Influencing Factors the Reintroduction of Larix gmelinii Seed Germination Under Secondary Betula platyphylla Forest After Fire Disturbance
In the southwestern part of Mohe City in the Daxing'anling region of Heilongjiang Province,following fire disturb-ance,we selected five types of forest stands formed by different management practices:(1)pure Betula platyphylla forest,(2)B.platyphylla forest with the regeneration of Larix gmelinii seedlings,(3)B.platyphylla forest with a main canopy of B.platyphylla and a secondary layer of L.gmelinii,(4)mixed forest of L.gmelinii and B.platyphylla,and(5)pure L.gmelinii forest.For each forest stand type,four experimental plots of 60 m×60 m were established,with four sampling sites of 20 m×20 m set at the corners of each experimental area to simulate natural seed dispersal.In the seed reintroduction ex-perimental plots,we simulated four different seed-soil contact methods:direct seeding(simulating seed contact with the litter layer),sowing after removing the litter layer(simulating seed contact with the soil surface),hole-shaped soil break-ing seeding(simulating seed contact with hole-shaped soil breaking),and strip-shaped soil breaking seeding(simulating seed contact with strip-shaped soil breaking seeding),with sowing conducted in early October 2022 before snow cover oc-curred.We recorded the plant species and the number of individuals(clumps)for shrubs and herbaceous plants in the sampling plots,measured the thickness of the litter layer,and surveyed the germination status of L.gmelinii seeds in each sowing area.We calculated the species diversity indices for the shrub and herb layers of the five forest types,including the Margalef richness index,Simpson index,Shannon-Wiener diversity index,and Pielou's evenness index.One-Way ANO-VA,Least Significant Difference(LSD),and Pearson correlation analyses were employed to assess the effects of sowing method(seed-soil contact method),forest type,and plant diversity on seed germination rates.The results showed that the hole-shaped and strip-shaped soil breaking significantly increased seed germination rates,whereas the influence of different forest stand types on seed germination rates was not significant.The seed germination rate for hole-shaped and strip-shaped soil breaking showed a significant positive correlation with the number of shrub species,the Margalef richness index of shrubs,the Shannon-Wiener diversity index,and the Pielou's evenness index,while displaying a significant negative cor-relation with the number of herb species and the proportion of B.platyphylla.For strip soil breaking sowing,the seed ger-mination rate was significantly positively correlated with the coverage of herbaceous plants,litter thickness,and Pielou's evenness index,while being negatively correlated with the herbaceous Shannon-Wiener diversity index and Simpson index.The seed germination rate for sowing after removing the litter layer was significantly positively correlated with the number of tree species.
万方数据
维普
