Science - October 22, 2009

Sheep cannot do their best

A flock of sheep on the campus is nice for the occupants, but their ecological value-added is limited at this moment. This is how Alterra employee Dr. Loek Kuiters sees it. Kuiters has written a report about sheep flocks in nature management six years ago. 'The campus is not a nature area, of course, and it does not have many special varieties.'

Kuiters: 'The ecological garden in Alterra is interesting. There are different soil types and as a result, a bio-diversity. In addition, different types of vegetation have been planted there and that's developing beautifully. Take the orchids, for example. In contrast, the land around the Atlas and the Forum is uniform and planted with a mixture of grass and clover. It is also compacted by heavy machines. The conditions there are not good for variety development.
The main value added by a shepherded flock of sheep is that the shepherd can direct his flock to spread pressure on grass usage over a wide area. The shepherd can drive his sheep in such a way that their stay on parts of the terrain is kept short, or to allow vegetation on certain parts to thrive longer to create a more moist environment to support insects and other creatures. He can also directly influence the spread of seeds. The sheep can carry seeds in their fur, hooves and droppings from the Alterra garden to the other side of the road.
The flock can graze the Alterra garden even after it is mowed and a part of the seeds is already gone. The sheep can be used mainly for prescribed post-grazing. Part of that grass will then survive for a while in the winter. Thanks to this, unusual species can germinate the following spring. But there should be enough spots with longer grass left over for all sorts of insects to make it through the winter. In grazing, you always have to look for the right balance between what is good for the flora and what is good for the fauna.'