燕山北部华北落叶松人工林与杨桦天然次生林土壤碳密度的比较

为了了解人工造林过程对土壤碳储量的影响,对燕山西部山地常见的华北落叶松人工林和杨桦天然次生林土壤有机碳含量进行了研究。结果表明,华北落叶松人工林和杨桦天然次生林的土壤剖面平均有机碳含量分别为30.45g/kg和28.45g/kg,二者没有明显差异;2种林分的土壤有机碳含量均随着土层深度的增加而降低,下降幅度则随深度的增加逐渐减缓,表层土壤对土壤的碳存储贡献更大。总的来看,土壤有机碳含量在深层(30cm以下)相邻土层之间差异不显著,说明深层土壤中,有机碳含量变化较小。由以上结果可以得出结论,在造林措施适当、人为干扰较少的条件下,人工林同样可以维持与天然林相近的较高的土壤碳储量。     

北亚热带土地利用变化对土壤有机碳垂直分布特征及储量的影响

利用野外调查的方法,研究了北亚热带地区土地利用变化对土壤有机碳的垂直分布特征及储量的影响.研究结果表明:(1)除茶园土壤外,不同林分土壤有机碳含量均以0～10cm土层最大,随着土层深度的增加,含量总体表现为下降的趋势;茶园土壤有机碳含量在0～30cm土层范围内增加,30cm以后表现下降的趋势;(2)次生林转变成农耕地以后土壤有机碳含量平均下降21.1%,而转变成集约经营早竹林后,土壤有机碳含量平均下降近48.5%;1m深度以内,土壤有机碳平均含量由高到低的顺序为:茶园、灌木林、次生林、粗放经营毛竹林、集约经营毛竹林、马尾松林、农耕地、杉木林和早竹林;(3)土壤有机碳储量随土层深度变化的趋势和土壤有机碳含量变化趋势基本一致;次生林转变成长期经营的农耕地后,土壤有机碳储量下降22.5%,而转变成长期集约经营早竹林后土壤有机碳储量则下降51.4%9种土地利用类型中,土壤有机碳储量由高到低的顺序为:茶园、灌木林、次生林、粗放经营毛竹林、马尾松林、农耕地、集约经营毛竹林、杉木林和早竹林.     

茂兰喀斯特植被主要演替群落土壤有机碳研究

摘要森林土壤有机碳是土壤有机碳库的重要组成部分,研究森林土壤有机碳对于应对气候变化具有非常重要.以茂兰自然保护区喀斯特植被3种演替换群落喀斯特乔木林、次生林和灌木林为研究对象,分析了不同演替群落的土壤有机碳含量和密度及其在土壤剖面上分布的差异,以及有机碳含量和土壤理化性状的相关性.结果表明:①3种不同演替群落在整个剖面上(0～20 cn)土壤有机碳含量和碳密度的表现均为喀斯特乔木林(81.950 8 g/kg、11.631 1 kg/m2)＞次生林(52.171 2 g/kg、10.744 7 kg/m2)＞灌木林(38.380 4 g/kg、7.411 8 kg/m2);②3种不同演替群落有机碳含量和碳密度均随着土壤深度的增加而降低;0～10cm有机碳含量为喀斯特乔木林107.259 4g/kg、次生林63.203 1 g/kg和灌木林51.226 7 g/kg,分别是其整个土壤剖面有机碳含量均值的1.31、1.21和1.33倍;土壤有机碳密度均以0～10 cm为最大,分别占整个土壤音面有机碳密度的55.11％、54.44％和63.50％,介于6.41～4.71 kg/m2之间,具有一定程度的表聚性;③3种不同演替群落的土壤有机碳含量与土壤全N、速效K和最大持水量均表现为显著或极显著正相关,与土壤密度表现为极显著负相关;不同演替群落影响其土壤有机碳含量的主导因子不同;各演替群落的土壤有机碳含量与土壤理化性状的回归方程具有很高的相关性,可以正确反映两者之间的关系.     

广西猫儿山水青冈林土壤剖面有机碳垂直分布特征及影响因素

通过分层采集水青冈林0～100 cm土壤剖面样品,测定不同土层有机碳含量,分析其垂直分布特征,并通过相关分析探讨土壤容重、总孔隙度、机械组成等物理性质及土壤pH值、速效养分等化学性质对土壤有机碳的影响。结果表明:水青冈林地不同土层土壤有机碳含量和有机碳密度变化范围分别为28.66～76.75 g/kg和5.52～10.77 kg/m2,且均表现出随土层深度的增加大致呈逐渐降低的变化趋势,其中0～20 cm土层有机碳总含量和有机碳密度最大,分别占据整个土壤剖面的33.82%和27.94%,具有明显的表聚性;水青冈林地土壤容重和总孔隙度的变化范围分别为0.71～1.05 g/cm3和54.58%～73.16%,0～20 cm土层其值与其他土层差异显著;水青冈林地各级粒径土壤颗粒含量从大到小的排列顺序为砂粒(53.51%)粉粒(29.93%)粘粒(16.56%),土壤质地为砂质壤土;水青冈林地不同土层土壤p H值的平均值为4.16,且土层之间变幅很小;速效氮、速效磷和速效钾养分平均含量分别为309.48 mg/kg、1.61 mg/kg和40.81 mg/kg,其随土层深度的变化趋势与土壤有机碳含量和有机碳密度相似;相关分析结果表明,土壤有机碳含量和有机碳密度均与p H值、粘粒(0.002 mm)呈显著负相关,与土壤总孔隙度、速效氮、速效磷和速效钾呈显著正相关;pH值、粘粒含量、总孔隙度、速效氮、速效磷、速效钾与有机碳关系密切,可以用于预测土壤有机碳的变化。     

退耕还林杉木林地土壤有机碳储量变化特征——以贵州兴义市三江口镇为例

为了解我国西南喀斯特地貌区退耕还林工程主要林分土壤碳储量变化,选取贵州省兴义市三江口镇退耕还林工程杉木林为研究对象,并以耕地为对照,对不同林龄及耕地的土壤有机碳储量进行了测定及分析。结果表明:各土层(0~20cm,20~40cm,40~60cm)土壤容重的年际变化除表层略有波动外均随林龄的增长而减少,0~60cm深度整层土壤容重随林龄增长年均减少4.27%,各层间土壤容重随土层加深而增加,不同林龄间增量各异;0~60cm深度内土壤有机碳储量在造林后5年内随林龄增长而减少,平均每年下降9.27%;5年后随林龄增长而增加,平均每年增加8.44%,但在退耕还林后11年土壤有机碳储量未能恢复到耕地水平;土壤有机碳含量及储量在垂直方向上均呈现随土层加深而减少,不同林龄间差异明显,其年际变幅也随土层加深而减少。     

海涂围垦区不同林分土壤活性有机碳垂直变化特征

[目的]探索海涂围垦区不同林分土壤有机碳和活性碳组分的垂直分布及其影响机制,为围垦区林分土壤碳库稳定性评价和树种筛选提供科学依据。[方法]以海涂围垦区3种主要林分（美洲黑杨、水杉和银杏）为研究对象,分析0～100 cm深度土壤有机碳、微生物量碳和溶解性有机碳垂直分布特征及其与土壤理化性质和酶活性的关系。[结果]3种林分土壤有机碳、微生物量碳和溶解性有机碳含量均随土层深度增加逐渐降低,其中,0～20 cm土层水杉和美洲黑杨林分土壤有机碳含量显著高于银杏林分,20 cm以下土层3种林分之间差异较小;0～60 cm土层水杉林分微生物量碳和溶解性有机碳含量最高,其次为美洲黑杨林分,银杏林分最低,60 cm以下土层3种林分之间差异较小。土壤溶解性有机碳/土壤有机碳和微生物量碳/土壤有机碳比值均随土层深度增加先增大后减小（除银杏林分土壤溶解性有机碳/土壤有机碳比值在各土层之间无显著差异外）,20～60 cm土层3种林分土壤溶解性有机碳/土壤有机碳和微生物量碳/土壤有机碳比值较高,总体上,3种林分土壤溶解性有机碳/土壤有机碳和微生物量碳/土壤有机碳比值在剖面分布差异较小。冗余分析和相关性分析表明,各...     

重度火干扰下不同恢复年限对土壤有机碳的影响

自然火干扰作为泰加林中最主要的自然干扰,是促进泰加林土壤碳循环的主要方式。为探讨火干扰对土壤有机碳的影响,以新疆喀纳斯地区重度火烧不同恢复年限的泰加林火烧迹地为研究对象,研究比较在重度火干扰下,火烧后不同恢复年限对土壤有机碳含量及碳储量的影响。结果表明:在不同恢复年限的同一土层中,只有火烧后52年的火烧迹地土壤有机碳含量与未火烧对照土壤存在显著差异(P0.05),且不同恢复年限的0~10cm土层中的土壤有机碳含量均大于10~25cm土壤中的有机碳含量;不同恢复年限的火烧迹地中土壤碳储量均与对照土壤存在显著差异(P0.05)。本研究表明重度火干扰对土壤有机碳的影响较为持久。     

科尔沁差巴嘎蒿群落土壤有机碳含量及其与土壤养分关系的研究

以科尔沁大青沟差巴嘎蒿群落的土壤为研究对象,采用挖掘法对土壤做剖面,研究了不同深度下土壤有机碳含量与土壤养分(氮、磷、钾)的分布及其相互关系。结果表明:1)在土壤深度0～60cm内,随土壤深度的增加,土壤有机碳含量整体呈下降趋势,其变化范围18.31～5.18g/kg,在0～5cm内,达到最大值为18.31g/kg;2)对土壤养分分析得知,速效钾平均含量为101.29g/kg,有效磷平均含量为2.89g/kg,碱解氮平均含量为18.77g/kg,全钾平均含量(33.60g/kg)比全磷平均含量(0.09g/kg)、全氮平均含量(0.69g/kg)都大;3)通过相关分析可知,土壤有机碳含量与速效钾含量存在极显著的相关性,土壤有机碳含量与全效钾含量不相关。     

柳杉人工林皆伐后初期土壤有机碳和微生物量碳动态

本文研究了华西雨屏区柳杉人工林皆伐后1年内土壤有机碳和微生物量碳动态。结果表明:柳杉人工林皆伐林地土壤平均有机碳含量比对照(未皆伐林地)减小2.01 gC.kg-1,但差异不显著,而土壤平均有机碳储量及微生物量碳分别比对照减少20.97 tC.hm-2、6.68 mg.kg-1(P0.05);皆伐林地土壤有机碳含量及微生物量碳均随季节的变化而逐渐降低,但有机碳储量随季节的变化无明显减少趋势;皆伐林地土壤四季的有机碳含量、碳储量和微生物量碳差异不显著。皆伐对柳杉人工林土壤有机碳储量的影响主要表现在0~20 cm土层(P0.05);皆伐林地和对照在0~40 cm土层的微生物量碳和有机碳含量都表现出显著相关性(P0.05),但对照的相关性高于皆伐林地。总之,柳杉人工林转变为采伐迹地后,其初期土壤有机碳储量和微生物量碳都明显减少。     

若尔盖高寒嵩草草甸湿地不同水分条件下土壤有机碳的垂直分布

研究若尔盖高寒嵩草草甸湿地常年积水、季节性积水(每年6-10月积水)和无积水3种水分条件下土壤有机碳的分布特征.结果表明:若尔盖高寒嵩草草甸湿地土壤有机碳含量极高,表土层(0 ～ 10 cm)最高可达73.2 g·kg-1,是中国森林、农田和草原生态系统土壤有机碳含量的6 ～10倍,且土壤有机碳的垂直分布深达400cm,远远超过中国森林、农田和草原生态系统;在浅土层(0～50 cm)和深土层(200～400 cm),不同水分条件下的高寒嵩草草甸湿地土壤有机碳含量差异显著(P＜0.05),在0 ～ 50 cm浅土层表现为常年积水区＞季节性积水区＞无积水区,在200 ～ 400 cm深土层表现为无积水区＞季节性积水区＞常年积水区,而在50 ～ 200 cm中间土层,不同水分条件下高寒嵩草草甸湿地土壤有机碳含量无显著差异(P＞0.05);在0 ～ 400 cm土层,不同水分条件下的高寒嵩草草甸湿地土壤C/N值多小于15,这有利于高寒湿地土壤碳的积累;若尔盖嵩草草甸湿地的有机碳储量极高,常年积水区、季节性积水区和无积水区在0 ～ 400 cm土层的有机碳储量分别为64.87,71.21和76.45 kt· km-2,是中国森林、农田和草原生态系统的20 ～ 40倍;约60％的土壤有机碳储量分布在l m以下土层;整个若尔盖高原地区的高寒嵩草草甸土壤总有机碳储量约为0.245 Pg.     

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.