Study On Site Suitability Of Toxicodendron Vernicifluum

The Toxicodendron vernicifluum is a unique species in China.Understanding the site conditions and growth characteristics of Toxicodendron vernicifluums can effectively guide the construction and management of lacquer plantations.Based on the plot survey data and small class vector data of Pingli County in the concentrated area of??the Toxicodendron vernicifluum,the relationship between the site factor and the growth of the stand of the lacustrine plantation in the study area was analyzed.Using the prediction results of the niche model,the dominant factors affecting the site conditions were determined.According to the dominant factor,the division type of the Toxicodendron vernicifluum in the study area was divided,and the orientation curve method,the quantitative model I theory and the Bayesian analysis method were used to further study the site suitable for the Toxicodendron vernicifluum.The results are as follows:(1)Analysis and prediction of the Toxicodendron vernicifluum distribution record and climate variable data,and the ecological suitability zoning results of the Toxicodendron vernicifluum were obtained.The Maxent model results show that the AUC value under the ROC curve reaches 0.776,and the area ratios of the highly suitable area,the moderately suitable area,the general suitable area,the low suitable area and the unsuitable area based on the aliquot method are 5.51%and 9.75%,respectively.14.33%,24.55%and 45.85%.The proportion of the basic suitable area with the suitability higher than 0.6 is 15.26%,which is obtained from the comprehensive analysis of the displacement important values and response curves of the model,and finally the altitude and river distance of the eight site factors.),position as the dominant factor affecting the distribution growth of Toxicodendron vernicifluums.(2)According to the dominant factor,the study area is divided into low-altitude near-upstream river type,low-altitude near-river mid-slope site type,low-altitude near-river downhill site type,low-altitude far river uphill site type,low altitude Long river mid-slope site type,low-altitude far river downhill site type,high-altitude near river uphill site type,high-altitude near river mid-slope site type,high-altitude near river downhill site type,high-altitude far river uphill site 12 types of site types,such as the type of high-altitude and far-riving rivers,the type of high-altitude and far-reaching rivers,and the type of site.The areas are 32477.76ha,6449.22ha,18345.69ha,19853.91ha,2878.74ha,4232.25ha,46158.66ha,5094.9ha,16751.61ha,97354.71ha,97354.71ha,6016.68ha,10044.81ha.Among them,the area of??high-altitude and far-reaching rivers has the largest proportion,reaching 36.65%.And the GIS software will draw the map of the type of establishment.(3)Using the average tree height and age data,six common tree height growth equations were selected to fit the paint tree growth guide curve in the study area.According to the regression results,the Korf model was selected as the optimal guiding curve.The formula is:H=3.413*exp(0.197*A^0.619),the coefficient of determination is 0.986;and the tree height standard deviation equation is fitted and selected,the formula is:lg(S_H)=0.242-4.856/A＿1,the coefficient of determination is 0.524.The status table of the growth of the Toxicodendron vernicifluum was compiled from the tree height and the standard deviation of the standard deviation.The accuracy of the drop point test was higher than 97.5%.(4)Using the quantitative theory I,the regression analysis of the site factor and the status index.The contribution of different site factors to the site quality is soil texture,river distance,elevation,slope position and soil type.The prediction equation of the site factor is obtained.A quantitative site quality evaluation form has been prepared.The range of scores is determined by the range method,and the site quality of the study area is divided into five levels.The area is26964.9ha,24386.67ha,89035.2ha,72925.92ha and 52346.25ha,of which the area of Grade III is the largest,reaching 33.51%,and the Grade II is the smallest,accounting for only 9.18%.(5)Using the Bayesian statistical method,using four main factors(X1 elevation,X2 river distance,X3 slope position,X4 soil texture)and the Toxicodendron vernicifluum fitness predicted by Max Ent model,an unconditional logistic regression model was established.The posterior distribution of the suitability probability of the Toxicodendron vernicifluum site was estimated.The iterative result discriminant model basically converges to obtain the regression equation:(6)Compare the physical and chemical properties and nutrient content of five soil quality grades of lacquer wood,and analyze the difference of these indexes between 0-30cm soil layers.With the soil layer deepening,the soil bulk density of each grade increased gradually;soil moisture,porosity,organic matter,total nitrogen,total phosphorus,alkali nitrogen,available phosphorus and available potassium decreased.Significant.The C,N,and P contents of Grade 5soil were significantly higher than Grade 1,which increased by 124.7%,161.0%,and 86.1%,respectively.The N,P,and K contents of Grade 4 soil increased by 105.2%,77.9%,and 47.6%,respectively.In the same soil layer,soil moisture,organic matter,nitrogen,phosphorus,and potassium all showed the highest Grade 5,There is no significant difference between Grade 1with Grade 2.The bulk density was significantly negatively correlated with soil moisture,porosity,nitrogen,phosphorus,available potassium and p H,and negatively correlated with non-capillary porosity,organic matter and available phosphorus;organic matter,nitrogen,phosphorus and potassium.There was a significant positive correlation,and total nitrogen,total phosphorus,and total potassium were significantly positively correlated.