冀北山地华北落叶松低效人工林节肢动物物种多样性研究

通过对冀北山地华北落叶松低效人工改造林的节肢动物取样调查,采得节肢动物2纲9目60科177种3985头。并初步统计分析该低效人工林的节肢动物群落组成,对人工林中5种不同处理样地进行分别取样,分析比较各样地节肢动物群落的物种组成、多样性指数、均匀度、相似性指数。结果表明：人工改造林中节肢动物多样性整体水平比未经处理的对照林略高,其中,人工促进更新的针针混交乔灌草复层结构林（样地1）的节肢动物多样性水平最高。     

华北落叶松人工林经营措施研究

为了提高该林区各国营林场经营落叶松林的水平，促使其早成材、成好材，对落叶松中幼林进行了为期5年的综合试验研究，结果表明：落叶松生长到10－15年时的最佳经营密度应在1800－1950株／hm^2之间，适当施肥可以提高落叶松幼林胸径和树高的生长量。     

华北落叶松人工林经营密度的研究

华北落叶松Larix principis-rupprechtii人工林的经营密度,多用冠幅与胸径的相关关系确定。我们从1973年开始就试图用固定标准地复查实测的方法研究人工林的经营密度,并与用冠幅与胸径的相关关系编制的落叶松人工林经营密度表(承德地区林业     

浅谈阳城县营造华北落叶松人工林技术

华北落叶松(以下简称落叶松)是一种寿命长、材质好、用途广泛、效益较高的优良树种，它在海拔高度1800m、坡向阴坡上表现良好，生长茂盛，位于阳城县境内的横河林场已成规模发展，但多数未郁闭成林。根据阳城县20多年来人工造林的经验，现提出发展及经营人工落叶松林的个人观点．供参考。     

低质低效次生林改造技术的研究

通过建立 10hm2 低改试验林 ,提出了低质低效次生林的改造技术和 5种改造模式 ,并从林分生物量、材积生长量和涵养水源、水土保持等方面进行了改造技术效果分析     

华北落叶松人工林林价初探

本文研究了河北省北部地区国有林落叶松人工林林价.在立地分类的基础上,对落叶松人工林生长过程进行了分析,确定落叶松人工林最优采伐年龄为18～22a,根据造林和管理等营林成本计算,不同立地质量(11和13地位指数)的每立方米林价为68.22～84.25元,比育林基金多23.22～39.25元.     

华北落叶松人工林根系生物量的研究

在华北落叶松人工林中设置标准地，分别按径阶选定样木，测定根粗大于１ｃｍ的根系生物量，同时用土柱法测定根粗小于１ｃｍ的根系生物量。结果表明，根系生物量占总生物量的１８．２％－３０．８％，概系生物量与林木径阶的变化有极显著的相关性，根粗小于１ｃｍ的根系生物量集中分布于０－２０ｃｍ的土层中。     

谈南岔林业局低质低效林改造项目

通过对低质低效林改造经营,探索黑龙江省南岔林业局森林经营的新模式,以促进森林资源管理工作不断发展。     

华北落叶松人工林改建母树林的营建技术研究

在成县为了解决华北落叶松Ｌａｒｉｘｐｒｉｎｃｉｐｌｓ－ｒｕｐｐｒｅｃｈｔｉｉＭａｙｒ生产种子的问题，我们采用华北落叶松人工林改建母树林的试验途径，在本县赵坝林场对１０６．２亩人工林进行了改建母树林的试验研究。经过８年的综合培育，改造的母树林在果率、结实率、产种量和种子品质等各项指标都比对照林分有显著提高，生产的种子用于育苗造林表现优良，达到了预期目的。     

EVALUATION OF SITE QUALITY FOR DAHURIAN LARCH FORESTS

INTRODUCTIONSitequalityisoneofthemostimpor-tantfactorsinfluencingtheproductivityofforeststands.Eva1uatingsitequalityisba-sictostudystandgrowthanddeviseman-agementtreatments.Basisofsitequalityissoil,whichhasacontrollinginfluenceontheforestproductivity-Soilpropertieschangeslowlyovertime,andsoilindexcanbeappliedincutover,deforested,andnonforestedareasinadditiontoareaswheretimberstandsarepresent.Underundisturbed,naturalconditions,somein-dicatorplantscomprisingthelesservegeta-tionmaybeassociat…     

A STUDY ON ENERGY OF ARTIFICIAL DAHURIAN LARCH COMMUNITY

By means of calorimetry measurement,the caloric values of various components,the standing crop of energy,not energy production and energy conversing efficiency of an artifi-cial dahurian larch community at Laoshan Plantation Experimental Station of Maoer Shan For-est Farm in the eastern part of northeast China were determined and studied in the present paper.The result of the experiment were as follows:(1)caloric value varied with plant species and plant organs,in general,the order of caloric value was tree,shrub and herb,and for different organs,was leaf, branch,trunk(stem),bark and root.(2)The standing crop of energy of larch community and tree layer were 269.719×10~(10)J/ha.and 264.440×10~10J/ha.respectively.Theree xisted different distributions of energy in various components and different layers.(3)Net ener-gy prduction of larch community and its tree layer were 264.346×10~8J/ha.a and 243.678×10~8J/ha.a respectively.To the photosythetical active radiation on the stand,its energy con-versing eff     

Age distribution patterns in open boreal Dahurican larch forests of Central Siberia

Tree age distribution determines stand size structure and is related to disturbance history and stand dynamics. Data are presented from 40 pure larch stands from six locations on the Taimyr peninsula and Evenk region in the northern open forests of Russian Siberia. A Weibull density function was used to describe actual age distribution and to simulate age distribution. Larch age distributions have similar patterns in different locations over the study area. All stands were found to have a multi-aged structure. The average coefficient of variation for age is about 48%. The range of tree ages exceed 400 years in the oldest forests. The patterns of age distribution change for different age groups. For the youngest stands (40–80 years old) the age distribution was leptokurtic and positively skewed, whereas for middle-aged forests (80–180 years old) it tended to be more mesokurtic and symmetric. In the oldest stands (more than 180 years old) the distribution had a platykurtic form. A high correlation was found between the Weibull function coefficients and the coefficient of age variation and for the mean age. The oldest forests were found in river valleys. Middle-aged forests occur more commonly on middle slopes and the youngest forests occupy top slopes and uplands. A more normal tree age distribution assumes a study area less damaged by forest fires than in the more southern parts of the boreal forest.     

毛竹残次林复壮技术试验

对毛竹残次林采取劈山、松土垦复、施肥抚育和合理采伐等技术措施进行复壮试验，每公顷增加毛竹609根，折价扣除复壮成本每公顷可净增加收入5317元，取得显著的经济效益、生态效益和社会效益。     

红松在落叶松林下天然更新及诱导混交林的研究

红松在落叶松林下更新能够将其诱导形成红松针阔混交林。文章在落叶松林内阔叶树组成、红松更新情况、林下灌木和草本状况调查基础上,就如何将其诱导为红松混交林进行了论述,就相关问题进行了讨论。     

Recovery of understory vegetation biomass and biodiversity in burned larch boreal forests in Northeastern China

Recovery of biomass and biodiversity of forest understory vegetation after fire disturbance has been widely studied; however, how this relationship changes and what are the determinants at different post-fire stages in larch boreal forests are still unclear. We investigated a chronosequence of 81 understory plots in larch boreal forests that were disturbed by fires in 1987 (S5), 1992 (S4), 1996 (S3), 2002 (S2), or 2007 (S1). Analysis of variance was conducted to test the differences of biodiversity and biomass among various post-fire stages. Different regression models were used to fit the relationship between biomass and biodiversity, while factors influencing this relationship were identified by boosted regression tree analysis. Results showed that total understory biomass increased from 2.51?t?ha^?1 in S1 to 8.47?t?ha^?1 in S3 and declined to 5?t?ha^?1 in S5. Similar dynamics were also found between species richness and species diversity. Positive linear correlations linked biomass and biodiversity throughout most of the post-fire periods. Slope and stand density were the two most important factors influencing the secondary succession of understory vegetation after fire. Geographical factors and overstory competition determine the orientation of vegetation recovery, and the impacts of climate on vegetation are muted after fire disturbances.     

核桃低产林改造技术

发展核桃是广元山区人民群众脱贫致富的一条重要途径,虽然经过多年努力,数量上去了,但质量和产量仍在低水平徘徊。其原因多种多样,但管理粗放,病虫害严重是主要原因,本文就此问题展开讨论。     

Productivity and growth efficiency in sugar maple forests

Sugar maple (Acer saccharum Marsh.)-dominated northern hardwood forests were examined at four locations along an acid deposition and climatic gradient in the Great Lakes region of the USA. The study sites were matched in terms of physiography, soils, stand history, and vegetative characteristics. Measurements of basal area and biomass growth were made for the 1988–1991 growing seasons. There were no significant differences in either basal area of biomass increment among the four sites over the 4 year period. There was a great deal of year-to-year variability with relative basal area growth rates ranging from as low as 0.2% to as high as 2.4% on a single site in successive years. Growth efficiency measures reflected this variability with as much as an 800% difference between successive years on a single site. When coupled with year-to-year variability of up to 34% in leaf area related to heavy seed years and defoliation, this indicates that growth efficiency and leaf area measures are not consistent indicators of aboveground productivity for tolerant deciduous species, especially if derived from short-term measurements or temporary plots.     

Changes in soil P chemistry as affected by conversion of natural secondary forests to larch plantations

To assess the impact of conversion of native forests to monocultural larch plantations on soil chemical properties, we compared the total and various fractions of soil phosphorus (P) and acid phosphatase activity (APA) between natural secondary forests (NSF) and Larix olgensis plantations (LOP) on a montane forest site in eastern Liaoning Province, Northeast China. We found that the concentrations of total P (TP), inorganic P, and iron-bound P (Fe-P) were significantly higher, and the concentrations of microbial biomass P (MBP), sodium bicarbonate-extractable organic P (NaHCO₃-Po), and APA were significantly lower, in the LOP stands than in the NSF stands; whilst organic P, sodium bicarbonate-extractable inorganic P (NaHCO₃-Pi), aluminum-bound P (Al-P) and calcium-bound P (Ca-P) were comparable between the two forest types. Our study also showed that the ratios of MBP/TP, NaHCO₃-Pi/TP, NaHCO₃-Po/TP, and APA significantly varied with time during the growing season. Moreover, the concentrations of NaHCO₃-Pi, NaHCO₃-Po, and MBP had significant (P < 0.01) and positive linear relationships with APA. Overall, results from this study suggest that conversion of native forests to larch plantations in the region is more likely to cause compositional change in soil P than to result in reduction in overall P availability.     

Intensified forestry as a climate mitigation measure alters surface water quality in low intensity managed forests

ABSTRACT

Climate change has led to a focus on forest management techniques to increase carbon (C) sequestration as a mitigation measure. Fertilisation and increased removal of biomass have been proposed. But these and other forest practices may have undesirable effects on surface water quality. In naturally acid-sensitive areas such as much of Fennoscandia a concern is acidification due to acid deposition in combination with forest practices that increase the removal of base cations and leaching of nitrate (NO₃). Here we apply the biogeochemical model MAGIC to the coniferous-forested catchment at Birkenes, southernmost Norway, to simulate the effects of forest fertilisation and harvest on soil and streamwater. The model was calibrated to the 40-year data for water quality, soil and vegetation and then used to simulate fertilisation and clearcutting of the mature forest by either conventional stem-only harvest (SOH) or whole-tree harvest (WTH). The 5 – 10-year pulse of NO₃ following clearcut was larger with SOH than WTH. WTH causes larger acidification of surface water relative to SOH, due to greater depletion of base cations, N and C from the soil. The use of forestry as a climate mitigation measure should take into consideration the potential effects on soil and surface water quality.