天然林保护工程存在的问题及完善对策

指出了尽管当前天然林保护工程已经取得初步成效,但是仍然存在一些问题,对天然林保护工程建设产生了极为不利的影响。从天然林保护工程取得的成效出发,分析了当前天然林保护工程建设中存在的问题,并针对这些问题提出了相应的完善对策,以期为天然林保护工程的实施提供参考。     

郴州市天然林管护工程问题及对策

随着我国林业事业的不断发展,天然林保护工程开展愈发受到人们的关注与重视。作为天然林保护的主要手段之一,森林管护开展关乎到天然林保护工程实施质量与效果,影响着我国生态环境的改善。基于此,以郴州市天然林保护工程实施现状为切入点,分析了森林管护工作尚存问题,提出了科学解决的对策来强化森林管理工作水平与效果,为天然林保护工程的高效全面落实打下良好基础。     

连续清查在天然林保护工程效益监测中的应用

天然林保护工程效益监测是天然林保护工程实施效果成效评价的重要手段,如何能科学、准确、定量地评价天然林保护工程实施效益是当前该项工程动态监测的重点与难点,本文试图通过"连清"为切入点,提出了该项工程效益动态监测新的思路与措施。     

论新干县天然林保护工程的成效、存在问题和对策

新干县自2016年全面实施天然林保护工程以来,尽管已经取得明显成效,但是仍然存在一些问题,对天然林保护工程建设产生了一些不利影响。本文从天然林保护工程取得的成效出发,分析了当前天然林保护工程建设中存在的问题,并针对这些问题提出了相应的对策,以期为天然林保护工程的有效实施提供参考。     

天然林保护与林业可持续发展浅论

指出了天然林资源是森林资源的主体,也是我国进行森林资源培育、生态环境保护和林产品生产中的主体,它对于我国社会和经济可持续发展有着重要意义。结合当前我国天然林资源的现状及天然林保护工程中存在的问题,分析了天然林保护与林业可持续发展之间的内在联系,并对如何实现我国天然林资源与林业资源的可持续发展提出了建议,希望能够为我国林业资源的可持续发展提供一定参考。     

借鉴“林分施业法” 开展天然林经营的探讨

我国天然林保护工程已经启动,许多地方的天然林已经基本上得到了有效的保护。当前急需研究的是如何进一步对已经保护起来的天然林进行科学合理的经营管理,最终达到可持续经营的目的。本文论述了日本天然林经营、研究现状,介绍了日本东京大学演习林的"林分施业法"经营技术,提出了借鉴"林分施业法"作好天然林保护工作急需研究解决的几个森林经营技术问题。     

天然林保护工程与林业分类经营的探索

根据闽北森林资源的现状与特点,论述当前闽北实施天然林保护工程为核心的林业分类经营的重要性和紧迫性,提出天然林保护工程要与公益林建设相结合,建设高效商品林基地是搞好公益林的有力保障,并对现行天然林保护工程和分类经营中存在的问题提出建议。     

小陇山林区实施天然林保护工程成效与对策探析

在全面调查林区实施天然林保护工程取得成效的基础上,以森林可持续经营理论为指导,综合运用科学分类和归纳的方法,分析了林区天然林保护工程在工程设计、实施与管理过程中存在的问题。分析得知,甘肃省小陇山林区天然林保护工程实施以来成效显著,但在工程经营管理上仍存在管理体制不顺、经营管理水平较低、思想观念落后等问题。根据实际,提出了解决天然林保护区实际问题的对策:加大科技投入,提高工程实施的科技含量;完善法律监督机制,强化天然林保护工程管理;加快发展天保工程区后续产业,提高天然林区自我发展能力。     

天然林保护工程的发展概况及建议

天然林保护工程作为重大生态修复工程之一,是生态文明建设的重要组成部分。通过对天然林保护工程的提出、发展、取得成效和存在问题方面进行概述,提出解决工程实施过程中突出问题的相关建议,以促进天然林保护工程更好的开展,从林业的角度为我国生态文明建设提供参考。     

湖北省天然林保护工程建设成效及建议

天然林是我国森林资源的重要组成部分,保护修复天然林资源,不仅关系到林业的发展与繁荣,更关系到国家战略和民族振兴。我省自2000年实施天然林保护工程以来,虽然在森林资源发展、生态环境保护等方面取得了显著成效,但同时也存在一定的问题,给新时期天然林保护修复带来了挑战。为此,本文总结了我省天然林保护工程建设成效,分析了存在的问题,并为今后一段时期天然林保护修复提出了意见与建议。 关键词：天然林保护工程;建设成效;存在问题;发展建议     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Development of Pinus sylvestris Main Stems Following Three Different Precommercial Thinning Methods in a Mixed Stand

Reducing competition by point cleaning may be an attractive alternative to conventional precommercial thinning in forestry. In this study, survival and development of main stems of Scots pine (Pinus sylvestris L.) following point cleaning were examined in a mixed stand of mainly Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Sweden. Treatments studied were: no precommercial thinning, conventional precommercial thinning, point cleaning of all secondary stems, and point cleaning of only the secondary stems that were higher than the main stem, within a radius of 0.8 m from the main stem, respectively. A randomised complete block design with three replicates was used. Measurements taken 13 growing seasons after these treatments showed that conventional precommercial thinning was the best treatment for retaining Scots pines as main stems. However, conventional precommercial thinning resulted in the poorest timber quality of the remaining Scots pines in terms of stem taper, thickest branch diameter and relative live crown height. In conclusion, point cleaning has to be followed by a complementary cleaning operation if the objective is to retain Scots pines as main stems in such mixed stands.     

Tree planting for dryland salinity control in Australia

Dryland salinity is emerging as a major form of land and water degradation in southern Australia, particularly in Western Australia, South Australia and Victoria, and to a lesser extent in New South Wales, Tasmania and Queensland.Tree planting, in combination with other vegetation treatments, is regarded as a leading solution to dryland salinity. Research has now shown that planting trees can significantly lower groundwater tables, and thereby reverse the causal process of salinisation. Substantial progress has been made towards answering the basic questions of which species to grow, how to plant, where to plant, at what density and configuration to plant, and how much area to plant. The economic potential for commercial tree planting has given impetus to partial reforestation in higher rainfall (> 600 mm yr^–1) areas. Even so, serious constraints are apparent, relating primarily to cost, uncertainty and attitude. The future should bring increasing community input and control, technical refinement and gradual adoption, provided all aspects of the issue are well researched, relevant information is well communicated and programmes are well administered. Some specific requirements for future research are identified in this review.     

Effect of Cuttings on the Scenic Beauty of a Tree Stand

The opinions of 207 respondents on the visual effects of seven different cutting types were asked using a nine-point verbal scale ranging from ''worsens very much'' to ''improves very much''. Other estimates were obtained by letting the same respondents evaluate photographs of stands which had been treated with different cuttings. The direct questions gave results quite similar to the evaluations of photographs for all but young respondents, indicating that most respondents were able to imagine the effect of the treatment correctly. The results based on the evaluation of photographs indicated that the effect of regenerative cuttings is negative while the impact of thinnings is positive. After a few years of cutting the stand is already regarded as clearly more pleasant than immediately after the cutting. Natural regeneration with seed trees seems to be a way to avoid the very negative immediate impact of clear-felling, especially in the case of Scots pine. Women, young, urban people and those who do not own forest or have work related to forests tended to experience thinnings less positively and saw regenerative cuttings as more harmful than the other test groups did.     

Pinus contorta growth in northern Sweden as affected by soil scarification

The aim of this study was to quantify the effects of different soil scarification methods on tree growth. Soil scarification influenced stem volume and stem biomass yield of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) in a 17-year-old field trial in boreal Sweden. Soil scarification (disc trenching, mounding and ploughing) resulted in an average stem volume yield of 3.1 and 34.2 m³ ha^–1 on the poor and intermediate sites, respectively, while corresponding values for no soil scarification were 0.9 and 16.7 m³ ha^–1. In comparison to no scarification, ploughing increased volume yields by 500% on the poor site and by 200% on the intermediate sites. The ranking according to stem volume yield was ploughing > disc trenching = mounding no soil scarification. Averaged over the two sites, the mean annual increment of stem biomass was 219% and 145% higher (in d.w., 0.26 kg and 0.34 kg per sample tree) after ploughing compared with no soil scarification, for the average and dominant sample trees, respectively. Although not significant, the increased growth rate after soil scarification decreased the average stem basic wood density of the sample trees with 1.6% and 5.3%, at the poor and intermediate sites, respectively. In conclusion, soil scarification significantly increased the 17-year stem volume yield compared with no scarification. The results also indicate that the difference in stem biomass yield between ploughing and the other methods, especially no soil scarification, will increase even more in the near future.