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Patterns and Influencing Factors for Natural Regeneration of Sorbus Pohuashanensis in Eastern Forest Region of Northeast China

Author: XuJianWei
Tutor: ShenHaiLong；ZhangPeng
School: Northeast Forestry University
Course: Forest cultivation
Keywords: Sorbus Seedling establishment Diameter class structure Seed dispersal Soil seed bank Seed germination
CLC: S792.25
Type: Master's thesis
Year: 2010
Downloads: 97
Quote: 1
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Abstract

Department of the rowan tree (Sorbus pohuashanensis) Rosaceae Sorbus species of deciduous trees, produced in the northeast mountains, north; monoclonal scattered cluster distribution in high-altitude mountain dark coniferous forest, cold temperate coniferous Lint associated with broad-leaved species. The tree has been developed as an important natural non-wood resources species of the northern China, efforts to increase year by year, in some areas there have been signs of population decline or even disappear. Therefore, this study by its wild seedling completed the survey of the way and population age structure configuration and its seed dispersal update process, the study of ecological processes in the soil seed bank and seedling germination unearthed, understanding the update feature of the species and the update process the impact of factors, its the expanding wildlife resources, and the rational development to provide a scientific basis. The results show that: the eastern forest region in the northeast, the rowan tree is propagated by seed, three ways to update the pile suckers and root suckers. Without the destruction of natural forests and harsh habitats under natural forest, the ratio of the number of seedlings built by three ways 1/3 each, no significant difference; formed after the destruction of secondary forest, pile suckers proportion (16.5% ) is significantly reduced. Seedling and root tiller seedlings in three habitats completion of proportion differences are not significant; pile tiller seedlings formed after the destruction of the secondary forest in the completion of the proportion of significant significantly lower than the other two kinds of raw throughout the proportion (P lt; 0.05). In secondary forest, formed after the destruction of natural forest and unspoiled natural forest under harsh habitats Ⅰ, Ⅱ grade seedlings accounted for 76.0% of the total diameter class proportions in the various habitats, 68.9% and 75.8%, respectively. 1.0 ~ 2.9 cm II size class to the 3.0 ~ 4.9cm of Ⅲ diameter conversion rate is very low, in secondary forest, formed after the destruction of natural forests under harsh habitats and unspoiled natural forest II diameter class Ⅲ the diameter conversion rate of 25.6%, 45.3% and 15.9%, respectively. The fruit of the rowan tree mature scattered in early September, has been basically completed for the mid to late 10 scattered about which lasted about 40 d. Naturally scattered with the wind speed, temperature, precipitation and humidity of the air was not significantly correlated. Natural scattered rowan tree fruit 96.1% of the mother plant 2 m within 2 cm of the litter layer and the soil surface seeds accounted for 97.0% of the soil seed bank. Sorbus soil seed bank discontinuity in the time distribution spread early November that year, 257.7 ± 69.2 Li · m-2; late July of the following year, the lowest number of seed banks or have disappeared, only 2.9 ± 2.9 Li · m-2. The temperature does not directly limit the rowan tree seed germination unearthed process seedling will be able unearthed ,0-5 ℃, the germination rate (67.5 ± 6.6)%; emergence rate highest at 20 ° C (81.5 ± 1.9)%. Temperature strongly regulate a high growth rate and seedling emergence of the rowan tree, 7d and 21 d before the maximum height of the seedlings at 25 ℃, respectively, 2.5 ± 0.1 cm and 3.1 ± 0.1 cm high seedlings decreases with temperature The growth decreased the the former 7d and 21 d seedling minimum height at 0 to 5 ° C were 0.6 ± 0.1 cm and 1.8 ± 0.2 cm. Soil moisture content not only affect the rowan tree seedling emergence, mortality and adjustment of Sorbus unearthed seedlings. Rowan tree seeds in soil moisture for the highest 50% of the rate of emergence (74.7 ± 4.2)%; seedlings in the water content of 60%, the lowest mortality (32.7 ± 0.6)%. In addition, seed burial depth on the germination rate of the rowan tree also has a significant effect. 0cm at the seed sown on the soil surface, germination rate highest (70.3 ± 3.3)%; burial depth reaches or exceeds 1.5 cm, the seedlings will not germinate unearthed by the above results analyzed: Habitat built on the rowan tree seedlings have an impact, vandalism can significantly reduce the pile of suckers built key link; adequate seedling bank is not limit Sorbus group of natural regeneration of tree species, diameter class II to the the Ⅲ diameter conversion limit Sorbus natural regeneration natural regeneration; seed diffusion process with the impact, but the seed bank spatial and temporal pattern of Sorbus natural update has a significant impact; temperature possible is by density constraints affect the rowan tree seedling groups unearthed and survival in turn affect the fact, students update, while not by limiting the individual seedling germination unearthed process is in fact raw update; soil moisture and seed burial depth is an important factor to affect the rowan tree seedling update.

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CLC: > Agricultural Sciences > Forestry > Forest tree species > Broad-leaved trees > Sorbus
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