River Ecology and Restoration - River Dynamics and Integrated River Management - page 660

2006; Morton, 1977a), hot water spraying to kill golden mussels (Morton, 1975), medicaments to kill
golden mussels rapidly (Yamada et al ., 1997), culture species of fishes preying golden mussels, injecting
certain steroids to disturb the normal spawning (John and Peter, 2001), and artificial or mechanical
clearance during overhaul periods. Nevertheless, no effective and safe measures have been found to
control the mussel. At present artificial or mechanical clearance during overhaul periods is the only
effective and safe measure although it is expensive and causes intermittence of water supply.
Introduction of plant species may also cause stress on animal species. It was reported in the China
Daily on Aug. 14, 2003, that the natural habitat of giant pandas, rare animals living mainly in China's
Qinling Mountain range, is being threatened by larch forests (Fig. 10.38). The story is as follows: “In
recent years farmers in Sha-anxi province introduced larch trees because of its low planting cost, high
survival rate and quick maturation into useful timber. However, the blind introduction of larch trees into
the panda protection zones has severely depleted the groves of bamboo, the food staple of pandas. Larch
trees have large crowns which can cause plants growing beneath them to die from a shortage of sunshine
and water. And larch seeds, spread by birds and the wind, grow quickly. This can seriously impact the
growth of surrounding plants. The introduction of larch into Qinling Mountain areas started in the early
1980s. In Foping County, the major home of pandas, more than 1,333 hectares of larch trees have been
planted and the damaged bamboo forest cannot be recovered. The situation is also worsening in other
protection zones, such as Changqing and Yangxian. The corridor linking panda clans in Ningshan and
Foping has now been destroyed by larches. The habitat was decreased and the animals will suffer from
the lack of food. Experts warned that the pandas will lose their home if the larch is not put under control,
and the local government is expected to take measures soon.”
Fig. 10.38 Natural habitat of giant pandas is being threatened by the introduction of larch trees and rapid development
of larch forests (See color figure at the end of this topic)
Introduction of exotic species has inevitably occurred worldwide and this is accelerating following
economic and ecologic globalization. Compared with faunal species, introduction of floral species is
quicker and more intensive because humans pay less attention to the negative impacts of the introduction.
The introduction of exotic species, whether intentional or not, can cause disruptions such as hybridization
and the introduction of diseases. Nonnative species compete with native species for moisture, nutrients,