【作者】 吴雪琼；

【导师】 杨文斌；

【作者基本信息】 中国林业科学研究院 ， 水土保持与荒漠化防治， 2013， 博士

【摘要】 低覆盖度行带式固沙林是近年来被广泛认可的一项低成本、高效益的防沙治沙体系，已经获得国家专利“低覆盖度固沙方法”。低覆盖度防沙治沙体系打破了传统研究认为的植被覆盖度在40%以下不能完全固定流沙的观念，达到了植被覆盖度在20%左右就能够完全固定流沙的效果，不仅能加快带间植被自然修复的时间，而且能够促进带间土壤的改良，是符合当地水量平衡的带状疏林，是一种长寿命的生物沙障。经过20多年的种植实验与观察发现，在低覆盖度行带式配置模式下的固沙林长势良好并可成材，林分稳定性更高，与均匀配置的片林相比具有显明的生长优势，但是其所表现出来的生长优势的机理尚不明确。笔者认为是这种特殊的人为干扰下的带状集群分布格局使林分具有了更多生态意义上的界面，从而使林内资源得到了更加高效、合理的分配与利用。本文以低覆盖度行带式配置（Low coverage banded scheme）模式下的赤峰杨（P.×xiaozhuanica W.Y Hsu et Liangcv. Chifengensis）固沙林为研究对象，在界面生态学的基础上，用传统的森林经理学方法研究了不同配置模式对固沙林生长的影响，通过标准地调查法及标准木解析法，结合带间土壤温湿度变化情况，对不同配置模式下植株的胸径、树高、材积生长过程、胸高比变化、径阶分布结构、林分竞争、林分稳定性等各方面进行了比较，对其生长优势进行了量化评价，主要结论有：1．低覆盖度行带式固沙林的生长优势是通过植株的树高、胸径与材积生长量增加体现出来的，赤峰杨固沙林胸径、树高、材积总生长量遵从Chapman-Richards函数生长；而连年生长量和平均生长量遵从多项式函数生长。低覆盖度行带式配置25~25m、35~15m、25~10m、35~8m（（株距行距～带间距）和均匀配置35m模式下的赤峰杨固沙林，胸径数量成熟龄分别为：9、8、20、17和25年，树高数量成熟龄分别为：9、8、23、16和15年，材积的数量成熟龄分别为：9、10、18、19和25年。胸径、树高和材积数量成熟龄随带间距的增大而减少；达最大平均生长量和最大连年生长量的年龄随带间距的增加而减小，而其值却随带间距的增加而增大。在一定带间距下，低覆盖度行带式固沙林的胸径和材积生长量大于均匀配置林分，而树高生长优势不明显，研究区适宜的带间距为10～25m，10m以下生长优势表现不明显。2．低覆盖度行带式配置模式下植株干、枝、叶生物量（鲜重）分配更为合理，其中，行带式配置模式下叶生物量在总生物量中所占的比例最高可达15.5％，而均匀配置模式下的林分叶生物量仅占总生物量的3.5％。行带式配置模式下植株胸高比较大，胸径生长优于树高生长，植株更加粗壮，更加适应于在干旱大风的环境在生长。数据分析表明，带间距越宽，死亡率越低。均匀配置（35m）林分死亡率高达9.7%，而行带式配置模式下林分死亡率最高为4.9%，最低的仅为2.2%；在同密度的行带式配置模式下，林分死亡率随着带间距的增大而降低。3．均匀配置的固沙林边缘效应率为1.17，界面效应表现为东边>西边>北边>南边，故林带走向以南北方向为宜，而且当地的主害风为西北风，根据防风固沙的需要，进行南北走向的林带设计也是相一致的。而行带式配置的固沙林是使所有的林木处于边行的位置，故在所有边行上都具有边缘效应。4．在低覆盖度行带式配置模式下，随着赤峰杨胸径的增大，其所受到的竞争强度在逐渐减小，竞争强度与林木径阶的大小符合幂函数关系。无论配置与林龄如何变化，胸径在15cm前受到的竞争压力较小，随后趋于稳定，故应在赤峰杨胸径达到15cm前进行必要的择伐或带状疏伐，以减少此后植株间的竞争，赤峰杨对象木周围2～3m范围内竞争强度是最大的。5．行带式配置模式下赤峰杨根系分布特征为，根长密度：株间＞行间＞带间，根长密度最大的是0～0.2mm径阶的细根，约0.61cm/cm3，根长密度最小的是径阶>2mm的根系，前者占到了根系根长密度的44.7%，而后者仅为1.6%，前者约是后者的30倍；0～60cm深度处根系占到了全根长（1~100cm）密度的74.6%，而深度在60～80cm的根系仅占25.4%。根重密度最大的出现在带间，根重密度最高可达22.58mg/cm3。距树不同径向距离处根长密度表现为开始最大而后减少又逐渐增大的趋势。赤峰杨根系主要吸收的是天然降雨。与均匀配置的人工林相比，低覆盖度行带式配置固沙林使所有的林木处于边行的位置，因此，具有明显的生长优势，林分结构合理，稳定性高。低覆盖度行带式配置模式是适宜于干旱半干旱地区种植的一种优良的配置模式。本文可为我国三北乃至相似地区生态恢复建设提供理论依据及参考，具有重要的现实与指导意义。更多还原

【Abstract】 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.更多还原