Vegetation management and biodiversity enhancement in vineyards

Vineyards in Northern Switzerland are covered by spontaneous weed vegetation. From 1994 to 1999, the influence of ground cover management on botanical and faunistic diversity was analysed in vineyards of various wine growing regions. Eleven botanically homogenous vineyards were each split into two plots. One plot each was maintained with the cultivation intensity that had been standard measure by the respective farmer (treatment ‘high intensity’). Typically, this practise consisted of mowing or mulching the green cover several times during the growth period (alternating sequence for adjacent alleys), and mechanical soil cultivation (e.g. spading) once every second year. In the second plot (called ‘low intensity’), the treatment was slightly less intense (no reduction in yield and vine vigour).<br><br>Six years of different treatment intensity did not result in significant differences in the average number of plant species found (high int.: 55.8, low int: 51.2). However, with respect to individual plots, we observed a dynamical succession of plant species from annual to perennial species with increasing time after soil cultivation. Alternating spading of adjacent alleys proved to be an excellent measure to increase botanical diversity in vineyards. The abundance of flowering plants (food source for many insects) greatly fluctuated depending on cultivation measures.<br><br>Groups of the arthropod fauna (some pest species, hymenoptera parasitoids, predators) were assessed by exposing yellow sticky traps. Treatment differences were not consistent but several trends suggest that some groups of insects may be more abundant in the low-intensity plots. For the familiy of Mymaridae (minute egg parasitoids) it became evident that a temporal shortage in flowers, representing a bottle neck in food availability, resulted in a temporal decrease of the populations.<br><br>Our results confirm that ground cover management in vineyards of Northern Switzerland can combine both objectives, high quality production of wine and enhancement of biodiversity.