【作者】 王梅；

【导师】 张文辉；

【作者基本信息】 西北农林科技大学 ， 植物学， 2010， 博士

【摘要】 以陕北黄土高原不同区域油松人工林为研究对象,通过样地调查,系统研究了油松人工种群的生殖特性、更新特征、林下植物群落多样性、生长特性及其沿环境梯度的变化规律,确定了影响油松人工种群生殖和更新的限制性因素,探索了应用模糊隶属函数综合评判模型来评价油松人工林天然化发育的评价方法,提出了油松人工林在陕北黄土高原可天然更新的地理分布北界和天然化培育途径,为油松人工林的造林区划与经营管理提供科学依据。主要研究结果如下:1.陕北黄土高原油松人工林均具有结实能力,结实母树比例在30%以上,中部和南部地区结实母树比例高于北部地区。不同县间单株球果产量变异幅度大,以神木和吴起最少,分别为8.3和7.3个;黄龙和宜川最多,分别为20.6和19.7个;同一地区植株间球果产量变异幅度也大。油松球果的长、宽、平均单果出种量、种子长、宽均是南部和中部地区显著大于北部地区。油松种子饱满率则以北部地区较高达到67.32 %-77.60 %,中部和南部较低为59.12 %-62.76 %。年均降水量和1月平均最低气温对油松的生殖特性影响最大,年均蒸发量和无霜期对油松的生殖的影响次之。2.油松种子千粒重以南部和中部地区为最大,北部地区最小。分布区北端的神木种子生活力最低,与其它地区的有显著差异,其它地区之间没有显著差异。在室内条件下各地区种子发芽率差异不显著。20℃-25℃是油松萌发的最适温度,最低发芽温度在8℃左右。土壤含水率8 %是油松种子发芽所需的最低土壤水分含率。3.在天然条件下,神木、吴起和绥德地区,种子落地后不能发育成幼苗(树)。志丹、延川、延长仅在林缘处发见到极少量的3-5年生幼树;在黄龙、宜川林下幼苗幼树较丰富,最大幼树年龄为10 a,幼苗(树)主要聚集分布于母树四周,但幼苗向幼树的转化率低。年均降水量、年均温度和≥10℃年积温对油松人工林的更新过程影响最大。油松人工林可天然更新分界线应该为年降水量550 mm的等降水线左右,550 mm等降水线以南地区为油松适宜栽培区。潜在更新区分界线应该在年降水量550 mm和500 mm的等降水线之间,该地区为油松亚适宜栽培区。不可更新区分界线应该为年降水量500 mm的等降水线左右,等降水线以北的地区为油松不适宜栽培区。4.由北向南,油松人工林林下乡土植物的科、属、种数均逐渐增加,75%以上的植物属是温带分布属。物种多样性的最小值均在神木。纬度和年降水量对草本层物种多样性影响较大,纬度、年降水量、年均日照时数和1月平均气温对灌木层物种多样性的影响较大。由北向南,Cody指数(βC)呈现递增的趋势,这说明沿纬度梯度物种替换数目逐渐增加,较好地反映了不同生境梯度上群落的差异。Whittaker指数(βWS)矩阵、Jaccard指数(Cj)和Sorenson指数(CS)均呈现不规则地跳跃式变化,表明各区域之间油松人工林群落相似性差异较大;并且Cj和CS具有相同的变化趋势。5.陕北黄土高原油松人工林各生长指标(平均胸径、树高、冠幅、冠高)由北向南逐渐增大,黄龙、宜川为适宜栽培区域,平均胸径、树高、冠幅、冠高分别达到8.9和8.5 cm、8.8和6.3 m、3.7和3.5 m、2.8和5.8 m。不同区域油松人工林各生长指标均有显著差异。宜川和黄龙县的油松人工林直径、树高分布遵从于近似正态分布。纬度、年均降水量和1月平均最低气温对油松的生长影响最大,无霜期对油松的生长的影响次之。6.通过应用模糊隶属函数评判模型对3个区域(8个县)油松人工林的天然化发育进行综合评价,所得的结果符合当地油松人工林的生长发育状况。油松人工林的天然化发育大小依次是:黄龙>宜川>志丹>延长>延川>绥德>神木>吴起。7.阴坡油松的胸径、树高、冠高和冠幅均显著大于阳坡。阴坡与阳坡林下分别有植物21,19种,共有种11种,群落相似系数为55 %。群落总体多样性表现为丰富度指数和多样性指数均是阴坡稍大于阳坡,而均匀度指数表现为阳坡稍大于阴坡。阴坡物种丰富度指数、均匀度指数和多样性指数均表现为草本层>灌木层;而阳坡的Shannon-wiener指数和Pielou指数(Jsw)则与阴坡相反,为灌木层>草本层。油松人工林的死亡率随初植密度的增大呈增加趋势,死亡年龄、胸径、树高、冠高和冠幅随栽植密度的增加而减小;但油松树高与栽植密度之间的相关性不显著。林下幼苗(树)的更新状况在低密度林地内最好。在各栽植密度油松人工林中,各层物种丰富度指数、均匀度指数和多样性指数均表现为灌木层>草本层。群落总体多样性表现为丰富度指数和多样性指数在3种栽植密度间的变化趋势一致,均为密度Ⅲ>密度Ⅱ>密度Ⅰ;均匀度指数Jsw和Ea则表现为Ⅰ>Ⅲ>Ⅱ,而Jsi则表现为Ⅲ>Ⅰ>Ⅱ。8.陕北黄土高原营造油松人工林,年降水量>550 mm的地区最好,阴坡最好,油松人工林合理的初始造林密度应在2800-3000株/hm~2。更多还原

【Abstract】 In this paper, Pinus tabulaeformis plantation were taken as the research object in the different regions, and growth, reproductive and regeneration characteristics, community structure were studied across environmental gradients on the Loess Plateau, in order to confirm the main factors affecting the natural regeneration and reproduction of Pinus tabulaeformis, to explore the evaluation method for the plantation communities naturalized development based on fuzzy membership function synthetic evaluation model, to present the boundary of natural regeneration and naturalized cultivation way, to provide theoretical bases for planting and management. The main results were as follows:（1） Sexual reproduction process was complete in southern and middle Loess Plateau in north Shaanxi. Mother tree rate accounted for more than 30%. Cone yield, length, width, average seed number per cone, seed length and width was higher in the south and middle region than that in the north region. Full seed rate was 67.32 %-77.60 % in the northern region, which was higher than that in the southern and middle region （59.12 %-62.76 %）. Annual precipitation and average temperature of January had the most influential effect on reproduction characteristics, while annual evaporation and frostless period took the second place。（2） The weight per 1000 seeds was higher in the south and middle region than that in the north region. The viability of seeds was the lowest in Shenmu. There was not significant difference in the viability and the germination of seed. The optimum temperature of seed germination was 20-25℃, the lowest temperature was 8℃. The lowest soil moisture of seed germination was 8 %.（3） Seed did not germinate after falling to the ground in Shenmu, Wuqi and Suide. There were few of saplings in the forest edge in Zhidan, Yanchuan and Yanchang. There were abundant seedling and sapling in Huanglong and Yichuan, and maximum age of sapling was 10. Seedling and sapling aggregately distributed mother tree around. Annual precipitation, annual temperature and≥10℃annual accumulated temperature had the most influential effect on regeneration.The region of annual precipitation more than 550 mm was suitable cultivation region. Potential regeneration region was that of annual precipitation between 550 mm and 500 mm, which was mild suitable cultivation region. The region of annual precipitation less than 500 mm was not suitable cultivation region.（4） Families, genera and species of indigenous plant gradually increase from north to south, 70% plant belonged to temperate distribution genera. The minimum of species diversity was in Shenmu. Latitude and annual precipitation had the more effect on species diversity herb layer, latitude, annual precipitation, annual sunshine hour and average temperature of January had the more effect on species diversity shurb layer. Cody index （β_C） present increasing trend from north to south, which explained species replacement rate increase with decreasing latitude, andβ_C was able to reflect the community changes as the latitude alters. Whittaker index (β_WS)、Jaccard index （C_j） and Sorenson index （C_S） changed irregularly and salutatory, which community similarity had great difference. C_j and CS had the same change trend.（5） Pinus tabulaeformis grew normally, and average DBH, height, crown width and crown height gradually increased from north to south. There was significant difference among growth index in the 8 sites. The diameter and the height distribution of Pinus tabulaeformis artifical forest obey described normal distribution function in Huanglong and Yichuan. Latitude, annual precipitation and average temperature of January had the most influential effect on growth, while frostless period took the second place.（6） Based on fuzzy membership function synthetic evaluation model, the plantation community naturalized development was evaluated. The result show that Huanglong>Yichuan>Zhidan>Yanchang>Yanchuan>Suide>Shenmu>Wuqi.（7） Stem diameter, height, crown height and crown width in the shady slope were significantly greater than that in the sunny slope. The community species richness and diversity index were shady slope>sunny slope; evenness index was sunny slope>shady slope. Species richness, evenness index and diversity index of the herb layer were higher than that of the shrub layer in the shady slope. Shannon-wiener index and Pielou index（Jsw） were shrub layer>herb layer in the sunny slope.Because of individual competition, mortality increased and death age, stem diameter, height, crown height and crown width decreased with increasing of density. Species richness, evenness index and diversity index in the shrub layer were higher than that in the herb layer in the different density plots. The community species richness and diversity index were densityⅢ>densityⅡ>densityⅠ; evenness index （Jsw, Ea） was densityⅠ>densityⅢ>densityⅡ, but Jsi was densityⅢ>densityⅠ>densityⅡ.（8） Pinus tabulaeformis what grow in the shady slope and the region of annual precipitation more than 550 mm on the Loess Plateau in north Shaanxi preceded than in the other place. The optimum stand density of Pinus tabulaeformis is 2800-3000 stocks/ hm2.更多还原