Effects of plant functional groups on vegetation dynamics and ecosystem properties
McLaren J. R. . 2006.
Abstract
Loss of biodiversity has likely been the most dramatic
change humans have imposed on ecosystems in the
past century (Chapin et al., 2000); the global extinc-
tion rate is currently between 100 and 1000 times faster
than pre-human extinction levels (Pimm et al., 1995).
There is growing concern that this species loss will have
important effects on ecosystem functioning: that species-
poor ecosystems may perform differently, or less effi-
ciently than the species-rich systems from which they are
derived (Zedler et al., 2001). This concern has prompted
much research to focus on how biodiversity loss affects
ecosystem functioning (e.g., Hector et al., 2000; Pfisterer
and Schmid, 2002) and the response of ecosystems to
global change (Reich et al., 2001).
The resulting studies have created a decade-long debate
on the relationship between biodiversity and ecosystem
function. An emerging conclusion is that the composition
of the community, as well as diversity, plays a major role
in controlling ecosystem function (see Hooper and
Vitousek, 1998; Scherer-Lorenzen et al., 2003): in fact,
the types of species in the community may play an even
larger role than the number of species. Despite this reali-
zation, virtually no studies have specifically examined the
independent effects of species composition on the func-
tioning of ecosystems.
Species composition is likely to play an important role
in determining ecosystem function because species differ
in their traits. The effect of the loss of a species on an
ecosystem is the result of both (1) the loss of the direct
effects of the organism on ecosystem functioning and (2)
the response of other organisms to that loss. These effects
and responses occur through numerous mechanisms. For
example, species can directly affect soil nutrient and water
content through varying root mass. In addition, specific
species can alter plant community composition through
varying competitive abilities and facilitative effects, which
in turn may affect ecosystem function
