Short-term effects of forest fire on the species composition and community structure of Larix olgensis forest
We investigated plant community for twice in a burnt area of Larix olgensis forest in Changbai Mountain Nature Reserve,to clarify the short-term impacts of forest fire on species composition,diameter class structure,and spatial distribution pattern of dominant species.The results showed that:(1)there were 14 tree species in the undisturbed plots,while 6 species was observed after 1 year of fire disturbance,and only 4 species were found after 4 years of fire disturbance.(2)The diameter class structure of the undisturbed plots showed an inverted"J"form,while the disturbed plots showed a normal distribution pattern.The fire resistance of dominant species(Larix olgen-sis and Betula platyphylla)of different diameter classes showed similar patterns,i.e.,large diameter class>medium diameter class>small diameter class.(3)In the undisturbed plots,each diameter class of larch and birch showed a random distribution on the 0-25 m scale.However,the small diameter class(DBH<11 cm)of larch after 1 year of fire disturbance showed an aggregated distribution on small scale(r<12 m)and a random distribution on a large scale(12 m<r<25 m).The medium diameter class(11 cm≤DBH<21 cm)showed an aggregated distribution at 0-251.m scale,and the large diameter class(DBH≥21 cm)showed a random distribution pattern.The medium and large diameter classes of birch were randomly distributed at the 0-25 m scale.After 4 years of fire disturbance,the spatial distribution pattern of small diameter class and large diameter class of larch was similar to that after 1 year of disturbance,while the middle diameter class showed a clustered distribution on a small scale and a random distribution on a large scale.The medium diameter class of birch basically showed an aggregated distribution.Our results revealed the short-term dynamics of Larix olgensis forest after fire disturbance,providing guidance for region-al forest restoration and management.