Grant, Gordon. 1990. Hydrologic, geomorphic and aquatic habitat implications of old and new forestry. In: Pearson, Audrey; Challenger, Derek A., eds. Forests--wild and managed: differences and consequences; 1990 January 19-20; Vancouver, BC. Vancouver, BC: University of British Columbia: 35-53.
The effects of timber harvest activities on hydrology, geomorphology and fisheries have been a subject ofresearch for many decades. It still is difficult, however, to make categorical statements as to what those effects are.
There is now a growing recognition that it is not just the presence or absence of logging within a watershedthat is significant, but the overall pattern of land use through space and time that determines what effects logging willhave. This introduces an entirely new level of complexity into the problem. Intelligent stewardship of forest resourcesrequires that we attempt to address the implications of alternative harvest strategies on stream and riparian resources.
Unfortunately, we have little basis from either field observations or modeling to allow us to predict howalternative cutting scenarios will affect the input or movement of water, sediment and wood with consequences forriparian and aquatic ecosystems. In this paper a general framework is presented for analyzing hydrologic, mass erosion,and aquatic habitat effects of alternative harvest strategies and present some preliminary results of modelling the effectof such strategies. Three scales of interest are examined: individual clearcuts, approximately 100 acres in size,aggregates of units of 2,000 to 3,000 acres and multiple aggregates which are medium sized watersheds of 10,000 to20,000 acres. The effects of both minimum fragmentation and staggered-setting harvest scenarios are explored. Thepaucity of field, modelling or historical data underscores the need for a major research initiative in this area.