The Buffer Effect On Aluminum Toxicity In China Fir Mixture Plantation Of Mountains Areas Around Sichuan Basin

China fir is an important timber species In south China with long history cultivation, which is an significant contribution for forestation. However, with atmospherically environmental deterioration as well as excessive afforestation such as China fir, eucalyptus and pinus, there appears some problems such as land productivity decline, pests, acid rain, fire disasters and ecological degradation globally which have became the major forestry and environmental problems, causing great economic losses.China fir aluminum poison have drawed highly attention from many national government which have launched a series of concerning researches. The present domestic research referring to China fir plantation soil degradation, have concentrated on the disequilibrium between supply and demand of nutrients, which was displaced by "plant nutrition stress" theory, to name a few, the aluminum toxicity, manganese toxicity and its mechanism. Research about aluminum-toxically-suffered trees in acidsoil have far-reaching significance on utilization of acid soil and exploitation of forest resources and land productivity.Based on the relevant forest community research methods inland and abroad and statistical analysis of sample number of the forest soil acidification, the research was designed to discuss the vegetation composition, biodiversity and soil acidification of the al toxicity by establishing eighteen provisional sample basis of cunninghamia lanceolata mixed plantation around the Sichuan basin and the surrounding mountains. Through analysing growth situation of various species of cunninghamia lanceolata mixed in allocation and content of several al-toxicity-related ion underground, the study aimed to figure out which configuration of Chinese fir tree was affected at least, which possessed al-toxicity-resistancy, which possessed better al-toxicity-alleiviating function, in order to pave the way for solving the problem in al-toxicity-alleiviating effect of artificially mixed forrest of chinese fir with different configuration, shed the light for selection of al-toxicity-resistant species and lay the foundation for discovering a biological approach to solve al toxicity in large area of southern china forest higher-effeciently, environmentally friendly and with lower comsumption, which have significant importance and promising prospects. the main research results was as follews:(1) The established eighteen provisional sample basis of cunninghamia lanceolata mixed plantation around the Sichuan basin and the surrounding mountains contains ferns, gymnosperms and angiosperms in total of.the composition of plant stands plots with single or meet basically meet various. The contains three or more of the three kinds of plants as the dominant family division, forest tree layer advantage is three, birch, ZhangKe and fagaceae. The shrub layer, as a dominant family rosaceae, herb layer advantage is grass and ferns.(2) Based on the classification number, the results was as follows:â… . In trees species, China fir plus Broad-leaf trees and Shrubs, arbor were not rich while shrubs were abundant, including sample nine and ten;â…¡. In two species, China fir pure plus Shrubs, China fir were abundant, shrub were rare and coverage-rate of herb was high, including sample four and seventeen;â…¢. In species, China fir plus Cryptomeria fortunei plus Broad-leaf trees, thr proportion of needle and Broad-leaf trees were nearly equivalent, shrubs were abundant, in approximately 20% coverage rate, including sample one three thirteen and eighteen;â…£. In species, China fir plus Schima superba plus Broad-leaf trees, Broad-leaf trees have rich species and the more count, Broad-leaf trees proportion larger, approximately 60%, including sample two six eight twelve fourteen and fifteen;â…¤. In species, China fir plus mao bamboo plus Broad-leaf trees, mao bamboo is obviously indicative species, Broad-leaf trees randomly spreaded and had larger proportion, Shrubs were not rich, including sample five seven eleven and sixteen.(3) Five different types of China fir suffered for Al toxicity degree, type 5< type 4< type 1< type 3< type 2, which reflected that when China fir mixed Broad-leaf trees, species of broad-leaved tree were various and abundant, advantagious hardwood species possessed better al-toxicity-alleiviating effect, shrubs were abundant and showed considerable al-toxicity-alleiviating effect, conifer crptomeria fortunei did not possess al-toxicity-alleiviating effect as considerable as broadleaf trees and shrubs.The most optimal types of configuration of al-toxicity-alleiviating China fir mixed hardwood species were fir mixed with hardhood species, which were abundant and equally distributed, coupled with the less-abundant shrubs. When planting broad-leaves trees, it was advisable to build some indicative arboreals which possessed considerable al-toxicity-alleiviating effect, whose coverage rate was above 50%.(4) Through the canonical correlation analysis, the species with al-toxicity-alleiviating effect was as follows:Schima superba, sassafrases, Machilusnanmu, Paulownia tomentosa, maple, tag alder, mao bamboo, Castanopsis Spach, Qucrcus, teabush, mountain ash, Rosa davurica, mayberry etc. According to the principle of proper fir tree in the main building growth station plant the above indicator species.