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1.
D. Edwin Swift William Knight Martin Béland Issifi Boureima Charles P.-A. Bourque Fan-Rui Meng 《Scandinavian Journal of Forest Research》2017,32(1):45-59
In the late 1980s, large forest companies began precommercial thinning (PCT) operations in young northern hardwood cutovers in New Brunswick, Canada. To provide supporting growth and yield information, an industrial experiment was established at residual stand densities of 1300, 1600, 1900, and 2200?stems?ha?1. Stand responses were examined for measurements recorded at 0 (1987), 5 (1992), 10 (1997), 16 (2003), and 23 (2010) years after establishment. Average diameter at breast height, quadratic mean diameter, stand basal area, and stand total volume growth increased as stem density decreased from PCT. There were significant linear differences for many of these variables between treatments and time periods (year). No significant differences were detected in tree height between treatments. In 2010, the four PCT thinning treatments did not exhibit any differences in potential sawlogs at 2.4?m (8?ft) and 3.6?m (12?ft) lengths. Significant differences were observed for 4.9?m (16?ft) sawlogs that were produced at the least dense spacing (1300?stems?ha?1). Results from this study and recommendations from the European literature suggest that value-added timber products may be produced from more intense PCT treatments than are currently being practiced on sites dominated by yellow birch (Betula alleghaniensis Britt.). 相似文献
2.
《Southern Forests》2013,75(2):91-98
The choice of spacing among trees for operational plantations is typically based on one or more experimental plantations that test for the response of tree and stand growth to a range of tree-to-tree distances. The most common design for spacing experiments entails rectangular plots that test different distances between rows, and between trees within rows, and with replication of plots covering one to several hectares within a single stand. Other designs may offer more information with simpler layouts, and we examined the insights that could be obtained from a Nelder (fan-shape) design, where spacing among trees varies with the radial distance from a central point. The response of Eucalyptus dunnii seed-origin trees to spacing was essentially similar between a classic plot design replicated in four blocks (tree spacing from 4.5 to 9.2 m2 tree?1, covering 1.4 ha of land), and a Nelder design (tree spacing from 2.1 to 44.0 m2 tree?1, covering 0.6 ha of land). The Nelder design showed slightly higher volume increment through 10 years of stand development than the block design (for the range of overlap in spacing), but the treatment effect of spacing was essentially identical between the designs at the level of both trees and stands. A second Nelder experiment used clonal-origin trees from six clones, testing for differences in responses to spacing among clones. In all three spacing experiments and for all clones, individual-tree growth was greatest at the widest spacing and stand-level growth was highest at the tightest spacing. These trends were much clearer across the wider range of spacing tested in the Nelder plots (228 to 4 760 trees ha?1) than in the narrower range of spacing tested in the block design (1 111 to 2 222 trees ha?1). Current annual increment reached a higher, earlier peak at narrow spacing. At 8.5 years, the light use efficiency (stem volume growth per unit of light intercepted) was about twice as great for trees at narrow spacing than at wider spacing. Overall, the Nelder designs provided the same information on responses to spacing as the classic block design. The simplicity and small size of Nelder designs provide valuable insights for basic decisions on spacing for operational plantations, particularly when forestry extends into new geographic areas, new genotypes, and new silvicultural techniques. 相似文献
3.
Oddvar Haveraaen 《Scandinavian Journal of Forest Research》2014,29(7):669-674
The effect of ash fertilization on height growth and volume production of Scots pine (Pinus sylvestris L.) was studied on oligotroph peatland in southeast Norway. In the year 1944, plots 15 m × 15 m size were fertilized with 0, 4, 7, and 10 tons ha?1 of wood or peat ash. The area was treeless, but a satisfactory number of pine seedlings were present. All measurements were confined to the central inner plot, 10 m × 10 m area. Most plots were re-fertilized with 10 tons of wood ash ha?1 in the year 1993. Wood ash had higher content of nutrients, and generally, it had greater growth enhancement effect than peat ash. When the amount of ash was increased, volume production significantly increased for the age period 38–50 years and the total production at age 50 years. The mean annual increment during the first 50 years was about 6 m3 ha?1 for the plots applied with 10 tons of ash ha?1. Trees on plots fertilized with 7 or 10 tons in 1944 and replenished with 10 tons ha?1 at age 50 years (1993) had a mean annual increment of 14 m3 ha?1 for the stand age period 51–68 years. Over time some tree roots from control plots and plots fertilized with 4 tons ha?1 have captured nutrients from richer plots. Such effect is to a smaller extent relevant for treatment 7 tons. It is concluded that the content of mineral nutrients of wood and peat ash makes these ashes well suited as fertilizers on peatland. 相似文献
4.
[目的]对香椿无性系的苗期生长进行分析,筛选优良香椿无性系,奠定遗传改良的基础。[方法]以49个香椿无性系为对象,分别于2015、2016、2017年测量其1、2、3 a生株高、胸径,计算材积,对表型性状及其增长量进行方差分析和遗传参数估算,采用独立淘汰法筛选排名前20%的无性系为优良,对中选无性系进行遗传增益等参数估算,并将试验地不同年份特征气象因子与无性系表型性状进行相关分析。[结果]株高、胸径及材积的生长连续3 a在无性系间存在显著差异,且生长性状的遗传变异系数、表型变异系数逐年减小,而变异幅度、重复力逐年增大;3 a生时,株高、胸径及材积的无性系重复力分别为0.55、0.50、0.67,重复力高。2015—2017年,49个香椿无性系之间胸径、材积增长量分别呈显著、极显著差异,3 a生材积与材积、胸径增长量呈高度正相关关系。以3 a生香椿无性系材积及其增长量为2组指标,独立筛选出优良无性系10个,中选无性系群体平均材积大于0.010 4 m~3·株~(-1),增长量大于0.009 7 m~3·株~(-1)。3 a生材积的遗传增益为17.38%,中选香椿无性系的稳定性系数b值均大于1,对年份环境敏感。气象因子-表型性状相关性分析显示,材积与年总降水量、日均降水量有显著正相关关系。[结论]参试香椿无性系间材积差异极显著,选择潜力大;中选的优良香椿无性系遗传增益超过15%,但其在不同年份差异大且稳定性差,这可能与年份降水量有关。 相似文献
5.
《Southern Forests》2013,75(4):311-318
Average wood density of 38-year-old Cariniana legalis (Mart.) Kuntze, a Brazilian native forest species, was found to increase with faster growth and lower stocking, while decreasing from pith to bark. A complete randomised block design was planted with five blocks. Ten trees were harvested in each of three spacing treatments. We hypothesised that the stand stemwood production would not significantly differ depending on tree spacing. However, tree growth would be higher in the wider spacing and wood density would be higher in the narrower spacing. The diameter growth of trees was higher at 3 m × 2.5 m than at 3 m × 2 m and 3 m × 1.5 m. Nevertheless, this higher individual tree growth at 3 m × 2.5 m did not compensate for the greater tree stock density at 3 m × 1.5 m with stand stemwood production at 38 years of 530 m3 ha?1 and 649 m3 ha?1, respectively. These results suggest that C. legalis, which can produce up to 17 m3 ha?1 y?1 of medium-to high-density timber – about 800 kg m?3 – is a promising native species for forest plantations in Brazil. 相似文献
6.
《Forest Ecology and Management》2001,141(3):165-174
The effects of long rotation periods and heavy low thinning on chestnut (Castanea sativa Mill.) coppices have been evaluated from a bio-ecological point of view. Aboveground tree biomass and its partitioning, bio-ecological indexes such as litter production, leaf area index (LAI), radiation regime, and growth efficiency have been analyzed for 4 years in thinned and unthinned permanent plots established in a coppice stand aged 11 years under normal rotation (NR) and in a coppice stand aged 35 years under long rotation (LR). A decrease in LAI, litter production and growth rate with the age was observed. LR showed high current annual increments (>16.0 m3 ha−1 per year and 8.0 Mg ha−1 per year for volume and aboveground biomass, respectively). Only slight differences in growth efficiency were observed. The adoption of heavy thinning (one third of basal area removal) affected stocking and determined significant differences in the light regime below the canopy, amount of gaps in canopy cover and LAI values, particularly in the years immediately after thinning, whereas slight differences were observed in growth efficiency. Nevertheless, chestnut showed a good aptitude, more evident in the younger stand, to re-build a homogeneous canopy cover: only a few years after thinning, canopy cover characteristics of thinned plots were similar to those of control plots and differences were not significant. Growth and increments in thinned plots were practically the same as in control plots, a consequence of consistently higher performances of released trees in the thinned plots. The results concur to a positive evaluation of a cultivation system based on long rotation periods and heavy thinnings, not only for the obtainable revenue, but especially from a bio-ecological point of view and make it a valid alternative either to abandonment or traditional over-exploitation of chestnut coppice stands. 相似文献
7.
《Scandinavian Journal of Forest Research》2012,27(6):605-610
Eight clones of poplar were used to compare the growth and productivity of monoclonal and polyclonal mixed plantations in short-rotation coppice. At the end of the eighth growing season, the diameter at breast height (DBH) and height of trees were measured and dry weight and yield were estimated. Polyclonal mixtures did not affect mortality. Few differences in growth were observed between clones in monoclonal plots. Polyclonal mixture slightly affected the growth and tree size of the clones compared with monoclonal plots. No increase in stand heterogeneity in relation to clone deployment was observed. A neighbourhood index was calculated for each tree and was significantly affected by polyclonal mixture. However, the relationship between the neighbourhood index and the DBH indicated that this effect did not cause a great change in DBH. Consequently, dry weight and yield productivity were not affected by clone deployment. 相似文献
8.
Populus deltoides Bartr., a native of North America, is generally grown in India above latitude 28 °N. One hundred and six clones were evaluated for four years at Raipur situated at 21°12N latitude and 81°36E longitude. These were grown on vertisol soil. Based on growth and survival performance in the nursery for two successive years, nineteen clones were selected for field evaluation. The best five clones (G3, G48, 65/27, D121 and S7C1) were planted in an agrisilviculture system at a spacing of 4 × 4 m with soybean grown as an intercrop. After 4 years these clones had an increment of DBH by 66.5 to 77.5% and of height by 42.2 to 78.6% within one year when compared to that observed at 3 years of age. In rank order of growth the best five clones were 65/27 > G3 > D121 > G48 > S7C1. Total biomass varied between 20.9 to 35.8 Mg ha–1 in different clones. Among the tree components, stemwood accounted for 52–61% of the total biomass, followed by branches (20–25%), bark (9–13%) and leaves (7–10%). No significant variation between net primary productivity and photosynthetic efficiency was found in different clones. Soybean productivity decreased as the trees aged, reaching 40.5 to 58.1% in 4-year-old trees. 相似文献
9.
《Forest Ecology and Management》2004,192(1):71-96
Two levels each of thinning and fertilization were applied to a 7-year-old loblolly pine (Pinus taeda L.) plantation on a nitrogen- and phosphorus-deficient West Gulf Coastal Plain site in Louisiana. Levels of thinning were no thinning, or thinning applied 7 and 14 years after stand initiation. Levels of fertilization were no fertilization or broadcast fertilization with diammonium phosphate at age 7 years plus refertilization with urea, monocalcium phosphate, and potash at age 14 years. Long-term measurements of climate, stand development and productivity, projected leaf area index, and foliar nutrition were initiated at age 11 years. We found that by age 17 years, thinning increased mean live-crown length from 4.2 to 7.8 m, and mean tree diameter from 15.0 to 21.8 cm compared to the unthinned treatment. After rethinning at age 14 years, stand basal area increased 1.2 and 19.2% between ages 15 and 17 years on the unthinned and thinned plots, respectively. Refertilization at age 14 years reestablished foliar N, P and K sufficiency, which increased leaf area index from 4.2 to 6.0 m2 m−2 on the unthinned plots and from 3.2 to 3.8 m2 m−2 on the thinned plots, and subsequently, increased gross stand biomass from 114 to 141 Mg ha−1 on the unthinned plots and from 78 to 95 Mg ha−1 on the thinned plots by age 17 years. Leaf area was an important factor controlling loblolly pine productivity. At our study site, however, competition for light and water and nutrition-limited foliage growth influenced the variability and scope of this relationship. Our results suggest that a positive and linear relationship between leaf area and loblolly pine productivity does not universally occur on loblolly pine sites. 相似文献
10.
[目的]探讨不同造林密度对米老排人工林生长的影响规律,为米老排人工林定向培育过程中的密度控制提供参考。[方法]以广东省云浮市造林后6年生米老排人工林为研究对象,对不同造林密度(625、833、1 111、1 667、2 500株·hm~(-2))林分平均树高、优势木高、胸径、保留率和枝下高等生长指标进行连续4年调查。[结果]表明:随着造林密度的增大,米老排林分平均胸径、胸径连年生长量、保留率、单株材积和材积连年生长量均显著减小,而枝下高、林分蓄积量和蓄积连年生长量显著增加。在一定密度范围内,造林密度对林分高生长的影响比较小。造林后第6年,密度1 667株·hm~(-2)林分的平均树高最大(11.4 m),优势木高以密度1 111株·hm~(-2)林分的最大(13.3m),树高连年生长量以密度625株·hm~(-2)林分的最大(1.5 m·a~(-1));密度625株·hm~(-2)林分的平均胸径、胸径连年生长量、单株材积和材积连年生长量均最大,分别为14.3 cm、2.5 cm·a~(-1)、0.097 3 m~3和0.038 2 m~3·a~(-1),比密度2 500株·hm~(-2)林分的分别增加27.7%、81.0%、49.0%和82.4%;密度2 500株·hm~(-2)林分的枝下高、蓄积量和蓄积连年生长量均最大,分别为6.0 m、149.4 m~3·hm~(-2)和44.8 m~3·hm~(-2)·a~(-1),分别是密度625株·hm~(-2)林分的2.61、2.52、1.95倍。[结论]分析了造林密度对米老排初期生长的影响,对米老排人工林的培育具有理论指导意义。 相似文献
11.
[目的]为了研究海南地区木麻黄无性系的生长过程,并确定其数量成熟龄和合理轮伐期。[方法]本研究利用海南岛3个试验点4个相同无性系10 a的生长数据分析了木麻黄无性系的树高、胸径和材积的生长规律。[结果]表明:木麻黄无性系树高和胸径的生长均呈"先快后慢"的生长模式,造林后1~6 a为快速生长期,6 a后进入缓慢生长期;材积生长则呈"慢—快—慢"的S型生长模式,造林后1~3 a为慢速生长期,4~7 a为快速生长期,8 a后进入缓速生长期。根据材积年平均生长量和连年生长量曲线的相交点,各无性系材积生长的数量成熟龄处于6~9a。利用3个试验点4个无性系获得的材积生长平均值,拟合了木麻黄无性系材积生长曲线的Richards模型,并得出材积快速增长的起始期t_1=4.9 a,终止期t_2=8.4 a,最大相对生长速率期t_m=6.9 a,最大材积增长速率25.8m~3·hm~(-2)。[结论]综合上述结果,建议海南地区将木麻黄无性系的轮伐期定为6~9 a。 相似文献
12.
Takuya Kajimoto Akira Osawa Yojiro Matsuura Anatoly P. Abaimov Olga A. Zyryanova Kazuma Kondo Naoko Tokuchi Muneto Hirobe 《Journal of Forest Research》2007,12(2):103-112
We present results of individual-based root system measurement and analysis applied for Larix gmelinii trees growing on the continuous permafrost region of central Siberia. The data of root excavation taken from the three stands
were used for the analyses; young (26 years old), mature (105 years old), and uneven-aged over-mature stand (220 years old).
In this article, we highlight two topics: (1) factors affecting spatio-temporal pattern of root system development, and (2)
interactions between aboveground (i.e., crown) and belowground (i.e., root) competition. For the first topic, the detailed
observation of lateral roots was applied to one sample tree of the overmature stand. The tree constructed a superficial (<30 cm
in depth) and rather asymmetric root system, and each lateral root expanded mainly into elevated mounds rather than depressed
troughs. This indicated that spatial development of an individual root system was largely affected by microtopography (i.e.,
earth hummocks). For these lateral roots, elongation growth curves were reconstructed using annual-ring data, and annual growth
rates and patterns were compared among them. The comparison suggested that temporal root system development is associated
with differences in carbon allocation among the lateral roots. For the second topic, we examined relationships between individual
crown projection area (CA) and horizontal rooting area (RA) for the sample trees of each stand. RA was almost equal to CA
in the young stand, while RA was much larger (three or four times) than CA in the mature and overmature stands. Two measures
of stand-level space occupation, crown area index (aboveground: CAI; sum of CAs per unit land area) and rooting area index
(belowground: RAI; sum of RAs), were estimated in each stand. The estimates of RAI (1.3–1.8 m2 m−2) exceeded unity in all stands. In contrast, CAI exceeded unity (1.3 m2 m−2) only in the young stand, and was much smaller (<0.3 m2 m−2) in the two older stands. These between-stand differences in RAI–CAI relationships suggest that intertree competition for
both aboveground and belowground spaces occurred in the young stand, but only belowground competition still occurred in the
two older stands. Based on this finding, we hypothesized that competition below the ground may become predominant as a stand
ages in L. gmelinii forests. Methodological limitations of our analysis are also discussed, especially for the analysis using the two indices
of space occupation (CAI, RAI). 相似文献
13.
在湖南会同县、绥宁县以33个杉木无性系和2个对照分别于1983年、1986年及1997年营造了单株、行状和块状3种造林形式的区组设计无性系试验林。研究发现参试无性系间胸径、树高生长量的差异在幼林期(4—7年)、中林期(13—16年)和成林期(28—31年)始终显著存在。不同无性系生长规律不同,有的无性系幼林期生长不是特别突出,但在中林期生长加快,到中林期后趋于稳定。优良无性系y18、y15在28或31年生时仍能保持前期所具有的生长优势,且在16 m立地指数和18 m立地指数条件下,生长同样突出,排名均为1、2名,表明这2个优良无性系的生长量具有一定的时间和空间稳定性。在块状造林条件下,优良无性系13年生时树高、胸径生长量和单位面积蓄积量分别大于生产种20.1%26.6%、27%31.1%、78.7%92.8%,表明发展杉木优良无性系造林可获得巨大的经济效益。 相似文献
14.
15.
《林业研究》2021,32(1)
High potential productivity together with short rotation periods have made hybrid aspen an interesting option for wood production on former arable land in Nordic countries.In this study,some of the oldest active experimental plots with hybrid aspen in Sweden were remeasured at 23-30 years of age.A main aim was to assess age and productivity at the time of maximum mean annual volume increment.In addition,the influence of commercial thinning on stand development and differences in genetic gain among clones were investigated.Data from five experiments in southern Sweden were used,including three genetic trials,one demonstration stand with a clone mixture and one stand regenerated from root suckers.The three genetic trials were treated as single plot experiments,subject to a standard thinning program.In the remaining experiments,different thinning strategies were tested in a balanced block design.Volume growth had culminated or was close to maximum at age25-30 years.Mean annual stem volume increment at culmination was 20-22 m~3 ha~(-1) a~(-1).Dominant height reached30-35 m at 28-30 years of age.Mean diameter at breast height was 27-29 cm after 29-30 years in the genetic trials.Clonal ranking based on diameter at age 7-9 years was positively correlated with the ranking at the final measurement in the genetic trials,20 years later.This indicates that clones can be selected for superior growth based on results from young trials.More intense thinning programs increased the mean diameter compared to light thinning.The study indicates that one or two early and relatively heavy thinnings can promote the development of crop trees,without jeopardizing total volume production during a rotation of 25-30 years. 相似文献
16.
A study was conducted from 1996 to 2001 on well drained sandy loam soils in the central plain region of Punjab to determine
the effect of initial size of planting stock and clones of poplar (Populus deltoides) on their height, diameter and volume growth. Two categories of planting stock viz. large size (height >4.7 m and collar
diameter >4.2 cm) and small size (height 2.5–4.3 m and collar diameter 2.5–4.0 cm) of ten poplar clones were used for the
experiment using a completely randomized design with single tree plots and ten replications. The large sized stock attained
significantly greater diameter and volume growth at all ages than those of small size, whereas, the superiority of the former
in plant height was only up to 3 years of age. The respective differences for diameter and volume between the stock sizes
decreased from 11.7 and 27.96% at 3 years to 4.9 and 11.42% at 5 years of age. Significant differences were observed among
clones for all the growth parameters. Clones G-48, 3167, WSL-31 and WSL-38 exhibited the highest growth. 相似文献
17.
18.
M. K. O’Neill C. C. Shock K. A. Lombard R. F. Heyduck E. B. G. Feibert D. Smeal R. N. Arnold 《Agroforestry Systems》2010,79(3):409-418
The rapid growth rates of hybrid poplar (Populus spp.) enable rotations of 3–6 years for biofuels or 10–15 years to obtain merchantable timber, but many clones are susceptible
to nutrient deficiencies when grown in alkaline soils. A 1995 Oregon study demonstrated that clone OP-367 (P. deltoides × P. nigra) was the only clone tested that performed well on alkaline soils. Tests in Colorado and New Mexico confirmed the adaptation
of this clone. A multi-clonal trial was established in 2003 at Farmington, New Mexico and Ontario, Oregon in order to screen
a larger number of clones for adaptability to alkaline soils. Trees were planted at 1.5 × 1.5 m spacing and irrigated by surface
drip irrigation. Diameter at breast height (DBH) and tree height were recorded annually (2003–2006); wood volumes (WVol) and
total aboveground biomass (TAB) were calculated from these measurements. Of the 25 clones tested, 19 were common to both sites.
Mean height was greater at the Ontario site through the first 3 years (2003–2005). By the end of four seasons, the tallest
Farmington entry was OP-367 at 9.4 m with 177 Mg ha−1 TAB while the tallest Ontario entry was Malheur-3 at 8.9 m with 195 Mg ha−1 TAB and several other clones had statistically similar production. Given the growth and productivity range at these two sites,
it is difficult to make generalizations across wide areas, but it appears feasible to identify clones suited to alkaline soils
in arid and semi-arid regions. 相似文献
19.
R. Picchio 《Forest Ecology and Management》2011,262(2):237-243
Damage to residual stand after partial harvesting or thinning may lead to serious economic losses in terms of both timber quality at the final harvest, and tree growth reduction. Logging damages and their effect on tree growth were studied in a long term experiment on Corsican pine in central Italy. Damage frequency, agent (felling, skidding), position (root damage, stem base, between 0.3 and 1 m a.g.l., >1 m a.g.l.) and severity (light, severe) and tree growth were measured after selective thinning from below and at 10 years after the treatment. In detail, we aimed at: monitoring mechanical damages to trees at the end of thinning and after 10 years; and assessing stand stability, growing stock, ring width and basal area at 10 years after the thinning. The thinning removed about 20% of volume, 38% of trees and 26% of basal area. The basal area decreased from 56 m2 ha−1 to 42 m2 ha−1 but after 10 years it increased again to 56 m2 ha−1. Immediately after thinning, 13.6% of the standing trees was damaged, out of these 36.17% showed severe injuries. Damages to standing trees were mainly due to skidding. Ten years after thinning, the percentage of damaged trees was about 17%, out of which 86.67% showed severe wounds. An increase of damaged trees and of trees with severe wounds was observed suggesting that a deeper knowledge on long-term effect of logging damages is needed. This study did not highlight any effect of logging damage on tree growth. In fact, no difference in ring width was recorded between damaged and undamaged trees. 相似文献
20.
Many of the world's Eucalyptus plantations are grown on short rotations of 15 years or less, which often covers the most rapid phase of stand development and peaks in growth rates and leaf areas. Since transpiration is related to stand leaf area these short rotations that make use of rapid early growth rates, may also maximise plantation water use, which has implications for predicting their water requirements and impacts on catchment hydrology. This study examined the transpiration, leaf area and growth rates of Eucalyptus globulus Labill. plantations aged 2–8 years. Transpiration (E), estimated using the heat pulse technique, increased from 0.4 mm day−1 at age 2 years to a peak of about 1.6–1.9 mm day−1 in stands aged 5–7 years. This was associated with similar trends for stand leaf area index (LAI) and periodic annual increments of aboveground biomass, which both peaked at about age 4–6 years resulting in a linear relationship between E and LAI. While stand sapwood areas were continuing to increase at age 8 years, E was already declining due to reductions in sap velocity, from 13.5 cm h−1 at age 2 years to 6.3 cm h−1 at age 8 years and reduced sapwood area growth rates. Trees compensated for this reduction in sap velocity with declines in the leaf area (AL) to sapwood area (AS) relationship (AL:AS) with age. There was also a reduction in growth efficiency (aboveground biomass increment per LAI) with age. However, reductions in WUE were small after age 4 years, which explained the linear relationship between E and LAI. If E continues to decline successive short rotation lengths may not only make use of rapid early growth rates but could also increase plantation water use compared to longer rotations over the same period of time. 相似文献