Pre-development and post-closure landscape dynamics in oil-sands mining : implications for assessment of reclamation and equivalent capability

Site-level evaluation of reclamation performance and residual impacts (i.e., post-reclamation effects) of large mining projects has conventionally used an approach in which landscape conditions (e.g., amounts of certain vegetation types or wildlife habitats) immediately prior to development are characterized and used as a baseline against which to assess post-reclamation conditions. This approach is static, in that it evaluates post-reclamation conditions, usually at a single time in the future, against a “snapshot” of conditions at a single pre-development time. However, many of the characteristics typically evaluated through this approach are both spatially and temporally dynamic, on both the “pre-disturbance” and post-reclamation landscape: • “pre-disturbance” – mining is almost always not the first disturbance of a landscape, which has generally been repeatedly subjected to substantial and recent perturbations such as wildfire, and thus has undergone many pre-mining cycles of disturbance and recovery; • post-reclamation – reclaimed landscapes evolve over time, and their characteristics and utility (to humans and other species) change with this evolution, which may be affected by new future cycles of disturbance and recovery. This conventional assessment conceptual model then is highly dependent on both the specific conditions existing in a project area immediately prior to industrial development, and on the future time selected for post-reclamation assessment. In this paper we argue that the broad application of this conceptual model has resulted in a simplistic understanding of landscape responses to industrial disturbances, and has contributed an arbitrary component to reclamation planning and assessment. We propose that alternative approaches (e.g., use of ecological simulation modelling) in which pre- and post-development landscape dynamics are explicitly acknowledged and accounted for are necessary to gain a more sophisticated and useful understanding of the role of mining and reclamation in the cycle of ecosystem disturbance and recovery. An example of such an approach is presented using a case study from oil-sands mining and reclamation in northeast Alberta, Canada.Non UBCUnreviewedOthe

Differences in bird species richness and abundance among three successional stages of aspen-dominated boreal forests

Birds and vegetation were surveyed in young, mature, and old aspen-dominated boreal forests in Alberta. Height and size of live trees, density of large dead trees, and volume of downed woody material increased during succession, whereas density of live trees decreased. Canopy heterogeneity had a bimodal relationship with succession: old forests had the highest, mature forests the lowest, and young forests an intermediate canopy heterogeneity. Old forests had greater bird species richness than young forests, which in turn had greater richness than mature forests. Twenty-seven, 3, and 10 bird species had their highest abundances in old, mature, and young forests, respectively. Seven bird species that nest and forage in canopy gaps and three bird species that nest and forage in large trees and snags were more abundant in young and old forests than in mature forests. Contrary to our predictions, patterns of richness and abundance for bird species that nest and forage in the canopy or in tree cavities were similar to those for bird species that nest or forage in the lower strata. Bird species preferring coniferous forests tended to be more abundant in old than in young or mature aspen-dominated forests, possibly because old aspen forests had more conifers than younger aspen forests