云南永平县森林资源动态分析及发展建议

利用永平县1990年森林资源调查报告和2006的森林资源规划设计调查资料,对森林资源动态变化情况进行了论述和分析：林业用地面积减少;有林地面积增加;林分面积增加;无林地面积减少;森林蓄积量减少;森林覆盖率增加;消耗量小于生长量。对永平县森林资源特点及今后发展方向作了论述。     

楚雄州森林资源动态分析及发展方向

利用楚雄州1993年和2000年森林资源连续清查资料，对森林资源动态变化情况进行了论述和分析：林业用地面积增加；有林地面积增加；林分面积增加；无林地面积减少；森林蓄积量增加；森林覆盖率增加；消耗量小于生长量。对楚雄州森林资源特点及今后发展方向作了论述。     

孟连县森林资源动态分析

孟连县1985年与1999年两次森林资源二类调查结果,其森林资源变化趋势是林业用地减少31936.6hm2(包括退耕地13201.1hm2),其中有林地增加41969.6hm2,疏林地减少3783.9hm2,灌木林地减少22271.0hm2,未成林造林地增加864.6hm2,苗圃地减少11.6hm2,无林地减少48704.3hm2;活立木蓄积量增加39170m3,平均每公顷蓄积量减少36.9m3.年均生长量211810m3,年均消耗量188720m3,生长量略大于消耗量.     

丽江地区林业发展战略

一、林区现状我区是云南省重点林区之一,根据一九八四年森林资源消长情况测算,现有林业用地面积有2314.58万亩,占全区土地面积的77.5％在现有林业用地面积中有林地面积为830.68万亩,占林业用地面积的35.9％,森林覆盖率27.3％。现有活立木蓄积量为6391.31万立方米,其中有林地蓄积量为5003.13万立方米,立木年总生长量为113。06万立方米,而消耗量     

牛达林场森林资源结构变化分析及经营对策

牛达林场建立并经营管理森林资源３０余年,其森林资源呈现逆向转化,资源结构发生了变化：经营面积减少,林业用地在向非林业用地转移或流失;蓄积量减少,消耗量大于生长量;林地利用率上升,林地生产力下降,林分质量变差;幼,中龄林上升,成熟林大量减少,     

恩施州森林资源动态变化分析

为合理地评价和经营恩施州森林资源,依据1985,1994,1999和2006年4次森林资源调查资料,并结合20年来恩施州林业生态建设的重大活动情况,从森林面积、蓄积量、组成结构、质量等角度对森林资源动态变化进行分析。经过20年来的努力,恩施州森林面积、蓄积量和覆盖率有了很大的提高,全州现有林业用地面积160.20万hm2,其中森林面积113.41万hm2,活立木蓄积量5 000.13万m3,森林覆盖率67.02%,有林地面积年均增长率为3.11%,无林地面积年均净减率为4.61%,防护林、特用林、经济林面积年均净增率分别为38.55%、20.88%、2.91%,用材林面积年均净减率为1.21%,森林资源结构得到改善,质量有所提高。最后揭示资源变化的原因与内在联系,提出资源管理与发展方向,为制定林业的可持续发展方针提供科学决策依据。     

梅州市森林资源动态变化及其保护探讨

将广东省梅州市林地分为有林地、灌木林地、疏林地、其它林地（未成林地和无林地）,利用Arc—GIS9．1软件,根据3期林地分布现状数据制成3幅梅州市林地分布图。利用梅州市1985～2005年（约5年为间隔）森林资源统计资料,对森林资源动态变化情况进行了分析和论述：林业用地面积减少389．1×10^3hm^2,有林地面积减少194．9×10^3hm^2,森林覆盖率下降了8．6％,无林地面积减少533．9×10^3hm^2,森林蓄积量增加2031．6×10^3hm^2,消耗量小于生长量。对梅州市森林资源特点作了论述：森林蓄积量偏低,但潜力大;分布不均匀,东、北部林地面积较多,其余较少;林种结构较合理,分类经营改革见成效;近熟、中、幼龄林面积比重较大,等等。力求寻找其动态变化的原因,并思考如何保护其平衡发展。     

我们是怎样执行限额采伐量的

<正> 一、森林资源基本情况吉林省永吉县是个半山区,面积为515.152公顷,林业用地面积为254.531公顷,有林地面积为182.054公顷,森林覆盖率36.6%;活立木总蓄积量1044.7万m~3,林分蓄积量967.6万m~3,年生长率5%;森林资源按权属国有林林业用地占49.5%,蓄积量68.2%,集体所有林业用地占50.5%,蓄积量占     

咸安区森林资源动态变化及分析评价

经调查统计,结果表明:咸安区国土总面积150745.33 hm~2,林业用地面积88340.71 hm~2,非林业用地面积62404.62 hm~2,活立木总蓄积量292.33万m~3,森林覆盖率43.71%。与2009年相比,林地面积增加8277.31 hm~2,乔木林蓄积量增加106.22万m~3,森林覆盖率上升1.71%。经过对咸安区森林资源动态变化分析,全区林地面积逐步增加、森林覆盖率上升、森林质量有待提升。提出了进一步利用信息化技术,完善林地规划、加强管理、提升林地保护和利用效率的建议。     

完善责任山的经营管理体制 落实森林采伐限额金额管理

<正> 我县是广东省重点林业基地县之一,全县土地总面积21.5万公顷,其中林业用地面积16.9万公顷,占78.6%;有林地面积14.7万公顷,占林业用地面积的87%。森林覆盖率69.03%,活立木总蓄积量960万立方米,年森林资源总生长量55.7万立方米。全县总人     

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.