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The oldest fossil remains of spruce are described under the name , and originate in the upper Cretaceous epoch. Additional fossil specimens of spruce occur in the sediments of the Tertiary ( in Paleogenian Baltic amber), and particularly the later Neogene, spanning the Miocene and Pliocene. The fossil evidence indicates a widespread occurrence of spruce taxa with epistomatic needles beginning in the lower Oligocene in the northern hemisphere. Contemporary species of possessing this needle type () belong to Tertiary relics in the Mediterranean and sub-Mediterranean mountain regions of Eurasia (Mai 1995). However, species with amphistomatic needles (including ) also adapted to changing climatic conditions (continentalization and climate cooling) and consequently occupied large geographic areas during the Quaternary.

The morphology of Norway spruce is linked to its systematics, genetics, and ecology. The species is highly variable and polymorphic, in large part owing to its widespread natural range that extends from the northern parts of Scandinavia and Siberia to southern Europe (see Chapter 4). This natural phenotypic variation is exhibited in crown form, twigs, cones, and bark and depends on environmental and genetic factors.

The genus spruce ( A. .) belongs to the family , which includes other key taxa of conifers such as pine, fir, and larch. The family is divided into the following three subfamilies: , which includes the genus only; , with the genera , and ; and , including the genera , and others. The absence of dwarf shoots is characteristic of the subfamily in which the needles are arranged only on long shoots. In contrast, in the subfamily , needles occur only on dwarf shoots except for the juvenile primary needles of the seedlings. The subfamily exhibits needles on both long and dwarf shoots.

The geographic range of the genus A. . is restricted to the northern hemisphere. Taxa of this genus occur between 71°N latitude in North America and Eurasia to 32°N in North America and 23°N in Southeast Asia (Fig. 4.1). The range is divided into two parts and is considered a classical example of a euroasiatic-North American intercontinental disjunction. Large portions of the range of the genus are occupied by . in Asia, (L.) . in Europe, and () and (.) . in North America. As a rule, the northern species cover extensive areas and form forests, whereas the southern taxa generally have restricted distributions in the mountains and many are relicts.

The determination of the geographic range of in central Europe and the origin of a spruceless belt between the mountains of central Europe and northeastern Europe has served as an intriguing puzzle for a number of investigators. Additionally, a natural disjunction in the species range in the western Carpathians has been discussed previously. The problems concerning both disjunctions have been summarized by (1967a, b) and the seminal study of (1977). The aim of the present work is to summarize the prior findings and include literature evidence from paleobotany, biogeography, as well as genetic and morphological evidence to understand the present geographic distribution of Norway spruce in central Europe.

The description of bud development presented here is based primarily on the findings of and (1995) and related studies. The embryonic shoots of vegetative and reproductive buds are visibly easy to differentiate in winter. With the aid of a microscope, it is possible to differentiate between bud types some months earlier. For example, in Poland the differentiation of the bud type takes place sometime in June (unpublished data; Fig. 6.1).

Plant growth and development are regulated by phytohormones or growth regulators, low-molecular weight compounds present in cells in relatively low concentrations, acting in tissues remote from the place of their synthesis. Plant hormones may be divided into five basic groups: auxins, gibberellins, cytokinins, abscisic acid, and ethylene. Recently, polyamines and brassinosteroids have also been recognized as growth regulators. Of the many studies of plant hormones, studies of forest trees and particularly the conifers, constitute only a small fraction of the published works. With regard to papers dealing with coniferous trees, most of the studies on hormonal regulation of growth and development have been conducted on Scots pine (). This review examines the role of plant hormones in regulating growth and development of Norway spruce [ (L.) .] and evaluates the current state of research in this field.

Initiation of the first reproductive organs (also termed strobili or flowers) is commonly considered the end of the juvenile phase and the onset of reproductive maturity in forest trees (Wareing 1959; Giertych 1976c; Poethig 1990). The evidence to date suggests that this phase change is correlated with some minimum number of growth cycles and/or minimum tree height or size (see and 1997). Consequently, (1968) proposed two ways of shortening the juvenile phase in under controlled conditions: (1) if the deciding factor is the number of completed growth cycles, it would be possible to accelerate a phase change by shortening the individual growth cycles; (2) if the deciding factor is determined by tree size, then an accelerated change in phase could be achieved by artificial stimulation of growth in phytotron conditions.

Provenance experiments are used to identify natural genetic variation. Provenance experiments consist of samples of various populations grown in a common environment. The oldest designed provenance experiment with Norway spruce dates from 1938. At that time the International Union of Forest Research Organizations (IUFRO) organized a series of trials in several countries, using seed collected from 36 sources in various parts of the species range. In 1939 another series was started with 14 seed sources; however, this series included only a small number of co-operators, owing to the onset of World War II. In 1964 IUFRO began the next series of experiments, collecting seed from 1100 origins, representing the entire geographic range of the species. In 1972 a series of trials was established in several countries with seeds originating from Polish seed stands and later obtained IUFRO status. All remaining trials with Norway spruce scattered throughout Europe were organized on a national basis, even though some of them also included several foreign provenances.

Plants come into contact with the soil environment through the rhizosphere, a complex interface between the root surface and soil. Specialized rhizosphere fungi colonize plant roots and form symbiotic structures termed ‘mycorrhiza’. In the mycorrhizal symbiosis, the root and fungus together constitute a mutualism that controls the metabolism of both plant and fungus. There are different types of mycorrhiza, distinguished primarily by the morphology of the contact zone between the partners. The roots of many important forest trees such as spruce, pine, fir, and larch naturally form obligate fungal associations termed ectomycorrhiza (ECM). In this type of interaction, hyphae extending from a mycelial layer cover the surface of fine roots (called the mantle or sheath) and penetrate between root cells and form characteristic structures (called the net) in the cortex. When not in contact with the mycelium, the root systems of many ectomycorrhizal tree species, but particularly those of pine and spruce, while functional, perform poorly in terms of total length growth, branching pattern, and ability to exploit the soil in which they develop. It is likely that these tree species co-evolved with their fungal partners and in so doing developed the strategy whereby carbon is allocated to fungal rather than root structures to facilitate nutrient absorption.