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1.
川西云杉人工林种群竞争规律初步研究 总被引：6，自引：1，他引：5
本文根据人工林固定标准地的定位观察资料,研究了川西云杉（Ｐｉｃｅａｂａｌ－ｆｏｕｒｉａｎａ）和云杉（Ｐ．ａｓｐｅｒａｔａ）人工林种群的竞争规律。结果表明：云杉人工种群初期生长缓慢,１２龄前平均生长量为０．０６ｃｍ～０．１１ｃｍ,以后生长加速,１８龄平均生长量为０．４ｃｍ～０．７ｃｍ;２０龄左右可能发生大的种内干扰,有一次较大自疏,但仍未出现年轮宽度的骤增;２６龄时,经人为干扰（间伐）,年轮宽度略有增加,说明密度在３０００株／ｈｍ２以上的云杉人工林种群密度仍然过大。采用干扰指数模型分析表明,云杉人工种群格局形成过程的主要动力为种内竞争 相似文献
2.
种群空间格局研究的零频率方法及其抽样技术 总被引：1，自引：0，他引：1
在建立Ｓ＾２＝ａ（－ｌｎｐ０）＾ｂ模型的基础上，结合Ｇｅｒｒａｒｄ＆Ｃｈｉａｎｇ模型（ｍ＝ａ（－ｌｎＰ０）＾β和系数Ｃ，本文提出一个种群空间格局研究的零频率方法。根据种群订临界零频率（Ｐ００＝ｅｘｐ「＝（α／ａ）＾１／（ｂ－β）」），可地空间格局连续统作出定量描述，按参数（ｂ－β）可将生物种群划分为“聚集度非零频率制约型”、“聚集度逆零频率制约型”和“聚集度零频率制约型”３种类型。通过１０种生物种 相似文献
3.
斑苦竹无性系种群生长发育规律的研究 总被引：8，自引：0，他引：8
本文通过对四川缙云山次生性斑苦竹无性系种群的取样调查，研究了笋芽的发笋规律，竹笋－幼竹的高生长和秆径生长动态，以及地上茎生长与气候因子的关系。结果表明：斑苦竹无性系种群的发笋盛期主要集中在６月中、下旬。无性系分株幼竹阶段平均高度呈Ｌｏｇｉｓｔｉｃ增长，回归模型为：Ｈ＝６２５。９７８１／１＋ｅｘｐ５．８５２６－０．１０１６ｔ（Ｐ〈０．０５）地上茎生长的主要制约因素为温度和湿度。高湿结合温暖有益于斑苦 相似文献
4.
冷箭竹更新幼龄种群密度的研究 总被引：4，自引：2，他引：4
应用构件生物种群理论，从构件生物的两个水平研究了卧龙自然保护区大熊猫栖息地内冷箭竹幼龄种群自然更新密度特征，结果表明：①冷箭竹幼龄种群的基株（竹丛）种群密度为２５．１基株／ｍ＾２，１９８３年开花枯死竹林次年萌发幼苗的种群密度低于第３年的幼苗种群密度，随开花枯死年限的延长，种群密度逐渐降低；②冷箭竹克隆种群密度平均为９４．４株／ｍ＾２，各龄级的排序为３年生〉４年生〉５年生〉２年生〉１年生〉６年生〉７ 相似文献
5.
亚热带次生常绿阔叶林主要乔木各自然恢复１５年来的变化 总被引：4，自引：0，他引：4
在瓦屋山定位研究了中亚热带湿性常绍阔叶林次生群落１５a来各乔木种且成及其重要值、密度，大小结构、高度结构和材积生产力的动态变化，结果表明，自然恢复过程中次生常绿阔叶林群落乔木层物种组成变化明显，有１１种从群落乔木层消失，也有１０种出现，乔木层树种多样性（丰富度）基本保持动态平衡和发展；优势种地位保持不变，但次优势种地位得以加强；群落结构变化较大，突出表现为种群密度、胸径和树高分布格局的变化和立体空间的分布，群落由单优或双优种向双优或多优势种发展，由单一乔木屋向多层次立体结构发展，空间加厚，群落更复杂、稳定性增强。乔木种群平均高生长速度在２４－４８cm.a^-1 ,平均ＤＢＨ生长率在０.３４－１.１０cm.a^-1，各种群生长速度差异明显，按生长速度可划分为适应性强的速生树种如细梗呈茱萸叶五加，华木荷（平均ＤＢＨ生长在０．７０cm.a^-1以上），中等速度的小叶青冈、扁制栲（平均ＤＨＢ生长在０．４０cm.a^-1以上），慢生种如润楠、石栎（平均ＤＨＢ生长在０．４cm.a^-1以下）；种群材积生产力高低不一，优势种扁刺种群材积生产力并不是直增长，而是在后期出现下降；次优势和睦产长速度较快。１９９７年３固定样地材积量２１８－２２５m^3.hm^-2，优势种群材积生产力是群落材积生产力的高低的关键，在相同的环境条件下和各种群相互作用下，密度是各种群生长和材积生产力高低的决定因素之一。 相似文献
6.
通过对２２种生物种群资料Ｌａ－ｍ关系的研究，提出了一个种群空间格局研究的Ｌａ－ｍ幂法则模型，并对模型参数的生物学意义进行了探讨。根据种群聚集临界密度，可对空间格局连续作出定量描述，按参数δ可将生物种群划分“聚集度逆密度制约型”、“聚集度密度制约型”和“聚集度非密度制约型”３种类型。 相似文献
7.
关于Iwao m^＊ -m回归模型在昆虫种群空间分布型的应用分析 总被引：3，自引：0，他引：3
本文对：Iwao m^＊ -m回归模型在检验昆虫种群空间分布型中的应用，以及存在的问题进行了系统研究，结果表明：（1）回归参数α／和β是用来控制m^＊与m变化程度的参变量，不具备特定的生物学含义。（2）用多项式回归模型改进的Iwao m^＊ -m模型只是在一定的程度上提高了模型的相关关系，使调查的资料可满足于检验昆虫种群空间分布型的需要，改进模型中的回归参数同样不具备特定的生物学含义。（3）Iwao模型和改进的Iwao模型检验昆虫种群空间分布型的依据是在m的取值范围内，m^＊与m的比值（m^＊／m）是否偏离1来决定的。 相似文献
8.
9.
用生态经济型植物控制豚草的"绿色污染" 总被引：5，自引：0，他引：5
豚草是一种严重危害农业生产、人体健康和生物环境的恶性杂草，是一种典型的“绿色污染”。根据群落演替规律，采用具有生态和经济功能的树种创造不利豚草生长的环境，人为创建多物种和谐共存的植物群落，能降低豚草的种群优势，使单一种群优势转变为良性演替的生态系统。 相似文献
10.
本文从龄级，等级度，胸径和树高结构以及空间分布格局分析了卧龙自然保护区五一棚麦吊云杉的种群特征。结果表明；麦吊云杉种群为一衰退种群，龄级结构呈倒金字塔模型，集中分布于８０年至１４０年之间；等级度结构主要由占总数的８０５以上的Ⅳ和Ⅴ级组成；胸径和树高分布分别以３２．０ｃｍ－６４．０ｃｍ和１６．０ｍ－３２．０ｍ为度；采用方差／均值比率法和ｘ＾２检验法对麦吊云杉种群空间分布格局的研究得出，该地区的麦吊云 相似文献
11.
《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
12.
《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
13.
《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
14.
《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
15.
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
16.
《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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18.
《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
19.
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
20.
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