# The Role of Cryptogams in Soil Property Regulation and Vascular Plant Regeneration: A Review
## 2 Effects of Cryptogam on Soil Properties  
### Effects of Cryptogam on Content and Vertical Distribution of Soil Water  
Many studies suggest that cryptogams exert limiting effects on soil water infiltration [19,40]. In the study of Mu Us Sandy Land in China, it was found that a high coverage (100%) of moss crusts limited the infiltration rate and cumulative infiltration of rainwater and increased soil evaporation, leading to a decrease in soil moisture content. Additionally, reducing moss coverage to 40% did not significantly alleviate this effect on soil water content reduction [41]. Similar results were found in the study of the Loess Plateau, where scholars found that moss crust leads to a decrease in soil infiltration rate and cumulative infiltration [13]. In the study of [PERSON] et al., the soil water content was reduced due to the strong water-holding capacity of the moss layer [4]. In addition to the important effect of precipitation on soil water content, non-rainfall water is also an important water input for soils in drier regions [42]. [PERSON]'s study found that moss crusts are able to intercept more non-rainfall water in the environment [43], but subsequent studies showed that typophytes intercept non-rainfall water at a comparable rate to the increase in soil evaporation caused by it [44]. [PERSON]'s research showed that lichen and moss crusts intercept a lot of dew due to their complex morphology and increased soil roughness. In addition, the authors discovered that soil under moss crusts cools faster at night, promoting the formation of dew. As such, the soil dew retention under different cover conditions manifests as moss crust > lichen crust > algae crust > bare soil [45]. The effect of cryptogam on soil water evaporation is another important cause of soil water change. In a study of the Loess Plateau wind-water erosion crisscross region in China, it was found that soils covered by moss crust had higher evaporation rates and cumulative evaporation capacity [7]. Conducting evaporation tests in both greenhouse and field environments, [PERSON] found that, in the greenhouse setting, when the water was fully absorbed by sandy soil, moss with higher morphology and higher biomass were more conducive to the maintenance of soil water. However, under natural outdoor conditions, both cyanobacteria and moss crust increased the evaporation of sandy soil and reduced soil water content [46]. [PERSON]'s study found similar results, discovering that when the soil water content is high, soil evaporation becomes weaker compared with bare soil moss crusting, which is conducive to the maintenance of soil water content. As evaporation progresses, in situations where the soil water content decreases to a certain level, moss crusts exercise the opposite effect, resulting in increased soil water loss [47]. One explanation for this phenomenon is that moss is not conducive to the transport of soil capillary water when the soil water content is high, and doing so will lead to a decrease in evaporation. In drier conditions, the unsaturated hydraulic conductivities of bare soil decreased rapidly, while those of moss-covered soil did not. This meant that the moss-covered soil maintained relatively high levels of evaporation, suggesting that mass promotes soil water accumulation in humid environments, and dry conditions may exacerbate soil drought [48]. Cryptogams exert important effects on soil properties, including improving soil texture, increasing soil organic matter content [8], expanding soil water holding capacity [7; 19], and elevating topsoil porosity and permeability [49], which results in a change in the vertical distribution of soil water. [PERSON]'s study found that the moss-dominated biocrust increased the topsoil (0-5 cm) water content in semi-arid areas, decreased the soil water content by 15-50 cm, and had no effect on the deeper soil water content [12]. [PERSON] et al.