纸桨材人工林复合轮伐

造纸工业的发展,促进了木材利用结构的变化,很多速生树种如:桉树、相思、马尾松、湿地松;火炬松等,都是很好的造纸原料树种,轮伐期一般5年、7年、10年或15年,周期短,效益好。但按照现行纸浆材轮伐期,林木将在很小年龄就被砍伐,而此时林木材积正处于速生期,砍伐无疑是对生产力的浪费。一个新经营概念——纸浆材人工林复合轮伐期,是现存问题的一个良好的解决方法。     

人工林纸浆材复合轮伐技术及效益分析

人工林纸浆材复合轮伐是一个林业经营新概念，适用于我省除平原湖区和高寒山区外的广大地区。本文就如何搞好纸浆材主要树种马尾松、国外松等的规划实施和经营管理，发展这一复合轮伐技术提出了一些见解。并以马尾松为例，对实施复合轮伐技术的人工林纸浆材的产量进行了计算分析。     

世界及部分国家、地区薪炭材的产量和消耗情况

超短轮伐期工业人工林是随着木材加工工业的发展而崛起的一种速生丰产林。目前,许多国家对超短轮伐期工业人工林的造林方式及其生物量的利用进行着广泛而深入的研究。超短轮伐期人工林经营对木材短缺国家的作用尤为重大,除了能在短期内生产纸浆材、减少木材进口外,还     

广西桉树人工林延长轮伐期效益分析及可行性策略

延长桉树人工林轮伐期,培育中大径材林,不仅契合国家储备林的培育理念,也能提升桉树经济、社会和生态效益,促进桉树人工林健康可持续发展。文中阐述广西桉树人工林的培育现状,分析了延长桉树人工林轮伐期的经济、生态和社会效益。在此基础上,提出延长轮伐期的可行性策略:1)金融机构强化桉树人工林认知,适当延长涉林贷款期限;2)林业主管部门澄清桉树种植诸多误解,加大延长轮伐期宣传工作;3)相关国企、国有林场率先延长轮伐期,作好桉树科学经营示范。研究可为推动广西桉树人工林延长轮伐期、加大中大径材林培育力度提供参考。     

江西省杉木人工林合理轮伐期的研究

根据江西省高丘陵区、山区和南岭山地3个杉木栽培区的生长特点,不同立地不同培育目标有不同的成熟龄,而当立地条件和培育目标相同时,3个栽培区的成熟龄差异不磊,可以按统一的轮伐期经营。12指数级培育小径材为主的轮伐期为18～22年,14指数级培育小径材轮伐期为16～20年,16指数级培育中径材轮伐期为20～24年,18指数级培育中径材轮伐期为14～18年,18指数级培育大径材轮伐期为24～28年,20指数级培育大径材轮伐期为22～26年。     

长白落叶松工业人工林复合轮伐收获量及风险分析

以长白落叶松工业人工林为对象,在综合分析数量成熟、工艺成熟和经济成熟得出基本轮伐期的基础上,借鉴纸浆材人工林复合轮伐期的概念,确定出2种复合轮伐模式的技术要点.比较2种复合轮伐模式与相对应基本轮伐模式的木材收获量及经济收获量,并进行风险分析.结果表明:复合轮伐模式1比2次基本轮伐得到的经济材和商品材分别多28.287 2 m3·hm-2(10.34%)和28.173 4 m3·hm-2(10.04%),经济收获量多4906.67元·hm-2(4.50%);复合轮伐模式2比2次基本轮伐得到的经济材和商品材分别多20.916 7 m3·hm-2(7.36%)和20.763 5 m3·hm-2(7.61%),经济收获量多739.56元·hm-2(0.63%);复合轮伐的风险与银行利率、优势木保留比例、木材价格有关.在银行年利率为r,优势木保留比例为10%,基本轮伐模式的经济材价格和复合轮伐采伐90%树木的经济材价格为χ,保留10%树木的经济材价格为γ,情况下,复合轮伐模式1中γ＞0.335 6[1 (1 r)18]χ、复合轮伐模式2中γ＞0.367 3[1 (1 r)21]χ时,复合轮伐模式的经济收获量才会大于基本轮伐模式的经济收获量.     

湿地松人工林间伐效果初步研究*

对湿地松人工林抚育间伐研究表明：在立地指数为１４条件下１５年生湿地松短轮伐期纸浆材的最佳经营密度为１８００～１６５０株／ｈｍ２；建筑材最佳经营密度为１３５０～１２００株／ｈｍ２，１５年生后，应立即进行第二次间伐。     

江河滩地优质大径杨木培育关键技术研究

大径材的缺乏 ,已严重制约了我国胶合板等相关工业的持续发展 ,如何利用我国东南沿海丰富的江河滩地资源营建大面积杨树优质大径材基地 ?作者通过近 10a的研究 ,就充分利用江河荒滩等劣质土地培育优质大径杨木 ,在进行产业化培育过程中对新无性系引选、主要立地制约因子、密度与林分工艺成熟年限、边行“优势配置式”造林、复合轮伐期经营、节痕控制技术、合理轮伐期确定及配套优化栽培模式等技术关键进行研究总结 ,为大面积营造杨树优质大径材基地提供了科学依据     

长白落叶松纸浆材人工林定向培育技术的研究

以定向、速生、丰产、优质、高效为目标,研究了长白落叶松纸浆材人工林不同种源、苗木和立地条件对生长的影响,同时通过对长白落叶松数量成熟龄、工艺成熟龄和经济成熟龄的研究分析,确定了长白落叶松纸浆材轮伐期。     

关于落叶松人工林短轮伐期经营的思考

通过对落叶松人工林短轮伐期经营与实践,提出了进行落叶松人工林短轮伐期经营的必要性,并阐述了进行短轮伐期经营的技术要点。     

Effect of resin‐top disease caused by Peridermium pini on the volume and value of Pinus sylvestris saw timber and pulpwood

The role of the resin‐top disease caused by Peridermium pini in volume and value losses to Scots pine (Pinus sylvestris L.) was surveyed in two heavily infected stands in northern Finland. Of the Scots pines, 26% were infected by the disease. Peridermium pini caused 2% volume losses to saw timber trees and 3% volume losses to pulpwood trees in the stem‐lesion class and 10% and 14% in the dead‐top class, respectively. The disease caused saw timber volume losses to saw timber trees of 34% and 22% in the stem‐lesion and dead‐top class, respectively. However, saw timber volume losses increased the pulpwood volume in both disease classes. The disease reduced the marketing value of saw timber trees and pulpwood trees by 18% and 3% in the stem‐lesion class and by 15% and 14% in the dead‐top class.     

Optimal Rotation Age of Larix kaempferi Pulpwood Plantation by Real Options Approach

The differentiation process including somatic embryogenesis in different Ginkgo explants in vitro culture were studied by cytological observation.The results are as follows:1) two complete cotyledons and a embryo bud were observed in mature embryos and several secretory acavitives appeared in maturation region of embryo buds,hypocotyls,cotyledons and radicles after culturing 20 days;two incomplete cotyledons and a embryo bud primordia were found in large cotyledon embryos.The proembryo of two cells,four cells, multi-cellular,and globular embroy were developed from the callus of the small cotyledon embryos.2) The differentiation of cotyledon explants started from epidermal cells,and gradually formed meristematic cell mass in the cortical cells,and eventually adventitious buds were observed.3) The adventitious roots of Ginkgo originated in the cells at the cross of vascular cambium and vascular rays. 4) The type of rooting belongs to induction type by root primordium.The formed adventitious roots were observed after 20 days.     

华南地区桉树可持续遗传改良与育种策略

从华南地区发展桉树工业纤维用材林对高产、优质、抗逆新品种需求的迫切性出发，分析了桉树引种成功之后遗传改良现状和存在问题，提出要实现华南桉树人工林可持续经营，必须建立和完善桉树长期可持续遗传改良体系，坚持以多世代群体遗传改良为基础，种间杂交无性转化利用为突破，加快育种增益转化为生产力的育种思路；强调新世纪桉树育种要重视常规育种与分子遗传研究相衔接，通过群体、个体、细胞和分子多层次多育种方式的相互交叉，充分利用各层次的遗传变异，提高育种效率。     

Lipophilic extractives in different tree fractions and forestry assortments of Pinus sylvestris due for thinning or final cutting

The objectives were to determine the content and composition of lipophilic extractives, particularly fatty and resin acids, in three Scots pine trees from each of two stands in northern Sweden, one that was due for thinning and one due for final cutting. Extractives content of branches, needles, barks, stem discs from branch whorls, and sapwood and heartwood samples from various heights was measured. Fractions had very different concentrations and distributions of extractives due to differences in the composition of tissues. The needles had the highest total extractive concentration (around 150?kg/ton d.w.), followed by the branches, bark, timber from the final cut stand, and then the pulpwood and timber from the thinning stand. The final cut stand generally provided higher yields of extractives in assortments per hectare than the thinning stand; the difference was five-fold for timber, three-fold for whole trees, two-fold for branches, needles and bark and similar for pulpwood. This information on the content and composition of extractives in different tissues, and the dependence of these quantities on tree age could be used together with information on conventional stand data such as tree numbers and dimensions to guide the selection and management of feedstocks for biorefineries.     

Product diversification in South Africa’s commercial timber plantations: a way to mitigate investment risk

We used the portfolio method to examine how a forest company can lower investment risk by producing a mix of timber products. We derived optimum combinations of pine (Pinus patula) saw timber production and eucalypt (Eucalyptus grandis) pulpwood production at landscape level. Our results indicate that producing a product mix rather than a single product improves aggregated financial returns and lowers investment risk over multiple rotation periods. The optimum mixture depended on past timber price correlations for pulpwood and sawn timber in South Africa between 1980 and 2011. This ideal mixture is comprised of areal ratios of about 45% saw timber and 55% pulpwood. Our example shows how economic risk of a forest investment can be reduced by creating a portfolio of a number of products. The risk that an investor has to accept for each monetary unit that is expected in return can be reduced by over 40% when comparing the risk–return combinations of a pure pine saw-timber stand with that of a portfolio of forest products. The risk associated with the production can be reduced by 20% when growing a portfolio of products rather than eucalypt pulpwood only.     

杨树工业用材林培育技术研究

本文通过对培育杨树工业用材林的立地条件,栽培品种选择,合理密度及最佳轮伐期的确定,以及栽植,林分抚育管理等关键技术措施的论述,为实现定向,速生,丰产,优质,稳定和高效的培育目标,建立了辽宁省的杨树工业用材林基地,提供了可靠的技术保障。     

THE MANUFACTURE OF RAYON PULP IN SOUTH AFRICA

The utilization of plantation soils for the growing of pine pulpwood is discussed.

Different tree species make different demands on soil fertility and all tree species grown in S. Africa for commercial purposes also show a fairly wide range ofadaptability to soil fertility and site quality.

Generally plantation soils in this country have reasonable soil depth, good drainage and fair moisture supply but soil fertility levels in higher rainfall areas are often low.

Fertilization in the nursery, at planting time and at an age of 7–10 years of the stand could increase pulpwood yields by about 50 per cent.

Fertilization, cultivation thinning and other silvicultural work which promotes tree growth, all seem to have a similar influence on timber quality. Generally improved rate of growth results in higher timber yields both in total volume and total cellulose yield.

Land available for forestry purposes is limited in this country and it is of great economic and even strategic importance that this land be fully exploited.     

Models for Assessing Timber Grade Distribution and Economic Value of Standing Birch Trees

In order to obtain a more precise prediction of the distribution of each timber grade or log grade with regard to the volume of birch (Betula pendula Roth., B. pubescens Ehrh.) in models for long-term planning, ordered probit models were developed. These models were developed by using data from three mixed birch and Norway spruce stands in Norway. The data consisted of 168 stems. In Norway, three ordinary birch saw log grades are commonly used, with pulpwood as a fourth grade. In this study, these four grades were applied in addition to waste timber, which was treated as a fifth grade. The developed models showed that the grade distribution of birch trees of mixed birch and spruce stands was highly correlated with tree height (p<0.01) and height to first visible dry branch (p=0.081). The statistical significance of both models was good (p<0.0001), as measured by log likelihood test statistics. Classifying the 168 stems by saw timber or pulpwood in butt log led to greatly improved estimates (p<0.01). The developed models would allow the incorporation of timber grade in stand simulators, enabling more precise predictions regarding the economic implications of alternative management strategies for birch trees.