Jura pastures under increasing pressure

Traditional Jura pastures are among the most species-rich habitats in Switzerland. Grazed at low intensity, the wooded pastures and shallow calcareous soils have created a complex landscape mosaic. This heterogeneous habitat with its typical small-scale structures such as outcrops, rock piles, uneven ground, bushes, free-standing trees and tree stumps provides ideal conditions for high biodiversity. Many threatened species or species that have become rare on the Central Plateau, like the Woodlark, still occur here. Core areas for this species include the Chasseral BE and Mont Racine NE with 18 territories (2017) and 14 or more territories (2016–2017), respectively. Substantial populations of the Eurasian Skylark are also still found here: up to 30 territories/km² were counted on the Chasseral. Northern Wheatear and Water Pipit mainly inhabit the upper reaches of the first and second Jura chains.

Steep decline of characteristic species

However, a sharp decrease of these characteristic species has become apparent since 1993–1996. Following a period of decline that lasted well into the 1990s, the overall Swiss population of Woodlarks has increased again in recent years, especially by colonising vineyards, but the same is not true in the Jura. In the eastern and central Jura in particular, its distribution has become smaller and patchier. The Tree Pipit has become scarcer since 1993–1996 as well. Distinctly negative trends were also recorded for the Eurasian Skylark during the same period, and singing males of Water Pipit and Northern Wheatear are now largely absent from the Jura east of Biel BE.

The overall Swiss population of Water Pipits has stayed the same since 1993–1996, making the steep decline in the Jura all the more striking. Similarly, the decline in Northern Wheatear numbers since 1993–1996 has occurred exclusively in the Jura. Tree Pipit and Woodlark populations have decreased more steeply in the Jura than in Switzerland as a whole. In the case of the Eurasian Skylark, the decline in the Jura corresponds to the Swiss average.

While land use has been intensified in the lower reaches of the Jura since the 1950s, the trend did not reach higher altitudes until the 1990s. As structural improvements and the streamlining of farming operations take hold, pastures are gradually intensified. The same development can be observed in the French Jura.

Devastating effects of intensification, especially where stone crushers are used

Among the numerous methods of intensification, the use of stone crushers is probably the most destructive. The machines break up the ground to a depth of 25 cm, completely eliminating rocks, stones, tree stumps, bushes and uneven patches of ground. The land is then sown with a species-poor seed mix or intensified through fertilisation and frequent mowing – with devastating effects for biodiversity. Managed in this way, once richly structured pastures lose their diversity forever.

Stone crushers have increasingly been put to use throughout the Jura since the early 1990s. Only the parts of the Jura range that lie in the cantons of Solothurn and Vaud have remained mostly unaffected. In the cantons of Jura, Bern and Neuchâtel, the machines have been used more frequently and across large areas (up to 13 ha). Although the use of stone crushers has been restricted by law in most cantons of the Jura since early 2000, they continue to be employed with or without a permit.

However, stone crushers are merely the tip of the iceberg. There are several other methods that produce a homogenised landscape (increased use of fertiliser, reseeding, more frequent and earlier mowing). Pasture and woodland are increasingly segregated, small structures are removed from pastures, and once open woodland is growing denser and darker. All bird species associated with naturally nutrient-poor pastures in the Jura are affected by this development. Recently, wind turbines installed on the Jura ridges have further restricted the potential habitat for these species of open landscapes.

Adequate compensation for sustainable land use is necessary

The few structurally rich Jura pastures that still remain today can only be preserved if they are inventoried according to standardised criteria and protected, with adequate compensation being offered for their maintenance. Important criteria for the protection of a site should include botanical quality, but also structural diversity. A general ban should be imposed on intensification methods that destroy habitat, such as the stone crusher, and their use penalised.