Ongoing Research

Predictive models of the environmental effects of riparian clear-cutting on land-water linkages in boreal forest lakes

Problem and scope

Few environmental issues in North America are as contentious as those concerning the multiple uses of resources. Forestry is the largest industry and contributor to international trade for many regions. Sport fishing can often be the largest tourism/recreational activity. The potential for disagreements in land use options is therefore profound. In particular, questions concerning the effects of forest harvesting on non-timber values are one of the most pressing environmental-economic concerns. Although the boreal forest is one of the world's largest eco-regions, little is known about how watershed alterations may impact aquatic systems there.

As a result of the Class Environmental Assessment for Timber Management in Crown Lands in Ontario, the Ontario Ministry Natural Resources (OMNR) has undertaken a broad scale "effects and effectiveness monitoring program for non-timber environmental values." Two sets of guidelines have been developed to mitigate or prevent undesirable effects of timber management on tourism/recreational uses of the Canadian Shield. A research program is underway to quantitatively assess the mechanisms through which sport fisheries may be degraded. To this end, OMNR has selected a series of small boreal lakes in north-western Ontario in which to study the effects of near-shore riparian clear-cutting.

Since 1990, many facets of the biology and chemistry of these lakes have been measured, and experimental logging took place for two of the watersheds during 1996-97. A multidisciplinary group of government scientists and land use managers are monitoring the physical, chemical, and hydrological effects of logging with emphasis on the demographics (particularly reproduction) of lake trout. My research is concerned with how dramatic changes in drainage basin land use may reduce the quantity of organic carbon supplied to the lake by the forest, and how reductions in the allochthonous food base for macroinvertebrates and forage fish will eventually influence the trout stocks. My focus is therefore on a comparison of carbon supply and utilization in experimentally cut and uncut (reference) lakes. These results will have direct application to timber management concerns for boreal forests.

Background - predictive management and experimental approach

Land use managers must be able to predict and evaluate effects of anthropogenic perturbations rather than react to observed damage; extrapolative methods are required. Recently, the need to develop predictive capabilities to move management sciences from a reactive mode to a proactive mode, with measurable benefits to human and natural systems, has been heralded as the essential requirement for aquatic resource management in the 1990s. My strategy is to develop predictive capacities that generalize from experience and therefore replace studies of each ecosystem and each new stress as if they were unique.

The present study is concerned with the short-term (1-5 yrs.) aquatic effects of experimental riparian clear-cutting and to compare these results with those from previous synoptic research by others and myself on the long-term (> 5 yrs.) repercussions of timber harvesting and wildfires on lake littoral zones. Integration of these data in the form of predictive models should provide landscape managers with proactive tools to judge objectively the proposed implications of logging practices and to minimize serious environmental consequences.

Objectives

The aim of this study is to determine the importance of the terrestrial environment as a source of energy fuelling the littoral macroinvertebrate and forage fish communities of lakes situated within experimentally manipulated watersheds on the Canadian Shield. This work includes the short-term effects of riparian clear-cutting on (a) inputs of terrestrial detritus to lakes; (b) processing of such inputs; (c) structural changes in littoral fauna as related to alterations in the light, temperature and sediment deposition of littoral regions; and (d) the relative importance of allochthonous litter inputs as food sources measured via stable isotope analysis.