Ecological applications of niche theory - Ecological Applications: Toward a Sustainable World - page 50

Aira caryophyllea

(a)

Trinia glauca

Thymus serpyllum

Festuca ovina

Hieracium pilosella

Bellis perennis

Lolium perenne

Nutrient-rich
moist soil

-2 -1 0 1 2 Nutrient-poor

dry soil

CCA axis 1

Fig. 2.9 Mean and variances of chalk grassland plant species' positions along two ordination axes (derived from canonical
correspondence analysis, CCA). (a) Axis 1 is negatively correlated with soil nutrient richness and water content (more
nutrient-poor and drier to the right). (b) Axis 2 is positively correlated with high intensities of mowing and grazing (more
intensive mowing/grazing to the right). The midpoint of each species line is its mean position along the axis, while the
length of the line expresses its niche width (variance in site scores where the species occurs). (After Barbaro et al., 2004.)

so-called halophytic plants such as Atriplex prostrata , which live in naturally salt-
rich areas and accumulate salt in their tissues, are prime candidates for restoring
land contaminated by saltwater spills from broken pipelines in oil-production areas
(Keiffer & Ungar, 2002). Phytostabilization , on the other hand, takes advantage of
the ability of root exudates to precipitate heavy metals and render them biologically
harmless. Finally, phytotransformation involves elimination of a contaminant by the
action of plant enzymes; for example, hybrid poplar trees Populus deltoides nigra

have the remarkable ability to degrade TNT and show promise for restoration of
munition dump areas. Note that microorganisms are also used for remediation in
polluted situations. A dramatic example is provided by the bacterium Pseudomonas
putida , a bug that can be said to cut the mustard. The concentration of a nasty
compound called 1,4-perhydrothiazine, a toxic remnant of the mustard gas

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