Life-history theory and management - Ecological Applications: Toward a Sustainable World - page 67

Fig. 3.3 Results of a
Principal Components
Analysis (PCA)
showing (a) the
relationships among
species traits of 29
species of pine ( Pinus )
(b) known to be
invasive or noninvasive.
The positions of the
species and the trends
in species traits are
shown in separate
panels for simplicity of
presentation. Key for
plant traits: relative
growth rate (RGR:
mg g plant −1 day −1 ), net
assimilation rate (NAR:
mg cm −2 leaf day −1 ), leaf
mass ratio (LMR:
g leaf g plant −1 ), relative leaf
production rate (RLPR:
leaf leaf −1 day −1 ), leaf
area ratio (LAR:
cm 2 leaf g plant −1 ) and
specifi c leaf area (SLA:
cm 2 leaf g leaf −1 ). The
invasive and noninva-
sive species cluster in
different parts of the
diagram. (After
Grotkopp et al., 2002.)

(a)

Leaf
thickness

NAR

Seed mass

LMR

RLP RGR

Generation
time

LAR

SLA

Leaf
density

Axis 1

(b) Invasive

Unclassified
Noninvasive

palustris

pinea

pinaster

coulteri

torreyana

muricata

ponderosa

thunbergii

jeffreyi

flexilis

lambertiana

halepensis

canariensis

sabiniana radiata

sylvestris

nigra

rigida

caribaea
resinosa

elliottii

virginiana
contorta
banksiana
patula

taeda

glabra

cembra

strobus

Axis 1

( Corvus frugilegus ) has fi ve reported novel behaviors while the unsuccessful Corvus
monedula only has two. Similarly, the successful house sparrow ( Passer domesticus )
and mallard duck ( Anas platyrhynchos ) have ten and fi ve reported novel behaviors,
respectively, compared with just two each for their unsuccessful counterparts Passer
montanus and Anas penelope .
In this disparate group of birds, and in contrast to the pine species, r / K status
does not appear to predict invasive potential. Success seems to be linked with high
competitive status (analogous to Grime's C categorization in Box 3.1), an advantage
that is conferred by behavioral fl exibility.
Something similar may be the case for certain plant invaders too. Japanese grass
( Microstegium vimineum ) is an important annual weed of Asian origin that is now
widespread east of the Mississippi River in the USA and in many other countries.
Gibson et al. (2002) studied four populations in quite different environments
in Illinois, USA. They concluded that the species' invasive potential is fueled
by a remarkably fl exible response to local microhabitat conditions, being able to
tolerate acidic, sandy and silty soils in both open and shaded locations. Such plastic-
ity, akin to the behavioral fl exibility of birds, may be a property of many invaders.