MKRF Tree Species Research

The effects of forest practices on the hydrology and water balance of watersheds are under constant debate. Forest practices have for example been blamed for both floods and droughts. While some aspects of the effects of logging on streamflow are well-established and understood, others remain unclear. Krystal Chin, a MSc student in the Department of Geography working with Dr. Ilja Tromp-van Meerveld, studies the effects of vegetation on the spatial dynamics of soil moisture in a small watershed in the UBC Malcolm Knapp Research Forest near Haney, BC, approximately 50 minutes east of the SFU campus. She compares the soil moisture distribution of a clearcut and a mature forest to assess the effects of vegetation on the spatial and temporal distribution of soil moisture. Tree canopies intercept and scatter rainfall, causing spatial and temporal variability in how much rainfall reaches the ground. Trees also affect soil moisture and the soil moisture pattern through water uptake and transpiration. Understanding the effects of vegetation on the spatial characteristics of soil moisture at the hillslope and catchment scales will provide useful information to better understand the effects of trees and forest practices on the hydrology and water balance of watersheds in the BC Coast Range.

Weekly field visits consist of soil moisture measurements at more than 200 locations and measuring throughfall and stemflow amount at both hillslope and catchment scales to assess the effects of trees on intercepting rainfall. Other measurements include soil moisture at different soil depths and sapflow in selected trees. Sapflow measurements allow for the estimation of transpiration rates. This information is necessary to determine how trees respond to soil moisture changes during different seasons.

On the photo, Krystal is measuring the diameter at breast height (DBH) of a tree. Together with Sheena Spencer (a SFU Geography Undergraduate Research Student) and Marieke Duineveld (an internship student from Wageningen University) she has mapped all 558 in the forested study watershed. These measurements allow her to extract information about the tree distribution and stem density in the study watershed. This information is necessary to interpret the throughfall, stemflow and sapflow measurements.

For more information about SFU hydrology research in the Malcolm Knapp Research Forest, see: http://www.sfu.ca/~ilja/MKRF.html