Type: dissertation
Abstract: Forest management is necessary to maintain water resources in watersheds, as forests are essential components of water-related ecosystems.Forest management aims to attain a balance between society, the economy, and especially the environment.Thus, sustainable forest management maintains and improves productivity, diversity, and forest ecosystems, which helps to stay healthy and provide important ecological and environmental services.Thinning is one technique of silvicultural management, which involves the selective removal of some trees to provide more space for the remaining trees to grow and improve their standing.The Japanese government promotes the thinning of managed artificial forests to improve timber quality, reduce greenhouse gas emissions, and maintain the environmental systems in headwater catchments.Previous studies have investigated the effect of thinning on hydrologic characteristics.Thinning effects on the headwater catchment can change the hydrologic response by decreasing evapotranspiration, reducing canopy interception, decreasing stemflow, and consequently increasing runoff.Many paired catchment experiment methods have examined the effects of thinning on water yields in headwater catchments.However, we have limited our efforts to the examination of long-term effects after thinning management, especially for artificially planted forests in Japan.Therefore, it is necessary to conduct long-term data analyses to clarify the effects of thinning on runoff, as forest ecosystems and the environment could change and disrupt over time.This study investigated the effect of thinning on runoff change using the observation data and hydrological model approach in the Hitachi Ohta watershed of the Forestry and iii Forest Products Research Institute located in Ibaraki Prefecture, Japan.The observation period was from 2006 to 2021, including the pre-thinning phase from January 2006 to February 2009, the post-thinning phase I from June 2009 to December 2012, and the postthinning phase II from January 2018 to December 2021.Three gauging stations were installed, including the catchment outlet HA, HB, and HV.The precipitation was monitored using the tipping bucket rain gauge at the weather station.All data were collected at tenminutes interval from 2006-2021.It was found that the catchment HA was unable to be used for long-term analysis because it was assumed to have weir leakage during the latter half of the analysis period.Therefore, it was designated that the control catchment, HB (2.50 ha), was untreated, while the treated catchment, HV (0.88 ha), was treated; trees were removed vi such as interception loss and evaporation, which could aid in the planning and mitigation of future water resources and disasters.vii
Author: Junsuk, Kannika
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W7208341799