| Fire disturbance is an important part in the succession of forest ecosystems, which determines forest species composition, community structure and biodiversity. In this study, based on the study of Daxing'anling, fire disturbance and community dynamics act as an integral whole.The Daxing'anling region Larix gmelinii response to disturbances is in-depth analysis with space instead of using time series method, The results showed:(1)Different fire disturbance succession of four Larix gmelinii were obtained:After heavy fire disturbance, the community of trees important value in the early recovery phase focused on broadleaf species, conifers will occupy later; Number of herbaceous species in the early recovery is larger than that in later time.The value of several key species is gradually important at last; shrub plant species number and importance value are nearly the same as herbs; After severe fire disturbance, Larix gmelinii forest community succession rules are: Weeds or shrub→Birch and poplar mixed forest→broad-leaved needle mixed forest→Larix gmelinii。After moderate fire disturbance, the ratio of the shrubs and bushes as well as the important value of Larix gmelinii in the recovery phase are large, holding the dominant position; Larix gmelinii forest community succession rules are:poplar-birch forest or broad-leaved needle mixed forest→Larix gmelinii forest; after the mild fire disturbance, there is little effect in larch community. It can not change the original species composition, and the change of forest community structure can only be seen in the shrub layer and herb layer as the replacement of some species. Mainly we see the replacement of some dry species and wet species.Different fire disturbance, such as strength without excessive interference from outside the case, may ultimately adapt into a succession of site conditions in the region of Larix gmelinii, in sunny, semi-sunny slope form Rhododendron dohuricum-Larix dahurica forest, in the flat and gentle slope of Grass-Larix gmelinii, Ledum palustre var.dilatatum-Larix gmelinii forest, in stream, valley, forming bundles Betula fruticosa -Larix gmelinii forest..(2) Different fire disturbance on species diversity in Larix gmelinii forest, research results increased with the intensity of fire disturbance. The species a diversity index and evenness are in a linear downward trend, power of dominance showed an upward trend; after severe fire in the vegetation succession, herb, shrub layer of species richness, diversity index showed a single peak with the year after the fire, the trend of tree layer is up. The stabilization of diversity need the 60 to 70a; After moderate fire disturbance, Larix gmelinii of tree layer species richness showed the trend of the overall increase; tree layer and shrub layer Shannon-Wiener index and Pielou index shows first increased and then decreased, and herb layer The Shannon-Wiener index and Pielou index were carried out with the recovery phase showed decreasing trend. Herb layer diversity maximum time is about 10-15a, shrub layer 20-30a, and the tree layer more than 30a, then the diversity index of each layer gradually decreased until stable; mild fire disturbance on Larch communities in various succession stages has little effect on the diversity. Gleason index of tree layer, Pielou evenness index did not change, Margalef index, and Shannon-Wiener index showed a slight decrease after the first increase in the trend.(3)Different intensity of fire disturbance on P diversity in Larix gmelinii forest results for the severe fire disturbance on forest community diversity in grasses-Larix gmelinii the greatest impact; and compared to Rhododendron dohuricum-Larix dahurica forest, moderate fire disturbance on (3 diversity Betula fruticosa-Larix gmelinii forest influenced; Mild fire disturbance on Betula fruticosa-Larix gmelinii forest bundle diversity the most. Performance of fire disturbance, the wet habitats and have greatly were improved, so the increase in community diversity benefit, and dry habitats and the maintenance of diversity more advantages.(4)After different intensity of fire disturbance, aboveground biomass was carried out with the succession of incremental positive trend, but the four Larix gmelinii at different succession stages of biomass are different, showing grass-Larix gmelinii forest>Rhododendron dohuricum-Larix gmelinii forest>Ledum palustre var. dilatatum-Larix gmelinii forest>Betula fruticosa-Larix gmelinii forest. After the severe fire disturbance early stages of the grass and shrub, the community total biomass is mainly herbaceous layer biomass and shrub layer biomass; biomass after the fire at about 20a concentrated in the tree layer, and this advantage extended to the climax stage.After moderate fire disturbance, the biomass of four Larix gmelinii mild fire disturbance impact little on four different levels of forest biomass of light, showing the proportion of biomass in different levels in total biomass is nearly the same after disturbance in all stages of the fire.(5) Fire disturbance has an impact on the litter accumulation amount of Larix gmelinii forest, different influences along with different intensity of fire disturbance.But with the succession of vegetation, litter accumulation amount of Larix gmelinii forest, gradually restored. After the severe fire disturbance, litter has been severely damaged; the recovery of the amount of litter accumulation was slowest. That of mild fire disturbance was fastest, also after the mild fire was stripped to the ground seeds and the soil to provide opportunities for contact, renewal processes of Larix gmelinii was promoted. The interference of the different stages of succession, the proportion of dead leaves was most, and proportion of needles and stood upon the total litter amount can be to the stage reflects the characteristics of succession.
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