| Larix principis-rupprechtii has been recongnized as a fast-growing species, which produces good quality timber can be widely used. It is highly resistant to bad weather, and also has good ability of soil and water conservation. Besides these outstanding characteristics, Larix principis-rupprechtii plays an important role in the process of forest ecosystem formation and maintenance. However, as the only constructive species of this ecosystem, many problems, such as sharp decline in biodiversity, soil deterioration, lower productivity, poor stability, serious pests and diseases infection were showed up.This research was conducted at Huoditang teaching forest farm of Northwest A&F University and Xunyangba forest farm of Ningdong Forestry Bureau in Shaanxi province from July to October2010. Based on the field investigation of21typical sample plots, stand structure, composition, biodiversity and regeneration of Larix principis-rupprechtii community were analyzed.According to the results and combining close-to-natural management theory, some treatments of adjusting stand composition and optimizing the stand structure were providedThe results showed as follows:1. Larix principis-rupprechtii plantation consisted of256vascular species in77families and154genera. Near-mature forest included99vascular species in51families and94genera, and the young age forest included157vascular species in74families and143genera.2. The Species Richness index, Simpson index, Shannon-Wiener index and Pielou Evenness index of different layers in young age forest was higher than its in near-mature forest were ranked as:herb layer>shrub layer>tree layer.3. The diameter distribution of Larix principis-rupprechtii plantation appeared to be single peaked curve, most of the trees were concentrated around the middle diameter class.4. The relationship between tree height and diameter at breast height of near-mature forest and young age forest were H=0.505+1.91×D-0.063×D2+0.001×D3and H=2.658+1.662×D-0.055×D2+0.001×D3, respectively. The optimal regression model of DBH- Cws was Cws=6.7533-0.7551D+0.0446D2.5.There were982regeneration seedlings and trees per hectare, total12species in near-mature forest, and1978regeneration seedlings and trees per hectare,total24species in young age forest.The regeneration in young age forest was better than in near-mature forest. This result indicated that the regeneration of Larix principis-rupprechtii plantation was poor, and the regeneration species were limited.6.The trees of the Larix principis-rupprechtii plantation were too dense, we suggest using crop tree management to reach the optimal management density. The optimal density of crop tree was124trees per hectare, so1or2major competitors need to be removed based on the thinning intensity and the degree of interference from the competitors around the crop tree.7.The suitable type of close-to-natural transformation for the Larix principis-rupprechtii stand development in near-mature forest and young age forest in Ningdong Forest Region of Qinling Mountain was Larix principis-rupprechtii mixed with Betula albo-sinesis or Picea wilsonii and Larix principis-rupprechtii with Quercus.Artificial regeneration should be considered in the future management. |
PDF Full Text Request