Sea Buckthorn and Coastal Dune Stabilisation in Northern Poland

Species Overview

Hippophae rhamnoides, sea buckthorn (Polish: rokitnik zwyczajny), is a thorny deciduous shrub native to central Asia and parts of Europe. Its natural European distribution includes river banks, gravel flats, and coastal dunes from the North Sea to the Baltic. Along the Polish coast it occurs both as an indigenous coastal population and — at several sites — as a result of historical deliberate planting carried out during dune stabilisation programmes in the twentieth century.

The shrub is dioecious (separate male and female plants), which limits the density of fruiting individuals in any given stand. It is drought-tolerant, salt-spray-tolerant, and capable of fixing atmospheric nitrogen through actinorrhizal symbiosis with Frankia bacteria — a characteristic that distinguishes it from most other dune shrubs and allows it to colonise nutrient-poor substrates.

Nitrogen Fixation and Soil Development

The ability to fix nitrogen has important consequences for the plant communities that develop beneath and around sea buckthorn stands. Leaf litter from sea buckthorn is substantially richer in nitrogen than that of most other dune shrubs. Over time, the accumulation of this litter leads to measurable increases in soil nitrogen levels, which in turn enables species requiring higher nutrient availability to establish.

In practice, this means sea buckthorn stands on Polish coastal dunes often develop a distinctive understorey. Nettles (Urtica dioica) and other nitrophilous plants may appear at the base of established plants. This successional facilitation makes sea buckthorn a structurally important species in the transition from white and grey dune to dune scrub, but it also means that very dense stands can eventually exclude the specialised low-nutrient dune flora that the habitat directive requires to be maintained.

Occurrence at Łazy and Surrounding Coastal Areas

The area between Dąbkowice and Łazy in West Pomeranian Voivodeship provides a well-documented example of sea buckthorn on Polish coastal dunes. Photographic surveys carried out in 2021 (A. Kwiecień, documented on Wikimedia Commons) show dense stands of Hippophae rhamnoides on the fixed dune surface immediately behind the foredune. The plants grow in pure thickets or in combination with other shrubs, covering substrates that would otherwise support open dune grassland or dune heath.

Similar populations are documented further along the coast at Mielno, along the barrier peninsula between Lakes Jamno and Bukowo, and at various points on the Hel Peninsula. At many of these sites, the sea buckthorn stands represent a later successional stage than the protected open dune habitats, and their management — partial removal, browsing promotion, or passive monitoring — is subject to individual site conservation plans.

Historical Use in Dune Stabilisation

During the twentieth century, particularly in the decades following the Second World War, sea buckthorn was deliberately planted along sections of the Polish Baltic coast as part of a broader programme of dune stabilisation and coastal protection. The rationale was practical: the species establishes quickly on bare sand, forms dense wind-resistant thickets, and does not require continued maintenance once established.

At the time, the negative consequences of over-planting — expansion beyond target zones, soil enrichment, competitive exclusion of open-dune flora — were not fully understood or prioritised. Contemporary conservation management is in part a response to the effects of those planting programmes, which altered the vegetation composition of significant stretches of dune habitat.

Current Conservation Assessment

Under the Habitats Directive, the open dune habitats on which sea buckthorn encroaches — particularly Annex I habitat types 2130 (fixed coastal dunes with herbaceous vegetation, "grey dunes") and 2140 (decalcified fixed dunes with Empetrum nigrum) — require maintenance of unfavourable status against a baseline of favourable status. Sea buckthorn is identified as a significant threat factor in the standard data forms of several Polish coastal Natura 2000 sites.

The General Directorate for Environmental Protection (GDOŚ) in Warsaw publishes guidance on the management of Natura 2000 habitats in Poland, including recommendations for dune scrub management. For sea buckthorn specifically, the typical recommended approach in sites where open dune habitat is the management target involves mechanical removal of expanding stands, with removed material disposed of off-site to prevent nutrient return.

The Plant Outside Conservation Contexts

Outside of areas managed for dune habitat conservation, sea buckthorn is generally regarded positively. It is the subject of commercial fruit production (the berries are used in juice, jam, and cosmetic products), and existing coastal stands often provide food for overwintering thrushes and other birds. The dual status — beneficial in some contexts, a management problem in others — reflects the complexity of coastal dune conservation, where goals are rarely uniform across the full length of the coastline.