Do Canopy Gaps Impact Soil Properties in a Monoculture Tree Plantation? A Case Study of Tropical Hevea Brasiliensis

ABSTRACT The study examined the impact of canopy gaps on soil properties in a tropical rubber (Hevea brasiliensis) plantation. The benchmarks for selecting canopy gaps and a systematic random sampling approach were adopted for the study. Fifteen (15) canopy gaps were selected, and soil samples were collected at a depth of 0-15 cm at 15 m intervals from both the center of the canopy gaps and the under-canopy of the adjoining trees. Thus, a total of 30 soil samples were collected and analyzed for their physicochemical properties. The manual gap center estimation method was adopted to establish the center of the canopy gap. Both descriptive and inferential statistics (Student’s t-test) were used to analyze the data. The results revealed that the gaps have higher contents of silt (174.00 g kg-1), clay (80.66 g kg-1), soil organic matter (4.98 g kg-1), soil organic carbon (2.89 g kg-1), total nitrogen (0.27 gkg-1), available phosphorus (0.79 mgkg-1), magnesium (1.68 mg kg⁻¹), potassium (0.85 mg kg⁻¹), zinc (5.31 mg kg⁻¹), copper (3.39 mg kg⁻¹), and iron (150.40 mg kg⁻¹), indicating their positive impacts. In contrast, the canopy gaps influenced sand (697.50 g kg-1), pH (5.71), effective cation exchange capacity (12.50 cmolkg⁻¹), calcium (9.40 mg kg⁻¹), sodium (0.59 mg kg⁻¹), and manganese (71.86 mg kg⁻¹) negatively. However, the lower values of BD (1.32 Mg m-3) observed in the gaps denote their positive influence on the soil. The study concluded that canopy gaps do impact soil properties in tropical Hevea brasiliensis plantations, and that soil properties respond differently to canopy gaps. The outcomes of this research contribute to a better understanding of the role of canopy gaps as ecological drivers of soil properties dynamics in a monoculture tree plantation such as Hevea brasiliensis, which is crucial for its functioning and sustainability.