Arthropod Communities and Their Role in Litter Decomposition and Soil Fertility in Urban Forest Growing on Artificial Fill Substrates

Commodities

Practices

Urban forests provide unique opportunities to study how soil fertility and ecosystem processes function in environments modified by human activity. In Puerto Rico's San Juan metropolitan area, many green spaces are established on artificial fill substrates composed of mixed materials such as sand, limestone, and construction debris (Webb & Gómez-Gómez, 1998). Although these substrates are used for agriculture and ecological restoration, they often lack the structural complexity and nutrient-holding capacity that natural soils have, which may limit their long-term productivity and ecological functioning (Lorenz & Lal, 2009). This project investigates the decomposition of Spathodea campanulata leaf litter and its associated arthropod communities in three urban forests growing on artificial fill. By analyzing nutrient content including carbon (C), nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), and manganese (Mn)-and studying how the structure of arthropod communities shifts during the process, we aim to understand how substrate composition and litter quality influence arthropod communities (González et al., 2017; Barberena-Arias et al., 2013). The results will inform strategies for managing organic inputs in degraded soils, offering practical guidance for enhancing soil health in urban agriculture and green infrastructure. In addition, this research highlights the role of arthropods in nutrient cycling and soil ecological resilience. Ultimately, this study will advance sustainable land management by improving our understanding of how artificial substrates affect key ecological processes, with direct applications for urban farmers, restoration practitioners, and land managers working in post-industrial or heavily urbanized environments.

This study analyzes arthropod community composition and trophic structure across different stages of litter decomposition and relates these patterns to litter nutrient content to understand how changes in community dynamics may influence nutrient cycling. Arthropods play direct roles in litter breakdown and microbial interactions, making them key contributors to soil fertility processes in degraded or artificial substrates. Understanding these relationships will inform sustainable land management practices by identifying the biological drivers of soil function in urban and disturbed environments relevant to agroecology, urban farming, and soil restoration.

Specific objectives:

1. Quantify decomposition rates of Spathodea campanulata leaf litter across three urban forests growing on artificial fill substrates using the litter bag method, using mass loss.
2. Measure changes in nutrient content- (C, N, P, Ca, Mg, K, Fe, Mn)-in the decomposing litter to assess how nutrient content varies over time and between sites.
3. Assess the abundance, diversity, and community composition of arthropods associated with decomposing litter at each site using the Berlese funnel extraction method.
4. Provide practical recommendations for land managers, urban farmers, and restoration practitioners on how organic matter management (e.g., leaf litter reuse) can enhance soil health in disturbed or artificial soils common in urban landscapes.