章古台沙地几个造林树种的树叶含水测定实验初报

自1980年在本场固沙造林试验地内,对沙地几个造林树种的树叶含水量进行了测定。目的是了解与掌握生长在沙地树种的耗水情况,以及经营培育好沙地绿化成果。一、供试材料的选择采集与测定供试材料采自章古台固沙造林研究所固定沙地上人工栽植的樟子松(Pinus sylvestris L.var mongolica Litvin.)、油松(P.tabulaeformis carr.)、赤松     

草牧场防护林适生树种研究

通过对科尔沁沙地草牧场防护林主要造林树种的立地条件与林木生长分析，可以看出，在碳酸盐沙质栗钙土上，白城２号和小黑杨是最优的造林树种；在沙土上白城４２号和加拿大杨是生长最快的杨树；樟子松在泥沙土的坨上和平坦沙地上生长最好；油松在栗沙土的平坦沙地上生长最旺盛；小黑杨最适宜的土壤是冲积土。     

半干旱沙地杨树机械造林的最佳栽植深度

在半干旱沙地利用新型植树机进行造林，最好采用苗根造林方式，最佳栽植深度为45cm。     

榆林市樟子松人工林分布及其生长特性调查研究

榆林市樟子松人工林调查结果表明,截止2014年榆林沙区樟子松人工造林面积75 454hm~2,主要分布在西北部6县区的沙地;樟子松人工林在树高、胸径生长均优于同龄油松人工林,不同基质(盖沙黄土地和沙地)对樟子松人工林的生长发育影响不大,均适宜樟子松的栽植;栽植密度对樟子松人工林生长影响明显,在树高、胸径和冠幅各指标相间差异性显著,合理稀植更有利于樟子松的生长发育;丘间地、平缓沙地更适宜于樟子松的生长,不同密度和不同立地条件对樟子松胸径、冠幅的生长影响较树高显著;目前存在的主要问题是纯林多,结构单一,自然更新困难等。     

敖汉旗沙地樟子松造林试验

为探讨樟子松在敖汉旗沙地的适生能力，进行了樟子松沙地造林试验，结果表明，24年生的樟子松林，表现基本稳定，生长较快，年平均树高生长量达0．22－0．38m，胸径生长量达0．34－0．59cm，比油松和小叶杨的生长量大。调查研究发现，影响樟子松林生长的主要因素是，当地的降水量较低，在干旱年分林分出现水分亏缺；部分地区的土壤下层有白土间层，水分和养分的含量低；有些林分密度偏大，林分出现枯死现象。     

沙地节水造林新技术-超深栽造林技术

为了提高沙地造林成活率和保存率,该文提出了一种节水造林新技术-沙地林木超深栽造林技术。该技术通过采用林木深根苗(垂直根系长度超过60cm的苗木)或长茎苗(具有较长主茎的苗木),造林时直接将其根系栽植到保有较多水分的下层土壤,使苗木根系能直接吸收到土壤中的水分,不仅能够大大提高造林成活率,且苗木生长亦优于常规技术造林苗木。该文对该技术所采用苗木的快速培育、超深栽造林以及栽后管护等方面进行详细阐述,以期推进林木超深栽造林技术在干旱半干旱沙地造林中的推广应用。     

石质山区阳坡辽东栎造林技术研究

辽东栎喜光，耐干旱，其适生环境与油松大致相同，能与油松形成稳定的松栎混交林，为探讨这一良好的混交树种的造林技术，在太行石质山区阳坡油松幼林地，进行了辽东栎造林试验，试验结果表明，在阳坡播种造林成苗率低于３０％，３年生幼枝年均高生长２．５～４ｃｍ，通过预整地，选用壮苗，栽植穴覆膜等措施，可取得较好造林效果，造林成活率可达９５％以上，幼树新梢高生长亦在１２ｃｍ以上。     

榆林南部丘陵沟壑区油松造林技术探讨

油松（PinustabulaeformisCarr.）为本区乡上树种，集中分布在桥山及黄龙山南端海拔1000～1700m间，北部可延伸到神木、府谷一带。1980年我所在米脂县东沟流域的高家沟村筹建一处树木引种观察园，其地形地貌典型地代表了榆林南部梁明丘陵沟壑区的特点。从1983年开始，针对油松等常绿树种在造林中存在的技术问题，进行了专题研究。经过几年的试验观测，应用新技术栽植8年的油松平均高度为2．62m，地径5．04cm，最高可达3．87m，地径八38cm，已形成一个林相整齐、生长茂盛、完整的油松林分，现将造林技术归纳如下。l选择林地，提前繁地在丘陵…     

辽西半干旱地区栎树人工造林技术的研究

针对辽西半干旱的自然条件，在油松砍伐带内、油松林冠下、油松疏林下等庇荫条件下进行了一系列栎树直播和植苗造林试验。结果表明，栎树在3～4年生以前虽以根系生长为主，但主要是主根的伸长生长，吸收根量极少，难以维持地上地下水量平衡，荒山造林很难成功。在庇荫条件下，在夏季，光照强度大大降低，蒸腾强度显著减小，减少了水分的无益消耗，在冬季和冬春之交，则避免了因生理干旱失水造成的枯梢甚至枯干死亡，从而使栎树造林成活率保存率大大提高，生长状况明显改善。在郁闭度较大的林冠下造林，初期成活率、保存率可高达100％，但树高和地径生长量均很小，而且随林龄增加，表现得越发明显。在合适的庇荫条件下，辽西6年生栎树保存率在90％以上，平均地径0．45～0．93cm，平均树高19．5～32．3cm，根系深超过70．5cm，直径1．728cm，挖断处(70．5cm深处)直径0．334cm，侧须根增多，吸收能力增强，已进入稳定生长期。根据本研究结果，可以得出如下结论：辽西半干旱地区栎树人工造林要获成功，应该做到：(1)庇护造林；(2)秋季直播造林；(3)选择土层较厚的立地；(4)细致的幼林抚育措施。     

燕山北部山地干旱阳坡不同造林树种生长状况的比较

为了了解燕山山地干旱阳坡人工造林树种生长状况的差异,对人工栽植的油松、樟子松及蒙古栎的生长状况及其幼林的空间分布格局进行了研究,结果表明:栽植5a后,油松、樟子松和蒙古栎的存活率分别达到了93.79%、87.98%和66.69%,其地径分别为4.68cm、5.34cm、1.52cm,树高分别为1.58m、1.75m、0.80m,油松、樟子松、蒙古栎的单株生物量分别为1 857.36g、2 018.30g、234.35g,形成的人工幼林的密度在867.00~2 183.00株/hm~2之间;立地条件较好的样地幼林的空间分布格局为均匀型,立地条件较差的样地空间分布格局为聚集型。油松、樟子松、蒙古栎均为燕山北部山地干旱阳坡的适宜造林树种,栽植5a后已基本形成稳定的乔木层,人工造林加速了干旱阳坡由绣线菊灌丛向乔木林的更新与恢复。     

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.