Environmental Engineering Reference
In-Depth Information
essentially, a green world.This green biomass, and the food energy contained
within it, supports herbivore species higher up in the food chain; herbivores
in turn are energy packets that support carnivore species further up the food
chain (see figure 8.2). It is easy to imagine, then, that increased production
of plant tissue available to herbivores can lead to more herbivores and more
carnivores. Plant production is probably the most fundamental ecosystem
function supporting life on earth. It also sustains natural resource economies.
Without sustained production or yield of grassland biomass, it would be dif-
ficult to support a cattle industry. Sustainable logging relies heavily on reli-
able production of plant biomass in the form of stems (timber). Ecological
research is now showing that species diversity contributes toward the
amount of plant biomass that is produced in ecosystems.
The most notable example that species diversity plays a role in plant bio-
mass production comes from a systematic multi-site comparative study,
called the BIODEPTH ( BIO diversity and E cosystem P rocesses in T er-
restrial H erbaceous systems) project (Hector et al. 1999).The BIODEPTH
project aimed to evaluate not only how plant species diversity contributed
toward plant production but also to see if this outcome was repeatable (a
hallmark of scientifically reliable insight) by conducting identical, simulta-
neous experiment protocols in grassland field sites within eight different
European countries.The experiment manipulated both plant species rich-
ness in experimental plots and functional group richness (e.g., grasses, ni-
trogen fixing herbs, etc.).Although the exact level of plant production varied
among sites owing to properties of the sites themselves (such as soil fertil-
ity and moisture and the plant species present at a location), there was nev-
ertheless a strong signal among all of the plots.As plant species richness and
plant functional group richness increased, so did plant productivity (Hec-
tor et al. 1999).The outcome arose largely because plant species had com-
plementary effects on productivity.That is, species tended to be rivets rather
than redundants.
Crop Pollination
Some of the most tightly coevolved relationships in nature involve plants
and the animal species that pollinate them. Plants have remarkable varieties
of adaptations such as flower shape and color or scent and nectar that are
used to attract specific pollinator species. In some cases, there are single or
very few animal species that pollinate a particular species of plant making
plant-pollinator associations an important source of biodiversity globally.
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