Category Archives: Lichens

97 new species for Bwindi, 33 for Uganda and 4 for science … and counting

You may remember we hosted a study of our lichens here in Bwindi Impenetrable National Park earlier this year. Recently I asked Andreas for an update. He sent an interim report developed with his colleagues in Sweden: Lena and Thor.

Let me share a short summary.

The collections have turned out to be richer, and indeed more exciting, than we had anticipated. To summarise progress : of 240 distinct species 99 have been identified and confirmed so far. Each record has to be carefully checked and confirmed. This process is continuing.

Of the 99 species identified, four are new to science. 33 additional species are reported for the first time in Uganda and one appears to be new for Africa. All but two of these 99 species (i.e. 97) are reported for the first time from Bwindi.

Andreas gives a training on lichens in ITFC Bwindi earlier in 2011

Still many new species out there? Bwindi near Ruhija

The species thought new to Africa is Coenogonium leprieurii. Andreas and co. say the four new species will be formally described within the next few months (provisional names: Acanthotrema nuda, Arthonia physcidiicola, Chiodecton sorediatum and Crypthonia coccifera). I shall be lobbying for an “ITFCensis” or two in there.

In the longer run when we have the species sorted the fuller ecological characterisation will be done (what species like what kind of environments etc) … We’ll keep you informed. That study will clarify the relationship of these species with climate and other factors.

It may be a while until lichen tourism competes with gorilla tourism — but who knows? Don’t underestimate Bwindi’s lichens.

Best wishes


Lichens Part II – the saga continues

Part II of our interview with Andreas Frisch

In our last article we introduced and interviewed Andreas Frisch, a post-doc lichenologist about the  significance of lichens and his study with ITFC in Bwindi. Here are some more excerpts.

Bwindi Researchers: What are the economic benefits of lichens?

Andreas Frisch : For many years, over different parts of the world, Lichens have been a source of natural dyes for wool and fabric. These dyes were distinguished by the type of lichens used and the way the color was extracted. Lichen dyes are extracted by the boiling-water method or the fermentation method. Today, they are still used by local artisans as they demonstrate their crafts.

Today two species, Evernia prunastri and Pseudevernia furfuracea, are still collected in the Mediterranean for expensive perfumery. Lichens are also eaten by many different cultures across the world. Although some lichens are only eaten in times of famine, others are a staple food or even a delicacy. In many Nordic countries lichens are also economically very important as the principal winter food of caribou, reindeer and musk-oxen.

Lichens are further used as environmental indicators for pollution monitoring around cities and factories and to trace microclimatic site conditions.

This kind of exposure and dependence on air for survival places lichens at a high risk resulting from air pollution. (Photo taken from southern Bwindi)

Bwindi Researchers: How threatened is the existence of lichens, are there some endangered species?

Andreas Frisch: Much as they are very resilient, lichens are also very vulnerable. In Sweden, for example, 238 lichen species are red-listed, representing over 10% of the lichen species in this country. In other countries, the figure is even higher. Unfortunately, in many regions of the world the knowledge of lichens is quite poor and we just do not know which of them are threatened. This is particularly true to many tropical countries including those of Africa, where information on distribution and ecology of the species is sparse and often not reliable. I believe that many tropical lichens are critically endangered but sadly, we have not enough data to prove this — not yet anyway.

Bwindi Researchers: What are the threats to lichens?

Andreas Frisch: The most serious threat is habitat destruction, either through clearing for forestry or agriculture, or through inappropriate grazing and forest management. About 45% of red listed lichens are found in forests and another 40% on rocks and alvars. Activities such as the repeated use of fire to regenerate forest or maintain fauna habitat, may have only subtle visible effects on the vascular vegetation, but can have a dramatic and deleterious impact on the often unique habitat requirements of lichens.

Because lichens do not possess roots, their primary source of most elements is the air, and therefore elemental levels in lichens often reflect the accumulated composition of ambient air. The processes by which atmospheric deposition occurs include fog and dew, gaseous absorption, and dry deposition. The sensitivity of a lichen to air pollution is in part directly related to the energy needs of the fungal component. Upon exposure to air pollution, the photosynthetic partner may use metabolic energy for repair of cellular structures that would otherwise be used for maintenance of photosynthetic activity, therefore leaving less metabolic energy available for the fungal component. The alteration of the balance between the photosynthetic partner and fungal component can lead to the breakdown of the symbiotic association. Therefore, lichen decline may result not only from the accumulation of toxic substances, but also from altered nutrient supplies that favor one symbiont over the other.

Collecting lichens for use in dye is a destructive activity. Although at present on a small scale, the activities of wool dyers can cause depletion of lichen numbers because of the large volume of material required. Local populations can be destroyed, and elimination of rare species can occur as dyers collect indiscriminately rather than selecting particular species. In the Rhön mountains in central Germany, where I have been born, the effects of lichen collecting for dying are believed to be still recognisable by the rarity or almost absence of certain lichen species as Pertusaria corallina, which have been collected for the dying of silk during the late 19th century.

Collecting specimens for science may only be a threat when over-enthusiastic collection of selected species could place local populations or rare species at risk. The amount of material collected of any one species (particularly exsiccates sets) should to be curtailed to prevent destruction of such populations by scientific activities.

These threats are by no means unique to lichens, and also apply to other groups of organisms.

Another of those lichens in Bwindi which grow hanging out in the air


In conclusion

Perhaps we can agree that despite their ecological and economic significance, very little is really known about lichens in tropical countries, especially in Africa.  More research is needed, especially to establish which species are at the risk of extinction and clarify how we might protect them. Perhaps you — readers — have some knowledge contribution to make. Let us hear your views and comments.

Documented by Ivan

Lichens: Little known but very significant

Lichens may be found all over the world, from the Antarctic continent to the tropics, in habitats ranging from spray-washed rocks by the sea, to boulders at the edge of the snowline on mountains; from rain forests to fogy deserts. In harsh, inhospitable environments they may be the only vegetation, and they are amongst the first colonisers of newly exposed rock surfaces, although sometimes algae and bacteria do the same. The only places where lichens might be rare is in or near cities, as they are very sensitive to atmospheric pollution.

These remarkable organisms are not really one plant but two — an association between an alga, or a cyanobacterium, and a fungus; an association so successful that a new entity results, capable of surviving under conditions in which either partner alone would perish.

Lichens are slowly emerging from their obscurity. Considerable work has been done in the last fifty years on the taxonomy of tropical lichens, which opens up the field for ecological and physiological studies.

Last month (May 2011), ITFC had the privilege of hosting Andreas Frisch, a post-doc Lichenologist from the Swedish University of Agricultural Sciences (SLU) in Uppsala. Andreas was in Bwindi to conduct an inventory of the ecology, distribution and diversity of lichens in the park, which is the first such study in Uganda. We managed to interview him about his work.

Here are excerpts from our discussion:

Andreas Frisch observing Lichens in Ruhija

Andreas Frisch observing Lichens in Ruhija, Bwindi INP.

Bwindi Researchers: What is your study about and what is it’s significant?

Andreas Frisch: I’m a lichen taxonomist and ecologist. Together with Lena Gustafsson and Göran Thor (from my department) we are investigating how lichens are distributed in the Bwindi Impenetrable National Park along lines of altitude, disturbance and slope position – meaning whether the epiphytic lichen vegetation of hilltops differs from that of valleys and the slopes inbetween. In the long run we intend to establish lichens in Bwindi as indicator species for forest communities and disturbance levels. We are also working on an inventory of lichens in Bwindi and want to establish a reference collection of lichens at ITFC. We hope in this way we can encourage further research in this fascinating group of organisms.

We feel this study is important as lichens constitute an integral part of the epiphyte communities in Bwindi. These contribute significantly to the microclimate and nutrient supply of the forest and are used by many organisms as fodder, nesting material etc. Lichens are also useful as indicators for environmental conditions, but can only be used as such when the species in the park and their distribution and ecology are well known.

Bwindi Researchers: So far you have spent about 5 weeks traversing several sections of Bwindi. What is your view about the diversity and distribution of lichens in this park?

Andreas Frisch: Bwindi still harbors a high diversity of epiphytic lichens, which might be comparable to that of other African tropical forests of middle altitudes. However, it is difficult to give exact figures as we have just started with our study. During the five weeks in the park I have collected about 250 species along the transects I made and in their surroundings. In total, there might be up to 500 species in Bwindi Impenetrable National Park. This is quite typical for a mid-altitude tropical rainforest in Africa. Low-altitude forests may have a richer diversity of lichens because they are mostly less moist and the epiphyte vegetation is less dominated by bryophytes. Lichens growing on living leaves of trees, shrubs and herbs are particularly common in the lowland rainforests and contribute significantly to the high species richness in these forests. Such foliicolous lichens are also found in Bwindi, but with lower species numbers.

On a single tree trunk, you can easily find 25 plus lichen species. (Photo taken from Bwindi).

On a single tree trunk, you can easily find 25 plus lichen species. (Photo taken from Bwindi).

Bwindi Researchers: What Is the Ecological Role of Lichens?

Andreas Frisch: Lichens are important partners in nature’s ecosystem. Together with bacteria and algae they are early colonizers that reestablish life on rock and barren disturbed sites. Lichens play an important role in soil formation over much of the earth. As lichens colonize rocks, they trap dust, silt, and water. Soil-crust lichens bind the topsoil and prevent erosion and so play an important role in the ecology of semi-arid and arid lands.

Because of their association with cyanobacteria, some lichens can provide themselves with nitrogen compounds. Lichens contribute to the nitrogen cycle by converting the nitrogen in the air into nitrates that contribute to their growth and development. Their ability to fix atmospheric nitrogen is beneficial to other plant life as well. When it rains, nitrogen is leached from both living and dead lichens and is available to plant life in the immediate areas. When lichens die, they contribute decayed organic matter to the area they inhabited, which enables mosses and seeds from vascular plants to begin developing among the pockets of new soil.

Animals utilize lichens in many inter-dependent ways. It is well documented that numerous animals use lichens for either food or shelter. Some 50 species of birds are known to regularly use lichens as their preferred nesting material. Small animals may use lichens to hide from natural predators through camouflage and direct cover. Mites feed on lichens and some gastropods include lichens in their diet.

In Bwindi, Lichens like in this photo (brownish/orange coloring) are quite resilent.

In Bwindi, Lichens are quite resilient even to the point of growing on rocks. This one is actually an not a true lichen but an Trentepohlia algae, a common symbiont in lichens, but also as here often free-living

To be continued in next update…