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
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