Current issue: 55(2)
There has not been complete agreement as to what is meant by ectendotrophic mycorrhizae, and there is a wide variety of opinion among authors on mycorrhizal terminology. In this paper ectendotrophic mycorrhizae are defined to be short roots with Hartig net and intracellular hyphae in the cortex. A mantle and digestion of intracellular hyphae may be found but are not necessary. In the study of Mikola (1965) ectendotrophic mycorrhiza was found to be common in Scots pine (Pinus sylvestris L.) seedlings in Finnish nurseries. The mycorrhizae had always similar structure and the mycelium isolated from the seedlings (E-strains) was similar. The aim of this study was to find out what kind of ectendotrophic mycorrhizae exist in forests and nurseries outside Finland, what kind of mycorrhizae do the E-strains isolated from Scots pine form with other tree species, and are these associations symbiotic.
Only one type of ectendotrophic mycorrhiza was found on the 600 short roots collected from the continents of Europa and America. The type was similar to the one described by Mikola: the mycelium is coarse and forms a strong Hartig net, and intracellular infection is heavy. Evidence is convincing that this structure was formed by the same fungus species. The species is unidentified. Mycorrhizae synthesized by E-strain with six spruce species, fir, hemloch and Douglas fir were all ectotrophic.
The E-type ectendotrophic mycorrhizae proved to be a balanced symbiosis. The seedlings of 13 tree species inoculated with the E-strain grew in the experiment better than the controls. The observation that ectendotrophic mycorrhizae dominates in the nurseries but is seldom found in forests, and then only in seedlings growing in the forest, was confirmed in the study. In synthesis experiments E-strain formed either ecto- or ectendotrophic mycorrhiza depending on the tree species.
Forestry has developed at an extremely rapid pace in the United States during the past eight years. This has created job opportunities for foresters educated in the schools of forestry. From 1946 to 1953 American schools of forestry graduated 9,719 foresters.
The schools of forestry are gradually being emancipated from the control by colleges of agriculture and mechanical art. Professional demands are growing at a rapid pace, and the schools are expanding their programs to meet these changes. Faculties have responded to these new needs by adding new courses and curriculums. Colleges can perform their task best through improving the faculty and organizing courses in which the student becomes an active learner rather than a passive recipient of information.
The Silva Fennica issue 61 was published in honour of professor Eino Saari‘s 60th birthday.
The purpose of the analysis presented in the article was to form an estimate as to future Finnish-American trade in forest products. The Finnish-American trade, that had its beginning in 1919, has been steadily growing and at the outbreak of the Second World War occupied third place in Finland’s total foreign trade. Over 90% of the Finnish exports consisted of forest industry products, pulp and newsprint being the most important items. The sales associations of the pulp and paper industries made it possible for the industries to gain a footing in the American market.
The production of pulp and most kinds of paper has increased in the USA up to 1942, but production of newsprint has tended to decrease. The timber resources of the country are large, but there is a considerable timber deficit in the northeastern states, therefore, these regions must be the principal aim for a campaign to build up the future market. According to the survey of future need of imports to the USA, more than two million tons of pulp and 2-3 million tons of paper products are needed in the immediate post-war period. The Canadian and Swedish competition will remain at about the same level, but one Finnish advantage, the quality, has disappeared on account of the progress made by research in the USA during the war.
The PDF includes a summary in Finnish.
This article is a book review on a book ’Lodgepole pine in North America’ by Peter Koch, which is based partly on a synthesis of more than 6,000 papers on lodgepole pine, and partly on a systematic collection and analysis of wood and bark from branches, stems, stumps, and roots, as well as of foliage, of lodgepole pines.
In this paper, different approaches and results concerning forest tax design are reviewed. In particular, comparisons are made between Scandinavian approaches, which rely on the two-period model, and North American approaches, which largely rely on the Faustmann model. Existing work is critically evaluated according to several stylized facts that are common among forest taxation problems. These include the second-best forest policy environment, joint production of public and private forest goods, the dynamic nature of forest capital, public and private ownership, competition between forest and non-forest sectors, and global policy constraints on taxation design. The gaps in addressing stylized facts are used to motivate new research directions. Problems and appropriate public finance literature are identified for investigating forest tax policy under government budget constraints, fiscal federalism, dynamic forest tax design, open economy forest tax policy, and econometric studies of reform. One conclusion reached from discussing future research is that two period and dynamic models will continue to prove useful in analysing taxation design from the government's perspective.
In a silviculture experiment in east-central Maine, USA, natural regeneration was sampled to measure the effects of: (1) a range of partial harvest intensities, and (2) repeated partial harvest at one intensity. Under the first objective, five treatments were compared with residual basal areas ranging from 15 to 24 m2 ha-1 for trees ≥1.3 cm diameter at breast height. For the second objective, regeneration was evaluated after four harvests at 5-year intervals. Prior to harvests, the overstory of all the treated stands was dominated by Tsuga canadensis (L.) Carr., Picea spp. A Dietr., and Abies balsamea (L.) Mill. Eleven species or species groups were identified among the regeneration: A. balsamea, T. canadensis, Picea spp., Thuja occidentalis L., Pinus spp. L., Betula papyrifera Marsh., Acer rubrum L., Betula populifolia Marsh., Populus spp. L., Fagus grandifolia Ehrh. and Prunus serotina Ehrh. Regeneration abundance was measured as counts of seedlings or sprouts taller than 15 cm but with diameters less than 1.3 cm at breast height (1.37 m). Regardless of harvest treatment, total regeneration was profuse, ranging from over 25,000 to nearly 80,000 trees ha-1. Regeneration was dominated by conifers with a total angiosperm component of 10 to 52 percent approximately 5 years after harvest and 11 to 33 percent after 10 years. Consequently, in forests of similar species composition, tree regeneration following partial harvests should be sufficiently abundant with an array of species to meet a variety of future management objectives.
There is no doubt that tree survival, growth, and reproduction in North America's boreal forests would be directly influenced by the projected changes in climate if they occur. The indirect effects of climate change may be of even greater importance, however, because of their potential for altering the intensity, frequency, and perhaps even the very nature of the disturbance regimes which drive boreal forest dynamics. Insect defoliator populations are one of the dominating disturbance factors in North America's boreal forests and during outbreaks trees are often killed over vast forest areas. If the predicted shifts in climate occur, the damage patterns caused by insects may be considerably changed, particularly those of insects whose temporal and spatial distributions are singularly dependent on climatic factors. The ensuing uncertainties directly affect depletion forecasts, pest hazard rating procedures, and long-term planning for pest control requirements. Because the potential for wildfire often increases in stands after insect attack, uncertainties in future insect damage patterns also lead to uncertainties in fire regimes. In addition, because the rates of processes key to biogeochemical and nutrient recycling are influenced by insect damage, potential changes in damage patterns can indirectly affect ecosystem resilience and the sustainability of the multiple uses of the forest resource.
In this paper, a mechanistic perspective is developed based on available information describing how defoliating forest insects might respond to climate warming. Because of its prevalence and long history of study, the spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is used for illustrative purposes in developing this perspective. The scenarios that follow outline the potential importance of threshold behaviour, historical conditions, phenological relationships, infrequent but extreme weather, complex feedbacks, and natural selection. The urgency of such considerations is emphasized by reference to research suggesting that climate warming may already be influencing some insect lifecycles.
Foreign tree species have been planted in Finland since 1900s, the most famous being Larix sibirica plantations in Raivola in Karelia, which now belongs to Soviet Union. One of the largest larch plantations of Finland today is situated in Tuomarniemi, in Central Finland. Ten larch stands were established in Tuomarniemi between 1912 and 1937 mainly by planting. The stand established in 1937 was sown. The trees represent five larch species: Larix sibirica Ledeb. (5 stands), Larix gmelinii var. kurilensis (2 stands, current name probably Larix gmelinii var. gmelinii), Larix americana Michx. (1 stand, now Larix laricina), Larix decidua Mill. (1 stand) and Larix occidentalis Nutt. (1 stand). The total area of the larch stands is 82.5 ha. This paper reports the studies made in the plantations in 1958.
In Tuomarniemi larch grows well in many types of soil from Vaccinium type sites to fresh mineral soil sites. The age of the stands varies from 19 to 48, height from 12 to 24 metres and annual growth from 5 to 12 m3/ha. Larix sibirca has the best stem form of the species, followed by L. gmelinii var. kuriliensis. Easiest to split is the straight-grained L. gmelinii var. kuriliensis. L. sibirica is almost as easy to process. The wood of L. decidua, on the other hand, is often spiral-grained and tough. The trees are seldom infected with decay fungi.
The PDF includes a summary in German.
This paper is a report of the authors visits to over 80 forestry nurseries in 20 countries mostly in the tropics or subtropics. The article aim is to describe the methods used in the various countries and compares them to the conventional methods of cool and temperate countries. The article introduces nurseries of Africa south of the Sahara, Mediterranean area, Australian and New Zealand and Latin America.
A complete revolution has taken place in the Finnish nursery practice, which used to raise the seedlings in natural field soil in open-air nurseries. The seedlings were usually transplanted into transplant beds at the age of two years. Now the use of plastic greenhouses of light construction and an artificial soil substrate (fertilized peat) are essential. The new technique has some similarities to the practises of the tropical and subtropical nurseries. In Finland cultivation in greenhouses has hastened the development of the seedlings and shortened the nursery rotation from four to two years, and provided better control of watering and fertilization.
Peat beds in greenhouses are used also in Swaziland. The advantage of peat is that it is free of weed seeds, which eliminates weeding. Peat substrate gives also better yield of seedlings, which decreases the need of seeds, which is important in Finland. Another technique common with tropical silviculture is the production of potted seedlings, which are easy to handle and transport. In tropics, peat pots (jiffy pots) have made it possible to grow plantable seedlings in one season without transplanting. The present Finnish technique means a decreased degree of mechanization compared to the conventional technique of modern European and American nurseries.
The article is a lecture given by A.K. Cajander in the International Congress of Plant Science. The lecture describes results of Finnish forest research that might be regarded significant also for North America. Because of similarities in nature and forest management, forest research may use similar methods in both areas.
For instance, line plot survey in the form used in Finland could well be applied in North America. In Finland, lines were drawn at 26 kilometer intervals. Visual estimates about, for instance, species, tree growth and productivity class, were made along the lines and sample plots were taken every other kilometer. To gain full advantage of the method, a productivity classification and yield tables are needed. When these are known, it is possible to find out how to increase the productivity of forests with suitable tree species and proper forest management. This kind of inventory of forest resources and the state of forests provides reliable information for forest policy. Another important issue for forest research is forest management, which requires understanding on their biology. At the same time, research must provide methods for practical forestry.
A summary in Finnish is included in the PDF.