Effect of Land Use on Diversity of Macrofungi in Kereita Forest, Kikuyu Escarpment and the Potential of Cultivation of Selected Species

Abstract

Tropical forests are a haven of biodiversity with the richest macrofungi diversity in the World. However, the rate of forest loss greatly exceeds the rate of species documentation and increased risk of losing biodiversity to extinction. There is also an increasing interest to exploit and domesticate wild edible mushrooms (WEMs) worldwide. The aim of this study was to determine the occurrence and diversity of macrofungi across the indigenous and Pinus patula land use systems in Kereita forest block, Kikuyu Escarpment Forest. This study was carried out to determine the diversity of macrofungi in indigenous forest and a 22 year-old Pinus patula plantation forest block, Kikuyu escarpment and to determine the suitable culture media for the laboratory cultivation of selected edible species. This was done during the short rains in December, 2014 and long rains in May, 2015 seasons. During the two seasons three transects 1 km apart were laid down and plots measuring 20 by 20m which were 500m apart were established in Kereita block. Sample of macrofungi were collected within each plot and the abundance of macrofungi fruit bodies were recorded by counting. The samples were identified using, reference collections, taxonomic keys and books. The common edible species were further identified using molecular techniques which was based on internal transcribed spacer (ITS) of Ribonucleic acid (RNA) genes 5.8s rRNA. Macrolepiota dolichaula, Auricularia polytrica and Pleurotus djamor were cultured invitro for mycelia growth at 250C for 7 days on potato dextrose yeast agar (PDYA), potato dextrose agar (PDA), and MALT extract Agar in a complete randomized design with 5 replicates. Mineral content for the three species was determined using Microwave Digestion Method and analyzed using Atomic Emission spectrometry method. A total of 224 species distributed across 28

families and 76 genera were encountered in Kereita forest across the indigenous and plantation land use types. Macrofungi species from Agaricaceae family (16%), was the commonly represented taxa in the Kereita ecosystem. 90% of the macrofungi fruitbodies were saprophytic followed by both ecto-mycorrhiza and parasitic fungi at 3%. Land use type significantly (p<0.05) affected species richness and density and the indigenous forest had 70% macrofungi diversity compared to the plantation forest. The indigenous forest and plantation forest (Pinus patula) showed altered species composition, but species diversity was not different. Seasonality also significantly (p<0.05) affected the diversity of macro-fungi, with 61% of the total macrofungi species being encountered during the wet season. Molecular characterization successfully identified the species as Agaricus inoxydabilis, Agaricus volvatulus, Macrolepiota dolichaula, Stropharia rugosoannulata, Fayodia leucophylla, Suillus luteus, Pleurotus djamor, Auricularia polytrica, Agaricus / Hymenagaricus were identified using molecular techniques. Macrolepiota dolichaula, Auricularia polytrica and Pleurotus djamor all showed the ability to develop mycelia on PDA, PDYA and Malt extract agar. M. dolichaula and A. polytrica fully colonized forming everage mycelial diameter of 4.5 by the 7th day on all the culture media (PDA, PDYA and malt extract agar) except P. djamor that took more than 7 days to colonize fully. The mineral content for the species was in the range of 0.66-2038 for P, K, Ca, Mg, Na, Fe, Mn, Cu and Zn. From the study, the indigenous forests harbor a wide range of macrofungi species compared to the exotic plantation forest while the wet season had higher diversity of macrofungi compared to the dry season. Key words: Macrofungi, Characterization, forest type, Season, Diversity, Edible