Research on Lichens in Tropical Africa and Germany & at the University of Koblenz-Landau

Prof. Dr. Eberhard Fischer - efischer@uni-koblenz.de
Dr. Dorothee Killmann - killmann@uni-koblenz.de  

Institute of Integrated Natural Sciences, Dep. of Biology, Univeritätsstraße 1, D-56070 Koblenz

Influence of anthropogenic and natural fragmentation on diversity of flora and vegetation in montane rainforests of East Africa (Kenya, Rwanda)

Kenya

Tropical lowland and montane rainforests are among the most species-rich ecosystems and on the other hand among the most endangered bioms. Rapid destruction of these forests has led to remnant stands, often surrounded by small fragments, which are isolated in an agriculturally used landscape. The a- and b-diversity of lichens is monitored along a transect of forest degradation and fragmentation from Kakamega Forest to Mt. Kenya. Some of the most important questions to be answered are:

• In what degree is a-diversity changed in different forest fragments under different anthropogenic and natural disturbance?

• What are the differences of the lichen flora between forests of different structure, fragmentation and distance to each other?

• Which groups of lichens are suitable indicators for a Rapid Biodiversity Assessment of Central and East African Forests.?

• Does a correlation between biodiversity and stability of isolated habitats exist? What is the influence of abiotic disturbance and biotic interaction on the biodiversity of fragmented habitats?

• How can a highly diverse rainforest ecosystem be maintained and what are the conditions for a sustainable use of these rainforests?

Existing  data-sets mainly cover vascular plants and studies on cryptogams are very rare. Thus, the lack of data for lichens from tropical forests is a major problem also for conservation planning and for assessment of biodiversity value.

While diversity of vascular plants in tropical Africa is comparatively well known, our knowledge of lichens is still rudimentary. Kenya is among the better known countries,  and 601 lichens and lichenicolous fungi have been recorded so far (Feuerer 2003). Also, a flora covering macrolichens is available (Swinscow & Krog 1988). However, if the species number is compared with the number of lichens occurring in South Africa (1676 lichens and lichenicolous fungi, Feuerer 2003), Central Europe (ca. 2100 species) or Scandinavia (2271 species, Santesson 1993), it is evident that our knowledge is still far from complete. It can be estimated that tropical countries like Kenya harbour at least between 1500 and 2000 species.

During the field-work in 2001 and 2002, 132 relevés could be studied in Kakamega Forest and 138 on Mt. Kenya. Within the investigation area at Mt. Kenya, 140 morphospecies could be recorded, which are currently identified. Here, the number of foliose lichens was comparatively high with 60 morphospecies. Especially the genera Parmotrema, Heterodermia and Lobaria play a dominant role. The genus Usnea, however, is characterised by its high percentage of biomass. aus. Especially Usnea articulata and U. trichodeoides dominate the aspect of vegetation with their beard-like growth. In the northern Kakamega-Forest, 132 relevés have been studied and more than 200 morphospecies could be recorded. In contrast to Mt. Kenya, the crustose lichens with about 100 morphospecies, among them e.g. the genera Cryptothecia and Phyllopsora, were dominating. The high number of gelatinous lichens with 18 morphospecies was surprising.

To describe the composition of the epiphytic lichen flora in Kakamega forest, the dense, rather undisturbed forest at Colobus-Trail will be compared with the ± open secondary forest south of the campsite. Within the primary forest, crustose lichens are dominating with 25 morphospecies, while only 3 foliose lichens, 6 gelatinous lichens and no fruticose lichen could be recorded. A completely different picture was observed in the secondary forest. Here, foliose and crustose lichens play an important role with 20 morphospecies each. The high percentage of gelatinous lichens with 10 morphospecies is remarkable, while diversity of fruticose lichens with only 3 species is comparatively low. A comparison of all dense, primary like-forests with the secondary forests in Kakamega shows, that disturbed, secondary habitats are much more species-rich than undisturbed, primary forests. In the secondary forest, a total number of 165 morphospecies could be recorded, whil species number was much lower in primary forests with only 100 morphospecies.

Rwanda

Rwanda, a small  East African country which covers only 26.000 km², is situated about 1-2° south of the equator. Due to its diverse geomorphology and altitudinal range, it harbours a species rich mosaic of montane rainforests, afroalpine vegetation, dry forests amd savannas. The vascular plants are comparatively well known and comprise 3500 species, among them 45 local endemics. In contrast to this number, only 62 lichen species are known (Lindau 1914, Thell 2001). During the last decades, natural vegetation has considerably decreased due to overpopulation and civil war. Today only 10 % of the surface are protected as National Parks (Volcano Park, Nyungwe Forest, Akagera National Park). Since 1984, the biodiversity of Rwanda has been investigated by the second author, and besides research on vascular plants and bryophytes about 1500 specimens of lichens have been collected.

After the independance of Rwanda, only a few botanists continued to work in this phytogeographically interesting region. During botanical exploration for the "Flore du Rwanda, Spermatophytes", Troupin collected mainly flowering plants. In 1971, 1972 and 1974, Lambinon during a research program on flora and vegetation of the Virunga Volcanoes and Kahuzi-Biega collected mainly lichens, among others in the Nyungwe Forest, on the Virunga Volcanoes and in Butare. Some results were published by Lambinon & Sérusiaux (1977, 1981) and Sérusiaux (1979a, b, 1981, 1984, 1989). Thus, the number of known lichens from Rwanda is actually 62 and the lichen flora has remained almost unknown. From 1988 to 2003, E. Fischer studied the lichens of Rwanda and was the first to collect in remote sites (e.g. Cyamudongo Forest, Busaga Forest, Kagitumba, Ibanda Makera) and lichenologically undercollected regions. In spring 2003, D. Killmann could collect lichens mainly in the Nyungwe Forest and on the Virunga Volcanoes.

Main aims of the research beside an inventory of lichens will be the comparison of the different afromontane and afroalpine forests and the savanna and dry forest biomes.

Literature

Lambinon, J. & Sérusiaux, E. (1977) Contribution à l’étude des lichens du Kivu (Zaïre), du Rwanda et du Burundi. I. Introduction. Genres Everniopsis, Normandina et Placopsis. Bulletin du Jardin Botanique Nationale de Belgique 47: 459-471.

Lambinon, J. & Sérusiaux, E. (1981) Contribution à l’étude des lichens du Kivu (Zaïre), du Rwanda et du Burundi. V. Le genre Leprocaulon. Bulletin du Jardin Botanique Nationale de Belgique 51: 205-207.

Lambinon, J. & Serusiaux, E. (1983) Contribution a l'étude des lichens du Kivu (Zaïre), du Rwanda et du Burundi. VII. Approche ecogeographique de la flore et de la vegetation licheniques dans l'est de l'Afrique centrale. Bothalia 14: 533-538.

Lindau, G. (1914) Lichenes. In Wissenschaftliche Ergebnisse der Deutschen Zentral-Afrika-Expedition 1907-1908 unter Führung Adolf Friedrichs, Herzog zu Mecklenburg (J. Mildbraed, ed) 2: 101-110. Leipzig: Klinkhard & Biermann.

Sérusiaux, E. (1978) Contribution a l'étude des lichens du Kivu (Zaïre), du Rwanda et du Burundi. II. Espece nouvelles de lichens foliicoles. Lejeunia 90: 1 - 18.

Sérusiaux, E. (1979a) Contribution a l'étude des lichens du Kivu (Zaïre), du Rwanda et du Burundi. III. Vezdaea, a new genus for Africa. Mycotaxon 8: 135-139.

Sérusiaux, E. (1979b) Contribution à l’étude des lichens du Kivu (Zaïre), du Rwanda et du Burundi. IV. Le genre Stereocaulon (Schreb.) Hoffm. Revue Bryologique et Lichénologique 45: 1-43.

Sérusiaux, E. (1981) Contribution a l'étude des lichens du Kivu (Zaïre), du Rwanda et du Burundi. VI. Les genres Coccocarpia Pers. et Lobaria (Schreb.) Hoffm. Cryptogamie, Bryologie et Lichénologie 2: 461-469.

Sérusiaux, E. (1984) Contribution to the study of lichens from Kivu (Zaïre), Rwanda and Burundi. VIII. New and interesting species of parmeliaceous lichens. Bryologist 87: 1-11.

Sérusiaux, E. (1989) Echinoplaca furcata, a new species of foliicolous lichen (Gomphillaceae) from Rwanda. Mycotaxon 35: 237-242.

Swinscow, T.D.V. & Krog, H. (1988) Macrolichens of East Africa. London: British Museum (Natural History).

Studies on epiphytic and epilithic lichens in the Westerwald (Rhine-Palatinate, Germany)

Since 1999, epiphytic lichen vegetation has been mapped in 40 selected relevés of the Westerwald area (north-eastern part of Rhine-Palatinate). Previously only John (1990) had visited the region and made some inventories. Numerous interesting new records have been made, among them Arthonia vinosa, Ochrolechia turneri, Parmelia flaventior, Parmotrema chinense, Usnea filipendula, U. hirta and U. subfloridana (Killmann & Fischer 2000, 2002).

An apparently neglected habitat proved to be rock outcrops and debris. In 2002, selected areas could be mapped on different rock-types (e.g. devonian .., limestone, volcanic rocks). Intersting findings were Cladonia strepsilis, C. symphycarpa, Endocarpon adscendens, Lasallia pustulata, Lempholemma chalazanum, Opegrapha gyrocarpa and Toninia sedifolia. Heavy metal debris could be shown as intersting and species-rich habitat for a lot of specialists. Thus large populations of Lecanora subaurea, Stereocaulon dactylophyllum, S. nanodes and S. pileatum could be discovered (Killmann & Fischer in press).

Killmann, D. & Fischer, E. (2000): Bemerkenswerte Flechten- und Moosfunde aus Westerwald und Lahntal. Hessische Floristische Briefe 49: 37-45.

Killmann, D. & Fischer, E. (2002): Weitere bemerkenswerte Flechten- und Moosfunde aus Westerwald und Lahntal. Hessische Floristische Briefe 51: 21-28.