Floral Splendour and Shortage of Nutrients - Soil: Reflections on the Basis of our Existence - page 49

The advent of artificial fertiliser was a disaster for meadow flora, which were
choked by grass when fertiliser was spread on meadows. Much of the nitrogen
ends up in watercourses and ultimately in the sea, where it can be a major haz-
ard. Increased concentrations of nitrogen and phosphorus in marine environments
can result in algal blooms. Eutrophication is today one of our most serious envi-
ronmental problems, on a par with the twin challenges of climate change and the
mass extinction of species that are accompanying our unrelenting exploitation of
the Earth's resources.
On pastureland, grazing by animals is the key factor that dictates the local
flora. It is important for plants in this environment to preserve their growth cen-
tres sufficiently deep below the surface to stay out of the reach of grazing live-
stock. Likewise, thistles grow prickles to deter grazing animals, while some plants
exploit the cover afforded by blackberry scrub as a nursery. Other species, such as
buttercups, emit poison to dissuade animals from eating them. Fortunately, butter-
cup toxins are destroyed when the leaves dry, making hay safe to eat. Some flow-
ers will choose to bloom beside heat-absorbing rocks, while others prefer a damp
hollow.
The pasture and meadow at Hörjelg￥rden farm has never been cultivated or fer-
tilised. Here, up to forty different species of plant can be found in a single square
Thoughtful thorns. In Africa, the leaves of the acacia tree are attractive food for grazing animals
such as wild gazelles, sheep and goats. To avoid being grazed bare, the tree has evolved strong
thorns on its lower branches within animals' reach. Higher up, towards the crown, it does not
need to waste its resources on these costly constructions