贵州省福泉市森林资源格局特征与组成结构

为了掌握福泉县森林资源情况,通过3S技术结合二调、贵州省森林普查数据,分析了福泉市森林资源的分布特征。研究表明:福泉市拥有森林资源面积103215.90hm2,占国土面积的60.65%;以乔木林地和特殊灌木林地为主,两者分别占森林资源总面积的52.22%和43.12%,乔木林分布比较零散,而灌木林相对连片集中;水土保持林、一般用材林和水源涵养林为福泉市主要林种,三者占了森林面积的53.90%。福泉市森林郁闭度整体上处于中等密度;福泉市森林资源类别总共有四种,分别为重点公益林、一般公益林、重点商品林、一般商品林,一般公益林为福泉市森林类别中面积最多的,在西部区域有集中连片分布,其次为一般商品林,在南、东和东南区域分布较多。此外,福泉市森林资源分布受生态建设工程的影响较大。     

大理市森林资源分布格局及其保护现状分析

基于GIS空间分析技术,分析了大理市森林资源结构及其保护现状.结果表明,大理市林地面积占国土面积的56.70％,主要由有林地和灌木林地组成,占林地面积的94.79％;森林主要由乔木林组成,占比达93.60％;林地资源分布均匀,整体上分布于洱海四周山区,龄组结构合理;林地资源保护强度较高.     

宾川县森林资源分布格局

基于GIS技术,以宾川县2019年林地“一张图”为基础,分析了宾川县林地资源结构及空间分布特征。结果表明:①宾川县林地资源丰富,但空间分布不均匀;②林地面积占国土面积的67.46%,其中有林地面积较大,占比达67.99%,其次为灌木林地,面积占比为27.04%,再次为无立木林地,面积占比为1.99%,森林面积占林地面积的79.59%,全县森林覆盖率为53.84%;③森林优势树种组成相对简单,以云南松林为主,面积占比达49.78%,其次为栎类林,面积占比为26.41%,再次为乔木经济林,面积占比为19.99%,其余优势树种面积占比较小。     

西藏森林资源现状分析

西藏是我国重点国有林区之一,生态战略地位极其重要。本文采用西藏森林资源清查数据,对西藏森林资源的现状进行分析,结果表明:西藏森林分布相对集中,森林储量巨大;林业用地以有林地和灌木林地为主,面积占97%以上;西藏森林目前形成以防护林为主、用材林和特用林为辅的林种格局,呈现薪炭林和经济林亟待发展的局面;无林地以宜林荒山荒地为主,面积占无林地89.84%,火烧迹地、宜林沙荒地面积分别占3.57%、6.59%;立木蓄积组成以森林为主;林分蓄积占立木总蓄积的98.76%。     

洱源县生态公益林结构分析

以2017年林地变更调查和2016年森林资源规划设计调查数据为基础,对洱源县生态公益林结构进行了分析。结果表明:洱源县生态公益林占林地面积的50.12%,其中省级占58.2%,国家级占31.5%,主要为有林地和灌木林地,占91.9%。林地使用权以集体为主,占60.8%。起源主要以天然林为主,占55.7%。乔木林占65.4%,灌木林占34.6%。乔木林公顷蓄积量低于全国平均水平,林地生产力偏低。灌木林树种主要为萌生栎和杜鹃。乔木树种的龄组以中龄林为主。洱源县生态公益林林种主要为水土保持林、水源涵养林和自然保护林,占98.7%。     

亚洲七国的森林资源

<正> 印度森林面积7,200万公顷,占国土面积的22%。总蓄积量35亿立方米。每公顷蓄积69立方米。从热带雨林到亚寒带林,具有多种森林,其中热带雨林占绝大多数。年采伐量约1.1亿立方米。薪炭材占94%,工业用材占6%。对薪炭材的采伐使森林遭受破坏和退化,但包括灌木林和休闲林的森林总面积在增加。     

勐海县热带林景观生态风险分析

以2005年和2015年森林资源二类调查空间数据库为主要信息源,对云南省西双版纳勐海县进行热带林景观生态风险研究.结果显示:勐海县各景观类型空间转移较频繁,橡胶林地、茶叶地、建设用地以流入为主,以天然林为主的其他林地、其他灌木林地以转出为主;2005—2015年景观类型生态安全度除其他灌木林、橡胶林分别降低4.38％和...     

青海高原高山灌木林植被特点及主要类型

青海高原高山灌木林分布区域主要在祁连山地、西倾山地和青南高原,是青海高山地区水源涵养林的重要组成部分,也是重要的水土保持林和高山护牧林.高山灌木林包括高寒常绿灌木林和高寒落叶阔叶灌木林,一般分布在海拔高度3000-4800m 的峡谷和陡峭山体的阴坡或局部地区的阳坡.优势灌木林类型主要有杜鹃灌木林、山生柳灌木林、金露梅灌木林、鬼箭锦鸡儿灌木林等.文中对青海高原高山灌木林植被分布、植被组成、生长特点,以及主要灌木林类型进行了较详细的分析和总结.     

永平博南山州级自然保护区森林资源现状分析

为掌握永平博南山州级自然保护区的森林资源特点及制定保护区的森林资源保护与利用规划提供依据,对保护区2019年森林资源监测数据进行了分析。结果表明:保护区林地资源丰富,林地面积占国土面积的100%,森林覆盖率高达95.85%;林地以有林地为主,面积占95.85%;森林起源以天然为主,面积占比为92.17%,人工起源占7.83%;优势树种以栎类为主,面积占比为62.18%,其次为云南松,面积占23.76%,再次为核桃,面积占5.78%;保护区的森林蓄积量主要来自栎类,达67.44%,其次为云南松,占25.09%,再次为华山松,占4.12%;森林的龄组以中龄林为主,面积占比为55.44%,其次为近熟林,面积占29.76%,中龄林和近熟林的蓄积量分别占50.65%和37.77%。     

包头市林业生态建设的实践与思考

包头市国土面积较大,且地形地貌特点鲜明。全市2.8万平方公里的地域,以达茂旗为主的荒漠化草原占到53%;以固阳县为主的低山丘陵占22%;以土右旗、九原区为主的大青山山区面积占14%;以土右旗、九原区为主的平原地区占11%。包头市的草场沙化退化严重,全市的森林覆盖率只有8.41%,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.