Jehanzaib et al. (2025) The influence of plantation forest legacy on blanket bog hydrology

Identification

• Journal: Journal of Hydrology
• Year: 2025
• Date: 2025-10-30
• Authors: Muhammad Jehanzaib, Raymond Flynn, Vicky Preece, Hannah Lehnhart-Barnett, Devin F. Smith, O. A. Leonard, Tiernan Henry, W. Berry Lyons, Anne E. Carey, Peter Croot
• DOI: 10.1016/j.jhydrol.2025.134498

Research Groups

• School of the Natural and Built Environment, Queen’s University Belfast, Belfast, United Kingdom
• Earth & Ocean Sciences, School of Natural Sciences, University of Galway, Galway, Ireland
• School of Earth Sciences, The Ohio State University, Columbus, United States

Short Summary

This research investigates the hydrological impact of legacy plantation forestry (clear-felled areas) on streamflow in a small (0.21 square kilometers) blanket bog catchment in Ireland. The study found that streamflow increased by 106% annually in the degraded catchment compared to an intact blanket bog, with significant seasonal variations.

Objective

• To estimate the impact of legacy of plantation forestry on streamflow in a small blanket bog catchment in the west of Ireland.
• To examine the relative impacts of legacy of plantation forestry on monthly, seasonal, and annual runoff regimes.

Study Configuration

• Spatial Scale: A small blanket bog catchment in Letterunshin, Co. Sligo, Republic of Ireland, with a total area of 2.14 square kilometers, comprising 1.93 square kilometers of intact blanket bog and 0.21 square kilometers (21 hectares) of degraded area (legacy of plantation forestry). Ground elevations range from 107 meters to 149 meters above mean sea level.
• Temporal Scale: High-resolution (15 minutes to 1 hour) hydro-meteorological and groundwater level data collected between December 2023 and November 2024. Model calibration period: February 17, 2024, to August 31, 2024. Model validation period: September 1, 2024, to November 20, 2024. Streamflow simulations for impact assessment: December 1, 2023, to November 30, 2024.

Methodology and Data

• Models used: Generalized Multistep Dynamic (GMD) TOPMODEL, calibrated using the Generalized Likelihood Uncertainty Estimation (GLUE) framework.
• Data sources:
  • Network of groundwater monitoring stations.
  • Hydro-meteorological stations recording rainfall, temperature, wind speed, solar radiation, humidity, atmospheric pressure, and evapotranspiration (ET) at 15-minute to 30-minute intervals.
  • Daily ET data from the Met Éireann autographic station at Belmullet.
  • Streamflow data from two flumes (intact and degraded catchment outlets) using CS451 Pressure Transducers at 15-minute intervals, with rating curves developed via tracer injection technique.
  • High-resolution (1 meter x 1 meter) Digital Terrain Model (DTM) derived from airborne Light Detection and Ranging (LiDAR) surveys conducted in 2017.
  • Google Earth imagery for land cover change visualization.

Main Results

• Annual streamflow increased by 106% in the degraded (legacy of plantation forestry) blanket bog catchment compared to the intact blanket bog.
• Monthly streamflow increases in the degraded catchment ranged from a high of 275% in February to a low of 16% in September.
• Seasonal analysis showed streamflow increases in the degraded catchment of 237% in winter, 116% in spring, 24% in summer, and 42% in autumn.
• Flood peaks were significantly higher in the degraded watershed compared to intact conditions.
• The GMD-TOPMODEL efficiently simulated streamflow in the intact watershed, achieving a Kling-Gupta efficiency (KGE) of 0.92, Nash-Sutcliffe efficiency (NSE) of 0.88, and Root Mean Square Error (RMSE) of 12.64 cubic meters during calibration, and KGE of 0.88, NSE of 0.82, and RMSE of 15.84 cubic meters during validation.
• Elevated runoff in the degraded area is attributed to minimal interception losses, reduced evapotranspiration, and compact bog conditions resulting from prior drainage and clear-felling.

Contributions

This study provides a comprehensive investigation into the hydrological impact of the legacy of plantation forestry (clear-felled areas with stumps, furrows, and brash remaining) on streamflow in small (tens to hundreds of hectares) blanket bog catchments, a scale previously under-researched compared to larger catchments. It quantifies the significant increase in streamflow and flood peaks due to these land-use alterations, offering crucial insights for water managers, stakeholders, and policymakers in flood risk assessment and land-use planning.

Funding

• Sensor Application to Peatland Hydrology in Remote Environments (SAPHIRE) project
• USI 177 research grant from the Department for the Economy, Northern Ireland
• Research Ireland/Science Foundation Ireland (21/US/3724)
• US National Science Foundation GEO EAR 2114028 under the US-Ireland R&D Partnership Programme

Citation

@article{Jehanzaib2025influence,
  author = {Jehanzaib, Muhammad and Flynn, Raymond and Preece, Vicky and Lehnhart-Barnett, Hannah and Smith, Devin F. and Leonard, O. A. and Henry, Tiernan and Lyons, W. Berry and Carey, Anne E. and Croot, Peter},
  title = {The influence of plantation forest legacy on blanket bog hydrology},
  journal = {Journal of Hydrology},
  year = {2025},
  doi = {10.1016/j.jhydrol.2025.134498},
  url = {https://doi.org/10.1016/j.jhydrol.2025.134498}
}