Some studies had reported a decrease in soil arthropods abundance with increasing altitude[
20,
21], which was consistent with the findings of this study. The present study revealed a trend where soil arthropods species richness increased initially and then decreased with altitude at the class and order levels (
Figure 4). This pattern aligns with the altitude gradient characteristics of soil arthropods communities observed by Wang et al. in Mount Lu[
22]. In a study of soil arthropods in mountainous forests in eastern China. Scholars found that both the number of individuals and species initially increased and then decreased with altitude[
23]. However, our study found an increasing trend in soil arthropods species with altitude, while the abundance decreased with altitude. This may be attribute to higher vegetation coverage, soil moisture, and leaf litter quantity in lower altitude areas, providing more favorable conditions for soil arthropods. Additionally, the study site chosen for this research is a low-altitude mountain with an elevation of only 400 meters. Due to the limitation of altitude, the distribution pattern of soil arthropods along altitude gradients may differ from that of higher altitude mountain areas.
Another study had reported that the difference of dominant species of soil fauna was not determined by a single environmental condition. It was pointed out that variations in soil pH significantly influence the dominant species of soil arthropods at different altitudes[
24]. In our study, among the six altitudinal gradient plots established, Plot3 (250 m above sea level) exhibited significantly lower pH values compared to other sites (
Figure 2). The dominant species composition of soil arthropods at this site was significantly different from other altitudinal areas. Low altitude dominant species
Aethus nigritus and high altitude dominant species
Eupolyphaga sinensis were both more abundant. This suggests that the unique acidic environment at this site may be an important influencing factor. This result was consistent with the findings of Luo et al., who reported a negative correlation between soil arthropods community density and taxa with pH[
25].
Furthermore, it had been found that soil fauna were strongly correlated with water content[
26]. Additionally, research had reported that the abundance of medium and small soil arthropods was significantly influenced by soil moisture content, with higher soil moisture content leading to higher abundance[
27], which was consistent with the findings of this study. We found that soil moisture content decreases significantly with increasing altitude (
Figure 2). As a result, species and abundance of soil arthropods adapted to moist environments, such as
Armadillidium sp., gradually decrease with decreasing soil moisture content. The dominant species transition to soil arthropods more adapted to higher altitudes and drier environments, such as
Eupolyphaga sinensis. This finding was consistent with those of Cao Lili et al., whose study indicated a significant increase in the number of isopods and their larvae in seasons with abundant rainfall, favoring humid conditions[
28]. Some foreign researchers found that the amounts of leaves and nutrients in litter of different vegetation types had obvious changes[
29]. Such differences had significantly effects on the diversity and community structure of soil animals[
30]. The present study found that in low-altitude areas dominated by herbaceous vegetation (Plot1 and Plot2), soil arthropods abundance was highest. As altitude increased, the dominant species transition to shrubs and arbors, and the vegetation density and coverage gradually decrease. The abundance of soil arthropods decreased gradually. In addition, areas with more leaf litter captured more soil arthropods at the same altitude gradient (
Figure 5). However, some studies had shown that soil arthropods abundance was higher in habitats dominated by arbors[
31]. It was speculated that this difference might be due to the fact that the leaf litter of herbaceous vegetation was more easily decomposed into humus by small and medium-sized soil arthropods. However, arbors litter was more prone to lignification and was not easy to decompose[
31]. Another study found that soil arthropods in the same altitude zone tend to aggregate near the surface, where abundant leaf litter provides food and suitable living conditions by increasing humus content through decomposition and excretion[
32,
33]. It can be seen that soil moisture and leaf litter drives the community construction of soil fauna.