祁连山寺大隆林区不同程度放牧草地水土流失的初步研究

本文根据试验区内不同植被类型的12个地表径流观测场的5年观测,研究了降雨对不同程度放牧草地水土流失的影响。结果表明:降雨强度是影响地表产流的首要因子;有林地各植被类型小区均不产生水土流失现象;过度、中度和轻度放牧草地类型其年径流量分别为210.5mm、42.1mm、5.2mm,土壤流失量分别为5262.42kg/ha,115.37kg/ha 和3.94kg/ha;并且过度放牧草地的地表径流系数变化最显著,在雨季有较大降雨量时是流域内产生水土流失的主要来源。     

太行山片麻岩区坡地水土流失规律研究

通过人工模拟降雨和野外观测试验,对太行山片麻岩区坡地水土流失规律进行了研究。结果表明:雨前土壤含水量越大,产流越早;土层越厚,土壤蓄水量越大;累积地表径流量与降雨时间的对数呈显著正相关,拟合方程为W=a+blnt,相关系数均大于0 92;径流量与降雨量呈显著正相关,并且径流量随降雨量的增加呈指数形式增加,拟合方程为Y=aebx,相关系数均大于0 95;径流量随降雨强度的增大而增大,并与30min最大降雨强度呈显著正相关;地表径流量与植被覆盖度呈显著负相关关系;相同土地类型,土壤侵蚀量与坡度呈对数曲线关系,坡度越大,土壤侵蚀量也越大,拟合方程为Y=a+blnx;相同土地类型土壤侵蚀量的增量随时间的增加趋于平缓;在其他条件相同的情况下,不同土地类型的土壤侵蚀量为坡耕地>油松林地>刺槐林地>荒坡草地。     

湿地松新造幼林地水土流失规律研究

为了解高度集约化经营湿地松林对环境的影响,以湿地松新造幼林地为对象,设置径流场进行了连续６年系统定位观测研究。结果表明,观测期间降水量为６４３５３ｍｍ,林地径流量为１６１１２４１ｔ／ｈｍ２,泥沙流失量为２７８４４７７７ｋｇ／ｈｍ２,流失Ｎ、Ｐ、Ｋ等主要养分为１３１ｋｇ／ｈｍ２,径流系数为３１６％;在安徽丘岗地区营造湿地松林,实行大块状（８０ｃｍ×８０ｃｍ×５０ｃｍ）整地,并集约经营,不致引起严重的水土流失,造林当年土壤侵蚀模数为１９５５９ｔ／ｈｍ２,属于无明显侵蚀类型,该区可提倡高规格整地和实行集约经营;５～８月为集中降水期,应避免相关营林活动;水土流失量与降水量呈幂函数关系,随着林木生长和植被的恢复,径流量逐渐减少,泥沙流失量则显著减少。     

旅游开发对若尔盖自然保护区土壤养分和物理性状的影响

对高原湿地若尔盖国家级自然保护区不同旅游开发强度下土壤养分和物理性状进行研究的结果表明：（1）不同旅游开发强度（强度等级）对若尔盖高原湿地花湖景区土壤养分含量（有机质、氮、磷、钾）有着较大差异。（2）不同旅游开发强度对土壤理化性质的影响表现为：随着放牧干扰强度的增加,样地土壤容重逐渐增大、孔隙度逐渐减小。干扰导致土壤持水量和含水量下降,重度和中度干扰下土壤持水量和含水量与无放牧干扰时相比均有显著下降（P〈0.05）。放牧压实造成土壤表层孔隙度下降,致使土壤初渗速率、稳渗速率下降,其中稳渗速率下降最为明显,轻度、中度和重度放牧干扰下土壤稳渗速率比未受放牧干扰时分别下降了49.81%,81.89%和92.34%。（3）旅游活动、过牧超载等人为干扰活动是引起生态退化的主要原因。气候寒冷造成土壤利用性能受限,植被生长缓慢且破坏后难于恢复,湿地中伴随着水的大量流失和进而引发的湿地功能的的丧失对若尔盖及附近地区乃至全球生态环境的形成与演变产生重大影响。应对若尔盖湿地自然生态环境进行保护。严禁挖沟排水和过度无序旅游,乃是保护土壤,稳定若尔盖湿地高原生态环境的重要措施。只有这样,保护土壤生态系统才有依托,才有物质基础。     

落叶松树皮厚度变化规律的研究

以黑龙江省带岭林业局大青川林场84株人工落叶松解析木数据为例,研究胸径处树皮厚度（BT）与胸径（D）、树高（H）、树冠宽度（CD）、冠长率（CR）、冠长（CL）和相对高度（RH）的关系。用多元逐步回归的方法建立落叶松人工林树皮厚度模型。结果表明,人工落叶松树皮厚度最优模型为BT=0.4221＋0.0583D-0.046H。模型检验（F=32.46,P〈0.0001）及拟合统计量（R2=0.5155,RMSE=0.1507）都表明该模型较好的描述落叶松树皮厚度的变化。这对于合理的经营和管理落叶松人工林具有重要的理论和实际指导意义。     

冀北山地华北落叶松人工林与天然次生油松林不同坡位生长状况研究

在冀北木兰围场自然保护区内,通过对比华北落叶松[Larixgmellini（Rupr．）Rupr]人工林与天然次生油松（P／nustabulaeformiscarr）林不同坡位的连年生长量与平均生长量,建立生长过程曲线方程并拟合树高与胸径之间的关系,分析两种林型内乔木树种的生长过程。结果表明：（1）落叶松人工林不同坡位样地内,标准木的拟合生长模型基本相似;材积连年及平均生长速率排序为：坡底落叶松〉坡中落叶松〉坡顶落叶松。（2）天然次生油松林不同坡位样地内材积平均生长量均随着年龄的增长而增加,油松标准木的生长过程基本相同,且标准木的拟合生长模型基本相似。但坡中油松立木材积平均生长量高于坡地和坡顶。（3）相同坡位样地内人工林与天然林间的连年生长曲线存在明显差异性。油松林生理年龄高于落叶松林,标准木达到材积数量成熟的年龄比落叶松大,单株立木材积量较大。（4）人工落叶松林和天然油松次生林内乔木树种的胸径与树高问存在密切的相关性,其相关系数均达到0．9以上。     

长江上游柏木人工林分生物量研究

应用生物量的结构特征指标、生长分析法研究分析柏木林生物量结构的合理性，研究结果表明：柏木人工林合理生物量结构指标：NMR=0．88，BNI=0．24，CRR=5．6，F／C=0．14；林分净生产量△W与叶面积指数NAI关系密切（相关系数（0．85），同净生产率NfR关系较小（r=0．06）因此影响林分生物量主要是叶量大小，而不是叶的机能（净生产率NfR）；叶的净初级生产力最高，其次为干材和枝量，40-50年枯落物年平均达到7．04t／hm^2。立地条件较好的柏木林在40-50年达10t／hm^2以上。灌木层年净初级生产力达0．13t／hm^2，草本层0．44t／hm^2。     

密云山区油松树轮δ~(13)C对气温和降水量变化的响应

【目的】探究北京市密云山区油松树轮δ~(13)C对气温和降水量变化的响应,重建1947—2014年密云山区气候资料,以期为揭示该地区的气候变化规律提供依据。【方法】测定密云山区红门川流域油松树轮δ~(13)C值,建立1947—2014年的树轮δ~(13)C序列,并剔除序列值中受大气CO_2碳同位素值影响产生的下降趋势,之后获得油松树轮δ~(13)C去趋势序列(DS),然后结合当地气象站资料分析油松树轮δ~(13)C值对降水和气温变化的响应,构建δ~(13)C与降水和气温的关系方程,进而重建1947—2014年的降水和气温资料。【结果】1947—2014年,密云山区油松树轮δ~(13)C呈下降趋势,其中,1995—2014年波动较大,剔除大气CO_2背景值的DS序列呈现二次曲线的走势,拐点出现在1980年附近;油松树轮δ~(13)C值DS序列与7月平均气温等极显著正相关(r=0.719 7,P0.01),利用回归方法重建1947—2014年密云山区7月份平均气温,平均值为25.67℃,重建曲线显示该地区气温呈先下降后上升趋势;油松树轮δ~(13)C值DS序列与夏季降水量极显著负相关(r=-0.696 7,P0.01),利用回归方法重建了1947—2014年密云山区夏季降水量,平均值为450.3 mm,自1980年以后,降水量年际变化出现较大波动,并且下降趋势明显。【结论】油松树轮δ~(13)C对7月份气温和夏季降水量响应极为显著;1947—2014年密云山区气候变化呈现波动性变暖变干趋势。     

北京市道路绿地对PM2.5浓度分布与消减作用的影响

摘要：选择北京市典型道路绿地类型为试验监测点,对0,6,16,26,36iTI不同绿带宽度下PM2。浓度分布、消减能力及与气象因子的关系进行了研究。结果表明：道路绿地空气中P№。浓度的日变化均呈现双峰单谷型特征,即早晚高、白天低,最低值出现在午后14：00左右,最高值出现在晚高峰20：00左右;0,6,16,26,36m绿带宽度下PM25浓度平均值分别为46．64,44．35,42．91,40．96μg．m-3和41．97μg．m-3,以26m绿带宽度最低,0m最高;无污染或轻度污染（P№s〈115μg·m-3）天气条件下,绿地对PM2.5消减作用十分明显,26m的绿带处消减作用最强,最高可达28．0％;中度污染及以A（PM2.5〉115μg·m-3）天气条件下绿地对P№s消减作用不明显;PM2.5浓度与气象因子中的温度、风速成负相关关系,与相对湿度成正相关关系。     

银杏叶聚戊烯醇对荷瘤鼠生命延长率的研究

以银杏叶为原料，采用皂化反应、溶剂冷冻和Ⅱ级分子蒸馏分离聚戊烯醇不皂化物，精制银杏叶聚戊烯醇（GP），纯度87．3％。通过建立人脑瘤SF763、人肺腺瘤A549和艾氏腹水瘤Ec移植小鼠模型，GP口服给药，研究GP对人脑瘤SF763裸鼠和艾氏腹水瘤Ec小鼠的生命延长率，观察GP对人肺腺瘤A549裸鼠的抑瘤率。结果表明：生药剂量320mg／kgGP联合2mg／kg阿霉素（ADM），其生命延长率为88％（P〈0．01），GP能明显延长荷人脑瘤SF763裸鼠生命；GP在大于40mg／kg时对人肺腺瘤A549裸鼠具有明显的抑制作用（P〈0．05），最佳剂量为GP80mg／kg，接种时间11d，抑瘤率为82．2％（P〈0．01）；GP对艾氏腹水瘤EC小鼠的生存期呈现负量效关系，GP最佳剂量范围在5-10mg／kg，最高生命延长率为32．77％（P〈0．05）。     

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。     

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.     

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.     

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.