| Chinese Oak (Quercus wutaishanica) forest is a kind of vegetation on Loess Plateau in China. Forest harvesting on the Loess Plateau, as in other places in China, especially the natural oak forest, has been ongoing since1949. But since the1990s, the Chinese government has implemented targeted restoration programs, such as "Natural Forest Protection Project (NFPP)," to enhance the restoration of forest vegetation on Loess Plateau. This program banned adverse forest activities including thinning. By minimizing these disturbances, managers hope to take advantage of the natural regeneration processes of the forests. To control intrusions from animals and people, the boundary of the forests were fenced to prevent livestock and signed to alert people of the conservation status.Although the natural forest was protected after the NFPP, the quality of natural forests continued to decline substantially in some regions. In the NFPP, all harvesting practices were prohibited, thereby preventing Silvicultural systems from being developed to promote healthy regeneration. Thus, Silvicultural practices such as clear cutting; seed tree systems; shelterwood and coppicing for even-aged stands; and single tree and group selection for uneven-aged stands were unable to be implemented. The complete halt of anthropogenic disturbances contributed to quality decline and outbreaks of insect pests and plant diseases.At present, some scholars and government advocate that appropriate Silvicultural systems would be implemented to oak forest on Loess Plateau. However, no one knows which Silvicultural practices are best to the banned oak forest. The purpose of this program was to determine the effects of forest regeneration methods on Loess Plateau.In this program, the majority of research contents are:1) The effects of Silvicultural practices on characteristics of oak forest, such as species diversity, potential of population regeneration, population dynamics of understory, soil physical and chemical properties and overstory-understory biomass changes over a5-year period. The result shows that,4-tending after5-year tending, arbor, shrub and herb layer of oak forest composition and abundance, species richness, diversity and evenness, regeneration has changed. Local afforestation is in favour of Quercus liaotungensis in forest arbor layer species increased. Synthetical tending can guarantee the stability of shrub species in the community, conducive to the stability of the shrub laye.4-tending of species of herb layer species of Quercus liaotungensis forest is increase. Strip reform’s species richness, diversity and uniformity in the community increased. Relative to Forsook, other4-tending is in favour of regeneration of seedlings of Quercus liaotungensis.2-tending (Synthetical tending and Strip reform) plays an important role in regeneration of seedlings of Quercus liaotungensis forest. Therefore, from the perspective of ecological characteristics, we should increase afforestation of Quercus liaotungensis forest on the tending and management.2) Established a model to assess forest quality at the stand level. We can select the appropriate methods of Silvicultural practices for oak forest on Loess Plateau, such as species diversity, potential of population regeneration, population dynamics of understory, soil physical and chemical properties and overstory-understory biomass changes. The result shows that, for natural conditions in the loess plateau of Oak Forest, tending transformation belt in strip reform. The tending of forsook on loess plateau effects the worst. Therefore, in oak forest on the loess plateau, tending of forsook was not the best. This program would suggest the government some suitable methods of Silvicultural practices to keep a high level of oak forest regeneration on Loess Plateau.3) The shade tolerance of oak forest. We will develop light response curves to examine the light compensation point (LCP) and light saturation points (LSP) of seedlings, saplings, and mature trees of oak species at the peak of the growth season. The result shows that, different canopy of oak forest has different shade tolerance. Negative resistance of seedlings of oak’s best, the normal minimum light intensity of the growth is125μnol·m-2·s-1. At the same time, Seedlings to intense light (light intensity1200~2000umol·m2·s-1) adaptation of the best. Overstory of oak shade tolerance is relatively poor, normal growth requirements of minimum according to the strength of316μmol·m-2·s-1. This description of oak seedlings’ shade tolerance is the best. |
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