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＞Ｆ０．０１＝５．９９）。经ＬＳＲ检验，变温层积（２０～２５℃４５ｄ＋２～５℃ ４５ｄ）的发芽率最高，可达５６．７％，且与其它各层积处理的发芽率之间存在极显著的差异；２～５℃层积９０ｄ、７０ｄ及对照（２～１５℃层积９０ｄ）的种子发芽率之间差异不显著；２～５℃层积３０ｄ的发芽率最低，仅为２２％（表２）。以上试验小结为：（１）成熟且发育完善的肉花卫矛种子在适宜的温度、水分等条件下不能发芽，种皮透气性差是肉花卫矛种子休眠的原因。（２）层积处理可以提高种子的发芽率，其中以２０～２５℃４５ｄ＋２～５℃４５ｄ变温层积处理的发芽率最高，可达５６．７％，解除了种子休眠。 相似文献
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不同环境条件下气孔和光合作用模型: 4个杨树无性系对光照、温度和相对湿度的反应(英文) 总被引：1，自引：0，他引：1
用配有Ｌｉ－６１０露点发生器的Ｌｉ－ｃｏｒ６２００在温室中测定了４个杨树无性系叶水平上的气孔导度（Ｃｓ）和净光合速率（Ｐｎ）．在３个相对湿度（ＲＨ）水平（７０％，５０％和３０％）控制下，不同温度（２５℃，３０℃和３５℃）条件下，杨树无性系的Ｐｎ、Ｃｓ、蒸腾速率（Ｅ）和胞间ＣＯ２浓度（Ｃｉ）表现出显著差异（Ｐ＜０．０００１）．随着空气湿度的减小，Ｅ、Ｃｓ、Ｃｉ明显下降．结果表明：ＲＨ低时，而不是ＶＰＤ高时，气孔关闭在调节蒸腾速率和胞间ＣＯ２浓度中起更大作用．另外，还选用了净光合速率－光照模型和Ｃｓ－Ｐｎ复合模型模拟了不同光照、温度和相对湿度条件下Ｐｎ和Ｃｓ间的关系．尽管无性系、温度和湿度间存在差异，但在模拟Ｐｎ对光照的关系上净光合速率－光照模型最合适．关于Ｃｓ－Ｐｎ模型，检验了Ｌｅｕｎｉｎｇ模型，建立了新的Ｃｓ－Ｐｎ模型：Ｃｓ＝Ｃｓ０＋ａ０Ｐｎ／［（ＣＯ２－Γ）（１＋ｆ（Ｔ）（１－ＲＨ／１００）／Ｄ０）］．基于它们之间的关系，式中加入了反映温度和ＲＨ的变量，代替了ＶＰＤ变量．与田间数据模拟结果相比较，新模型和Ｌｅｕｎｉｎｇ模型一样适合．并且，为了预测气孔和气体交换的行为，可以用净光合速率－光照模型修正Ｃｓ－Ｐ 相似文献
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巨尾桉组培苗的节段（包括茎尖、第１和第２节段）用海藻酸钠包成胶丸，胶丸埋于无营养的琼脂培养基内，在２５～３０℃，１５００１ｘ（１０～１４）一般培养室条件下，保存１０个月时，再生率可达５２％，研究证实这是一种可行的种质保存方法。光照是保存的必要外部条件。低浓度（１．５％～２％）海藻酸钠比高浓度（５．５％）有利于维持种质的活力。胶丸基液筛选结果表明，蔗糖浓度是制约种质活力和再生率的关键因子，低浓度蔗糖（０．５％）和无机盐表现出有益影响，蔗糖易导致胶丸内节段变黑、降低种质活力和再生率；保存期间，胶丸颜色由绿逐渐转白或转黑，是胶丸种质丧失活力和再生能力的两个主要表现过程；由此显示，可用种质胶丸颜色估测保存种质的活力状态。 相似文献
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通过３ａ的研究，掌握了白跗平腹小蜂（ＡｎａｓｔａｔｕｓａｌｂｉｔａｒｓｉｓＡｓｈｍｅａｄ）繁殖技术的关键是：蜂种源－柳杉毛虫卵中羽化出来的白跗平腹小蜂；繁蜂用卵一柞蚕（ＡｎｔｈｅｒａｅａｐｅｒｎｙｉＧｕｅｒｉｎｍｅｎｅｖｉｌｌｅ）、水青蛾（ＡｃｔｉａｓｓｅｌｅｎｅｎｉｎｇｐｏａｎａＦｅｌｄｅｒ）等卵，繁殖时温度为２２～２５℃、相对湿度７０％～８０％，接蜂的蜂卵比为１：１０～２０；接蜂时间为２４ｈ为宜；母蜂利用时间１５～２０ｄ；蜂量积累办法，在上述温湿度条件下接种８～９ｄ的寄生卵置于８～１０℃范围内贮存２０ｄ左右，解除低温控制后的寄生卵能正常羽化繁殖后代，达到积累目的。 相似文献
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正红菇的生长与生态环境的关系 总被引：3，自引：2，他引：3
通过对正红菇生态环境各因子调查观察，为人工模拟生态环境、引种栽培野生红菇提供依据。历时４年的调查研究表明：正红菇是一种外生共生菌；在相对稳定的生态条件下（平均温度２５－２７℃，湿度８０％－１００％，降雨量（土壤含水量）达４０％以上），正红菇发生，降雨量为其主导因子；正红菇年发生２次，在夏秋季节高温、闷热阵雨之后为发生盛期；发生地海拔不限，以山的中下部为多，林间郁闭度０．８左右，土壤ｐＨ值５．６－７．０之间；其共生树种以壳斗科为主。 相似文献
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小窄径茧蜂在检疫室温度２０－２７℃，相对湿度７５％－８５％，以日光灯和电风扇调节室内光照和通风，蛹期发育良好，羽化率达８７．９％；在饲料室温度２０－２５℃，相对湿度６０％－７５％，有良好的通风光照条件下，成虫取食，交尾活动及后期发育正常，成虫死亡率仅为１．４７％；雄蜂交尾前需要补充营养，检疫观察期间雌雄要分养１－３天，以促进雄蜂性成熟，饲养室内雌雄混合饲料，按雌雄性比３：１或２：１饲养５－７天，在 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
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本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):131-138
The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided. 相似文献
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《Scandinavian Journal of Forest Research》2012,27(5):472-479
Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken. 相似文献
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Srisuda Thippayarugs Banyong Toomsan Patma Vityakon Viriya Limpinuntana Aran Patanothai Georg Cadisch 《Agroforestry Systems》2008,72(2):137-148
In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic
or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts
(stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea
(Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content
as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest
N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized
to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea,
largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for
N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant
components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N
released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures
were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality
components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in
the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols.
Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest
age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its
components are mixed. 相似文献
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A. Rigueiro-Rodríguez M. R. Mosquera-Losada E. Gatica-Trabanini 《Agroforestry Systems》2000,48(3):245-256
The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste
disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization,
(2) milk sewage sludge at 40 kg N ha−1 target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two
pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha−1. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1); (2) Lolium perenne L. var. Tove (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea
(Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m2, with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect
on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage
sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but
affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral
systems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献