| The types of coniferous forests that has multiple ecologic serving function, such as waterresources conservation, soil and water conservation and biodiversity keeping in Qinlingmountains are rich. Through the investigations of the typical sample plots, taking theimportant value of tree species and woody plant regeneration layer, Diameter structure ofdominant tree species and regeneration characteristics of woody plant layer as the index, weanalyzed regeneration characteristics of the four coniferous forests. And we also analyzed theeffects of different factors on the regeneration layer by the densities of the regeneration layer,to provide theoretical reference for judging the nature regeneration trend of the forests andnear-nature restoring them.The results showed that the important value of Pinus tabulaeformis was158%, whichwas the constructive species. The tree population were lack of0~5cm in the diameter levelstructure. The species in regenerated layer were rich, the proportion of trees was lager, theimportant value of the Quercus was lager. The main regeneration type in understory wasseedling. When the stand density went up to1500stems/hm~2from580stems/hm~2, thedensity of seedlings and saplings were both increasing, After that, as the stand densityincreasing, they were both falling. When the altitude was rising up, the density of seedlingsconstantly increased. While When the altitude rose up from1159m to1449m, the densityof saplings gradually increased. the density of saplings decreased with the altitude ascendingto1658m.With the slope changing direction from the sunny slope to the semi-sunny slope tothe semi-shady slope and then the shady slope, the density of seedlings was showing a declinetrend. In contrast, the density of saplings decreasing in the process of the changing directionfrom the sunny slope to the semi-sunny slope to the semi-shady slope, then it was increasingas the direction changing to the shady slope.The results showed that the important value of Pinus armandii was163%, which was theconstructive species. The tree population were lack of0~5cm in the diameter level structure. The species in regenerated layer were rich, Quercus aliena was the secondary dominant speciesof the tree species, The important value of Pinus armandii was only0.43%. The mainregeneration type in understory was seedling. When the stand density went up to1170stems/hm~2from670stems/hm~2, the density of seedlings was at the maximum value. After that,as the stand density increasing, the density of seedlings was falling, when the density reachedat1870stems/hm~2, there was nearly no seeding in understory. However, the saplings densitywas in the peak at the minimal stand density, then dropping substantially. When the altituderose up from1310m to1456m, the density of seedlings gradually increased. While thedensity of seedlings decreased with the altitude ascending. With the slope changing directionfrom the sunny slope to the semi-sunny slope and then the shady slope, the density ofseedlings was up to the highest point at the semi-sunny slope SE70°, then showing a declinetrend. In contrast, the density of saplings decreasing in the process.The results showed that the important value of Picea asperata was228%, which was theconstructive species. The small and middle diameter of trees were excessive. The mainregeneration type in understory was sprouting. Both of the two tree population were lack of0~5cm in the Diameter level structure. When the stand density went up to700stems/hm~2from440stems/hm~2, the density of seedlings was at the maximum value. After that, as thestand density increasing, the density of seedlings was falling. However, the saplings densitywas in the peak at the minimal stand density, then dropping substantially. When the altituderose up from1837m to2176m, the density of seedlings gradually increased. While thedensity of seedlings decreased with the altitude ascending, The density of saplings showed thedecreasing trend with the altitude increasing. With the slope changing direction from thesunny slope to the semi-sunny slope and then the shady slope, the density of seedlings was upto the highest point at the semi-sunny slope SE85°, then showing a decline trend. In contrast,the density of saplings decreasing in the process.The results showed that the important value of Abies fargesii Franch was194%, whichwas the constructive species. Betula albo-sinensis var．septentrionalis was the dominantspecies. Both of the two tree population were lack of0~5cm in the Diameter level structure.There were7tree species in regenerated layer, just occupying20.5%of the total number ofspecies. The important value of Fargesia spathacea was90.78%. The main regeneration typein understory was shrub sprouting. When the altitude rose up from2300m to2726m, thedensity of seedlings gradually increased. While the density of seedlings decreased with thealtitude ascending, The density of saplings showed the decreasing trend with the altitudeincreasing. When the stand density went up to880stems/hm~2from460stems/hm~2, thedensity of saplings was at the maximum value. After that, as the stand density increasing, the density of saplings was falling. However, the saplings density was in the peak at the minimalstand density, then dropping substantially. With the slope changing direction from the sunnyslope to the semi-sunny slope and then the shady slope, the density of seedlings was up to thehighest point at the semi-sunny slope SE84°, then showing a decline trend. In contrast, thedensity of saplings decreasing in the process.The Pinus tabulaeformis and Pinus armandii secondary forests are at the middle stage ofsuccession of mixed forest, the Picea asperata and Abies fargesii natural forests are at the endof succession, the population of Picea asperata had certain regeneration ability, thepopulation of Abies fargesii was in the degenerate stage. The over growth of F.spathacea inthe understory affected seriously the development of tree species. Stand density, altitude,slope direction were the main influencing factors on regeneration. |
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