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Litterfall Patterns and Decomposition of Selected indigenous Tree Species Litter in Farmed Parklands of Bawku West District of Ghana

This study conducted in Ghana's Bawku West District reveals that indigenous tree species *Lannea microcarpa*, *Piliostigma thonningii*, and *Diospyros mespiliformis* exhibit significant variations in litterfall production and decomposition rates, with *L. microcarpa* demonstrating the highest productivity and fastest decomposition, thereby supporting their conservation for enhancing soil fertility and sustainable agroforestry in northern Ghana.

Original authors: Joshua Amodabila Adombire, Abdul- Wahab Mbelayin Imoro, Douti Nang Biyogue, Eunice Essel

Published 2026-10-07

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CC BY 4.0

Original authors: Joshua Amodabila Adombire, Abdul- Wahab Mbelayin Imoro, Douti Nang Biyogue, Eunice Essel

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

In the dry, sun-baked landscapes of northern Ghana, the soil faces a constant battle against depletion. For farmers growing crops like maize and millet, the ground often lacks the organic richness needed to sustain high yields. Nature, however, has a built-in recycling system that operates quietly beneath the canopy of scattered trees. This system relies on litterfall—the steady rain of leaves, flowers, fruits, and twigs that drop from trees onto the ground. When this organic material breaks down, it releases nutrients back into the earth, acting as a natural fertilizer that sustains the entire farm ecosystem. The speed and quantity of this process depend heavily on the type of tree involved. Some species drop their leaves in a massive, synchronized burst, while others shed them slowly throughout the year. Some leaves rot away quickly, feeding the soil immediately, while others linger, building up a long-term reserve of organic matter. Understanding these differences is crucial for anyone trying to restore soil health in the region, as choosing the right trees can mean the difference between a farm that struggles and one that thrives.

Researchers recently set out to map these hidden dynamics in the Bawku West District, a farming area in the Upper East Region of Ghana. They focused on three specific indigenous trees that are common in the local parklands: Lannea microcarpa, Piliostigma thonningii, and Diospyros mespiliformis. To understand how these trees contribute to the land, the team spent a full year, from August 2023 to July 2024, collecting fallen material from beneath mature trees. They placed large mesh traps on the ground to catch everything that fell, sorting the debris into categories like leaves, flowers, fruits, and twigs. They also conducted a separate experiment to see how fast the leaves would decompose. They took dried leaves from each species, placed them in small bags, and buried them in the soil under the trees. Over four months, they dug up these bags periodically to weigh the remaining material, tracking exactly how much mass was lost as the leaves broke down.

The results revealed a clear hierarchy in how these trees feed the soil. Lannea microcarpa was the most generous producer, dropping a massive amount of material—nearly 7,000 grams for every square meter of ground each year. This was significantly more than Piliostigma thonningii, which produced about 5,865 grams, and far more than Diospyros mespiliformis, which contributed just over 2,154 grams. For all three species, leaves made up the bulk of the litter, accounting for more than two-thirds of the total drop. However, the timing of this drop varied. In general, the trees shed the most material during the dry season when the rains stop and temperatures rise, a natural response to conserve water. Lannea microcarpa showed a dramatic peak in November, right as the dry season began, while Piliostigma thonningii peaked later in February. Diospyros mespiliformis was different; it shed its leaves more evenly throughout the year, reflecting its semi-evergreen nature.

When the researchers looked at how quickly this litter turned into soil nutrients, the differences were just as striking. Lannea microcarpa leaves decomposed the fastest, losing half their weight in just 101 days. This rapid breakdown means the nutrients locked inside those leaves become available to crops very quickly after the rains return. Diospyros mespiliformis was a close second, taking about 102 days to lose half its mass. Piliostigma thonningii, however, was the slowest, taking 148 days to reach the same point. This slower pace suggests that while it provides less immediate food for the soil, its lingering residues help build long-term soil structure and hold moisture for longer periods. The study also found that while weather patterns like rain and temperature influenced when leaves fell, the specific biological traits of each tree species were the dominant force controlling how much litter was produced and how fast it broke down.

These findings offer a practical roadmap for farmers in northern Ghana. The research suggests that a mix of these trees is likely the best strategy for sustainable farming. Lannea microcarpa acts as a quick-release nutrient source, ideal for boosting crop growth at the start of the rainy season. Piliostigma thonningii, with its slower decomposition, helps build a lasting foundation of organic matter that improves the soil's ability to hold water and nutrients over time. Diospyros mespiliformis sits comfortably in the middle, offering a balance of both benefits. By encouraging farmers to keep and manage these specific indigenous trees rather than removing them, the region can move toward a more resilient form of agriculture. The study concludes that protecting these natural parklands is not just about preserving trees for their own sake, but about actively managing a living system that recycles nutrients, restores soil fertility, and supports the livelihoods of the people who depend on the land.

Technical Summary: Litterfall Patterns and Decomposition of Selected Indigenous Tree Species in Farmed Parklands of Bawku West District, Ghana

Problem Statement
Soil degradation and nutrient depletion are critical constraints to sustainable agricultural production in sub-Saharan Africa, particularly in the savannah regions of northern Ghana. While indigenous trees in parkland agroecosystems are recognized for their role in soil fertility through litter production and nutrient cycling, there is a scarcity of empirical data regarding the specific litterfall dynamics and decomposition rates of indigenous tree species in the northern part of Ghana. Existing literature often lacks species-specific comparative data for less-studied indigenous trees found in cultivated parklands, limiting the ability to optimize species selection for sustainable land management and climate-smart agriculture.

Methodology
The study was conducted in the Tilli and Widnaba communities of the Bawku West District (Upper East Region, Ghana) within a Sudan savannah agroecosystem. The research focused on three indigenous tree species: Piliostigma thonningii, Diospyros mespiliformis, and Lannea microcarpa.

Study Design: Six mature trees (20–25 cm DBH) of each species were selected in two communities, totaling 18 trees.
Litterfall Measurement: Litter traps (1 m × 1 m) were installed beneath the canopy of each tree. Litter was collected bi-weekly from August 2023 to July 2024. Samples were sorted into six categories (leaves, floral parts, fruits, bark, twigs, miscellaneous), oven-dried at 80°C, and weighed to determine annual production in grams per square meter per year (g m⁻² yr⁻¹).
Decomposition Experiment: Freshly senesced leaf litter was collected, dried, and placed in nylon mesh bags (15 cm × 10 cm, 1 mm mesh) containing 50 g of litter. A total of 90 bags (30 per species) were buried 20 cm deep under the respective trees. Bags were retrieved at 30, 60, 90, and 120 days to measure residual mass.
Data Analysis: Decomposition rates were modeled using Olson's single exponential decay equation to calculate the decomposition constant ( $k$ ) and half-life ( $t_{50}$ ). Pearson correlation analysis was used to assess relationships between litterfall, rainfall, and temperature. ANOVA and Least Significant Difference (LSD) tests were used to compare species means.

Key Results

Annual Litter Production: Significant differences ( $p \le 0.05$ ) were observed among species. Lannea microcarpa produced the highest annual litterfall (6,938.5 g m⁻² yr⁻¹), followed by P. thonningii (5,864.7 g m⁻² yr⁻¹) and D. mespiliformis (2,153.7 g m⁻² yr⁻¹). Leaf litter constituted the predominant component (>2/3) for all species.
Litter Composition: P. thonningii produced the highest quantity of fruit litter (914.4 g m⁻² yr⁻¹), while L. microcarpa produced the most twig litter. Bark litter was minimal and not significantly different across species.
Seasonal Patterns: Litterfall generally peaked during the dry season and declined during the rainy season, showing a negative correlation with rainfall and a positive correlation with temperature, though these climatic relationships were modest. L. microcarpa showed a distinct peak in November (dry season onset), while P. thonningii peaked in February. D. mespiliformis exhibited a more uniform distribution throughout the year, consistent with its semi-evergreen nature.
Decomposition Rates: L. microcarpa exhibited the fastest decomposition rate ( $k = 0.0069$ ; half-life = 101 days), followed by D. mespiliformis ( $k = 0.0068$ ; half-life = 102 days) and P. thonningii ( $k = 0.0047$ ; half-life = 148 days).
Mass Loss: After 120 days, L. microcarpa lost 28.53 g of its initial 50 g mass, significantly more than D. mespiliformis (22.16 g) and P. thonningii (21.79 g).

Significance and Claims
The authors claim that the study provides essential baseline data for understanding the nutrient cycling roles of indigenous trees in the Sudan savannah of Ghana. The findings highlight that:

Species-Specific Dynamics: Litter production and decomposition are highly species-dependent, driven by phenology and litter quality rather than solely by climatic variables.
Complementary Ecological Roles: The study suggests a complementary function among the species. L. microcarpa offers rapid nutrient cycling due to high litter production and fast decomposition, suitable for immediate soil fertility enhancement. Conversely, P. thonningii provides the slowest nutrient release and longest persistence of organic matter, contributing to long-term soil organic matter accumulation and structure. D. mespiliformis occupies an intermediate niche with a decomposition rate slightly lower than L. microcarpa but significantly faster than P. thonningii.
Agroforestry Implications: The conservation and integration of these specific indigenous trees into agroforestry systems are recommended to enhance soil fertility, reduce reliance on inorganic fertilizers, and support sustainable land management in northern Ghana.

The paper concludes that promoting a diversity of these native species, rather than a single species, can optimize both short-term productivity and long-term soil sustainability in farmed parklands.

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