**4.3 AMF Community and species richness**

As all natural plant communities, the argan tree contains arbuscular mycorrhizal fungi at rhizospheric soil level. The total number of AMF morphotypes was 35 in 2016 [53] and 39 in 2021 [41] illustrated in **Figure 6**.

The specific richness of this assembly of community attains 18, 14, and 9 species in some sites (**Figure 7**). Almost the same number of AMF spore morphotypes (31) was found in the rhizosphere of *Ceratonia siliqua* developing in different ecological zones (Afourar, Ksiba Khénifra, Taroudant, and Nador) [54]. El Maati *et al.* [55] detail a low specific richness (nine species) of native AMF communities from *Argania spinosa*, *Acacia gummifera,* and *C. siliqua* in southwest Morocco, 11 morphotypes from the argan tree in northwest Morocco [56]. Several factors can explain these

**Figure 7.** *Specific richness of mycorrhizal species in the rhizosphere of argan tree according to studied sites.*

disparities. Relative air humidity and rainfall are significant drivers for AMF spore density, especially for members of the families Acaulosporaceae, Diversisporaceae, and Glomeraceae, which were positively correlated with these abiotic factors [57]. The precipitation and water availability could drive the changes in AMF communities at a regional scale [58]. Spore abundance and species richness can also be influenced by elevation gradients [59, 60] and mycorrhizal fungi pH tolerance [61], plant density [62], and productivity and land-use intensity [63].

Regarding the dominance of genera *Glomus* and *Acaulospora* in the rhizospheric soil of argan tree, it was also cited by El Maati *et al.* [55], in the rhizosphere of diverse plant species [64–69], in soil from different ecosystems, in Senegal [70], in China [71], Burkina Faso [72], Kenya [73], Sudan [74], and in central Europe [75]. The high occurrence of the *Glomus* genus is due to its ability to produce more spores in a shorter time than other genera, such as *Gigaspora* and *Scutellospora,* and its adaptation to drought and soil salinity [76]. In disturbed habitats, the high abundance of Glomeraceae is related to the considerable capacity of some of its most frequently found members, for example, *Rhizophagus irregularis*, to sporulate [77]. *Acaulosporaceae* members may be confined to the harsh environmental conditions of uplands [78] and are dominant in protected areas. In fact, the high anthropic impact may modify the AMF community and cause decreased AMF biodiversity, root colonization, and sporulation [79]. It was emphasized that degraded lands harbor low levels of AMF abundance and diversity [80]. Several studies found that disturbance of semi-arid ecosystems decreased mycorrhizal spore density and root colonization [81]. It was also reported that livestock and human disturbances decreased AMF spore density, root colonization, and nutrient availability [82].
