Treesearch

Critical loads are a broad-scale modelling approach designed to assess the potential risk of pollutants to ecosystems. A description of the methodology for estimating critical loads (sulphur and nitrogen) for acid deposition (CL(A)) for upland forests in eastern Canada is presented, using a case study in central Ontario. In eastern Canada, CL(A) have been calculated for upland forests, with the objective of maintaining the molar ratio of base cations to aluminium in soil solution above 10. In the current approach, nitrogen (N) dynamics including N fixation, N immobilisation and denitrificat...

A rational approach to monitoring and assessment is prerequisite for sustainable management of ecosystem resources. This features innovative ways to advance the concept of monitoring ecosystem sustainability across spheres of environmental concern, natural and anthropogenic processes, and other hemispheric issues over a variety of spatial scales and resolution levels. Individuals and institutions, committed to mutual sustainability of ecosystem resources and human institutions, shared experiences and outlined a foundation for advancing the science and practice of monitoring and assessment...

American society has a general cultural bias toward controlling nature (Glover 2000) and, in particular, a strong bias for suppressing wildfire, even in wilderness (Saveland et al. 1988). Nevertheless, the Federal Wildland Fire Management Policy directs managers to "allow lightning-caused fires to play, as nearly as possible, their natural ecological role in wilderness" (FWFMP 2001). Each year, however, approximately 85% of natural fire ignitions in national forest wilderness areas are suppressed (Sexton 2004).

The regulated hydrograph of the Kootenai River between Libby Dam and Kootenay Lake has altered the natural flow regime, resulting in a significant decrease in maximum flows (60% net reduction in median 1-day annual maximum, and 77%-84% net reductions in median monthly flows for the historic peak flow months of May and June, respectively). Other key hydrologic characteristics have also been affected, such as the timing of annual extremes, and the frequency and duration of flow pulses. Moreover, Libby Dam has impeded downstream delivery of sediment from the upper 23,300 km2 of a 50,000 km2...

Black-tailed prairie dogs (Cynomys ludovicianus) historically occupied grasslands throughout much of the Great Plains and the American Southwest from Canada to Mexico (Hall 1981: 412-415). During the last 100 years this species has declined to a small fraction of its historic range and abundance because of eradication programs, loss of habitat and sylvatic plague (Yersinia pestis) (Miller et al. 1994). As more attention is focused on the plight of prairie dogs and the potential for their restoration, it becomes important to assess the compatibility of prairie dogs with ranching, the...

This paper will provide perspectives of Canada’s experiences in applying Criteria and Indicators (C&I) to measure progress towards Sustainable Forest Management (SFM) at the National, Regional (Provincial) and local levels. SFM is rooted in Bruntland’s concept of Sustainable Development and is about providing for present forest-based needs without compromising future options.

Sedimentation problems with the Middle Rio Grande have made it a subject of study for several decades for many government agencies involved in its management and maintenance. Since severe bed aggradation in the river began in the late 1800's, causing severe flooding and destroying farmland, several programs have been developed to restore the river while maintaining water quantity and quality for use downstream. Channelization works, levees, and dams were built in the early 1900's to reduce flooding, to control sediment concentrations in the river and to promote degradation of the bed....

Loose rock structures, called trincheras or rock curtains, can be constructed across streambeds to slow water flow, allowing water to seep into the ground. Soil and debris collect behind the rocks, forming a bed for vegetation.

Fuel treatments such as prescribed fire are a controversial tenet of wildfire management. Despite a well-established theoretical basis for their use, scant empirical evidence currently exists on fuel treatment effectiveness for mitigating the behavior and effects of extreme wildfire events. We report the results of a fire severity evaluation of an escaped prescribed fire that burned into an area previously treated with repeated prescribed fires. We observed significantly lower scorch heights, crown damage, and ground char in the treated area. We attribute the moderated fire severity in the...

This essay argues that an awareness of the historical relationships among land use, land tenure, and the political economy of Mongolia is essential to understanding current pastoral land use patterns and policies in Mongolia. Although pastoral land use patterns have altered over time in response to the changing political economy, mobility and flexibility remain hallmarks of sustainable grazing in this harsh and variable climate, as do the communal use and management of pasturelands. Recent changes in Mongolia’s political economy threaten the continued sustainability of Mongolian pastoral...