Study On The Growth Advantage And Interface Effect Of Low Coverage Banded Sand-fixing Forest

In recent years, the type of low coverage scheme sand-fixing forest belts was widelyconsidered as a low-cast and high-efficiency way to prevent and control desertification, whichhas got a patent named low coverage sand-fixing method.The type achieved the quicksand could be fixed completely when the vegetation coveragereached20%, which broked the traditional concept that the quicksand could not be fixed untilthe vegetation coverage under40%. Not only it could accelerate the natural restoration of theinter-band vegetation, but also promote the soil improvement, this zonal sparse woodlands fitfor the local water balance and was a biological barrier with long-life.After more than20years of planting experiment and observation, it has been found thatthe sand-fixing forest bands grew well and became lumber under the low coverage bandscheme, it has higher stability and more obvious growth advantage compared with the regulardistribution sand-fixing forest. However, the mechanism of the growth advantage still unclear.The author believed that the special zonal clumped distribution type of sand-fixing forestwhich under human disturbance created more ecological significance interface, thus realizedthe resources could be used and distributed more reasonably and efficiently.The thesis regards the P.×xiaozhuanica W.Y Hsu et Liang cv.‘Chifengensis’ as theresearch object, which planted under the lower coverage banded scheme, on the basis ofinterface ecology, the traditional forest management methods were used to study the effect ofdifferent configuration type on the growth of sand-fixing forest. Through the ample-plotsurvey and standard stem analytical methods, combined with the soil temperature and humiditychanges between inter-band, compared the difference of DBH, height, volume, the ration ofDBH and height, the diameter distribution structure, the competition index and the standstability of P.×xiaozhuanica cv. Chifengensis sand-fixing forest which planted under different type, the growth advantage was evaluated quantitatively. The main conclusions are asfollows:1. The growth advantage of sand-fixing forest planted under low coverage banded schemewas reflected by the tree height, the DBH and the volume growth. The DBH, the height and thevolume growth of P.×xiaozhuanica cv. Chifengensis followed the Chapman-richardsgrowth function. The current growth and the average growth followed the polynomial growthfunction.The P.×xiaozhuanica cv. Chifengensis sand-fixing forest planted under low coveragewith banded scheme of25~25、35~15、25~10、35~8m (stem row~band) andregular type of3x5m, the DBH quantitative maturity age were9,8,20,17and25yearsrespectively, the height quantitative maturity age were9,8,16,23and15years, respectively,the volume quantitative maturity age was9,10,18,19and25years respectively. The matureage of DBH, height and volume decreased with the band-width increased; the largest age ofaverage growth and the largest age of current growth decreased with the band-width increased,but the values were increased with band-width increased. Under certain band-width, the DBHand volume growth of sand-fixing forest which planted under low coverage with band-rowscheme were better than the regular type, but it was not obvious for the tree height growthadvantage, the appropriate band-width was between10~25m, the growth advantage wasindistinctive when the band-width less than10m.2. The stem, branch and foliage biomass allocation of P.×xiaozhuanica cv.Chifengensis were more reasonable which planted under low coverage band-row scheme,the foliage biomass proportion could up to15.5%among total biomass, on the contrary, it onlyaccounted for3.5%of the total biomass under regular type. The ratio of DHB and height washigher and the DBH growth was better than the height, it showed more adapted to grew in thedry wind environment. The data analysis showed that the more band width higher, the mortalityrate lower. Regular type (3x5m) forest mortality rates up to9.7%, but the mortality rate underlow coverage with banded scheme was only2.2%; when the low coverage with banded scheme sand-fixing forest planted under the same density, the mortality decreases with the band-widthincreased.3. The edge effect rate of sand-fixing forest which were planted under regular typewas1.17, the order of edge effect were east>south>west> north, so it was benefit for thedirection of the blet from north to south, and trees planted under low coverage with bandedscheme were all located at the edge, therefore, all the band and row have the edge effect.4. The competition intensity of P.×xiaozhuanica cv. Chifengensis planted under lowcoverage banded scheme decreased with the DBH increased, the relationship between theintensity of competition and the order DBH corresponed the power function. No matter howforest type and age changed, the competition of DBH under15cm has more lower, therefore, itwas not necessary to carry out selective cutting or band thinning until DBH up to15cm inorder to reduce competition identity, the most fierce competition appeared within distance fromP.×xiaozhuanica cv. Chifengensis2~3m scopes.5. The root distribution characteristic of P.×xiaozhuanica cv. Chifengensis plantedunder low coverage with banded scheme was: the order of root length density, inter-stems>inter-row> inter-band, the fine roots diameter class at0~0.2mm had the maximum rootlength density, about0.61cm/cm3, the fine root diameter class>2mm had the minimum rootlength density, the former accounted for44.7%of root length density, while the latter was only1.6%, the former was about30times than the latter; root system at depth of0~60cmaccounted for74.6%of the total root length density, while the root system at60~80cmaccounted for only25.4%. The Largest root weight density appeared at the inter-band, the rootweight density up to22.58mg/cm3. The root length density at different distance exhibited withmaximum in the beginning, then reduced and gradually increasd ultimately. The mainlyabsorbed of P.×xiaozhuanica cv. Chifengensis root system was natural rainfall.The low coverage banded sand-fixing forests under were all located at edges compared tothe regular sand-fixing forest of. Therefore, it has higher growth advantage, the stand structurewas reasonable and stability. The low coverage with banded scheme was suitable for arid andsemi-arid region. It could also be benefits to provide reference basis theory for the ecological restoration and vegetation construction of the Three-North even the same areas in our country,it has important practical and guiding significance.