缺苞箭竹竹笋—幼竹期生长节律研究

缺苞箭竹(Fargesia denudata)是大熊猫喜食竹种之一,过去研究甚少。本文拟通过缺苞箭竹竹笋—幼竹期生长节律的研究,探论其生长过程中的某些规律,为大熊猫主食竹更新,复壮,造林,营建大熊猫食料基地提供理论依据。 本文共分四部分探讨缺苞箭竹竹笋—幼竹期的生长节律:1、年生长节律。幼龄竹表现最明显,在未达成竹之前,年高生长,径生长及重量生长均大于前一年。2、季节生长节律。在一年之中。不同季节生长节律不同。大体可分为四个阶段。延缓期在4月10日—6月10日。共62天。绝对生长率G=0.09;指数生长期在6月11日—8月26日。共77天。G=2.54;相对生长下降期在8月26日—9月23日,共28天。C=0.43。3、日生长节律。据观测,在竹笋—幼竹的生长季节里,夜间生长量略大于白天生长量,其出现频率为52％,夜间高生长量为0.63cm,白天高生长量为0.59cm。4、竹笋—幼竹生长与气候的关系。通过气温,相对湿度,幅射量,地温与竹笋生长量的定位观测资料,进行回归分析,发现温度因子是支配竹笋—幼竹生长的主导因素,这和实际情况相符合。     

密度对川西亚高山针叶林缺苞箭竹种群生物量、碳及养分贮量的影响

在缺苞箭竹-紫果云杉原始林下选取5个密度的缺苞箭竹,研究密度对缺苞箭竹生物量、C及养分贮量分配的影响.结果表明:在一个生长季中,缺苞箭竹生物量、净生产量、平均单株生物量、植物及土壤的C、养分贮量在(80±5～260±9)株·m-2密度范围内随密度的增大而增大,在高密度(310±15)株·m-2时有所降低,210～260株·m-2是缺苞箭竹最适密度范围.各密度缺苞箭竹养分元素贮量排序总体上均为K＞N＞Ca＞P＞Mg.在密度较低时,地下部分C及养分贮量分配比例相对较高,有利于其占据土壤空间资源,而随密度的增高,地上部分比例增高,有利于其占据地上空间资源,反映了缺苞箭竹随密度变化的克隆生长生态适应对策.在缺苞箭竹-土壤系统中,植物与土壤C库贮量比率随密度的增大逐渐升高,在高密度时有所降低.土壤5种主要全量养分库贮量较丰富.土壤速效N、K养分库在各密度之间差异不显著,而速效P库则随密度的增大而逐渐降低.表明土壤速效P库的不足是缺苞箭竹生长的主要限制因子.     

缺苞箭竹更新与生态因子关系的研究

通过对王朗自然保护区不同地段箭竹——冷云杉林下单位面积上缺苞箭竹生物量和其它16个生态因子的17块标准地的调查,以缺苞箭竹地上部分在单位面积上的生物量代表其更新质量作为因变量,其它生态因子作为自变量,采用逐步回归的方法进行计算筛选,其结果表明:影响缺苞箭竹更新的主要因子是林冠郁闲度,其次是地面活苔藓层厚度;更新质量与坡向存在显著相关关系.     

王朗自然保护区引种竹笋：幼竹期异速生长规律的研究

本文以王朗1985年大熊猫主食竹类引种试验以来,筛选出的四个适应性最强的种:石棉玉山竹(Yushania lineolata)、青川箭竹(Fargesia rufa)、糙花箭竹(Fargesia scabrida)和冷箭竹(Bashania fangiana)及本地缺苞剪竹(Fargesia denudata)作材料,研究了各竹种当年生笋、一年生幼竹和二年生成竹的秆、枝、叶、箨和单株间以及与竹笋——幼竹期高径(D~2H)生长间的异速生长常数K的变化规律,建立了数学模型,并对竹笋到一年生幼竹的各器官(组分)的K值进行相关性研究,探讨在竹笋——幼竹期K值的变化规律。另外还根据笋秆K_s值与缺苞箭竹比较,确定各竹种竹笋——幼竹期的长短及进入稳定加固期的时间,评价各竹种的适应性能力。结果表明:笋期秆异速生长最显著的是糙花箭竹,顺次为石棉玉山竹、青川箭竹和冷箭竹。一年生幼竹器官异迷生长缺苞箭竹向多枝性发展,青川箭竹枝与秆之间生长近似于线性关系,秆、枝、叶和单株间成均衡性生长,而石棉玉山竹、糙花箭竹和冷箭竹则向少枝大秆型发展。单株生物量累积速度的主要因子是叶的生长,其次是秆、枝。二年生成竹的K值出现明显的变化,各竹种经竹笋——幼竹期进入稳定加固期的时间是不同的,石棉玉山竹和青川箭竹一般为1—2年,糙花箭竹和冷箭竹约为2—3年。竹笋——幼竹期K值因种和不同生长年龄而发生变化。笋期(秆、单株)生长速度与其笋成竹的秆、枝、叶和单株K值成负相关,但是笋期异速生长越快,则竹笋——幼竹期越长,进入稳定加固期较晚。对于可塑性强, 较为敏感的竹笋——幼竹来说,时间经历越长,对环境的生态适应能力将会变大。生产实践中,可用笋期秆异速生长常数K_s的大小来确定各竹种其笋进入幼竹和成年稳定后的适应能力及适应程度。表中的数字模型可用来预测生物量。     

缺苞箭竹开花结实和自然更新观察

1983年以来,甘肃文县境内部分大熊猫受灾是因为缺苞箭竹Fargesia denudata Yi成片开花枯死。缺苞箭竹营养生长年限长达60年左右,所以观察它开花的机会是难得的。现将该竹开花结实和自然更新情况调查观察的结果作一简介。一、形态特征缺苞箭竹分布在甘肃文县、武都县南部及四川的青川、平武、北川等县,生长在海拨1950—3150米地段林下。地下茎合轴型,秆柄两端不等粗,实心,长4—13厘米,直径7—10毫     

王朗引种区大熊猫主食竹生长发育规律的研究

本文对平武王朗自然保护区引种大熊猫主食竹生育规律进行了研究。选用引种3年后生长表现较好的糙花箭竹(Fargesia scabrida)、石棉玉山竹(Yushania lineolata)、冷箭竹(Bashania fangina)、青川箭竹(F.rufa)4个竹种生长量与本地缺苞箭竹(F.denudata)作对比。通过生长过程的数学模拟和多元变量分析,探明5个竹种竹笋—幼竹期生长节律,日生长率及其生长与气象因子的关系。结果表明:引种的4个竹种都能适应本区条件,但在生长量上存在着种间差异。发笋多、生长快、长势好的竹种是糙花箭竹、冷箭竹和石棉玉山竹。影响竹种高生长的主要因素是热量因子。     

缺苞箭竹生物学物侯学特征的初步研究

本文通过对四川王朗自然保护区缺苞箭竹研究分析表明：１．缺苞箭竹生长受热量因素的制约，具有与温度变化同步趋势；２．缺苞箭竹地下茎为合轴型，其分蘖生长具有同期分蘖效应的特点及按序分蘖特征；３．缺苞箭竹物候期除自身生物特征（遗传特性）表现外，环境因素也直接或间接地起一定作用；４．缺苞箭竹物候期随海拔的变化，系统发育年龄的变化，其始日、终日、长短也有差异；５．按海拔梯度绘制的物候谱，在主食竹造林时间的选择、森林生态系统研究和森林经营等方面，具有重要的应用价值。     

甘肃白龙江阿夏自然保护区大熊猫主食竹的分布格局

甘肃省是中国大熊猫的3个分布省份之一,阿夏自然保护区是甘肃省大熊猫主要栖息地之一,分布有缺苞箭竹和华西箭竹。缺苞箭竹在其分布地区内为大熊猫最主要的食用竹种,在旺藏保护站管辖区域分布最广,在海拔2 600～3 000 m分布最为集中。华西箭竹在洛大保护站和旺藏保护站管辖区域分布较多,在海拔2 400～2 800 m分布最为集中。旺藏保护站辖区海拔跨度较大,是最适宜大熊猫生存的区域,四季均适宜大熊猫生存;而达拉保护站和阿夏保护站辖区更适宜大熊猫夏季生存;洛大保护站辖区适宜大熊猫冬季生存。阿夏保护区曾经历长期皆伐,森林破坏严重,缺苞箭竹也曾大面积开花,严重影响大熊猫的食物来源和栖息地环境,因此需要高度关注林下缺苞箭竹和华西箭竹的生长和恢复状况。     

缺苞箭竹生物学物候学特征的初步研究

本文通过四川王朗自然保护区缺苞箭竹研究分析表明：１．缺苞箭竹生长受势量因素的制约，具有与温度变化同步趋势；２．缺苞箭竹地下茎为合轴型，其分蘖生长具有同期分蘖效应的特点及按序分蘖特征；３．缺苞箭竹物候期除自身生物特征（遗传特性）表现外，环境因素也直接或间接地起一定作用；４．缺苞箭竹物候期随海拔的变化，系统发育年龄的变化，其始日、终日、长短也有差异；５．按海拔梯度绘制的物候谱，在主食竹造林时间的选择、     

缺苞箭竹的繁殖和生长

本文调查分析了缺苞箭竹的繁殖和生长特性,初步认为:缺苞箭竹的繁殖力较强。在其开花迹地上,竹林的更新复壮,应以天然更新为主。天然更新的竹苗,12年即可生长发育成郁闭稳定的幼林。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

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.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

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.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

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.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

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.     

CAD与建筑设计的关系

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。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

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.     

Risk Perception Among Non-industrial Private Forest Owners

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.     

Interactions in decomposition and N mineralization between tropical legume residue components

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.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

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.