Natural and anthropogenic determinants of biodiversity of grasslands in the Swiss Alps

This thesis studies natural and anthropogenic determinants of grassland
biodiversity in the Swiss Alps at the levels of plant communities within a landscape
(Chapter 2), species diversity within plant communities (Chapter 2 and 3), biological
interactions between plants and herbivores and pathogens (Chapter 4), and diversity
within a species (Chapter 5-8). Within-species diversity is studied in the widespread and
agriculturally important grass species Poa alpina L.
Conclusion
With our comprehensive study across 12 villages we could demonstrate that
human land use affects biodiversity at all levels and has largely shaped present
biodiversity during the hundreds of years of agricultural activity. Additionally, we
showed that cultural traditions still affect man-made landscape diversity. Still persisting
socio-economic differences among cultural traditions are likely to be responsible for this
cultural effect.
The reduction of labor for farmers by grazing of formerly unfertilized meadows or
abandonment of pastures and meadows will reduce land use diversity, and the number of
parcels of high biological value used at low intensity will decrease. Thus, biodiversity
will decrease both between and within grassland parcels. Therefore, financial incentives
are needed to stop the ongoing changes in agriculture in order not to risk losses in
biodiversity. Financial incentives should promote high biodiversity within parcels of
land, but as not all levels of biodiversity react in the same way a high landscape diversity
at the village level is also necessary.
Unfertilized meadows are the most laborious type of grassland, and therefore they
are most likely to get abandoned, especially when they are steep and at high altitudes and
thereby not easily accessible. Due to their significance for plant species richness and
composition, financial incentives for the conservation of these unfertilized meadows are
especially important.
We showed that, in contrast to widespread reservations against grazing,
particularly low-intensity grazing has several positive aspects at all levels of biodiversity,
and from a biodiversity point of view, grazing is clearly preferable to abandonment of
grasslands.
In summary, to protect biodiversity at all levels of biological integration, a highly
diverse landscape has to be promoted. Therefore, financial incentives should aim at high
land use diversity, which is likely to be most successfully promoted at the village level.
A reduced diversity of land use types or even abandonment of whole regions will
severely reduce biodiversity. At the same time, landscape attractiveness for tourists will
be reduced and the remnants of cultural heritage in the Swiss Alps will be endangered.
The conservation of all levels of biodiversity and of their cultural, esthetical, ecological,
and economic value requires the persistence of the diverse landscapes of the Alps.