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为揭示干热河谷次生稀树灌木林种群现状、分布状况及发展动态规律,以四川攀枝花苏铁国家级自然保护区内1 hm2永久固定样地为研究对象,对样地内所有种群植株个体进行每木调查,以重要值分析群落优势种群组成,并运用O-ring统计对样地内攀枝花苏铁种群空间格局及种间关联性进行计算。结果表明：干热河谷次生稀树灌木林群落除攀枝花苏铁为灌木生长型外,其余优势物种皆为乔木或小乔木型。6个优势种群空间分布格局均以随机分布为主,聚集分布次之,均匀分布尺度占比最小。种群优势度随聚集规模增大而增大,二者线性正相关,回归方程为：y=(127.49±9.04)x+(4.78±1.88)(Adj-R2=0.98,P=1.46993E-4 <0.01)。种间关联尺度占比以无关联最大,负相关次之,正相关最小。群落中种群聚集规模决定种群在群落中的优势程度,也是改变当前群落种群优势地位的主要驱动力。滇榄仁种群主要生存压力源于攀枝花苏铁和蒙桑种群,也极易受群落环境影响。铁橡栎和滇榄仁种群与蒙桑种群的种间竞争是其两次种内密度调节的主要原因。 相似文献
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为了解攀枝花苏铁种群主要功能性状分布特征及其对土壤有效养分的响应规律，在四川攀枝花苏铁国家级自然保护区干热河谷次生稀树灌木林内设立15个固定取样地(10 m×10 m)，采集样地内攀枝花苏铁主要功能性状(PHMAX（种群最大植株高度）、LA（小叶的叶面积）、SLA（比叶面积）、LDMC（叶片干物质含量）、土壤有效养分(AN、AP、AK)等数据，并运用Kruskal-Wallis test及多元统计分析各样地间攀枝花苏铁种群主要功能性状、土壤有效养分的分布特征及二者间关系。结果表明：攀枝花苏铁种群之间LA、LDMC、SLA以及土壤Al、AK、pH等均存在显著差异，但PHMAX、AN及AP并无显著差异。土壤有效钾AK和pH对攀枝花苏铁种群分布影响最大，攀枝花苏铁种群各主要功能性状间和各土壤有效养分间均呈现显著关联，且LA、SLA及LDMC等功能性状与AN、AP、AK均呈较微弱的正相关。攀枝花苏铁种群主要功能性状的分异主要源于土壤有效养分的异质性分布，AN、AP及AK的共同限制机制是该演替阶段森林群落内局域小尺度下攀枝花苏铁种群的主要生存压力，但随着森林进展演替的进行，相较AK而言，AN和A... 相似文献
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苏铁是一类起源古老而孑遗的裸子植物,攀枝花苏铁国家级自然保护区内所保护的攀枝花苏铁Cycas pan-zhihuaensis,是迄今为止世界上发现的纬度最高,面积最大,数量最多的野生苏铁种群。攀枝花苏铁群落共有物种82科253属318种;珍稀濒危植物除攀枝花苏铁外,还有云南梧桐Firmiana major、栌菊木Nouelia insignis和龙棕Trachycarpus nana。区系组成以热带性质为主,尤以泛热带为多。单种科、单种属和寡种属占绝对优势,表现出区系明显的古老性和残遗性现象。干热河谷区系特征明显,金沙江干热河谷特有种和标志种占到总种数的近1/3。一些残遗种或其后裔的起源和发生背景与古地中海有密切关系。结合当地的丰富的苏铁类植物和种子蕨化石植物群的发现,可以初步推断攀枝花苏铁群落是这些古生代类型的延续,其植物区系起源古老。该地区应是中国植物区系的分化中心,也很可能就是世界苏铁植物重要的起源与发展中心。 相似文献
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四川省攀枝花市巴关河岸的马鞍山上有一片古老珍贵的苏铁林.一秣株棕榈状、呈环形纹路的木本植物道劲挺拔;一片片雁翎似的羽状复叶,迎风轻摇.透过山间轻纱似的晨雾远远望去,俨如云端降下的只只孔雀. 苏铁俗名铁树,是一种四季常绿的多年生植物.攀枝花苏铁生长在古老的康滇古陆中段.这里自古生代时期从地中海隆起 相似文献
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楚雄州野生苏铁植物资源现状及保护 总被引：1，自引：0，他引：1
经研究判定,楚雄州分布有4种野生苏铁:攀枝花苏铁、篦齿苏铁、单羽苏铁、元江苏铁.其分布范围为金沙江流域及支流河谷、礼社江流域及支流河谷.说明了保护管理的现状,分析了存在的问题,提出了保护建议. 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