In the world of botanical invasions, the attention of biologists has focused almost exclusively on vascular plants, in Poland including: Impatiens parviflora, Padus serotina or Reynoutria japonica. Meanwhile, in the shadow of these spectacular expansions, a phenomenon that is far more difficult to monitor and control has been taking place 鈥� invasions of spore-bearing plants, including bryophytes. The evolutionary specificity of this group of plants means that the in their case traditional approach to crisis management in nature conservation proves entirely ineffective.
In Poland and Europe, one of the most widespread invasive moss species is Campylopus introflexus (Fig. 1). Understanding why invasive mosses pose such a major ecological challenge requires an analysis of their reproductive biology and life strategies. Bryophytes, as evolutionarily older plants, have developed unique adaptive mechanisms which, under conditions of anthropogenic pressure, become their greatest advantage.
Fig. 1. Campylopus introflexus
They grow rapidly and are capable of colonising almost any substrate 鈥� in our geographical zone they occupy virtually every available habitat. These plants produce millions of microscopic spores, the diameter of which often does not exceed a dozen or so micrometres. This enables them to travel thousands of kilometres through the air. Moreover, these spores can remain viable for many years, awaiting optimal conditions. At the same time, invasive species form sporophytes far more frequently and therefore produce spores much more often than native species.
Furthermore, a major problem in the control of invasive bryophytes is their ability to produce propagules, which serve for vegetative reproduction. This means that mechanical removal of moss through tearing or raking turf leads to the generation of thousands of microscopic fragments which 鈥� carried by wind, water or footwear 鈥� give rise to new centres of invasion. As a result, the application of classical methods produces the opposite effect to that intended, while the use of common herbicides is ineffective due to the different metabolism of these plants.
The history of the moss Campylopus introflexus, native to the Southern Hemisphere, is a classic and at the same time one of the most aggressive examples of bryological invasion on a global scale. It was introduced to Europe, specifically to Great Britain, in the 1940s. Within a few decades, it colonised almost the entire continent, reaching Poland as well, where it is now widespread. This moss prefers acidic, oligotrophic and highly sunlit habitats (Fig. 2). Its invasion follows a pattern of drastic habitat modification. Campylopus introflexus forms extremely dense, compact turfs that can cover areas of up to several hundred square metres (Fig. 3). These dense, compact carpets not only prevent the germination and any growth of plants but also drastically reduce the pool of all other taxa.
In this context, a key question arises: which native bryophyte or vascular plant species in Poland are most threatened by the expansion of Campylopus introflexus? Where in the country is the situation most alarming?
If we consider the decline of native species as a result of the invasion of Campylopus introflexus, the process is not limited to flora alone. Research clearly indicates that the decrease in biodiversity affects all groups of organisms 鈥� both plants and animals 鈥� and examples of taxa declining under the dominance of this moss could be multiplied many times over. Unfortunately, our knowledge in this area remains limited due to the lack of long-term studies conducted on permanent research plots. Only such studies would make it possible to clearly determine the direction of ongoing changes and the actual scale of this phenomenon. Nevertheless, the problem affects all species associated with the habitats in which this invasive moss is recorded.
Campylopus introflexus occurs en masse in open habitats and on mineral soils, and is therefore recorded in all young pine stands in managed forests 鈥� both along roads and within these forest ecosystems. Thus, in spatial terms, the problem concerns the entire country 鈥� emphasises dr hab. Grzegorz J. Wolski.
Fig. 2. Open habitats are typical sites where the invasive moss is recorded.
Fig. 3. Compact turf of Campylopus introflexus forms a barrier for native plants and animals.
At first glance, the situation might seem hopeless. However, hope for change has emerged from the latest British studies. Their origin lies in a discovery made by Dr George Greiff, the details of which stirred the scientific community in May 2026. During fieldwork, Dr Greiff identified an unusual phenomenon of regression in populations of Campylopus introflexus. Within dense patches of the invasive moss, regular brown, necrotic zones began to appear, in which plant tissues underwent complete destruction. Further analyses led to the identification of the cause of this phenomenon. It turned out to be a completely new species of parasitic fungus, previously unknown to science, exhibiting extreme pathogenicity towards Campylopus introflexus. This phenomenon has provisionally been termed 鈥渕oss die-back鈥�.
Has the 鈥渕oss die-back鈥� syndrome already been observed beyond Great Britain, for example at sites in Poland?
Apart from literature data and media reports from Great Britain, there is no analogous information from other areas. My research conducted in Poland does not indicate the presence of this syndrome in domestic populations. However, it may be assumed that the emergence of this phenomenon in Poland is only a matter of time 鈥� comments dr hab. Grzegorz J. Wolski.
Importantly, the action of this pathogen is characterised by high host specificity 鈥� the fungus precisely attacks anatomical structures exclusively of Campylopus introflexus, causing rapid lysis of gametophyte cells, while neighbouring native bryophyte species remain unaffected.
This discovery demonstrates that in the era of the biodiversity crisis, an effective weapon against botanical invasions may come from within the ecosystem itself. The case of Campylopus introflexus opens a new chapter in research into biological methods of controlling populations of these plants. At the same time, it shows how crucial fieldwork and reliable taxonomic research remain for modern ecology 鈥� without them, the identification of such precise mechanisms of natural self-regulation would be impossible.
Source and photos: dr hab. Grzegorz J. Wolski (Department of Geobotany and Plant Ecology, Institute of Ecology and Environmental Protection, Faculty of Biology and Environmental Protection, 91桃色)
Edit and graphics: Mateusz Kowalski (Promotion Centre, Faculty of Biology and Environmental Protection, 91桃色)