Forests cover 31% of the Earth’s terrestrial biodiversity (FAO, 2022). However, they are continuously decreasing in the tropics due to natural disasters and anthropogenic activities. The Ethiopian highlands constitute 60% of the Afromontane tropical forest ecosystems of eastern Africa that are rich in plants and animals and endemic plants and animals species (Schmitt et al., 2010). The woody plant species are the important components of forest ecosystems that deliver resources and habitats for the different biological entities.
Ethiopia is a center for biological diversity due to its wide range of altitude and diverse topography with high and rugged mountains (Zegeye et al., 2011). The natural forest coverage of Ethiopia was 35–40% of the land area in 1950s and 1960s which has been dramatically decreased to less than 3% around 1990s (Asfaw, 2014).
Munessa forest is one of the major timber supplier forests in central Ethiopia. Although the forest is rich with indigenous trees, it suffers from deforestation due to the uncontrolled use of timber, overgrazing, and encroachment due to agricultural activities (Anissa and Eyasu, 2020). Thus, accelerated conversion of forests to agricultural land-use types and overutilization of forest resources have contributed to a decrease and loss of biodiversity.
Mycorrhizal symbiosis is one of the most widespread and ecologically important mutualistic associations that occur between land plants and arbuscular mycorrhizal fungi. Arbuscular mycorrhizal fungi (AMF) interact with a broad range of vascular plants (~ 80–90%) in tropical forests, grasslands, alpine and crop lands (Smith and Read, 2008). AMF can enhance the uptake of poorly mobile soil nutrients such as P, K and Mg to plants (Yadeva et al, 2017), increase tolerance to water stress, induce resistance to pathogens and other abiotic stresses in the soil (Siddiqui and Pichtel, 2008). They are also very important for crop production and growth and establishment of perennial plants, particularly woody plants with deep roots. Moreover, they help in a buildup and maintenance of mycorrhizal networks, or hyphal bridge (hyphal linkage) to exchange resources amongst tree species (Muthukumar et al., 2022). AMF also increase the volume of soil to be exploited and thereby improve phosphorous (P) use efficiency and P access to plants and its cycling in the soil (Muleta et al., 2008).
It is well established that different plant species have differential growth responses to AMF, so that the composition and diversity of the AMF communities in a natural ecosystems could potentially affect the way plant species coexist, and determine plant community structure (Heijden et al., 1998). Moreover, knowledge about AMF diversity may help forest scientists to understand relationships of species selection, AMF production and inoculation.
In Ethiopia, research works were undertaken on AMF species diversity and abundance in different land use types. To mention few, mycorrhizal status of different coffee shed trees in agro-forestry systems south west Ethiopia (Muleta et al., 2007; Channie and Assefa, 2013), dual function of AM fungi and rhizobia with Acacia polyacatha (Yohannes and Assefa, 2007), species diversity and population density of AMF in Acacia woodland ecosystems and agro-forestry systems in central Shewa (Belay et al., 2013; Belay et al., 2015), species diversity and population density of AMF in Sidama agro-forestry systems (Dobo et al., 2016), AMF status of Erythrina brucei in different land use types in Ethiopia ( Berza et al., 2021) and species and population density of AMF in the highlands of northern Ethiopia (Birhane et al.,2021).
Several studies have been undertaken to investigate AMF species diversity and abundance among different forest ecosystems across the globe. To mention few, AMF species diversity and abundance studies have been conducted in planted forest in eastern China (Wang et al., 2019), in natural forest in south west China (Zhang et al., 2003), in tropical rain forest in south west China (Zhao et al., 2003), in Atlantic and Amazon forests in Brazil (Winagraski et al., 2019) and in natural forest in south Ethiopia (Belay et al., 2020).
Although Wubet et al. (2003) have worked on mycorrhizal diversity in dry afromontane forests in Ethiopia; there is still dearth of sufficient information on species and population density of arbuscular mycorrhizal fungi in dense and protected forests in Ethiopia. Therefore, the objective of this study was to evaluate the AMF species diversity, abundance, population density and root colonization in indigenous trees in Munesa Forest.