30a杉木萌生林和实生林木材的材性比较

以采自湖南省金洞林场同一立地条件、不同海拔高度山地上营造的杉木萌生林和实生林30 a时的木材为研究对象,按照国家标准测定其气干密度、基本密度、顺纹抗拉强度、顺纹抗压强度、抗弯强度、抗弯弹性模量、横纹全部抗压强度(径向、弦向)、横纹局部抗压强度(径向、弦向)等10个指标,并运用Excel、Spss等软件进行数据统计、方差分析。结果表明:萌生林30 a时10个指标的测量均值分别为0.439 g·cm^-3(范围0.398~0.480 g·cm^-3)、0.353 g·cm^-3(范围0.318~0.389 g·cm^-3)、122.79 MPa(范围112.44~133.40 MPa)、51.10 MPa(范围50.09~54.67 MPa)、77.15 MPa(范围74.14~82.84 MPa)、9.16 GPa(范围8.43~9.99 GPa)、2.40 MPa(范围2.13~2.73 MPa)、2.17 MPa(范围2.00~2.30 MPa)、3.68 MPa(范围3.50~3.93 MPa)、3.54 MPa(范围3.17~3.94 MPa);实生林30 a时10个性状的测量均值分别为0.404 g·cm^-3(范围0.380~0.422 g·cm^-3)、0.320 g·cm^-3(范围0.312~0.336 g·cm^-3)、102.21 MPa(范围91.89~118.52 MPa)、46.19 MPa(范围41.52~50.72 MPa)、67.35 MPa(范围61.40~73.62 MPa)、8.05 GPa(范围7.641~8.400 GPa)、2.00 MPa(范围1.70~2.40 MPa)、1.83 MPa(范围1.53~2.03 MPa)、3.38 MPa(范围2.99~3.63 MPa)、3.33 MPa(范围2.90~3.53 MPa)。萌生林与实生林木材的10个指标均存在显著、极显著或极极显著差异。杉木林分的生长状态和木材密度的地理变异有明显的规律性,即生长特性随垂直高度(海拔)增高而减少,但木材密度和木材抵抗外力作用的能力却随垂直高度(海拔)的增高而加大。     

Examination of the consistency of plant traits driving oil yield and quality in short-rotation coppice cultivation of Eucalyptus polybractea

The value of eucalyptus oil for medicinal purposes is based largely on its cineole content. The prime commercial species for cineole production in Australia is Eucalyptus polybractea (blue mallee). Despite the long history of blue mallee harvesting in Australia, there has been little research on the establishment of plantations of the species or on the efficacy of short-rotation coppice cultivation with respect to the consistency of oil yield and quality from rotation to rotation. This study aims to assess if subsequent coppice oil traits reflect sapling traits and if the coppice oil traits under short-rotation cultivation are consistent from one rotation to the next. A trial plantation was established in a key eucalyptus oil harvesting district in Victoria. Firstly, the oil-related traits of 20 saplings harvested 3.5 years after planting were compared with those of their subsequent coppice harvested after 12 months regrowth. Despite the expected differences in total biomass, the oil-related traits of blue mallee saplings were mostly well reflected in their subsequent coppice. Total above ground biomass and foliar oil concentration were significantly related between saplings and coppice, and cineole proportion showed a Pearson's correlation of 0.93 between harvests. Nevertheless, the mean foliar oil concentration in the coppice was 148 mg g⁻¹ dw compared with 107 in the saplings, and the coppice foliage, on average, showed significantly reduced cineole with a mean of 87% in the saplings (maximum of 95.6%) compared to a mean of only 80% in the coppice (maximum of 87.0%). Secondly, the oil traits of 20 coppice plants from one 12-month harvest rotation to the next were compared. Again, total above ground biomass, foliar oil concentration and cineole proportion were significantly related between the harvests, with cineole proportion having a Pearson's correlation of 0.90 between rotations. The coppice between rotations were remarkably consistent in terms of biomass and oil traits and indeed mean coppice cineole yields were 28.6 and 29.7 g in rotations 1 and 2, respectively. The results support the screening of key oil-related traits in saplings for the selection of elite genotypes for plantations, and the use of short-rotation cultivation of the plantations for continued oil harvesting. Furthermore, no relationship was observed between biomass and oil concentration in the blue mallee saplings or coppice, suggesting selection gains in a given key oil trait will not result in losses in another.     

Adverse effects of simulated harvesting of short-rotation willow and poplar coppice on vertical pressures and rut depths

Little is known of the effects of mechanized harvesting on ground conditions during the harvesting of short-rotation coppice. An investigation was therefore carried out in which different vehicles were used to simulate the effects of wheeling from heavy and light harvesters and crop removal equipment. The experiments were carried out on sites containing Bowles hybrid willow (Salix viminalis) and poplars (Populas rap) and on clay and sandy loam soils. The effect of different vehicles was assessed in terms of rut damage and direct measurements of soil stress using buried sensors. Maximum stresses measured 0.3 m below tractor wheels ranged from 50 to 200 kPa, but the greatest stresses, 350 kPa, were recorded under laden trailer wheels. Maximum stresses measured beneath crawler tracks were only 25 kPa. Similarly, substantial ruts were caused by vehicles simulating wheeled harvesters, the deepest ruts were caused by laden trailers but crawler tracks created least disturbance. Wheeling was carried out at soil water contents above the plastic limit and the deepest ruts were created on clay rather than sandy loam soil. The effects of the stresses generated in the soil could impede future root growth, and the deeper ruts formed could damage existing root systems of coppice.     

灌丛植物-乌柳

通过对乌柳生长状况及与柽柳生物量的比较分析，结果表明，乌柳虽然在林区广泛生长，在共和盆地干旱半干旱沙地引种也能很好生长，是干旱半干旱区的生态治理好帮手。     

刺槐萌生林的初步研究

对刺槐萌生林的生长和生物产量的研究结果表明:2年生的更新苗。以株高,地径和株数对比,萌芽苗优于根蘖苗。从树干解析表明,萌生林树高的连年生长量在第4年达到最大值(2.0m);而胸径和材积的连年生长量第8年时最大,分别为1.15cm和0.00775m~3/株。9年生萌生林乔木层地上部分生物量为54.826t/ha,年平均净生产量为10.229t/ha.a。与实生林相比,在相同的生长条件下,萌生林具有较高的木材量和生产力。     

Stockplant Management for Optimized Rhizogenesis in Tectona grandis Stem Cuttings

A 5-year stand of teak (Tectona grandis L. f.) was coppiced in 1999 and converted into a vegetative multiplication garden. Subsequently, three harvesting regimes for the collection of single node stem cuttings were imposed: (1) once – in March (H₁), (2) twice – in March and September (H₂) and (3) three times in March, July and November (H₃). Cuttings were treated basally with either:- T₀ – control (6 h in water), T₁ – half the recommended dose of a mixture of IBA and thiamine (500 ppm IBA + 400 ppm thiamine) or T₂ – the full dose of the same mixture (1000 ppm IBA + 800 ppm thiamine). Cuttings receiving IBA + thiamine rooted significantly better than untreated cuttings, but even the best treatment only resulted in 38.3 ± 3.8% rooting. This treatment produced the greatest number of roots (5.2–12.1). The full dose treatment appears to have been supra-optimal. Rooting ability was also affected by the frequency of stockplant pruning, with cuttings from stockplants pruned twice per year having the greatest rooting percentage (27.8 ± 3.8%) and the most roots (9.2 ± 4.8). This bi-annual pruning (H₂) resulted in the greatest number of rooted propagules (2.6 and 4.2 times more than H₁ and H₃, respectively). There was a significant interaction between Treatment × Pruning frequency. Bi-annual hedging of teak stockplants is recommended for practical purposes, although further work is required to achieve commercially acceptable levels of rooting from coppiced tree stumps.     

Kouebeskadiging van houtagtige plante in die Suuragtige‐Gemengde Bosveld

Cold damage to woody plants in the Sourish Mixed Bushveld. An incident of damage to woody plants by cold in the Sourish Mixed Bushveld was investigated. Woody plants in eight paddocks which were subjected to long‐term grazing treatments and which gave rise to different tree densities, were examined. The most common form of damage was top kill, and these plants subsequently coppiced from the base. Four woody species, namely Dichrostachys cinerea (the dominant woody species in the area), Acacia nilotica, A. gerrardii and A. robusta were severely damaged by the cold. The greatest effect was on trees in a certain height range; 1,0–3,0 m in the case of D. cinerea and 0,5–2,0 m in the case of the Acacia species. There was a negative curvilinear relationship between the number of trees larger than 2,0 m per hectare and the percentage damage. In paddocks where the tree density was relatively low the number of tree equivalents (equivalents of a tree 1,5 m high) was reduced by as much as 30%.     

棚栽台湾青枣主干更新试验

引种台湾青枣 5个品种至辽宁省朝阳市 ,为适应棚内栽植 ,进行了主干更新试验以确定各品种的最佳截干高度。试验结果表明 :(1)主干更新是棚栽台湾青枣必不可少的一项重要栽培措施 ;(2 )截干高度以 30cm为佳 ;(3)主干更新高度在各品种间差异不显著。     

杉木地膜覆盖除萌技术研究

杉木根际萌蘖条是影响杉木高生长的关键.采用简便易行的地膜覆盖除萌法,抑制了萌蘖条的蔓延,促进了杉木生长.     

杉木无性系采穗母株药剂处理促萌试验

为快速扩繁增殖杉木优良无性系，应用生长素、赤霉素、细胞分裂素和ＫＭｎＯ４等化学药剂处理杉木采穗母株根颈试验，探讨促萌机理。结果表明，０．２％ＫＭｎＯ４液，１０×１０－６２．４－Ｄ和５×１０－６三十烷醇三个处理有促萌效果，萌条数量分别比对照增加４６．２％，２５．８％和１４．０％。