Biology Reference
In-Depth Information
Fig. 7.2
Example of a mature S.
chrysophylla
tree 14 years after being experimentally seeded
into a grass-dominated burned Hawaiian submontane seasonal habitat. A fruiting individual of a
second seeded species,
D. viscosa
(a shrub), is at the base immediately to the left of the tree. The
matrix in which they are growing is the African grass
Melinis minutiflora
that has dominated these
sites since invasion and the first fire in the early 1970s (photograph by C. D'Antonio)
Our next experimental burns occurred in July 1995 in two patches of vegetation
burned previously in 1972 that were also dominated by
M. minutiflora, S. conden-
satum
, and
D. viscosa
. In contrast to the previous burn, these experimental burns
were of very high intensity, consuming 98% of aboveground biomass and 20% of
root and soil organic matter in the upper 20 cm (Mack et al. 2001). Plots were again
seeded with
D. viscosa
and
S. chrysophylla
both before and after fire and in
unburned control plots. Establishment was generally higher in postburn compared
with preburn seeding and declined after initial germination due to periodic drought
(Loh et al., unpublished report). Nonetheless, the successful germination and early
growth of
D. viscosa
and
S. chrysophylla
in the burned plots compared with the
unburned control plots suggested that high-intensity reburning of grass-dominated
sites could promote native species establishment.
Over the next 5 years, the National Park Resources Management Division under
direction of J.T. Tunison and R. Loh conducted five more experimental burns. Six
additional species were planted in the submontane zone to evaluate regeneration
and persistence with the ever-present invasive grasses; several of them showed
potential for postfire revegetation and fire tolerance (Table 7.1). Because of the
funding limitations the results have been monitored only sporadically but they sug-
gest that several species of native plants are suitable for postfire rehabilitation and
will persist under the exotic grass-dominated site conditions. In addition to these
