华北落叶松人工林根系生物量的研究

在华北落叶松人工林中设置标准地，分别按径阶选定样木，测定根粗大于１ｃｍ的根系生物量，同时用土柱法测定根粗小于１ｃｍ的根系生物量。结果表明，根系生物量占总生物量的１８．２％～３０．８％，根系生物量与林木径阶的变化有极显著的相关性，根粗小于１ｃｍ的根系生物量集中分布于０～２０ｃｍ的土层中。     

华北落叶松人工林根系生物量的研究

在华北落叶松人工林中设置标准地，分别按径阶选定样木，测定根粗大于１ｃｍ的根系生物量，同时用土柱法测定根粗小于１ｃｍ的根系生物量。结果表明，根系生物量占总生物量的１８．２％－３０．８％，概系生物量与林木径阶的变化有极显著的相关性，根粗小于１ｃｍ的根系生物量集中分布于０－２０ｃｍ的土层中。     

桤木生物量及根系分布规律

采用全部、分层挖取法,研究洞庭湖区9年生桤木人工林的生物量及根系分布规律。结果表明：桤木单株生物量为44.39ks／株,各器官生物量大小排序为树干〉树根〉树枝〉树皮〉树叶;林分总生物量为96.06/hm^2;林分净生产力为10.67/（hm^2·年）。桤木根系发达,根深60～80cm;根系中以根桩和粗根的生物量所占的比例最大,两者之和占根系总生物量的84.27％。在垂直分布上,根系主要分布在0～40cm的土层中,其生物量占根系总生物量的84.51％。在水平分布上,根系主要分布在离树桩0～50cm的范围内,其生物量占根系总生物量的84.49％;特别是粗根,其生物量占根系总生物量的29.47％;茵根的生物量占根系总生物量的0.39％,主要分布在离树桩50～100cm的范围内,该区域根系的生物量占茵根总生物量的70.97％。     

干旱山区油松幼林根系分布特征研究

笔者以不同树龄油松为研究对象,采用剖面挖掘与分层取样法,研究了2年生、3年生、4年生、5年生、6年生油松的根系。结果表明,随着树龄增大,根系在垂直方向上,随着深度增加分布范围变大;水平分布范围随深度变化不明显。在垂直方向上,根生物量随着土层深度的增加先增大后减小,呈现倒V的变化趋势;随着树龄增大,油松根系生物量显著增大。在0 cm～10 cm土层内,很少有细根;而在30 cm以下的土层内,只有细根和近似细根的根。2年生、3年生油松幼苗的根生物量主要分布在0 cm～20 cm土层内,4年生、5年生、6年生油松根生物量主要分布于0 cm～30 cm土层内。其中,土壤质地条件是影响根系分布的一个重要因素。     

油茶根系分布规律调查研究

以不同树龄油茶为试材,运用剖面法研究根系的垂直分布、水平分布以及分析不同径阶根系的比例.结果表明:油茶根系数量在第5～15年增长迅速,第15～30年根系数量增长幅度不大;根系主要集中在0～40 cm的土层,该层根系数量占根系总数的70%～800,40～60 cm土层中根系只占20%左右,但数量随着树龄增加逐渐上升;5～10年生油茶根幅都在2m以内,15～30年生扩展到4m左右,根系主要分布于距树干基部1 m的范围内,该区域内的根系数量占根系总数的58.2%以上,但根系所占比例随着树龄的增加逐渐降低;由于水肥、地理等因素影响,南北剖面的根系数量出现明显差异,表明油茶根系具有明显趋水肥的特性.     

窄冠刺槐根系的研究

2006年10月用全挖法和分层分段挖掘法,研究了窄冠刺槐根系的分布特征、根系生物量以及不同密度林分根系空间分布特征.结果表明:窄冠刺槐个体根系水平分布在株间可达到6.6 m,在行间可达到5.0 m;主根可深达2 m以上,侧根垂直分布集中在10～40 cm土层内.窄冠刺槐根系生物量占全株生物量的16.82％,主根、侧根的生物量在根系生物量中分别占87.13％、12.87％.窄冠刺槐林分根系生物总量和根总长分别为6 160.2～10 940.55kg·hm-2和970.35～1 607.4 km·hm-2,并呈现出根系生物总量和根总长与林分密度成正相关的规律.在垂直方向上,林分根系中直径D<15 mm的根主要分布在地下0～20 cm土层内,而直径D≥15 mm的根主要分布在地下20～40 cm土层内;在水平方向上,直径D≥5 mm的根数量随距树干距离增加而减少,而直径D<1 mm的根数量则随距树干距离增大而增大,主要集中分布在距树干0.5～1.5 m范围内.     

林龄对思茅松人工林根系生物量的影响

[目的]以云南省普洱市主要植被思茅松人工林为研究对象,探讨不同林龄思茅松人工林根系生物量的大小分布及变化特征。[方法]分别在5、8、15、25、36年生思茅松人工林内,利用内径为8.5 cm的根钻分3层(0~10、10~20、20~30 cm)获取思茅松与其它物种的细根、粗根及死根生物量数据。[结果]表明:随着思茅松人工林林龄的增长,思茅松细根生物量呈减少的趋势,而其它物种细根生物量呈增加趋势,细根生物量最大出现在36年生思茅松人工林。不同林龄思茅松人工林的思茅松粗根和死根生物量之间无显著差异,而其它物种及林分的粗根生物量和根系生物量则随林龄增长而增加。思茅松人工林的细根生物量主要分布在土壤深度0~10 cm内,其中,思茅松、其它物种、林分细根生物量以及根系生物量随土层深度的增加呈减少趋势。林龄和土壤深度对思茅松与其它物种的细根生物量有显著影响,林龄与土壤深度的交叉作用对思茅松细根生物量有显著影响,林龄对死根生物量有显著影响,林龄、土壤深度及林龄与土壤深度的交叉作用对粗根与根系的生物量有显著影响。[结论]思茅松人工林随着林龄增长,群落结构与树种组成随之发生变化,从而对根系生物量产生较大影响。     

黄土高原丘陵区不同立地条件下柠条根系研究

对黄土高原丘陵区不同立地条件下3年生柠条的根系作了初步研究,结果表明:柠条侧根发生的主要部位在距地表0～20 cm的土层中,除在阳坡、半阳坡分布的植株外,其它的在50 cm以下没有侧根发生,侧根总数以阳坡最多,半阴坡最少;不同立地下根系生物量的垂直分布,均表现为从土壤表层到深层逐次递减;在各土层中,0～60cm土层中分布的根系生物量所占的比重最大,超过了总量的80%.不同立地条件下单株根系生物量以阳坡最大,为66.63 g,阴坡最低,仅为6.69 g.不同立地条件下柠条的地上部分差异显著,阳坡、半阳坡的株高、生物量等都高于阴坡和半阴坡的.柠条在幼龄期适宜生长的立地类型为阳坡和半阳坡.     

6年生互叶白千层根系形态与缩根技术

研究6年生互叶白千层自然生长的根系组成与分布,并对3年生互叶白千层采取切根与滴灌的缩根处理。自然生长根系水平根系较长且粗壮发达,根基部细根分布较少,影响互叶白千层移栽恢复。切根和滴灌处理可以缩短主侧根长度,诱导细根生长,细根生物量明显增加,且大部分集中在植株根系20 cm水平范围内。综合考量以3年生苗木根茎外10 cm处切根,并在种植株根系20 cm范围内采用导向性滴灌处理苗木根系生长较好,有利于互叶白千层大苗的移栽恢复。     

湘北四川桤木人工林根系空间分布特征

对湘北地区6年生四川桤木(Alnus cremastogyne)人工林不同径级根系生物量分布、根长、比根长、根长密度的空间分布特征进行研究。结果表明:四川桤木人工林大根、中根、小根、细根生物量分别占林分根系生物量总和的55%、22%、14%、9%;约66%的根系生物量集中在0～30cm土层;不同径级根系根长变化趋势是:细根小根大根中根,比根长的变化趋势是:细根小根中根大根;各径级根长密度变化趋势各不相同:垂直方向上,在0～60cm土层,大根的根长密度随土层深度的增加先增后降,中根、小根、细根的根长密度随土层深度的增加而减小,水平方向上,在0～80cm距离,大根的根长密度随距树干距离的增加而减小,细根的根长密度随距树干距离的增加而增大,中根、小根的根长密度在距树干0～60cm内逐渐减小,而在距树干60～80cm又略有增加。     

Biomass distribution in 40-year-old trees of Japanese black pine

Measurements were carried out to survey the quantity of above- and below-ground biomass and its distribution of five Japanese black pines (Pinus thunbergii Parl.) growing on a sandy soil. The roots, divided into diameter groups, were surveyed using two methods—soil coring and excavation. Average dry weight of total biomass of the trees was 176,185 g. Roots represented 13.2%, below-ground stump 6.5%, stem 70.4% and branches with needles 9.9% of total biomass. Roots made up about two thirds and stump one third of below-ground biomass. Total length of below-ground biomass (except roots with diameter < 0.1 cm) was 479.1 m/tree. Roots with diameter of 0.1–0.2 cm represented only 0.7% of below-ground biomass, however as much as 49.9% of their total length. Roots with diameter over 10.0 cm constituted as much as 21.6% of below-ground biomass, however were only 0.3% of its total length. Root systems had well developed tap roots to maximal depth of 231 cm. The results indicated that mass and length of roots with diameter 0.5–2.0 cm had a close correlation with branch mass. Mass and length of roots with diameter 2.0–10.0 cm closely correlated to stem mass. Stem mass, root mass and root length closely correlated to DBH. A rather low correlation was found between DBH and mass of branches and below-ground stump. DBH was a suitable variable for predicting total biomass.     

不同坡位6年生杉木木荷混交林生物量分布格局分析

对不同坡位6年生杉木木荷混交林林分生长及生物量进行分析研究。研究结果表明,杉木木荷混交林平均胸径、平均树高生长量以及地上部分和地下部分各个器官生物量均体现为下坡位>中坡位>上坡位;杉木各器官生物量表现为树干>树叶>树枝,木荷各器官生物量表现为树干>树枝>树叶;就杉木及木荷不同径级根生物量差异而言,杉木各径级根表现为骨骼根>中根>大根>粗根>小根>细根,木荷则表现为骨骼根>中根>大根>小根>细根。     

Larrea tridentata根系形态及其与地上部分相关关系的研究

通过整株法,观测1 a生与2 a生Larreatridentata根系的生长分布状况,并通过地径建立根系生长状况的数学模型。结果表明:L.tridentata根系庞大,主根长,侧根发达,根型利于对水分的吸收,具有典型沙漠植物的根系特征;地径与主要根参数(总根长、根总断面积、根干重)有极显著的指数函数相关关系,可用地径建立预测根系生长的模型。地上部分生物量与地下部分生物量有极显著的幂函数相关关系,且随着地下部分生物量的增加,地上部分生物量成幂函数递增。     

The effect of red wood ant (<Emphasis Type="Italic">Formica rufa</Emphasis> group) mounds on root biomass,density, and nutrient concentrations in boreal managed forests

Red wood ants (Formica rufa group, RWAs) are common insects in boreal forests in Fennoscandia, and they build large, long-lived mounds as their nests. RWA mounds are enriched with carbon and nutrients, but little information is available about how they affect root distribution and the nutrient uptake of trees. In this study, we investigated the biomass, biomass density, nutrient concentrations, and amounts of fine (<2 mm) and coarse (>2 mm) roots in RWA mounds, and compared them with those of surrounding forest soil in mixed coniferous stands of different age classes in Finland. Neither fine nor coarse root biomasses differed significantly between the aboveground parts of the mounds and the organic layer of the soil. Root biomass density was lower in mounds than in the organic layer. However, fine root biomass and biomass density were higher in the belowground parts of mounds than in the surrounding mineral soil. Macroelement (N, Ca, K, P, S, Mg) and Zn and Cu concentrations in roots in the mounds were significantly higher than those in the organic layer. Root biomass and biomass density did not differ between stands of different age classes. The results of this study indicate that RWA mounds increase heterogeneity in root distribution in forest ecosystems, and also increase the availability of nutrients for plants that extend their roots inside RWA mounds.     

Distribution of biomass and carbon in even‐aged stands of Norway spruce (Picea abies (L.) Karst.): A case study on spacing and thinning effects in northern Denmark

The main objective of this case study was to explore the possible influence of forest management on the levels and distribution of biomass and carbon (C) in even-aged stands of Norway spruce [Picea abies (L.) Karst.] in Denmark. Data originated from a long-term thinning experiment and an adjacent spacing experiment at stand ages of 58 and 41 years, respectively. Biomass of 16 trees from different thinning and spacing treatments was measured or partly estimated, and soils were sampled for determination of C stocks. All trees in each plot were measured for stem diameter and some for total height, to allow for scaling-up results to stand-level estimates. For trees of similar size, foliage biomass tended to be higher in the spacing experiment, which was located on slightly more fertile land. Foliage biomass increased with increasing thinning grade, but the effect could not be separated from that of tree size. At stand level, foliage biomass tended to increase with increasing spacing as well as with increasing thinning grade. For branchwood, stems and roots (including below-ground stump), the biomass increased with increasing tree size and stand volume at tree and stand level, respectively, but no differences between stands, spacings or thinning grades were observed, apart from that expressed by tree size or stand volume. At stand level, C stocks of all biomass compartments decreased with increasing thinning grade, while the distribution between compartments was hardly influenced. The ratio between above-ground and stem biomass was about 1.21 at stand level, while the ratio between below- and above-ground biomass was about 0.17. Thinning influenced the C stock of the forest floor and mineral soil oppositely, resulting in no effect of thinning on total soil C.     

Quantification of two-year-old hybrid poplar root systems: morphology, biomass, and (14)C distribution

Root morphology, biomass, and (14)C distribution were studied in two 2-year-old Populus trichocarpa x P. deltoides hybrids, which originated from hardwood cuttings, to determine the pattern of root distribution in a plantation and to refine methods for root recovery. The trees were labeled with (14)CO(2) and harvested after a 72-hour chase period. Roots attached to each labeled tree were analyzed for morphological traits at the time of harvest. Detached roots from within a 1-m(3) volume of soil surrounding each tree were separated from the soil and sorted on the basis of rooting depth and root diameter. Lateral roots > 2 mm in diameter had a largely horizontal orientation at their point of origin from the cutting and extended horizontally up to 4 m from the cutting. This resulted in considerable overlap of root systems in the plantation. Results from (14)C labeling indicated that 24 +/- 4% (+/- SD) of the carbon exported from branches-labeled within two weeks after branch budset-was translocated to the root system. Dilution of the root (14)C label indicated that from 0 (> 5 mm diameter roots) to 75% (< 2 mm diameter roots) of the roots recovered from within the 1-m(3) volume of soil surrounding a harvested tree originated from other trees. Total root biomass was 6 +/- 1 Mg ha(-1) for both hybrids. Sixty percent of the root biomass was recovered directly from excavation, 16% from coarse-sieving excavated soil, and 24% from re-sorting sieved soil. The study indicated that root growth of hybrid poplars may be rapid and extensive and that detailed sorting of soil subsamples substantially improves the recovery of fine roots < 2 mm in diameter.     

Thinning effects on carbon allocation to fine roots in a Quercus ilex forest

The dynamics of the fine root system are relevant to calculations of the carbon balance of the ecosystem, and there is also a need to quantify changes in this component caused by disturbances. Mediterranean forest systems have historically been coppiced to obtain charcoal. As a result of the resprouting capacity of holm oaks (Quercus ilex L.), these forests present more than 50% of their biomass below ground (stump + roots > 1 cm in diameter), but the effects of thinning on the fine root system are unknown. Fine root biomass, production, mortality and longevity were studied in a control and a thinned Mediterranean holm oak forest by minirhizotron methodology. Observations of fine roots started 2 years after thinning and continued for almost 3 years. Extraction of 80% of the former basal area of the forest greatly affected carbon allocation patterns. Biomass increased by more than 100%, production increased by 76%, mortality increased by 32% and longevity decreased by around 2 weeks. The greatest differences between treatments were associated with differences in growth during autumn months in the top 40 cm of soil, particularly between 10 and 20 cm depth.     

庆元林场阔叶林主要类型生物量测定及其评价

根据样地调查获得的数据,选择已建立的各种相关生物量预测模型进行统计,对千岗坑林区分别不同的阔叶林类型进行生物量的测定研究,结果表明,4个主要类型由于树种组成和林龄的不同,其直径分布变异较大,在生物量上阔杉混交林生物量最高达337.3t/hm2,常绿与落叶阔叶林的生物量最低为166.0t/hm2,在各类型的生物量组分中,树干组分的比例最大,其次为枝,再次是根,最低是叶。而生态功能的强弱序列为常绿阔叶林>常绿与落叶阔叶混交林>阔松混交林>阔杉混交林,木材生产能力的大小序列为阔杉混交林>阔松混交林>常绿阔叶林>常绿与落叶混交林。