天然松阔混交林林分改造试验

通过研究天然马尾松与阔叶树混交林改造,结果表明：将以天然马尾松为主的天然松阔混交林,改造为以天然阔叶树为主的天然阔松混交林,改造小区林分密度大幅提高57．2％,蓄积量超过对照林分,混交比例由6松：4阔,改为8阔：2松;改造小区林分总持水量比对照小区大4．3％;改造小区0—20cm土层有机质、全N、全K、水解N、速效P、速效K分别比对照小区增加31．6％、28．9％、32．O％、10．7％、33．2％和25．6％;其林分生长、林分持水量、土壤肥力均得到改善,可有效提高林分质量。     

不同密度管理措施对杉木林分的生长、生态效应的研究

通过定位观测，对不同密度杉木林的树高、胸径与材积生长规律、林分结构、林木分化和材质的差异；并对不同方式间伐后林分的生长变化，以及不同间伐强度对林地土壤肥力、林下植被种类和数量的影响及其经济效果进行了研究。结果表明：林分密度和间伐强度对杉木树高生长无显著影响，而胸径和单株材积则随着林木株数的增加而减小；林下植被种类、数量和土壤肥力均随着间伐强度的加大而有所增加；中度间伐强度的生长、生态和经济等综合效果最佳。     

马尾松生态公益林可持续经营研究

通过对马尾松生态公益林间伐后套种香樟的经济效益、林木生长状况、土壤结构、土壤水分养分等方面进行对比分析,结果表明,马尾松间伐的木材收入能够维持改造混交林进行绿化苗木培育所需的费用,混交林中香樟生长良好,同时明显促进了马尾松的生长。混交后形成的异龄混交复层林分土壤物理性质状况明显改善,林分结构更趋合理,防护功能明显增强。     

沙地樟子松人工林结构调整及更新改造技术措施

结合章古台沙区特点 ,对樟子松固沙林更新改造划分为 5种林分模式 :(1)抚育间伐林分 ;(2 )疏林草地林分 ;(3)绿伞林 ;(4)带块状皆伐 ;(5 )母树林和种子园。更新改造方法有 5种 :(1)彰武小钻杨用材林 ;(2 )樟、油、赤、班克松、彰武松针针混交林 ;(3)五角枫、暴马丁香、新疆杨、锦鸡儿景观林 ;(4)樟子松、胡枝子、怀槐等带状乔灌混交林 ;(5 )樟、油、赤、云杉、糖槭、柞树等不规则针阔混交林。文中对更新改造技术措施也提出了相应的具体方法     

人工针阔混交林的综合评价

通过对红松、落叶松分别与紫椴混交的林型进行综合评价研究,结果表明：宽带状混交的林分生长表现优于窄带状混交的林分,混交林生物量大于纯林,针阔混交林综合效益明显;混交林物种丰富度的种类、数量都远远高于纯林;混交林中物种多样性复杂,土壤营养含量丰富,能加快枯落叶的分解速度,提高土壤肥力,改善土壤结构,加速营养元素的释放量。     

马尾松杜仲混交林的调查分析

对马尾松杜仲混交林的系统调查结果表明,混交林中28年生马尾松平均胸径高于对照纯林10.6%,近两年平均生长量提高7.1%;林分蓄积量增加25.5%;乔木层生物量为112.57吨/公顷,与纯松林接近,但其生产结构显著优于纯林,具有良好的叶和根系的空间配置;改善了林内小气候;增加了林地有机质含量,促进了土壤理化性质的改良,提高了土壤肥力和蓄水保水能力;增强了林分对病虫害的自我抑制能力。马尾松杜仲混交是一种很有前途的针阔混交林。     

千岛湖马尾松次生林林相改造技术研究

千岛湖国家森林公园林地中约有3／4(2万hm^2)为马尾松次生林，森林景观单一，生态功能脆弱。1996年5--7月在小金山林区进行了砍松留阔间伐试验，经过6a多的观察，马尾松纯林已逐步向针阔混交林过渡，且有向原始常绿阔叶林演替的趋势。     

贵州黎平典型马尾松混交林的林分空间结构研究

探究贵州省黎平县典型马尾松混交林的林分空间结构特征，为该地区混交林经营及改造提供理论依据。以黎平县马尾松混交林中的马尾松为研究对象，根据混交树种及混交比例将研究区典型马尾松混交林划分为7种林分类型，分别是马尾松占40%(类型A)、50%(类型B)、70%(类型C)的与多种阔叶混交的针阔混交林，马尾松占30%(类型D)、50%(类型E)、70%(类型F)的与杉木混交的针叶混交林以及马尾松纯林(类型G),采用角尺度、胸径大小比数、树高大小比数、混交度和空间结构综合评价指标，对其空间结构进行分析。结果表明，在研究区中：1)7种林分类型中，马尾松均为轻度聚集分布状态，趋向于随机分布格局；2)类型F中，马尾松的树高、胸径处于中庸状态，其余类型中，马尾松的树高、胸径均处于亚优势状态；3)马尾松混交林的树种混交程度较高，通常在中度混交强度以上，而马尾松纯林处于弱度混交，接近于零度混交；4)林分综合评价排序为类型A>类型D>类型E>类型B>类型F>类型C>类型G;5)典型马尾松混交林中，马尾松的角尺度、胸径大小比数、树高大小比数之间无明显差异性，其空间结构的差异主要...     

章古台沙地樟子松人工林经营问题的思考

文章总结现有文献，结合生产实践提出利用樟子松林分的自然力、发展多树种造林等方法营建樟子松混交林，以促进林分的稳定性；提出通过提高林地土壤肥力、调整林分结构和密度的方法实现樟子松林地生产力的提高，延长樟子松的防护周期；建议大力推广东宁赤松、彰武松、班克松。     

杉阔混交林地土壤肥力研究综述

营造杉阔混交林是改良杉木林地土壤肥力，提高林地生产力和林分稳定性的重要途径。综述了我国营造杉阔混交林对土壤物理性质、土壤微生物、酶活性、土壤养分循环、土壤养分贮量和供应状况的影响，提出了该领域今后的研究设想。     

Mountain pine beetle scarring of lodgepole pine in south-central Oregon

Three forest disturbance periods, 1973—present, 1922–1929, and 1827–1946 were determined by aging scars on stems of lodgepole pine trees. All of the scars from the 1970's and 1920's, and most of the scars from the 1820's–40's were determined to be caused by the mountain pine beetle. A few scars from the earliest period may be the result of fire. Diagnostic characteristics of beetle scars are: resemblance to fire scars, pitch tubes, beetle emergence holes, blue stain, beetle galleries, retained bark on the scar face, and an orange or red discoloration around healthy sapwood. Beetle attacks tend to have a northeastern aspect and extend approximately two-thirds around tree boles at breast height.By recognizing beetle scars it is possible to accurately age previous mountain pine beetle attacks. Many scars which had been thought to be of fire origin are actually caused by the mountain pine beetle.     

Quantifying the effect of pine mistletoe on the growth of Scots pine

Mistletoe infection results in substantial growth losses in mistletoe‐infected forests. This study reports and evaluates the results of retrospective analyses of radial growth of Scots pine (Pinus sylvestris) in relation to the level of infection of pine mistletoe (Viscum album ssp. austriacum). A total of 43 Scots pine trees were destructively sampled from different sites. Of these trees, 14 were uninfected and 29 were infected. Infection classes were determined using six‐class dwarf mistletoe rating system (DMRS). All needle and mistletoe biomass were removed completely and weighed for each sampled tree. Subsamples from needles and all mistletoe biomass were taken to the laboratory for oven‐dried weight determinations. Five‐cm‐thick wood discs were cut from the stem at the breast height (1.3 m) to determine annual basal area increment for the last 25 years. In addition to DMRS, new infection classes were created using mistletoe‐to‐needle biomass (MB/NB) ratio. The results showed that the radial growth losses could be as much as 41% to 64% at different infection levels. The rate of growth loss in relation to DMRS and MB/NB ratio was similar, but with a larger variability in DMRS values. The results showed that both DMRS rating and MB/NB ratio seem to be important for quantifying growth loss on Scots pine trees infected with mistletoe. The results of this study can also be invaluable in modelling the effects of mistletoe on the growth of Scots pine trees.     

Perpetuating old ponderosa pine

We review current knowledge about the use of management treatments to reduce human-induced threats to old ponderosa pine (Pinus ponderosa) trees. We address the following questions: Are fire-induced damage and mortality greater in old than younger trees? Can management treatments ameliorate the detrimental effects of fire, competition-induced stress, and drought on old trees? Can management increase resistance of old trees to bark beetles? We offer the following recommendations for the use of thinning and burning treatments in old-growth ponderosa pine forests. Treatments should be focused on high-value stands where fire exclusion has increased fuels and competition and where detrimental effects of disturbance during harvesting can be minimized. Fuels should be reduced in the vicinity of old trees prior to prescribed burns to reduce fire intensity, as old trees are often more prone to dying after burning than younger trees. Raking the forest floor beneath old trees prior to burning may not only reduce damage from smoldering combustion under certain conditions but also increase fine-root mortality. Thinning of neighboring trees often increases water and carbon uptake of old trees within 1 year of treatment, and increases radial growth within several years to two decades after treatment. However, stimulation of growth of old trees by thinning can be negated by severe drought. Evidence from young trees suggests that management treatments that cause large increases in carbon allocation to radial xylem growth also increase carbon allocation to constitutive resin defenses against bark beetle attacks, but evidence for old trees is scarce. Prescribed, low-intensity burning may attract bark beetles and increase mortality of old trees from beetle attacks despite a stimulation of bole resin production.     

INFLUENCE OF FIRE ON KOREAN PINE AND SCOTS PINE TREES IN PLANTATION

The plantations of korean pine(Pinus koraensis)and scots pine(Pinus sylvesrisvar.mongolica)are mainly pure stands.Fires are gradually causing problems in theseplantations and being paid much more attention recently.Study on the influence of fire ontrees and the adaptation to fire,therefore,is of great important to probe the fire ecologicalproperties and the protection ways of these two species.The results are as follows:Bothof the species are easily damaged by fire,but korean pine is more susceptible.In the samefire,korean pine is damaged more seriously than scots pine although they have the samesize.Young individuals have low fire resistant capacity and can be damaged seriously,andolder ones have strong fire resistance and can be damaged lightly.Up-hill fire makes aserious damage to the trees distributed in up-slopes with the reason of higher fireintensity.Down-hill fire makes a serious damage to the trees distributed in down-slopcswith the reason of higher fire severity.The larger deocambium area in t     

Loblolly pine and slash pine responses to acute aluminum and acid exposures

In response to concerns about aluminum and HCl exposure associated with rocket motor testing and launches, survival and growth of full-sib families of loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) were evaluated in a nursery bed experiment. Each species was exposed to a single soil application of aluminum chloride (0.33 M AlCl(3), pH 2.5), hydrochloric acid (0.39 M HCl, pH 0.6) or water, with or without mycorrhizal inoculation with Pisolithus tinctorius (Coker and Couch). After 20 weeks without inoculation, survival in AlCl(3) and HCl treatments averaged 52% for loblolly pine and 72% for slash pine. Inoculation improved survival of loblolly pine, receiving HCl from 49 to 73%, and of those receiving AlCl3, from 55 to 90%. Inoculation also resulted in improved survival and growth of individual families in AlCl(3), but not in HCl treatments. Results illustrate the relative resistance of both pine species to the acute treatments supplied, the improvement in resistance associated with mycorrhizal inoculation and the importance of field testing, following hydroponic screening, to verify the resistance to soil-supplied stresses.     

Proactive intervention to sustain high-elevation pine ecosystems threatened by white pine blister rust

Only recently have efforts begun to address how management might prepare currently healthy forests to affect the outcome of invasion by established non-native pests. Cronartium ribicola, the fungus that causes the disease white pine blister rust (WPBR), is among the introductions into North America where containment and eradication have failed; the disease continues to spread. Ecosystem function is impaired by high rust-caused mortality in mature five-needle white pine forests. This paper evaluates five proactive management options to mitigate the development of impacts caused by white pine blister rust in threatened remote high-elevation five-needle pine ecosystems of western North America. They are: reducing pest populations; managing forest composition; improving host vigor; introducing resistant stock with artificial regeneration; and diversifying age class structure to affect the natural selection process for resistance. Proactive intervention to manage and facilitate evolutionary change in the host species may sustain host populations and ecosystem function during pathogen naturalization.     

A comparison of needle retention on Japanese black pine and Japanese red pine

Needle retention (number of needle sets), needle density, height increment and radial increment were surveyed on seven Japanese black pines (Pinus thunbergii Parl.) and seven Japanese red pines (Pinus densiflora Sieb. et Zucc.) growing on the same site. Number of needle sets on branches with respect to whorl position was estimated visually. In 1999, maximum summer needle retention was observed on the fifth and sixth whorl from the top, with values of 3.4 needle sets for the black pines and 2.4 needle sets for the red pines, respectively. The needle trace method (NTM) was used to determine needle retention and needle density along the main stems retrospectively for the years 1968–1998. The long-term mean summer needle retention along the main stem was 3.7 needle sets for the black pines and 2.2 needle sets for the red pines. In both pine species, the number of needle sets varied from year to year. However, the long-term budget between newly born and annually shed needle sets was in equilibrium. The long-term average of needle density per cm of stem shoot was 9.4 needle pairs for the black pines and 7.4 needle pairs for the red pines. The results showed clear intra-specific and inter-specific similarities in needle retention, height increment and radial increment trends. The values for number of needle sets, height increment and radial increment positively increased with favorable growing conditions, whereas the value of needle density had an opposite tendency.     

Effect of damaged pine needles on growth and development of pine caterpillar larvae

Chinese pine caterpillar (Dendrolimus tabulaeformis) larvae were fed with pine needles of different degrees of damage to evaluate the effects of pine needles on the growth and development of larvae. The results showed that the nutritional index of the larvae declines after feeding on the damaged pine needlings. The lowest amount of food ingested and voided feces, the lowest nutritional index, slowest development, lightest pupae and most mortality were found in those pine caterpillar larvae fed with pine needles which were 50% damaged. The damaged pine needles significantly affected the population dynamics of Chinese pine caterpillars. The nutritional indices of larvae fed with 25% and 75% damaged pine needles were similar. The nutritional index of the dark morphs was higher than that of the tinted morphs, however, their mortality was lower than that of the tinted morphs. This phenomenon was reversed at the later stage of development when the larvae were fed on 50% damaged pine needles. __________ Translated from Journal of Beijing Forestry University, 2005, 27(6): 83–88 [译自: 北京林业大学学报, 2005, 27(6): 83–88]     

Effects of mechanized pine straw raking on population densities of longleaf pine seedlings

Longleaf pine communities occupy a small fraction of their original extent in the southeastern United States and are in great need of restoration and conservation management. Recent anthropogenic disturbances, such as pine straw raking, may interfere with seedling survival and, hence, restoration efforts. We examined the effects of mechanized straw raking on longleaf pine (Pinus palustris Mill.) seedlings (pre-grass stage, or <3-yr-old) in natural, fire-maintained plant communities in Croatan National Forest, North Carolina, by testing the effects of number of rakings (0–4 times during a 2-yr period (1992–1994)) and community type (pine-turkey oak, dry savanna, and mesic savanna) on seedling densities in 1-m² quadrats. Despite initial differences in densities of seedlings among communities, analyses of variance did not detect significant differences among communities as averaged over time and raking treatment. Both raked and unraked quadrats exhibited declines in seedling density during the study, but the declines were greater for raked quadrats. After 2 yr, initial densities were, on average, reduced by 34% in unraked quadrats and by 47%, 63%, 78%, and 77% in quadrats raked one, two, three, and four times, respectively. In quadrats raked four times, censuses performed after each raking indicated significant declines in densities in response to all but the first raking. Raking either injures pine seedlings directly and/or modifies microsite conditions in ways unfavorable for seedling survival. Having established a link between raking and mortality, we now recommend additional work to reveal the causal mechanisms. Land management decisions should accommodate the potential adverse effects of mechanized raking on pine regeneration.     

Aluminum sensitivity of loblolly pine and slash pine seedlings grown in solution culture

To probe variation in Al sensitivity of two co-occurring pine species, seedlings from six full-sib families of loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) were grown in solution culture containing 4.4 mM (high-Al) or 0.01 mM (low-Al) AlCl(3) at pH 4 for 58 days. On average, both pine species had 41% less total dry weight in the high-Al treatment than in the low-Al treatment. Stem volume growth of slash pine was more sensitive to the high-Al treatment than that of loblolly pine. In both species, the high-Al treatment inhibited root dry weight more than shoot dry weight. Within-species variation in Al sensitivity among families was greater in loblolly pine (24 to 52% inhibition of seedling dry weight) than in slash pine (35 to 47% inhibition of seedling dry weight). Foliar Al concentration was positively correlated with Al sensitivity in slash pine but not in loblolly pine; however, in both species, the concentration of Al in roots was 20-fold greater than in foliage.