Plant species that invade an alien area and outgrow the native vegetation, establishing
and increasing their own territory, often lead to negative economic, environmental,
and social impacts. Even native species can behave like invasive species by their
exponential spread. Similarly, not all non-native species are invasive. Many alien
invasive species, however, do threaten the health and integrity of our terrestrial and
Biological invasions are one of the major threats to our native biodiversity. The
magnitude of biodiversity losses, land degradation and productivity losses of managed
and natural ecosystems due to invasive species is enormous. It has an adverse
impact on our efforts to maintain biodiversity and on our conservation programs,
and thus could create societal instability.
Our goal in writing this book was to describe
why weeds occur where they do. We have
made no attempt to discuss their management
and control: there are excellent texts
available for that. Rather, we think that students
should understand how and why
weeds fit into their environment. This text
presents ecological principles as they relate
to weeds. Ecology is central to our understanding
of how and why weeds invade and
yet there are few books that make this connection.
That is the niche we hope to fill.
When the early bands of English invaders came over to take Britain from its Celtic owners, it is almost certain that the soil was held by groups and not by individuals, and as this was the practice of the conquerors also they readily fell in with the system they found.  These English, unlike their descendants of to day, were a race of countrymen and farmers and detested the towns, preferring the lands of the Britons to the towns of the Romans. Co-operation in agriculture was necessary because to each household were allotted separate strips of land, nearly equal...
Blackleg fungi [Leptosphaeria maculans(asexual stage Phoma lingam) and
Leptosphaeria biglobosa] are devastating plant pathogens with well-estab-lished stratagems to invade crucifers, including the production of enzymes
that detoxify plant defenses such as phytoalexins.
In the spirit of place, Steve Apfelbaum and his partner, Susan
Lehnhardt, have found a unique spiritual connection through
their love of the land. To be “rooted in the land” involves actively
participating in a known landscape. Steve and Susan have
worked directly on the land, connecting both with it and with
each other as members of a community of interdependent parts
—soils, waters, plants, and animals.
They use geological and distribution
data on the island’s 1,284 plant genera and more than 2,000 endemic plant taxa to
identify 19 biomes there, and they describe complex conservation challenges. The next
chapter by Benny Chan and Pei-Fen Lee explores the biogeography of the barnacles of
Taiwan, relating taxon distributions to coastal geomorphology and the complex array
of oceanic currents around the island. Global climate changes in ocean water
temperature may permit southerly, warmwater taxa to expand northward, invading
habitat presently occupied by coldwater taxa....