growing season is lost before such secondary shoots produce new foliage, and the result is usually smaller leaves than normal. In the Basel region, oak leaves were in some cases barely half their usual size this year, according to the Office for Forests.

The fruit yield of affected trees is correspondingly reduced, though this is less noticeable in a poor mast year. If plants bud earlier more frequently due to climate change, the risk of damage from sporadic late frosts will also increase.

Drought damage

The severe drought of the ending year has also weakened trees in some areas. For instance, in some apparently healthy forests, an increased number of apparently healthy branches were found lying on the ground — a stress signal, according to the WSL.

In particular, the Jura arc and western Switzerland were below the long-term average rainfall for almost the entire year, according to precipitation data from MeteoSwiss. Conditions were especially dry at the beginning of autumn, when in many areas less than a third of the usual rainfall was recorded. It was not until November that large parts of Switzerland received significant precipitation.

The dry year of 2017 is no anomaly: while the southern foot of the Jura, from Lake Geneva to Schaffhausen, has long been one of the drier regions of the country, the northern foot of the Jura is also becoming increasingly dry, which is altering the range of species present. Researchers anticipate cycles of 80 to 100 years in this regard.

For example, sycamore maple and silver fir are increasingly struggling in the Basel region, and according to the Office for Forests of both Basels, they are visibly suffering from the drought. Some forestry operations already see their disappearance on the horizon. More on this under Environment and Nature Conservation.