| Property of windbreak and sand fixation of four types of shelterbelt (pure forest of Casuarina equisetifolia, pure forest of Dendrocalamopsis oldhami, mingled forest of various kinds of bamboo and Casuarina equisetifolia and mingled forest of various kinds of bamboo) in coastal sands by field investigation and laboratory analysis was studied. Further, wind speed reduction effects of four types of shelterbelt, species diversity of vegetation from four types of shelterbelt, differences in soil nutrient dynamics, physical properties of soil moisture, vertical distribution and root soil erosion resistance in different soil depth of various kinds of bamboo and Casuarina equisetifolia was discussed. Finally, cluster of sand fixation of various kinds of bamboo and Casuarina equisetifolia was analyzed based on composite score of various kinds of bamboo and Casuarina equisetifolia by principal component analysis and hierarchical clustering method after the research of property of sand fixation. These studies aim to provide a logical and scientific theoretical foundation for choice of tree species increased in coastal sandy theoretical basis.The major results were as follows:1.The positive correlation between observing points and wind speed reduction effects was very significant. However, correlation of wind speed reduction effects related with types of shelterbelt was significant. The pure forest of Dendrocalamopsis oldhami possessed the best wind speed reduction effect of 57.36% and 52.96% respectively under the observing site at windward and observing height of 20cm and 200cm.The mingle forest of various kinds of bamboo and Casuarina equisetifolia possessed the best wind speed reduction effect of 71.29% and 72.21% respectively under the observing site in forest and observing height of 20cm and 200cm.However, the best wind speed reduction effect of 62.90%,70.67% under the observing site at Leeward and observing height of 20cm and 200cm was possessed by mingled forest of various kinds of bamboo and mingled forest of various kinds of bamboo and Casuarina equisetifolia respectively2.According to complexity of families and genera compositions as a reference index of ability of potential sand fixation existing in vegetation community, mingled forest of various bamboo possessed the greatest potential ability for due to the shelterbelt in which there are the largest number of species and the most complexity of families and genera compositions, then was pure forest of Dendrocalamopsis oldhami, mingled forest of various kinds of bamboo and Casuarina equisetifolia and pure forest of Casuarina equisetifolia in order. However, in important value of four types of shelterbelt, Casuarina equisetifolia was constructive species and dominant species in tree layer both in pure forest of Casuarina equisetifolia and mingled forest of various kinds of bamboo and Casuarina equisetifolia. While Dendrocalamopsis beecheyanus var.pubescens and Dendrocalamopsis oldhami with important value of 110.93, 265.39 in respective shelterbelt was dominant species in tree layer of mingled forest of various kinds of bamboo and pure forest of Dendrocalamopsis oldhami respectively.3. The variation of indexes about soil moisture physical properties of four types of shelterbelt was basically consistent. Soil bulk density of four types of shelterbelt increased with the increase of soil depth. While other indexes including maximum water holding capacity, minimum water holding capacity, capillary water, capillary porosity of soil, total porosity, optimum moisture content limit, degree ventilation were basically declined with soil depth. Comprehensive analysis of indexes indicated that mingled forest of various bamboo showed best in regarding of soil moisture physical properties of types, then was pure forest of Dendrocalamopsis oldhami, mingled forest of various kinds of bamboo and Casuarina equisetifolia and pure forest of Casuarina equisetifolia in order. In addition, in aspect of mechanical composition of particles,the order of strong coarsening phenomenon of soil was pure forest of Casuarina equisetifolia, mingled forest of various kinds of bamboo and Casuarina equisetifolia, pure forest of Dendrocalamopsis oldhami , mingled forest of various kinds of bamboo.4. Results of soil nutrient dynamics in four types of shelterbelt showed that in annual average pH value, soil acidification was most obvious in pure forest of Casuarina equisetifolia, followed by mingled forest of various kinds of bamboo and Casuarina equisetifolia, pure forest of Dendrocalamopsis oldhami, mingled forest of various kinds of bamboo. The content of total soil nutrients and available soil nutrient in 0-20cm soil layer are basically more than that of 20-40 cm. Result of correlation analysis were as follows: there exited very significant negative correlation between total N and soil depth(r=-0.938),significant positive correlation between total N and total K, very significant positive correlation between soil organic matter and soil depth, significant positive correlation between soil organic matter and season, total N and total P in which correlation coefficient was 0.695,0.839 and 0.881 respectively.Little differences between available phosphorus content were found in types of shelterbelts but large differences existed in content of hydrolysis of N and available phosphorus in variation in season of available nutrients. There were significant differences of Hydrolyzable nitrogen content in different types of shelterbelt. According to annual average value of hydrolysable nitrogen, in 0-20cm soil layer, the hydrolysable nitrogen content was in order of mingled forest of various kinds of bamboo and Casuarina equisetifolia, with content 43.917 mg·kg-1, mingled forest of various kinds of bamboo, pure forest of Dendrocalamopsis oldhami and pure forest of Casuarina equisetifolia. While in 20-40cm soil layer, the hydrolysable nitrogen content was in order of mingled forest of various kinds of bamboo with content 25.096mg·kg-1, mingled forest of various kinds of bamboo and Casuarina equisetifolia, pure forest of Dendrocalamopsis oldhami and pure forest of Casuarina equisetifolia. And the amount content of available phosphorus in coastal land was significantly low except mingled forest of various kinds of bamboo with available phosphorus content in 0-20cm and 20-40cm soil layer 119.140 mg·kg-1,58.417mg·kg-1 respectively.5. Total amount of soluble salts in 0-20cm soil layer was highest in mingled forest of various kinds of bamboo and Casuarina equisetifolia with content value 0.645g·kg-1,followed by mingled forest of various kinds of bamboo about 0.586 g·kg-1, pure forest of Dendrocalamopsis oldhami about 0.547g·kg-1 and pure forest of Casuarina equisetifolia about 0.513g·kg-1.While in 20-40cm soil layer was highest in pure forest of Dendrocalamopsis oldhami about 0.615 g·kg-1, followed by mingled forest of various kinds of bamboo about 0.491g·kg-1, mingled forest of various kinds of bamboo and Casuarina equisetifolia about 0.462g·kg-1 and pure forest of Casuarina equisetifolia about 0.439g·kg-1. In content of composition anion, the order was as follow: HCO3–> CO32-> SO42- in 0-20cm soil layer of pure forest of Casuarina equisetifolia. In addition to 20-40cm soil layer of pure forest of Casuarina equisetifolia, the order was Cl-> CO3(2-0> SO42- both in 0-20cm and 20-40cm soil layer in other types of shelterbelt. While In content of composition cationic, the order was as follow: Ca2+> Na+ > K+ >Mg2+ in both 0-20cm and 20-40cm soil layer of four types of shelterbelt in which Ca2+and Na+ account for most of proportion. Result of correlation analysis were as follows: there exited significant positive correlation between total salt content and Na+ and very significant positive correlation between total salt content and K+ in which correlation coefficient was 0.784 and 0.871 respectively.6. Vertical root distribution depth of Casuarina equisetifolia on the coastal land was more deeper than that of various kinds of bamboo reaching to 100cm.The root of various kinds of bamboo and Casuarina equisetifolia distributed mainly in 0-40cm soil layer but it was accounted more proportion in 10-20cm soil layer. Total amount of root of in various kinds of bamboo and Casuarina equisetifolia ranked in the order of Dendrocalamopsis beecheyana var. pubescens with value16995.44g,Bambusa tuldoides, Dendrocalamopsis oldhami with value 15659.2g,Dendrocalamopsis oldhami with value 14649.24g, Dendrocalamus latiflorus with value 14233.12g,Bambusa ventricosa with value 12880g, Dendrocalamopsis vario-striata with value 12227.48g, Bambusa eutuldoides with value 9537.36g, Bambusa multiplex var. multiplex cv.Alphonse-Karr with value 6478.64g, Dendrocalamus minor var. amoenus with value 6344.32g, Bambusa tuldoides cv. Swolleninternode with value 3958g and Casuarina equisetifolia with value 3280.2g.7. The variation of soil anti scour index was basically the same with that of vertical root distribution, that is to say ,anti scour index value were basically declined with soil depth with maximum in 10-20cm soil layer which accounted most of proportion. The amount of soil anti scour index in 10-20cm soil layer was highest in Dendrocalamopsis oldhami with value 23.01L·min·g-1,followed by Bambusa tuldoides about 22.86 L·min·g-1,Dendrocalamopsis beecheyana var. pubescens about 22.58L·min·g-1,Dendrocalamus latiflorus about 22.36 L·min·g-1,Dambusa ventricosa about 20.52 L·min·g-1,Dendrocalamopsis vario-striata about 19.62 L·min·g-1,Dendrocalamus minor var. amoenus about 15.26 L·min·g-1,Bambusa eutuldoides about 13.24 L·min·g-1, Bambusa tuldoides cv.Swolleninternode and Bambusa multiplex var.multiplex cv. Alphonse-Karr with same value 9.84 L·min·g-1,the lowest soil anti scour index value existed in 10-20cm soil layer of Casuarina equisetifolia.8. According to the study of relationship between root tensile strength and root diameter in different root length of 10cm, 15cm, 20cm among various kinds of bamboo and Casuarina equisetifolia, the results indicate that both power function and exponential function could be applied to fit the function between root tensile strength of various kinds of bamboo and its diameter. But regarding to both correlation coefficient between variables and fitting precision, mathematical model by using power function was better than that by exponential function.9. Six principal components extracted by principal component analysis of cumulative contribution rate of greater than or equal to 85% were comprehensively scored from ten kings of bamboo and Casuarina equisetifolia. The result was shown as follow:in 10-20cm soil layer, the highest score was the number 6, followed by 8,2,1,7,4,3,5,11,9,10.Cluster analysis results were divided into four categories provenance, the first category was the number 6 with the strongest sand fixation. The second category was the number 8. The third category was the number1, 2, 3, 4, 5,7, 10,11.The fourth category was the number 9.In 20-40cm soil layer, the highest score was the number 9. followed by 6,5,2,1,8,10,11,7,4,3.Cluster analysis results were divided into four categories Provenance, the first category was the number 9 with the strongest sand fixation. The second category was the number 1,3,4,5,6,7,8,10.The third category was the number1.The fourth category was the number 11.
|
PDF Full Text Request