| The ecosystem function of plantation in Mt. Ziwuling, the Loess Plateau, was impaired because of lower species diversity, native woody species colonization obstacle, and recruitment handicap. How to accelerate the native woody species colonizing towards plantation in order to improve community structure and increase succession, was a very important project in restoration ecology. So, it's necessary to study the recruitment of native woody species, especially the limitation factors in establishmnet. Liaodong oak (Quercus wutaishanica) is the main native woody species and the dominant species of the climatic climax community in Mt. Ziwuling. In this study, three methods, including community investigation, field seeds sowing experiment and lab planting experiment, were used to research the seedling recruitment of Liaodong oak in three typical habites (Pinus tabulaeformis plantation, Liaodong oak forest, and grassland) by supervising the seedling growth and microsite factors. The main aims were to confirm the recruitment limitation type and to select the key ecological limitation factors during seedlings establishment. Moreover, the recruitment mechanism of Liaodong oak population will be unclosed, and the probability of plantation successing to climate climax community was discussed. This study will supply the new proof to recruitment limitation theory, and will be the gist of the plantation restoration in the Loess Plateau.In this paper, the biomass allocation in seedling development, the seedling and microsite spatial heterogeneity, and the recruitment of seedlings in different ecological factors and habitats were researched, and the main results of were summed up as follows.1. The seedling of Liaodong oak was the dominant species in the woody seedlings layer in the Ziwuling forest region. The vegetation in Mt. Ziwuling forest region was investgated comprehensively, and it was observed that the Liaodong oak seedlings distributed in all of the forest communities in this region and had higher frequency, but the density was largely variant in different community.2. The Liaodong oak seedlings spatial pattern were both the clumped type in conifer plantation and oak forest, but there were significant difference in clumped scale and correlated microsite factors. Semivariogram analysis showed that, in oak forest, the data of seedlings was spatial autocorrelated in 1-5.94 m range, and the data of seedlings was spatial autocorrelated in 1-1.94 m range in the conifer forest. Using forward selection method and DCCA, some main factors were selected. In oak forest, they were litter thickness (LT), soil available kalium (K) and soil temperature (T). In conifer forest, they were soil humidity (H), soil pH (pH) and soil organism (O).3. The dynamic life table was builted according to the Liaodong oak seedling growth data in three years. The results showed that:1) The survival curve of the seedlings cohort in three habits tended to be the type Deevey -â…¡. The seedlings survival probability in closed forest canopy was higher than it in opened grassland.2) In the forests, the seedlings death climax presented in the spring of the third year after seedling emergence, and the expected life span was 23 monthes.3) In the grassland, the seedlings death climax presented in the spring of the second year after seedling emergence, and the expected life span was 15 monthes.4. The relative influence of seed and microsite availability in the seedling emergence and recruitment of Liaodong oak was examined by seed sowing experiments, which were performed in three typical stands (conifer plantation, Liaodong oak forest and grassland). A seed augmentation experiment was performed in an oak forest and a conifer plantation, and a seed introduction experiment was carried out in the grassland. Three main factors were considered:seed addition, disturbance and shrub cover. The seedling number and growth in every plot were recorded continuously over 3 years. GLM multivariate was used to analyze the relationships between seedling emergence-recruitment and the explanatory variables in every stand. The results showed that:1) The recruitment of Liaodong oak was limited by seed and microsite availability in this region.2) In closed forest, litter was one of the factors leading to microsite limitation, and shrub cover did not affect the recruitment of Liaodong oak in the three stands.3) In the grassland, no treatments improved recruitment, indicating that the grassland was not suitable for seedling recruitment because of intense light and soil drought.4) In the conifer forest, more recruited seedlings, and lower herbivory on seedling leaves, as well as thicker stem basal diameters, indicated that the P. tabulaeformis plantation was safer for Liaodong oak seedling establishment.5. The results of lab planting experiments showed that:1) There were two stage of Liaodong oak seedlings root developing. The first rapid stage was present in 60 or 90 days after seeds sowing.2) The dry weight of cotyledon was still decreased in whole seedling growth progress, but it was stoped after seedlings emergence 90 days.3) The leaves dry weight continuously increased, but the stem dry weight was stop increasing after seedlings emergence 90 days.4) The energy from photosynthesis was translated to roots in Augest or September, so the damage frome animal or insect would negatively affected the seedling survival.5) The litter thickness was significant affected the oak seedling emergence, and 3 cm litter thickness was the best suit condition. In 5 cm litter thichness, the dry weight of cotyledon, which still keeped in seedlings, was decreased significantly, and it would be disbennifit for the seedling establishment in future.6) The higher concentration conifer litter extracted liquid (1:10) was disadvantage for oak seedling establishment. It constrained the seedling height and the total dry weight, but was not decreased the seedlings emergence.Drawing a conclusion, Liaodong oak had the ability of establishing in conifer forest, and the seedling growthed well in the environment. The Liaodong oak population recruitment will be limited by seed and mirosite availability in conifer plantation. The limited factor for recruitment was seed source and litter layer in community. The lower light intensity in closed forest would not negatively affect the seedling in early development. So, during the P. tabulaeformis plantation alteration, disturbing the litter layer and reserving the shrubs and underwood to keep shady will be benefit for Liaodong oak regeneration by seeds.
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