Focus

      Jura pastures under increasing pressure

      bild

      Structurally rich wooded pasture near Cortébert BE, providing habitat for Woodlark, Tree Pipit and a diverse flora. © Anatole Gerber

      Traditional pastures in the Jura support a great diversity of animals and plants, including endangered species like the Woodlark. But intensified farming practices are putting this valuable habitat under increasing pressure – with devastating consequences for its inhabitants. The use of stone crushers and the mechanisation of grassland management pose a serious threat to the Woodlark and other species.

      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.

      Population trend of the Tree Pipit from 1999–2016 with data from the common breeding bird monitoring scheme; the base year is 1999 with an index value of 100. The population has declined markedly in the Jura (blue curve), whereas the overall Swiss population (red curve) fluctuates.

      Population trend of the Eurasian Skylark from 1999–2016 with data from the common breeding bird monitoring scheme; the base year is 1999 with an index value of 100. The population in the Jura (blue curve) has declined more steeply than the overall Swiss population (red curve).


      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.

      Population changes of some characteristic breeding birds in the Jura (blue) and in Switzerland (red). The graph shows the 2013–2016 population size in % of its original size in 1993–1996. 100 % means that population size stayed the same; 50 % means that the population decreased by half from 1993–1996 to 2013–2016. The figures are based on the modelled maps for the corresponding survey period.

      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.

      In the foreground, the image shows a pasture that has been dug up by a stone crusher and re-seeded with an agricultural grass mix. The background shows the pasture near Cortébert BE in its original state, rich in species and structure.

      © Anatole Gerber


      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.

      Text: Nadine Apolloni


      Recommended citation of the Atlas online:
      Knaus, P., S. Antoniazza, S. Wechsler, J. Guélat, M. Kéry, N. Strebel & T. Sattler (2018): Swiss Breeding Bird Atlas 2013–2016. Distribution and population trends of birds in Switzerland and Liechtenstein. Swiss Ornithological Institute, Sempach.

      References

      Apolloni, N., P. Aeby, G. Hauser & I. Henry (2018): Alouette lulu dans le Jura suisse 2016/2017. Situation actuelle et évolution depuis les recensements 2004/2005. Station ornithologique suisse, Sempach.

      Apolloni, N., M. Lanz, S. Birrer & R. Spaar (2017): Intensification des pâturages maigres et pâturages boisés dans la chaîne jurassienne. Pratique et réglementation du girobroyage. Station ornithologique suisse, Sempach.

      Buttler, A., F. Kohler & F. Gillet (2009): The Swiss mountain wooded pastures: patterns and processes. S. 377–396 in: A. Rigueiro Rodríguez, J. H. McAdam & M. R. Mosquera-Losada (Hrsg.): Agroforestry in Europe. Current status and future prospects. Advances in Agroforestry series 6. Springer, Dordrecht.

      Gallandat, J.-D. & F. Gillet (1999): Le pâturage boisé jurassien. Bull. soc. neuchâtel. sci. nat. 122: 5–25.

      Gerber, A. (2018): Alouette lulu dans le Parc Chasseral: recensements 2017. Parc régional Chasseral, St-Imier, et Station ornithologique suisse, Sempach.

      Gerber, A., S. Müller, T. Schwaller, H. Schmid & R. Spaar (2006): Répartition de l'Alouette lulu Lullula arborea dans le Jura suisse. Situation actuelle et évolution depuis la fin des années 1970. Nos Oiseaux 53: 131–144.

      Gillet, F., F. Kohler, C. Vandenberghe & A. Buttler (2010): Effect of dung deposition on small-scale patch structure and seasonal vegetation dynamics in mountain pastures. Agric. Ecosyst. Environ. 135: 34–41.

      Gillet, F., L. Mauchamp, P.-M. Badot & A. Mouly (2016): Recent changes in mountain grasslands: a vegetation resampling study. Ecol. Evol. 6: 2333–2345.

      Gobbo, D. (1990): Avifaune nicheuse du pâturage boisé du Jura neuchâtelois. Nos Oiseaux 40: 385–406.

      Lachat, T., D. Pauli, Y. Gonseth, G. Klaus, C. Scheidegger, P. Vittoz & T. Walter (2010): Wandel der Biodiversität in der Schweiz seit 1900. Ist die Talsohle erreicht? Bristol-Schriftenreihe Bd. 25. Bristol-Stiftung, Zürich, und Haupt, Bern.

      Lachat, T., D. Pauli, Y. Gonseth, G. Klaus, C. Scheidegger, P. Vittoz & T. Walter (2011): Evolution de la biodiversité en Suisse depuis 1900. Avons-nous touché le fond? Collection Bristol vol. 25. Fondation Bristol, Zurich, et Haupt, Berne.

      Niemelä, J. & B. Baur (1998): Threatened species in a vanishing habitat: plants and invertebrates in calcareous grasslands in the Swiss Jura mountains. Biodivers. Conserv. 7: 1407–1416.

      Schläpfer, M., H. Zoller & C. Körner (1998): Influences of mowing and grazing on plant species composition in calcareous grassland. Bot. Helv. 108: 57–67.

      Stöcklin, J., V. G. Meier & M. Ryf (1999): Populationsgrösse und Gefährdung von Magerwiesen-Pflanzen im Nordwestschweizer Jura. Bauhinia 13: 61–68.

      Species concerned
      Subject
      Mountains & Alpine habitats
      Farming area
      Dry habitats and cliffs
      Land management & land use
      Species in decline
      Atlas bestellen