Past forests of Europe

European forests have varied in their composition, structure, and extent over the last 5 million years or more in response to global climate changes. European forests have also undergone very major changes due to the alternating glacial-interglacial cycles of the Quaternary (last 2.6 million years). European forests have greatly changed in their extent and structure in the last 5 000 years due to human activities (the Homo sapiens phase) in the current Holocene interglacial in which we live. Contemporary ecologists and foresters can learn from ‘lessons from the past’ about forest responses and resilience to environmental changes in the past.

Abies – Circum-Mediterranean firs in Europe: distribution, habitat, usage and threats

Most European firs occur predominantly in small to medium-sized populations in the Mediterranean region, sometimes with fragmented and limited distributions, except for silver fir (Abies alba). They all are genetically closely related and can easily hybridise, perhaps as a consequence of late speciation during the late Quaternary. Circum-Mediterranean firs occur principally in mountain areas with medium to high precipitations rates which are mostly concentrated during the winter period. The species are able to tolerate long droughts in summer and tend to form pure stands when in optimal habitats. In the past firs have been extensively logged for construction and fire wood and their stands were replaced by other more disturbance adapted species or converted into rural areas. Nowadays with the exception of silver fir and Caucasian fir (Abies nordmanniana), circum-Mediterranean firs do not have a wide commercial interest. In Turkey they are still exploited for timber wood, while other firs have an ornamental use in gardening. Great importance is given to their preservation, especially to those populations which have very limited areas and specimens, with the creation of protected reserves and conservation programmes. Wild fires, livestock grazing and genetic drift represent actually their main threats.

Betula pendula, Betula pubescens and other birches in Europe: distribution, habitat, usage and threats

Silver birch (Betula pendula Roth) and downy birch (Betula pubescens Ehrh.) are short-lived, relatively small broadleaved trees that occur throughout most of Europe, particularly in northern regions. In southern Europe, birch trees are confined to mountainous areas, as they do not tolerate prolonged summer drought. Birch has a light canopy of small serrated leaves, and characteristic smooth, white to grey bark. In northern regions, birch trees can dominate the landscape up to the tree-line, whereas in the centre of their range they often occur early in secondary succession because of their abundant seed production, low demands on soil quality, and intolerance of shade. Birch trees provide the predominant hard wood source in northern Europe, and some varieties of Betula pendula produce highly priced veneers, while Betula pubescens is mostly used for pulp and fire wood. Other rarer species of birch are endemic to Europe contributing to the continental biodiversity even at high elevations and latitudes.

Castanea sativa in Europe: distribution, habitat, usage and threats

The sweet chestnut (Castanea sativa Mill.) is the only native species of the genus in Europe. The broad diffusion and active management by man resulted in the establishment of the species at the limits of its potential ecological range, which makes it difficult to trace its original natural area. The present distribution ranges from North-Western Africa (e.g. Morocco) to North-Western Europe (southern England, Belgium) and from south-western Asia (e.g. Turkey) to Eastern Europe (e.g. Romania), the Caucasus (Georgia, Armenia) and the Caspian Sea. In Europe the main chestnut forests are concentrated in a few countries such as Italy, France and the Iberian Peninsula. The sweet chestnut has a remarkable multipurpose character, and may be managed for timber production (coppice and high forest) as well as for fruit production (traditional orchards), including a broad range of secondary products and ecosystem services.

Fraxinus excelsior in Europe: distribution, habitat, usage and threats

Common ash (Fraxinus excelsior L.) is a medium-sized deciduous tree with large compound leaves that develop relatively late in spring. It flowers before leaf-buds burst and trees can carry male, female, or hermaphrodite flowers, or different combinations of the flower types. It grows throughout the European temperate zone, but is absent from the driest Mediterranean areas because it does not tolerate extended summer drought, and from the northern boreal regions, with its seedlings in particular being vulnerable to late spring frost. Soils exert a strong control on common ash distribution locally. The species grows best on fertile soils where soil pH exceeds 5.5. It rarely forms pure stands, more often it is found in small groups in mixed stands. Ash trees produce high quality timber that combines light weight, strength, and flexibility. Before the mass use of steel, it was used for a wide range of purposes, from agricultural implements to construction of boat and car frames. Today

Larix decidua and other larches in Europe: distribution, habitat, usage and threats

The European larch (Larix decidua Mill.) is a pioneer, very long-lived, fast-growing coniferous tree, which occurs in the central and eastern mountains of Europe, forming open forests or pasture woods at the upper tree limits. Larch is the only deciduous conifer in Europe as an adaptation to continental alpine climates. In fact, it is able to tolerate very cold temperatures during winter and, by losing its needles, avoids foliage desiccation. It is a transitional species, colonising open terrain after natural disturbances. It forms pure stands but more often it is found with other alpine tree species, which tend to replace it if no other disturbances occur. Thanks to its adaptability and the durability of its wood, the European larch represents an important silvicultural tree species in the alpine regions, planted even outside its natural ranges. Its wood is largely used for carpentry, furniture and pulp for paper. In lower altitudes or with high precipitation rates, larch is more susceptible to fungal diseases. Outbreaks of insect defoliators, principally caused by the larch bud moth (Zeiraphera diniana), can limit tree development, with economic losses in plantations, but they rarely lead to the death of the trees.

Picea abies in Europe: distribution, habitat, usage and threats

Among the coniferous species, Norway spruce (Picea abies (L.) Karst.) is one of the most important trees in Europe both for economic and ecological aspects, with a long tradition of cultivation. It can be a big tree, reaching 50-60 m in height with a straight and regular trunk, particularly used for timber constructions, pulpwood for paper and furniture. This widespread species dominates the Boreal forests in Northern Europe and the subalpine areas of the Alps and Carpathian Mountains. Thanks to its high performances in different site conditions, it can also be found outside its natural distribution on lower elevations in more temperate forests. Norway spruce has been massively planted up to its niche limits, where it is particularly susceptible to heat and drought, due to its shallow root system. For this reason it is expected to be severely affected under global warming conditions. Disturbed and weakened plants can be easily attacked by rot fungi such as Heterobasidion annosum and Armillaria, or by the bark beetles Ips typographus, one of the most destructive spruce forest pests.

Juglans regia in Europe: distribution, habitat, usage and threats

Juglans regia L., commonly known as common, English or Persian walnut, is an economically very important tree species, prized both for its nuts and for its attractive high-quality timber. It is the most widespread nut tree worldwide.