Ancient Forests and New Needs

How Forests Defy the Passage of Time

July 15, 2025

“A primary forest is to a secondary forest what a chilled vintage champagne served in a crystal flute is to a lukewarm Coca-Cola in a plastic cup” [1].

Now, the analogy may be neither particularly scientific nor refined, yet it conveys the difference between the two forests in the clearest possible way.

And indeed, the quotation explicitly advocates for the revival of primary forests as both a pathway and a challenge for the future [2].

All well and good, then. But what exactly are these primary forests, secondary forests, and any other categories one might use to describe them?

In this context, the German terms convey the underlying concept of these definitions much better.

The first distinction is between virgin forests (Urwälder = primeval woods) and natural forests (Naturwälder). The former are forest formations that have never been touched, modified, or influenced by humans, having arisen solely through the forces of nature. The latter, although similar in origin, may have experienced anthropogenic influences over the centuries while still retaining a high degree of naturalness [3].

Within natural forests, we can therefore distinguish (1) primary forests and (2) secondary forests. The two are distinguished by the extent of human interference they have undergone: virtually none in primary forests and only minimal in secondary forests.

Today, the term most used for these forest formations is “old-growth forests”, which denotes very old stands containing extremely ancient elements, though not necessarily virgin, as traces of past human interventions may still be discernible.

Old-growth forests are therefore “stands in primary or secondary forests that have developed the structures and species normally associated with old primary forest of that type have sufficiently accumulated to act as a forest ecosystem distinct from any younger age class” [4].

In this sense, old-growth forests—regardless of their origin—are simply the climax stage of forest dynamics, the point of maximum development that can remain stable for a longer or shorter span, influenced only by potential biotic, abiotic, or anthropogenic disturbances [5].

Figure 1: “A poorly managed woodland. This larch is beyond maturity: it is decrepit and will soon be of no use. Preserving it is fetishism, not a reverence for the tree. The forest must be brought into order through a regular rotation of cuts, removing the mature elements—but none should be left to become decrepit”. That is how overmature forest elements were regarded in early-20th-century classical silviculture. Photo: Mario Tasso – Porto Maurizio [6].

Old-growth forests represent the last living remnants of the ancient woodlands that once blanketed the European continent. Traditionally deemed useless for silvicultural purposes, they now play a vital role in studying forest dynamics.

TAGS: forests ecology ecoystem

But what characterizes an old-growth forest?

It is the structure of these forests that has traditionally highlighted their distinctive features compared with other formations.

By their very nature, old-growth forests mirror the senescent stage of forest development: mortality is limited and irregular, and biomass accumulates on the ground in large quantities. This downed dead biomass—coarse woody debris (CWD)—is what most characterizes these formations; unaffected by human intervention, they display vast, heterogeneously distributed layers of necromass on the forest floor. Moreover, woody necromass is found not only on the ground but also as standing dead trees (snags), elements that would be incompatible with a forest managed for production purposes.

Moreover, their structure is highly complex, with pronounced vertical stratification and numerous canopy gaps. Needless to say, the trees present are invariably very old, which is reflected in their considerable diameters and heights.

Nowadays, old-growth forests are truly rare across the European landscape. In Italy, we cannot identify genuine old-growth forests, because every stand in the country has been touched—at least to some degree—by human hands. In Europe, well-preserved examples still survive in Montenegro (“Biogradska Gora”) and in Poland–Belarus (“Białowieża”). Within these extensive stands are some of the continent’s largest—and oldest—native European trees, including silver fir, Norway spruce, and beech.

What future awaits old-growth forests?

Until the nineteenth century, forestry traditionally neglected any use or control of old-growth forests, except to convert them into other, more easily managed and exploitable formations. Indeed, abundant downed and standing deadwood, large trunk diameters, and a chaotic, multilayered structure are ill-suited for convenient and efficient harvest management.

Yet their continued presence on the landscape has, since the second half of the 20th century, enabled researchers to refine the study of forest dynamics in their natural state, free from anthropogenic interventions that might alter their course. This has provided not only an ecological and biological understanding of how these stands develop, but also deeper insight into the role played by natural disturbances, which in such settings are the sole forces capable of shaping their evolution. Concepts such as salvage logging or the use of downed biomass—once inconceivable—have proved useful in the wake of extreme events such as Storm Vaia.

References:

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[1] F. Hallé, Pour une forêt primaire en Europe de l’Ouest: Manifeste, Éditions Actes Sud, 2021.
[2] Association Francis Hallé pour la forêt primaire, «Derrière la renaissance d’une forêt primaire, des voies nouvelles pour un futur,» 17 12 2020. [Online]. Available: https://www.foretprimaire-francishalle.org/s-informer/derriere-la-renaissance-dune-foret-primaire-des-voies-nouvelles-pour-un-futur/.
[3] H. Leibundgut, «Über Zweck und Methodik der Strukturund Zuwachsanalyse von Urwälder,» Schweiz. Z. Forstwes, pp. 111-124, 1959.
[4] Convention on Biological Diversity, «Definitions – Old growth forest,» 30 11 2006. [Online]. Available: https://www.cbd.int/forest/definitions.shtml.
[5] P. Piussi e G. Alberti, Selvicoltura generale. Boschi, società e tecniche colturali, Compagnia delle Foreste srl, 2015.
[6] G. di Tella, Il Bosco Contro il Torrente, Touring Club Italiano, 1910.

Cover image: Forest hit by Storm Vaia, with dead wood still lying on the ground and standing as snags. Gallio (Altopiano di Asiago, Vicenza, Italy). Photo: Author. 17.07.2024

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