Effects Of Different Tending Thinning Intensities On Stands And Soil Properties Of Eucalyptus Plantations

Eucalyptus plantation is a major component of Chinese plantations and an important source of industrial raw materials.However,the current rule between the intensity of tending and the growth of eucalyptus plantations and a series of soil indicators is not fully understood.The influence of eucalyptus plantation on the soil fertility is also questioned.By exploring the influence of tending and thinning on eucalyptus plantation,it can provide a theoretical basis for better management and management of eucalyptus plantation in the future,and promote the green development and sustainable management of eucalyptus plantation to some extent.In this paper,four species of thinning intensity plots were set up for the eucalyptus plantation in the state-owned Qipo forest farm in Guangxi(control 0%,weakness 20%,moderate 30%,intensity 40%),and comparative analysis of different thinning intensity pairs.The effects of a series of indicators such as growth factors.biomass,productivity,soil enzyme activity and soil physical and chemical properties in eucalypt plantations indicate that:(1)The distribution of the diameters of each plot under different thinning intensity is a normal distribution.The number of large diameter trees in the stand increases with the increase of the thinning intensity.The DBH of the stand increases with the increase of the thinning intensity.The growth process of eucalyptus plantation tree height under different thinning intensity is basically the same.The thinning measure slows down the average growth rate of tree height to some extent,but has little effect on the growth of tree height.With the increase of thinning intensity,the volume of single plant in eucalyptus plantation forest gradually increased.When the thinning intensity was 40%,the unit volume of forest stand was the largest.(2)In the intensity thinning plot,the biomass per plant was the largest,and the forest with moderate thinning plot was the largest.In terms of forest productivity,the medium-sized thinning plot is the largest and the weakest thinning plot is the smallest.The leaf index(BNI)of each plot is close.Tending thinning has little effect on the ratio of photosynthetic organs to non-photosynthetic organs(FC)in different eucalyptus forests.The moderately thinned plot and the intensity thinning plot have a crown-to-root ratio(CRR)of 2 or more.(3)The activities of soil invertase,urease,catalase and acid phosphatase decrease with the increase of the depth of the soil layer.The soil urease activity increased with the increase of the thinning intensity.The soil sucrase activity was the highest in the control plots.There was no significant difference in soil urease activity between the plots in the 0-20 cm and 40-60 cm soil layers.The activity of catalase increased with the increase of thinning intensity.There was no significant difference in soil catalase activity between 20-40cm soil layers.With the increase of thinning intensity,soil acid phosphatase The activity was continuously increased,and there was no significant difference in each soil layer.(4)In each soil layer,the difference in soil bulk density between the various plots reached a significant level.As the intensity of thinning increases,the soil bulk density decreases.Soil capillary porosity in moderately thinning and intensity thinning plots was significantly higher than that in the control plots.The variation of non-capillary porosity in different soil layers in different thinning intensity plots is different.The total soil porosity increased with the increase of thinning intensity,and the total soil porosity of the intensity thinning plot was significantly different from that of the control plot.(5)The maximum water holding capacity and capillary water holding capacity of each soil layer also increase with the increase of thinning intensity,and decrease with the increase of soil depth.There was no significant difference in field water holding capacity in each soil layer.Thinning has a greater impact on maximum water holding capacity and less impact on capillary water holding capacity.(6)The soil pH value increases with the increase of soil depth,and there is no obvious regularity with the thinning intensity;in the 0-40cm soil layer,the organic matter content of the moderate thinning plot is the highest;in the 40?60cm soil layer,the intensity thinning The highest sample area,the content of organic matter in the control plots was the smallest in all soil layers;the contents of total nitrogen,total phosphorus,total potassium,hydrolyzable nitrogen,available phosphorus and available potassium decreased with the increase of soil depth.The weakly thinned plot has the highest total nitrogen content.With the increase of thinning intensity,the content of hydrolyzable nitrogen in soil increased gradually.The order of soil total phosphorus content was weak<intensity<control<moderate,and the soil available phosphorus content was the highest under moderate thinning intensity.The change of total potassium content was not obvious,and the content of available potassium increased with the increase of thinning intensity.