Abstract:
Mangroves are vital ecosystems that provide essential services such as shoreline
stabilization, carbon sequestration, and nutrient cycling. Though numerous studies have been
conducted on mangrove vegetation, their soil nutrient dynamics remain poorly understood.
This research focuses on the relationship between tidal inundation and soil nutrient dynamics
in the Kadolkele Mangrove Reserve, Negombo, Sri Lanka. Soil samples were collected
along three (03) 100 m transects at 20 m intervals from seaward to landward zones during
the early southwestern monsoon season (May–July 2025). Surface soil (2–10 cm depth) was
collected and soil pH, electrical conductivity (EC), organic matter (OM), available nitrogen
(N), available phosphorus (P), and exchangeable potassium (K) were measured using
standard analytical procedures. A data matrix comprising soil nutrient data from plots
established along the transects was analyzed using multivariate statistical methods to identify
trends and relationships. Results showed substantial spatial variability in soil properties: pH
ranged from 4.63 to 6.10, EC from 0.01 to 17.21 dS/m, P from 5.85 to 30.50 mg/kg, K from
85.27 to 1047.67 mg/kg, and OM up to 13%. Principal Component Analysis (PCA) indicated
clustering of samples from frequently inundated seaward plots, reflecting homogenization
by tidal mixing, whereas landward plots exhibited greater heterogeneity under reduced tidal
influence. In conclusion, these findings highlight the complex interaction of hydrology,
salinity, and tidal factors in regulating nutrient availability, which is important for the health
and stability of mangrove ecosystems.
