Exotic species introductions

Exotic species. The voluntary or accidental introduction of exotic species may influence the trophic stractrrre of aqrratic systems (Hrabik et al. 1998), thereby affecting MeHg concentratiorrs in aqrratic organisms in upper... 

A downside of the rise of mammals, specifically including humans, is that the sixth major extinction of life on Earth is happening now. As noted above, we are losing 4-6 species an hour, 27,000 0,000 species a year, mostly in the tropical and subtropical forests. The tremendous loss of species is the result of habitat destruction, overhunting, introduction of exotic species of animals and plants into new habitats, and the diseases carried by these exotics. One of the most valuable resources on Earth— biodiversity—is being sacrificed, fhe result of a burgeoning human population and its activities. 

Terrestrial recovery is even more difficult to project than aquatic recovery. Given the life span of trees and the delay in the response of soil to decreases in acidic deposition, it is reasonable to suggest that decades will be required for affected trees on sensitive sites to recover once chemical conditions in the soil are restored. Overall, the timing and extent of chemi cal and biological recovery depend on how soon and how significantly emissions that cause acidic deposition are reduced. Moreover, human influences (e.g., land disturbance, introduction of exotic or invasive species), in addition to acidic deposition, can delay biological recovery after chemical recovery has occurred. 

In the introduction we defined exotic as beautiful, exceptional, weird, paradoxical, and counterintuitive. We also indicated that such species could represent fragile and rare as well as simple and well-characterized classic inorganic compounds. In this section we will look at two of the simplest inorganic classes of compounds polyphosphorus and polynitrogen species. We will dwell on the following elementary question Why is it that polyphosphorus allotropes of the element are well known (white phosphorus black phosphorus in its orthorhombic, rhom-bohedral, and cubic forms red, amorphous phosphorus). 

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