陇东山地核桃抗旱保墒试验初报

为了解决陇东山地核桃挂果晚、产量低、品质差的问题,2013—2014年连续2a于4—10月份在环县刘家塬项目区选择长势基本一致的3a生核桃幼树进行覆草、覆膜试验,定期、定点测定并记载土壤含水量和核桃树新梢生长量。结果表明:覆草较对照可提高土壤含水量12.70%,覆膜较对照可提高土壤含水量4.68%;通过对核桃树体生长量调查,覆草较对照树体年新梢生长量平均提高18.42%,覆膜较对照核桃年新梢生长量平均提高9.01%,其中覆草对土壤含水量和新梢生长量的影响最大。     

退化人工梭梭林的恢复技术研究

对退化人工梭梭林进行恢复试验研究发现:滴灌可使梭梭林地土壤含水率显著提高;梭梭光合作用增强;群落物种数增多,盖度增大;防风固沙作用增强.布设机械沙障可使退化梭梭林地表粗糙度增大,林内近地面层风速、输沙量显著下降.春灌3 a后,不仅退化梭梭个体恢复正常生长,同时梭梭林群落物种组成数明显增加,盖度显著增大,生态功能也逐渐恢复.雨水集流和雨水下渗改造两种模式应用1～2 a后,退化梭梭林地土壤含水率均有明显提高.滴灌、布设机械沙障、春灌和改造结皮4种技术措施对退化梭梭林生长及其环境均有明显的恢复作用,其中滴灌、机械沙障恢复技术是当前和今后推广的主要措施;春灌和改造结皮可作为前两种技术的补充措施.     

无性系油茶苗嫁接口种植深度研究

为探索无性系油茶Camellia oleifera造林嫁接口种植的最佳深度,于2017年12月,选择在老油茶林地、杉木采伐迹地、山垅田、茶园地4种不同土地对其开展不同种植深度的对比试验。结果表明,油茶苗当年新梢生长量与嫁接口种植深度(D)为0～10 cm处理间呈明显的正相关关系,与D 10～15 cm处理间呈明显的负相关关系,且相关关系紧密(R2均达到0.856以上)。5D≤10 cm处理,其平均造林成活率达95.81%,新梢生长量平均达24.16 cm,比D=0 cm处理造林成活率提高12.38%,新梢生长量增加47.68%;比0D≤5 cm和D10 cm处理造林成活率分别提高11.58%,6.95%,差异均达到极显著性水平(P0.01);新梢生长量5D≤10 cm处理比0D≤5 cm和D10 cm处理分别增加21.90%,22.76%,差异达到极显著性水平(P0.01)。由此可见,无性系油茶苗的嫁接口最佳种植深度为5D≤10 cm。     

不同保水措施对陇南旱地油橄榄园土壤含水量、新梢生长量及根系的影响

通过对无灌溉条件的半干旱坡地油橄榄园进行覆盖和深翻试验,研究了不同保水措施下油橄榄园土壤含水量、新梢生长量及深翻后根系变化。结果表明:土壤含水量不同保水措施间存在差异,覆盖提高了园地土壤含水量,以薄膜最高,秸秆覆盖最小。随着土壤深度增加,不同覆盖处理之间土壤水分含量具有差异性。深翻则改变了土壤结构,改善持水能力,修剪根系,促进树体健壮生长。     

不同植物的咸水滴灌量试验研究——以新疆尉犁县为例

2008年在新疆尉犁县的苗圃地,通过测定不同咸水滴灌量(3000,4 500,6 000 m3·hm-2·a-1)下5种植物的主要形态指标的生长量,包括株高、地径、冠幅和根冠比,确定了各植物合适的咸水滴灌量.结果表明:在试验设计的3个咸水滴灌量中,多枝柽柳和银新杨的合适咸水滴灌量为6000m3·hm-2·a-1,9月份时该咸水滴灌量下多枝柽柳的株高生长量为26.2 cm,冠幅生长量为9 925.7 cm2;银新杨的株高生长量为8.3 cm,地径生长量为0.242 cm,冠幅生长量为605.0 cm2;中天杨和四翅滨藜的合适咸水滴灌量为4 500 m3·hm-2·a-1,9月份时该咸水滴灌量下中天杨的株高生长量为23.5 cm,地径生长量为0.269 cm,冠幅生长量为4 560.0 cm2;四翅滨藜的株高生长量为50.8 cm,冠幅生长量为24 900.0 cm2.不同咸水滴灌量下,土壤表层0～5 cm的含水量最低,而含盐量最高;当土壤深度超过10 cm时,土壤的水盐变化已经不明显.     

秋季巴丹吉林沙漠东南缘人工梭梭林水分来源

2009 年秋季( 9 月份) 在巴丹吉林沙漠东南缘的绿洲 - 荒漠过渡带,选择栽植 2,5,10,20 和 30 年的人工梭梭林,测定 20,30,50,100,150 和 200 cm 土深的土壤含水量,应用稳定氧同位素方法研究人工梭梭林的水分来源。结果表明: 梭梭林 20 ～ 30 cm 土层含水量显著高于 150 ～ 200 cm 土层; 土壤浅层的水分来自夏末和秋初的自然降雨; 随林龄增加,梭梭对地下水的利用比例逐渐增加,而对浅层土壤水分的利用比例逐渐降低; 2 年生梭梭依次主要利用 100,20,30,50 和 200 cm 土壤水分,5 年生梭梭依次主要利用地下水以及 200,150,100 和 30 cm 土壤水分,10 年生梭梭依次主要利用地下水以及 200,150,30 和 20 cm 土壤水分,20 年生梭梭依次主要利用地下水以及200 和 150 cm 土壤水分,而 30 年生梭梭依次主要利用 50,100,150,200,30 和 20 cm 土壤水分; 在巴丹吉林沙漠东南缘,随着林龄增加,梭梭对降雨补充的土壤浅层水分的利用能力降低,而对土壤深层水分与地下水的利用又不足以维持其正常生长需要,这可能是导致人工梭梭林大面积退化的一个原因。     

地下滴灌条件下杨树速生丰产林生长与光合特性

研究了北京沿河沙地I 2 1 4杨树人工林地下滴灌和常规灌溉林地树木生长与光合特性 ,结果表明 :与常规灌溉相比 ,地下滴灌能大大增加树木的生长量 ,提高林地生产力。 2 0 0 0年 (栽植第 4年 ) ,地下滴灌区树木平均胸径、树高和单株材积分别达到 2 1 1 8cm、1 4 2 3m和 0 1 81 5m3,比常规灌溉增加了 5 4 5 %、36 9%和 2 4 7 6 % ;林地生产力达到 2 2 78～ 2 5 81m3·hm- 2 a- 1 ,比常规灌溉增加了 3 9～ 4 6倍。树木生长改善和林地生产力提高的生理机制是地下滴灌可促进树木光合作用和水分利用效率。地下滴灌区树木叶净光合速率在一天中几乎一直显著高于对照 ,幅度达 1 0 0 %～ 2 1 4 % ;从一个滴灌周期来看 ,滴灌区树木叶净光合速率显著高于对照 9 0 %～ 9 9% ;滴灌区树木水分利用效率也较对照区显著提高。通过相关分析表明 ,表层土壤 (1 5～ 2 5cm)水分含量在 5 %～ 8%时树木叶净光合速率能在长时间维持较高水平 ,而水分含量低于 4 % ,树木叶净光合速率将降低。建议在干旱半干旱和季节性干旱地区营造速生丰产用材林时应结合当地经济条件推广地下滴灌技术 ,这不仅有利于水资源的可持续利用 ,而且将大幅度提高林地生产力 ,使我国人工林生产力赶超世界先进水平。     

祁连山青海云杉林土壤温湿度变化特征分析

以祁连山大野口流域100m×100m青海云杉林样地为试验地,采用野外测定和室内分析相结合的方法,分析了青海云杉林地土壤含水量、土壤温度在剖面上的变化规律及土壤温湿度两者之间的相关性。研究表明:试验地青海云杉林土壤含水量随土层深度增加,其含水量逐渐减小,0~30cm土层属于土壤水分相对稳定层,30~60cm土层属于土壤水分活跃层。土壤温度随土层深度增加,其温度亦逐渐减小,土壤变异系数在不同深度土层呈现出先高(0~10cm)后低(10~30cm)而后又高(30~60cm)的变化特点。土壤温湿度两者之间拟合公式为y=0.083 1 x-5.259 8(R2=0.489 2,P0.01)。     

不同类型薄壳山核桃苗木栽植效果研究

以淮安地区种植园的1年生和泰州地区种植园的2年生‘波尼’薄壳山核桃苗为试材,研究裸根苗、土球苗、无纺布容器苗等3种不同类型薄壳山核桃苗栽植后生长发育的差异。结果表明:3种类型苗木栽植后新梢和根系生长差异较为显著。两处均以无纺布容器苗成活率最高,达到100%;新梢生长量最大,1年生和2年生苗木的生长量分别为110.77 cm和53.44 cm;根系也最为发达。土球苗次之,裸根苗的新梢、根系生长量最小。分析表明,在江苏淮安和泰州这两个地区,无纺布容器苗的成活率、平均新梢生长量、分枝数、总的新梢生长量、主根长度、粗度、侧根数量等均优于土球苗和裸根苗的。此外,3种类型苗木栽植后,2年生苗木的地上、地下部分生长均优于1年生苗木的。     

三种嫁接方式对枣树新枝生长的影响研究

研究3种嫁接方式对枣树生长的影响,在大平顶枣果园进行了嫁接试验,结果表明:在朝阳地区的气候条件及立地条件下,嫁接后一个月以切接方式的成活率最高,为70%,平均单株新梢生长量最大,达到5.23cm;以插皮接方式的成活率最低,为35%,平均单株新梢生长量最少,为1.32cm。     

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.