梨竹在两种对照条件下果实的产出

摘要：本研究介绍了梨竹2005—2006年在两种不同条件下（未干扰的天然竹年和进行轮垦的竹林燃烧竹区）聚生开花后果实的产出情况。记录了该竹种在米佐拉姆有规律地每48年开花1次，观察发现，两个研究区域中的竹秆密度相差很大。在竹林燃烧地区，竹秆的数量为25株／9m^2。而在天然竹林中的密度为21株／m^2。     

梨竹在两种对照条件下果实的产出

摘要：本研究介绍了梨竹2005—2006年在两种不同条件下（未干扰的天然竹年和进行轮垦的竹林燃烧竹区）聚生开花后果实的产出情况。记录了该竹种在米佐拉姆有规律地每48年开花1次，观察发现，两个研究区域中的竹秆密度相差很大。在竹林燃烧地区，竹秆的数量为25株／9m^2。而在天然竹林中的密度为21株／m^2。     

印度西孟加拉邦德赖地区梨竹生长基质标准化、萌发种子尺寸和实生苗生长

2008年2-4月,在印度西孟加拉邦德赖地区开展了试验,该试验对6个生长基质和3个种子的重量进行了分析,以找出其对梨竹萌发和实生苗生长的影响。与其他基质相比,将50 g的种子种在土壤、沙土和FYM以同一比例混合的基质中,种子萌发较好,实生苗生长更好。     

密度变化对天然次生金佛山方竹林分的影响

在金佛山方竹中心分布区内,选择低质低效的天然次生林,建立密度等级试验区。经过5年的研究,乔木层密度1623株/hm^2～2587株/hm^2、方竹林层片密度87632株/hm^2、平均胸径0．86cm的林分,适宜的经营密度为4．5万株/hm^2。在由保留林分、1年生竹、笋产量径级结构,林分和间伐物特征构成的评价指标体系中,间伐和产笋是方竹异龄林系统的输出部分,1年生竹的径级结构通过影响保留林分的径级结构进而影响林分的特征指数。分析表明,采笋直接影响蓄竹质量、林分质量,适度间伐可优化方竹林分的年龄结构、径级结构。因此,蓄竹、间伐和采笋措施是提高金佛山方竹林分质量的3种主要手段,三者互为关联、其中蓄竹较为关键。     

火烧对树木种子的影响

1　火烧强度对种子的影响研究表明 ,大部分树木种子能耐较高的温度 ,并且树木种子经过一定的温度处理后 ,种子萌发能力会显著增强。如果树木种子被土壤轻轻埋藏 ,即使强度较大的火烧后 ,种子也不会失去生命力 ,甚至经过火的高温处理后 ,树木种子的发芽率还会提高。对于草地火来     

盐分和干旱胁迫对鼠尾草种子萌发的影响

为明确鼠尾草种子在逆境条件下的萌发特性,通过试验模拟研究不同浓度的氯化钠(NaCl)和聚乙二醇(PEG6000)溶液对鼠尾草种子萌发的影响,结果表明:NaCl和PEG6000对鼠尾草种子萌发有不同程度的抑制作用,发芽率、发芽势和发芽指数均有所下降;在0.10mol/L NaCl溶液胁迫中,发芽率、发芽势最高,分别为88.33%和66.67%,0.40mol/L时种子不能萌发;在4%PEG6000溶液胁迫中,发芽率、发芽势最高,分别为81.67%、66.89%。由此可知,鼠尾草种子在中轻度盐土壤中能较正常萌发,在重度盐土壤中则丧失萌发能力。     

林龄、密度对华北落叶松人工林下生物多样性的影响

生物多样性维护是人工林经营过程中必须考虑的重要因素。而林龄、密度变化对于生物多样性的影响,则是确定人工林经营措施的重要依据。以地处燕山山地木兰林管局境内华北落叶松人工林为研究对象,选择林龄、密度、郁闭度3个指标对生物多样性的影响,采用物种丰富度指数（d1）,物种多样性Simpson指数（D）,和Pielou均匀度指数（JD）,分析生物多样性特征。结果表明：华北落叶松人工纯林生物多样性各指数,随林龄、密度、郁闭度的变化趋势基本一致。随着林龄的增大灌木层的多样性指数最大出现在林龄11a,草本层最大出现在林龄16a。随密度的变化趋势是随着密度的增大,灌木层呈现逐渐增大的趋势,草本层则是先增大后减小的趋势。随郁闭度的变化趋势是灌木层和草本层都随郁闭度的增大呈现先增大后减小的趋势。     

人工授粉对杉木种子发芽,形态及生物大分子的影响

应用混合杉木优树花粉进行人工授粉,能明显促进杉木种子发芽、减少涩籽率,提高种子品质;运用微量生化分析方法表明,应用混合优树花粉进行人工授粉所产生的种子种胚中所含生物大分子的量都明显高于用散生木花粉人工授粉所产生的种子,表明应用混合优树花粉进行人工授粉不仅能促进种子萌发,还能提高种子品质。     

NaCl胁迫对黄芪种子萌发及幼苗生长的影响

研究不同浓度NaCl的处理下,对黄芪种子萌发及幼苗生长的影响.结果表明：低浓度盐处理有利于促进种子萌发,对幼苗的生长也未表现出不利影响;随盐胁迫浓度的增大,黄芪种子发芽率、发芽指数、幼苗的生长在形态上都表现出盐害效应.     

氮和生物炭添加对毛竹林AMF侵染率和孢子密度的影响

目的 探讨氮沉降和生物炭添加对毛竹林丛枝菌根真菌特征的影响,为全球变化背景下毛竹林的可持续经营提供科学参考。 方法 以毛竹林为研究对象,探讨了不同梯度的氮沉降（0、30、60和90 kg·hm−2·yr−1）和生物炭添加（0、20和40 t ·hm−2）及其复合作用对毛竹林AMF侵染率和孢子密度以及土壤理化性质的影响。 结果 与对照（0 kg·hm−2·yr−1 N + 0 t·hm−2 BC）相比,氮添加显著降低了AMF侵染率（16.1%～51.7%）。高生物炭添加（40 t·hm−2）显著降低了AMF侵染率（46.0%）,但提高了孢子密度（162.5%）。在氮添加处理下,生物炭添加提高了AMF侵染率,对孢子密度无显著影响。AMF侵染率与土壤pH呈显著正相关关系,与有效氮和有效磷呈显著负相关关系。AMF孢子密度与有效磷呈显著正相关关系。 结论 在氮添加处理下,生物炭添加提高了AMF侵染率,增强了毛竹与AMF的共生关系,表明在氮沉降背景下生物炭添加是实现毛竹林可持续经营的有效措施之一。     

冷湿层积法对印度冷杉(Abies pindrow)和长叶云杉(Picea smithiana）种子萌发的影响

研究赤霉素(GA3),冷湿和温度 对五个种源的印度冷杉(Abies pindrow)和长叶云杉(Picea smithiana)种子萌发的影响.种子被浸泡在GA3 (10 mg(L-1)中24小时,然后在3(5(C温度的条件下冷藏15天.设计4个温度(10(C, 15(C, 20(C 和 25(C)条件来促进种子的萌发.结果表明,浸泡和冷湿处理明显增加种子的萌发率.在10 (C时种子的萌发率最高.总体结果表明,种子被浸泡在GA3 (10 mg(L-1)中24小时,冷湿藏15天,可以有效地促进印度冷杉和长叶云杉的种子萌发.统计数据表明,浸泡处理、温度和种源以及与温度的相互作用都对种子的萌发有明显的影响.     

Estimation of stand attributes in <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> and <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> stands using QuickBird panchromatic data

This study aims to estimate stand density and stand volume in Cryptomeria japonica and Chamaecyparis obtusa stands from high-resolution satellite data and verify the reliability and uncertainty of the data. Sixty circular sample plots of 0.04 ha each were established. Their stand densities were estimated from the number of tree crowns derived from high-resolution satellite data using the watershed method. Stand densities derived from field surveys in the sample plots were compared with those obtained from high-resolution satellite data by stand age class. As a result, there was a positive correlation between them for sample plots of 41 years of age and over (R = 0.82); however, there was no correlation between them for sample plots of 40 years and under. Individual diameters at breast height (DBH) were estimated from crown areas obtained from high-resolution satellite data for the two species. Using the estimated DBH, individual tree heights were predicted from the height–diameter curves. Stand volumes were estimated from the sum of individual volumes, which were derived from volume formulas having two variables, i.e., DBH and height. Stand volumes derived from the field survey were compared with those obtained from high-resolution satellite data. The correlation coefficient between them for stands of 41 years of age and over was 0.78.     

Adaptive management rules for <Emphasis Type="Italic">Pinus nigra</Emphasis> Arnold ssp<Emphasis Type="Italic">. salzmannii</Emphasis> stands under risk of fire

Key message

We generate flexible management rules for black pine stands, adaptable to alternative stand management situations and entailing thinnings, final-felling, and salvage cuts, based on the results on 270 stand level optimizations.

Context

Forest management instructions often rely on the anticipated prediction of the stand development, which poses a challenge on variable economic and environmental conditions. Instead, an alternative approach to better adapt forest management decisions to changing conditions is defining flexible rules based on thresholds that trigger management operations.

Aims

This article develops rules for the adaptive management of P. nigra stands in Catalonia (Spain) addressing the risk of fire and post-fire forest management.

Methods

The stochastic version of the simulation-optimization system RODAL was used to optimize the management of forest stands in three sites under different fire probability levels. A total of 270 optimizations were done varying site fertility, fire probability, and economic factors. The results of the optimizations were used as the basis of flexible forest management rules for adaptive stand management.

Results

The developed management rules defined the basal area limit for thinning, the thinning intensity, the mean tree diameter at which regeneration cuttings should start, and the basal area below which a salvage cutting should be done. Fire risk was not a significant predictor of the models for thinning and final cutting rules.

Conclusion

The presented rules provide a flexible tool for forest management during the stand development and under changing conditions when the management objective is to maximize economic profitability of timber production.

     

Enzymatic saccharification and ethanol production of <Emphasis Type="Italic">Acacia mangium</Emphasis> and <Emphasis Type="Italic">Paraserianthes falcataria</Emphasis> wood,and <Emphasis Type="Italic">Elaeis guineensis</Emphasis> trunk

We examined the saccharification and fermentation of meals from Acacia mangium wood, Paraserianthes falcataria wood, and Elaeis guineensis trunk. The levels of enzymatic hydrolysis of cellulose and ethanol production were highest for P. falcataria wood and lowest for A. mangium wood. Ultrasonication pretreatment of meal further increased the rates of hydrolysis and ethanol production in meal from P. falcataria wood. Through this pretreatment, hemicelluloses (xylan and xyloglucan) and cellulose were released in the meal from P. falcataria wood. Loosening of hemicellulose associations can be expected to make P. falcataria wood more useful for bioethanol production.     

Optimum lifetime for Swedish <Emphasis Type="Italic">Picea abies</Emphasis> seed orchards

The optimum lifetime of Picea abies seed orchards in Sweden was calculated using a model which considers changes in seed yield over time, annual progress of genetic gain, establishment, management and seed costs, and both the monetary and genetic value of the seeds produced. The longer the seed orchard is active, the more genetically outdated the produced seeds will become, and thus their value will decline with time. A main scenario was constructed using the best available estimates for Swedish Norway spruce and was compared to various alternatives reflecting likely variations. The optimal lifetimes in all of these scenarios was in the order of 40 years. Sensitivity analyses showed that use of orchards for slightly more or less than their optimal lifetimes does not lead to large losses. A more effective tree breeding program could slightly reduce the optimal lifetimes. The optimal lifetime depends strongly on the relationship between monetary value and genetic gain. Thus, in cases where genetic progress is sufficiently rapid, the optimal lifetime may be less than 30 years.     

Successful <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of <Emphasis Type="Italic">Populus tomentosa</Emphasis> with apple <Emphasis Type="Italic">SPDS</Emphasis> gene

The problem of salinized soils has become one of the most serious constraints to agricultural and forest productivity. With the purpose of enhancing salt stress tolerance of Populus tomentosa, we transformed this tree species with spermidine synthase （SPDS） genes derived from an apple by an Agrobacterium-mediated method. Four transgenic clones were confu＇med by PCR and Southern blot analysis. As well, the expression of introduced SPDS genes was analyzed by real-time quantitative PCR.     

Effect of seed coverings and seed pretreatments on the germination response of <Emphasis Type="Italic">Alnus glutinosa</Emphasis> and <Emphasis Type="Italic">Betula pubescens</Emphasis> seeds

The germination of common alder (Alnus glutinosa (L.) Gaertn.) and downey birch (Betula pubescens Ehrh.) seeds is often poor in bare-root nurseries. The effect of a variety of seed coverings and a few seed pretreatments on seedling emergence was examined in this study in an attempt to address this problem. Seeds of each species were sown in trays containing nursery soil, covered with grit, gravel, sand, combinations of these coverings, a hydromulch or a sealed plastic cloche and then incubated for 6 weeks at 17–20°C. The grit combined with sand or gravel, the hydromulch and the cloche increased seedling emergence when compared with the standard grit. In another experiment, seeds of each species were fully imbibed (FI) (>50% moisture content, MC), as per standard practice, or adjusted to target MC (TMC) (30–35% MC) levels, and then chilled to release dormancy. Some seeds of each MC treatment were primed at 20°C for 2 days following chilling, after which all seeds were evaluated in laboratory tests and a nursery trial. Germination potential of the FI seeds declined in the lab tests by the second test date, which was reflected in low seedling emergence in the nursery in birch. The primed FI seeds of alder germinated most rapidly in the nursery, but other effects were not significant. Seedling emergence was better in the nursery in response to the TMC than the FI pretreatment in birch.

Cultivation of <Emphasis Type="Italic">Pleurotus eryngii</Emphasis> on umbrella plant (<Emphasis Type="Italic">Cyperus alternifolius</Emphasis>) substrate

Mycelial growth and mushroom yields of three strains of Pleurotus eryngii produced on wheat bran-supplemented umbrella plant (Cyperus alternifolius) substrate were assessed using surface brightness, bromophenol blue color reactions, ergosterol and glucosamine contents, and water potential as indicators of strain performance. Mycelial growth was 31%–46% greater, depending on strain, on the umbrella plant substrate compared with the mushroom industry standard sugi (Cryptomeria japonica) substrate. Mushroom yields on the first flush were 20%–23% higher, depending on strain, on the plastic bottle-contained umbrella plant substrate. However, yields on the second break were lower from the umbrella plant substrate. Because many growers in Japan only harvest one flush, production of P. eryngii on umbrella plant substrate may offer commercial producers an alternative basal ingredient to diminishing supplies of sugi sawdust.Part of this report was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002.     

Effects of different treatments on seed germination and breaking seed dormancy of <Emphasis Type="Italic">Prosopis koelziana</Emphasis> and <Emphasis Type="Italic">Prosopis Juliflora</Emphasis>

For improving seed germination of Prosopis koelziana and Prosopis juliflora, different treatments of seeds were conducted, including scarification with sulfuric acid 98% for 10 and 15 min, sandy paper, hot water for 5 and 10 min, potasium nitrate 0.1%, gibberellic acid at 250 mg·L⁻¹ and 500 mg·L⁻¹ and combinational treatment of scarification with gibberellic acid of 250 mg·L⁻¹ and 500 mg·L⁻¹. The results show that scarifications with sandy paper and sulfuric acids 98% were the most effective treatments on breaking seed dormancy and seed germination induction. Scarification with sulfuric acid 98% for 15 min was the best treatment. According to the positive effect of scarification and lack of reaction of seeds against KNO₃ and gibberellic acid, the kind of seed dormancy was determined as exogenous.     

Insecticidal properties of <Emphasis Type="Italic">Thymus persicus</Emphasis> essential oil against <Emphasis Type="Italic">Tribolium castaneum</Emphasis> and <Emphasis Type="Italic">Sitophilus oryzae</Emphasis>

Red flour beetle Tribolium castaneum (Herbst) and rice weevil Sitophilus oryzae (L.) are considered to be the major insect pests in storage. Essential oils from aromatic plants are recognized as proper alternatives to fumigants. Thymus persicus (Ronniger ex Rech. f.) is one of these plants that have medicinal properties and is indigenous to Iran. The essential oil was obtained from aerial parts of the plant and analyzed by GC and GC–MS. Carvacrol (44.69%) and thymol (11.05%) were the major constituents of the oil extracted. In this experiment, fumigant toxicity of the essential oil was studied against T. castaneum, S. oryzae at 27 ± 1°C and 60 ± 5% RH in dark condition. The adult insects were exposed to the concentrations of 51.9, 111.1, 207.4 and 370.4 μl/l air to estimate median lethal time (LT₅₀) values. The fumigant toxicity was increased in response to increased essential oil concentrations. The LT₅₀ values at the lowest and the highest concentrations tested were ranged from 28.09 to 13.47 h for T. castaneum, and 3.86 to 2.30 h for S. oryzae. It was found that S. oryzae adults were much more susceptible to the oil than T. castaneum. After 24 h of exposure, the LC₅₀ values (95% fiducial limit) for T. castaneum and S. oryzae were estimated to be 236.9 (186.27–292.81) and 3.34 (2.62–4.28) μl/l air, respectively. These results suggest that T. persicus essential oil merits further study as potential fumigant for the management of these stored-product insects.