Succession and management - Ecological Applications: Toward a Sustainable World - page 231

(a) (b)

0.4

0.3

Maningrida

Darwin

Study
area

0.2

Kakadu
National
Park

Arnhem Land plateau

N

0.1

Nitmiluk
National
Park

0 100 km

Unburned Little

burned

Substantially
burned

Fig. 8.13 (a) Location of the aboriginal fi re management study area near the northeastern end of the Arnhem Plateau in the
Northern Territory of Australia; the position of two National Parks is also shown. (b) Mean number (and standard error) of
kangaroo groups sighted during a helicopter survey of 0.25 km 2 plots with different recent burning histories. (After
Yibarbuk et al., 2001.)

and regularly make their way into Kakadu and Nitmiluk National Parks (Figure
8.13a). It seems that continued aboriginal occupation of the study area and tradi-
tional fi re management practices limit the accumulation of fi re-promoting grass
species and plant litter. In the absence of this excellent fuel, the probability is much
lower of the massive fi res that can eliminate the most fi re-sensitive vegetation. A
return to indigenous-style burning seems to hold promise for restoration and con-
servation of threatened species and habitats in these Australian landscapes and
provides clues for the management of fi re-prone areas elsewhere.

8.4 Using
succession to
control invasions

Given the contrasting features of different successional stages it would not be sur-
prising to fi nd that invaders are hindered (or helped) according to the stage that a
succession has reached. I address this topic for both grassland (Section 8.4.1) and
forest settings (Section 8.4.2)

8.4.1 Grassland Early-successional agricultural weeds can be characterized as r -selected, with short

lives, rapid growth and abundant seed production (Box 3.1). This pioneer life-history
stategy depends on high resource availability, and such weeds are unlikely to
do well in the resource-poor, competitive environments that characterize late-
successional grassland. Restoration of prairie grasslands may therefore be expected
to reduce the problem of weed invasion and provide a cost-effective alternative to
traditional weed control techniques (Chapter 6).
Blumenthal et al. (2003) examined the cumulative effects of restoration on weed
populations after 7 years of restoration of tallgrass prairie in Minnesota. Density
and biomass of weeds were compared among plots with: (i) no restoration; (ii)
prairie seed addition; and (iii) 'full restoration' involving tilling and raking together
with prairie seed addition. In comparison to unrestored sites, full restoration reduced
weed biomass by 94%, total weed density by 76%, and the densities of four important
weed species ( Berteroa incana , Elytrigia repens , Euphorbia maculata and Setaria