ObjectiveFrom the four aspects of tree species composition, density, growth character (base diameter, plant height, crown diameter) and spatial distribution pattern, the forest characteristics of Pinus tabuliformis plantation in Liaoheyuan Nature Reserve of northern China were discussed, which could provide reference for vegetation restoration and forest management.
MethodTaking the Pinus tabuliformis plantation in burned area of Liaoheyuan Nature Reserve as research object, three 20 m × 20 m sample plots were set separately according to different renewal methods (natural renewal and artificial promoting natural renewal) under severe fire, different fire intensities (severe fire, moderate fire and light fire) under natural renewal and control (not burned). The natural renewal sample land under severe fire was the same as severe fire land under natural renewal, so there were 15 sample plots in total. We investigated the amount and type of trees after updating, measured the ground diameter, plant height, crown diameter of renewed trees. For each wood gauging sample, we recorded the information such as the geographic coordinates and site factor. Single factor variance analysis was used to analyze the difference of tree regeneration density and growth character, and variance/mean method was used to analyze the spatial distribution pattern of tree regeneration.
Result(1) The tree species of tree regeneration in the burned area of Pinus tabuliformis were mainly Quercus mongolica and Populus davidiana, accounting for 38.1% and 42.3% of all regenerated trees, respectively, also including Pinus tabuliformis, Ulmus laciniata, Ulmus macrocarpa, Ulmus pumila, Acer mono, etc. Under severe fire, there was a significant difference in the density of tree regeneration between different renewal methods (P < 0.05), there was no significant difference in the density of tree regeneration between different fire intensities under natural renewal (P > 0.05). (2) There was no significant difference in the growth traits and characteristics of all tree regeneration in different regeneration modes under severe fire (P > 0.05), there was an extremely significant difference in the growth traits of all tree regeneration under natural renewal with different fire intensities (P < 0.01). (3) The spatial distribution pattern of tree regeneration was affected by fire intensity, regeneration mode and tree species. The factors such as suitable microhabitat, animal carried seed diffusion can promote the small scale aggregation of renewal.
Conclusion4 years after fire, the regenerated tree species in the burned area of Pinus tabuliformis forest were mainly Quercus mongolica and Populus davidiana. Moderate and low intensity surface fire could promote the natural regeneration of stands. Adopting salvage logging and other management measures to artificially promote natural renewal can speed up the restoration of vegetation in fire area.