|
Based on dendrochronological studies of fire-scarred trees,
there were at least 3 fires at Taiwan red pine (Pinus
taiwanensis) forest in Huanshan during the past 20 years. The
last fire occurred in Dec. of 1995 and burned 170 hectares.
73.1% of Taiwan red pine were completely killed by the last
fire. Mosthardwoods, however, sprouted from the base. Only 1.6%
were completely killed. After burning, Miscanthus
transmorrisonensis and Pteridium aquilinum subsp. wightianum
were dominant ground cover species, but Pteridium aquilinum
subsp. wightianum showed seasonal fluctuation. The postfire
canopy composition were related with fire intensity, original
vegetation type and elevation. Postfire regeneration of Taiwan
red pine was related with seed source. The generation and
mortality of Taiwan red pine seedlings were related with
microenvironment and monthly rainfall. If there is no more fire
in this area, the vegetation will succeed to hardwood forest at
lower elevation or to hardwood-conifer mixed forest at higher
elevation. However, more frequent fires are probably inevitable.
Thus all this area may eventually change to grasslands. The
white snag landscape near the Xueshan 369 Cabin was resulted
from fires at Taiwan fir (Abies kawakamii) forest. The last two
fires occurred around 1903 and 1957. Those snags have rotten and
fallen down gradually. The dominant understory species were
grasses and deciduous shrubs at the burned snag site, and were
moss and Ainsliaea reflexa var. nimborum at the unburned fir
forest. Most fir seedlings exist in the range between 32m from
edge to forest interior and 9m from edge to exterior. The fire
that occurred at the southeastern slope of Shesan peak in Jan.
of 1991 completely killed about 11 hectares of Juniperus
squamata and Rhododendron pseudochrysanthum. So far no postfire
regeneration of Juniperus squamata has been found. Even though
there is no more fire, it will still take very long time to
succeed to original stand.
|