Natural Regeneration And Its Impact Factors Of Fraxinus Mandshurica

Manchurian ash (Fraxinus mandshuricd) is a hardwood species in the genus Fraxinusin Oleaceae and one of the three valuable hardwood species in Northeast China.Investigation on the amount of regenerating, distribution of regenerating sapling, theenvironment factors of affecting regeneration in different stand types of Manchurian ash inthe north of Changbai Mountains to know the natural regenerative situation and mainaffecting factors of regeneration. The results of this study shows: the amount ofregenerating manchurian ash saplings were higher in the natural miscellaneous stands andlarch plantations which closed to provenances of manchurian ash, and the amount ofregenerating saplings were from 34000 to 24000 per hectare. However, under themanchurian ash, the amount of regenerating saplings were fewer, it's from 5200 to 3250per hectare. Analysis of the relationship between forest sites and natural regeneration ofmanchurian ash showed that, the density of herbage layer, the coverage of shrub layer, andthe thickness of litter were the most significant factors to the natural regeneration ofmanchurian ash saplings. In the near-mature stand of manchurian ash, the distancebetween 10 and 12 m had more regenerating saplings, and it was between 6 and 8 m in thehalf-mature forest, and 4 to 6 m in the young forest. There were 4 types in the analysis ofpoint pattern of manchurian ash population, diameter at breast height≤2.5 cm saplingsshowed cluster distribution; diameter at breast height in 2.5 ~ 10 cm showed randomdistribution in the distance less than 16 m and cluster distribution in the distance between16 and 50 m; diameter at breast height in 10 ~ 20 cm and above 20cm saplings showedrandom distribution. Except the first type which was diameter at breast height≤2.5 cm,the relationship of each individual sapling in the other 3 types showed significantlypositive correlation, which meant that the space of different age-classes showedinterleaving distribution, and those were beneficial to fully utilization of resources anddevelopment of the whole population. The sowing experiment in different forests showedthat emergence rate of sowing under the larch plantations was 3 times than undermanchurian ash forests, which meant that seed germination under manchurian ash forestsmay be inhibited. In the two forests, emergence rate of sowing in the quadrats withoutlitter was the higher than sowing in the quadrats with two times litter, and lowest in thecontrol, whether the seeds contact to the soil was the main reason.