Many species infire-prone landscapes are notonlyfire tolerant, but depend onfire to completetheir life-cycles and to retain a competitive edgein their environment. Such species typicallybenefit from the conditions that prevail follow-ing afire, such as increased resource availabilityassociated with the destruction of both livingand dead biomass, nutrient-rich ash, and high

The key to eradicating an introduced species be-fore it can spread widely is an early warning-rapid response system, and early warning re-quires an ongoing monitoring program. Becauseof the great expense of trained staff, few if anynations adequately monitor consistently for allsorts of invasions, although for specific habitats(e.g. waters in ports) or specific groups of species(e.g. fruitfly pests of agriculture) intensive ongo-ing monitoring exists in some areas.

inmany tropical countries comprise an‘invisible’commodity and local offtakes often proceed un-restrained until the sudden perception that theresource stock is fully depleted. This is reflectedin the contrast between carefully regulated andunregulated systems where large numbers ofhunters may operate. For example, Minnesotahunters sustainably harvest over 700 000 wildwhite-tailed deer (Odocoileus virginianus) everyyear, whereas Costa Rica can hardly sustain anannual harvest of a few thousand without push-ing the same cervid species, albeit in a differentfood environment, to local extinction (D. Janzen,pers. comm.)

Prevent further destruction and fragmentation ofhabitats.·Increase the size of existing fragments and thetotal amount of habitat in the landscape.·Increase the area specifically managed for conser-vation.·Give priority to protecting large fragments.

Microbial assemblages can be found at consid-erable depths (in some instances up to a few kilo-meters) below the terrestrial land surface and theseafloor, often exhibiting unusual metabolic cap-abilities (Whiteet al.1998; D’Hondtet al.2004).Knowledge of these assemblages remains, how-ever, extremely poor, given the physical chal-lenges of sampling and of doing so withoutcontamination from other sources.

Flagella

purine

Ae starch in the seeds provides food for the embryo as it germinates and canalso act as a food source for humans and animals.

hemical reactivity

Figure1.2Formerly called blue-green algae, these (a) cyanobacteria, magni^ed 300x under a light microscope, aresome of Earth’s oldest life forms. These (b) stromatolites along the shores of Lake Thetis in Western Australia areancient structures formed by layering cyanobacteria in shallow waters. (credit a: modi^cation of work by NASA; creditb: modi^cation of work by Ruth Ellison; scale-bar data from Matt Russell)