International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.5, 206-216 http://ecoevopublisher.com/index.php/ijmec 2 12 rise and precipitation increases, microorganisms and soil animals become active, and a large number of fallen leaves left over from the previous year are rapidly decomposed within a few months. One notable feature is that the Litter layer in temperate forests is more prominent: due to the accumulation of a large amount of seasonal fallen leaves in autumn and winter, a layer of dead leaves several centimeters thick often forms in spring to cover the ground. Studies have shown that deciduous piles mixed with multiple tree species in temperate forests often produce positive mixing effects, that is, the overall decomposition rate is higher than the average value of each individual species. The reasons include that microorganisms obtain nutritional complementarity after the mixture of nitrogen-rich leaves and carbon-rich leaves (Liu et al., 2020). Therefore, creating mixed forests is conducive to improving the efficiency of leaf decomposition and nutrient cycling. Figure 2 Global distribution of leaf litter decay rate (k) observations included in our dataset (Adopted from Keller and Phillips, 2018) Image caption: Yellow dots, leaf litter from arbuscular mycorrhizal (AM)-associated trees; red dots, leaf litter from ectomycorrhizal (ECM)-associated trees (Adopted from Keller and Phillips, 2018) 6.2 Mechanism of high decomposition rate in tropical rainforests Tropical rainforests are renowned for their extremely high rate of leaf decomposition and almost no accumulation of fallen leaves. In a typical tropical humid rainforest ecosystem, dead branches and fallen leaves are often completely decomposed within a few months after falling, and it is difficult to see a thick layer of dead leaves on the surface (Wu et al., 2025). The high decomposition rate of tropical rainforests can be attributed to the effects of three aspects: the high-temperature and high-humidity environment, the high nutrient content of fallen leaves, and the extremely rich and active decomposition biological community. Tropical rainforests thus achieve a high-speed nutrient cycle, ensuring the huge demand for nutrients from dense vegetation. However, this also means that once forests disappear or the amount of litter decreases, the nutrient cycle will be disrupted and soil fertility will drop sharply. This is one of the reasons why the land rapidly becomes infertile after slash-and-burn farming in tropical regions, as there are no fallen leaves to decompose and replenish nutrients (Santiago, 2007; Silva et al., 2018). 6.3 Reasons for the slow decomposition rate in arid and cold regions In sharp contrast to tropical rainforests, the rate of leaf decomposition in arid regions and high-latitude cold areas is extremely slow, and the fallen leaves accumulate on the ground throughout the year. This is mainly attributed to the harsh climatic conditions that impose strong restrictions on the decomposition process. In arid and semi-arid environments (such as desert steppes and savannas), water shortage is the primary limiting factor for decomposition. The fundamental reason for the slow decomposition of fallen leaves in arid and cold regions lies in the unfavorable temperature and humidity conditions, which greatly limit the activity of decomposing organisms. Coupled with the fact that fallen leaves contain a large amount of self-defense substances, these two factors lead to a low decomposition rate and the accumulation of organic matter. This phenomenon reminds us that
RkJQdWJsaXNoZXIy MjQ4ODYzNA==