Effects Of Fire Disturbance On Leaf Functional Traits And Functional Diversity Of Larix Gmelinii Community

Fire is an important ecological factor in boreal coniferous forest,which directly affects plant taxonomic and functional diversity and consequently forest succession.The forest stand had been naturally recovered for 12,20 or 31 years under different fire intensity levels(low,medium,heavy)in Yakeshi area.We analyzed the changes of leaf functional traits,taxonomic and functional diversity of a Larix gmelinii community,and which can provide theoretical basis for vegetation restoration and ecosystem protection of the study area.The main results are as follows:With the increases of fire intensity,leaf tissue density,leaf total carbon content and leaf total phosphorus content showed a generally increased trend,specific leaf area,leaf thickness and leaf total nitrogen content decreased after forest fire disturbance,while leaf N:P decreased first and then increased.Low and medium fire intensities could maintain higher species diversity and functional diversity of the community,with maximum species richness index,Shannon index,Simpson index,Pielou index,and functional richness index(FAD and MFAD),functional evenness,functional divergence and Rao quadratic entropy index in low or medium fire.In addition,the effects of fire intensity on the functional traits and species diversity were most obvious in the early stage of forest restoration.The increase of post-fire time had a significant effect on the restoration of leaf functional traits in the community,which was basically close the unburned level(CK)at 20 or 31 years after fire.Species diversity index of the community with low intensity fire was not significantly different from that of the unburned community at 20 years after fire,while the medium fire was not significantly different from that of the unburned community at 31 years after the fire;The species richness of the community with heavily fire was not significantly different from the unburned community at 31 yearsafter fire,and there was no significant change in other species diversity indexes.With the increases of post-fire time,the community functional diversity indexes was close to the the level of unburned community at 31 years after the fire(except FRic).Functional richness index FRic significantly decreased after the fire and it would take longer for the recovery in the medium and heavy burned areas.The interaction between fire intensity and post-fire time had significant effects on the leaf thickness,leaf water content,leaf tissue density and leaf total phosphorus content,and functional richness index FRic and Rao quadratic entropy index.