Abstract
Typhoons are the common natural disturbances in Taiwan. In order to study species regeneration,
coexistence and maintenance of biodiversity of forests, immediate field surveys and monitoring
should be done. In 2008, we surveyed a forest after typhoon season, and monitored species
regeneration in the Lienhuachih forest dynamics plot in central Taiwan. Our results showed 11
landslide areas caused by typhoons totalled 9159.47 m2, and most landslide areas were located in
the valley and on lower slopes. Strong winds caused trees to fall down and branches or the canopy
to be damaged; heavy rainfall caused tree death or disappearance. The typhoon caused greater
damages to trees with a small diameter at breast hight than to larger ones. The typhoon also caused
greater damage to the number of individuals and basal area of pioneer and rare species than it did
to dominant species.
In addition, we set up 1×1 m plots and divided landslides into 3 areas, the center of the landslide
area, edge of the landslide area, and non-landslide areas, to study differences in regeneration
of tree species and understory coverage during 2009~2012. Our results showed that for landslide
areas and edges of landslide areas, the density, number of species, and understory coverage increased,
but the proportion of pioneer species decreased. The number of seedlings that regenerated
changed very dramatically, especially in landslide areas. In contrast, in non-landslide areas, the
density, number of species, recruitment, and proportion of pioneer species changed less than in the
other 2 areas or were stable. The proportion of pioneer species and average growth per seedling
were significantlies higher than in the other 2 areas. Then, we used the Sorenson similarity index to
understand similarity between regenerated seedlings and overstory trees. The Sorenson similarity
index was the lowest at 26.82% in landslide areas, 37.38% in edges of landslide areas, and 41.65%
in non-landslide areas.
Overall, our study concluded that when typhoons hit landslide formed, more trees were damaged
by heavy rainfall than by strong winds in 2008, and new niches were formed, which benefited
tree species regeneration and maintained tree diversity and coexistence in the Lienhuachih broadleaf
forest.