Molecular Soil Biology 2024, Vol.15, No.3, 99-108 http://bioscipublisher.com/index.php/msb 100 2 Composition and Decomposition of Leaf Litter 2.1 Chemical composition of leaf litter Leaf litter is composed of various chemical constituents, including lignin, cellulose, hemicellulose, tannins, and nutrients such as nitrogen (N), phosphorus (P), and calcium (Ca). These components play crucial roles in determining the decomposition rate and nutrient cycling within forest ecosystems. For instance, cellulose is a dominant polysaccharide in plant litter and significantly influences the decomposition process due to its abundance and the specific microbial communities it attracts (Štursová et al., 2012). Lignin, another major component, is more resistant to decomposition and requires specialized enzymes produced primarily by fungi (Bani et al., 2018). The nutrient content, such as N and P, also affects the microbial activity and decomposition rates, with higher nutrient levels generally promoting faster decomposition (Luo et al., 2017). 2.2 Decomposition processes and factors influencing decomposition rates The decomposition of leaf litter is a complex process influenced by both abiotic and biotic factors. This process is essential for nutrient cycling and maintaining soil fertility in forest ecosystems. 2.2.1 Abiotic factors (temperature, moisture) Temperature and moisture are critical abiotic factors that significantly influence the decomposition rates of leaf litter. Higher temperatures generally accelerate microbial activity, leading to faster decomposition rates. Moisture availability is equally important, as it affects the microbial community structure and their enzymatic activities. For example, in a study on macrophyte leaf litter, it was found that decomposition rates varied significantly with temperature, with higher rates observed at elevated temperatures (Zhao et al., 2020). Similarly, soil moisture levels can impact the microbial community composition and activity, thereby influencing the decomposition process (Dong et al., 2021). 2.2.2 Biotic factors (microbial activity, fauna) Microbial communities, including bacteria and fungi, are the primary agents of leaf litter decomposition. Fungi, in particular, play a dominant role due to their ability to produce specific enzymes that break down complex organic compounds like lignin and cellulose (Bani et al., 2018). Bacteria also contribute significantly, especially in the later stages of decomposition when simpler compounds are more prevalent (Štursová et al., 2012). Soil fauna, such as earthworms and insects, also play a crucial role by physically breaking down litter and enhancing microbial access to organic matter. A meta-analysis revealed that soil fauna could contribute up to 30.9% to the forest litter decomposition rate, with their impact being more pronounced in warmer and moister climates (Xu et al., 2020). 2.3 Role of leaf litter in nutrient cycling Leaf litter plays a pivotal role in nutrient cycling within forest ecosystems. As litter decomposes, it releases essential nutrients back into the soil, which are then available for plant uptake. This process is crucial for maintaining soil fertility and supporting plant growth. The decomposition of leaf litter contributes to the formation of soil organic matter (SOM), which is vital for soil structure and nutrient retention (Prescott and Vesterdal, 2021). The nutrient content of the litter, such as N and P, influences the rate of nutrient release and the overall nutrient dynamics in the soil. For instance, mixed leaf litter has been shown to enhance microbial diversity and nutrient release compared to single-species litter, thereby promoting more efficient nutrient cycling (Liu et al., 2022). 3 Impact of Leaf Litter on Soil Fertility 3.1 Contribution of decomposed leaf litter to soil organic matter Decomposed leaf litter plays a crucial role in contributing to soil organic matter (SOM). The decomposition process, primarily driven by microbial communities, breaks down complex organic compounds in leaf litter into simpler forms, which are then incorporated into the soil. This process not only enriches the soil with organic carbon but also enhances its overall fertility. For instance, the addition of leaf litter has been shown to increase soil organic carbon mineralization, thereby contributing to the soil's organic matter content (Wang et al., 2014). Furthermore, volatile organic compounds (VOCs) released during leaf litter decomposition can diffuse into the soil matrix, contributing to various soil carbon pools and altering soil microbial communities (McBride et al., 2020).
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