Effects Of Different Burning Degree On Soil And Vegetation Composition Of Pinus Thunbergii Forest

In 2013, the forest fire broke out on the Sanbiao mountain of Chengyang District in Qingdao city, resulting in more than 40 acres of forest destruction. In this study, we took the burned area with black pine on this mountain as research object and conducted a comprehensive investigation. According to different burned intensity, all of the fire-slash was classified to four plots like not burned area, mild burned area, moderate burned area and severe burned area. Three plots about 20x20 meters from each area were chosen. The vegetation conditions and plant characteristics of tree layer, shrub layer and herbaceous layer in each plot were surveyed. The soil physical and chemical properties including soil pH, organic matter, total potassium, total phosphorus, total nitrogen, soil bulk density, total porosity and soil aeration porosity et al in different fire degree were also researched and analyzed. Through the influence analysis on the soil from different fire degree, we discussed the changes on individual densities of trees, the woody plants and herbaceous plant recovery situation after fire disturbance. The total damaged condition and herbal regeneration progress on the Sanbiao mountain fire degree were uncovered and evaluated. The result can provide a theory basis for leading herbal recovery of burned forest. The main research results are summarized as follows:1. The different effects fire disturbance on soil physical and chemical properties of forest were significantly affected. The soil pH, soil total potassium content and soil bulk density were increased with fire disturbance ponderance increased. The soil organic matter content, total porosity and soil aeration porosity were decreased with the fire disturbance increased. The soil total nitrogen was not significant on different fire degree. The soil total phosphorus was the highest on mild burned area and moderate burned area, while was the lowest on the not burned area and severe burned area.2. The influence is huge on the trees of forest ecosystem of Sanbiao Mountain by fire, especially on the black pine which was the dominant tree species of tree layer. With the increase of fire degree, the number of woody plants such as black pine decreased gradually. Notably, there was nearly never regeneration of black pine seedlings from moderate and above burned area.3. From plots investigation, the amount of regeneration woody plants on burned area was less on never burned area, but the average height of woody plants was increased with the increase of fire intensity. The average height of woody plants was the highest in the severe burned are with much more gaps from never burned area. Meanwhile, the cover degree of new woody plants was increased with the increase of fire intensity. In the new woody plants, there were large heliophilous plants and nitrogen fixation plants, which was a greater change.4. After fire, there were a lot change on the type, quantity, cover, average height of herbaceous layer compared between fire degree and normal forest. The number of the herb was the largest on severe burned area, followed by moderate burned area. It was significant that the number of herbaceous plant found in two burned area was higher than the number of plants in the never burned or lightly burned. The fewest number of herbaceous plants was in never burnd plots. There was great difference of herb among different plots. The regeneration of herbaceous plants had a lot of changes on fire degree.The Shannon-Weiner and Simpson diversity index of the herbaceous plants in the mild burned area was the highest and significantly higher than other, which revealed that the moderate fire disturbance was beneficial to the vegetation regeneration.