Jim Schieck

CHANGES IN BIRD COMMUNITIES IN BOREAL MIXEDWOOD FOREST: HARVEST AND WILDFIRE EFFECTS OVER 30 YEARS

A current paradigm in conservation biology is that forest harvest practices that better approximate natural disturbance processes are more likely to conserve biodi- versity. We contrasted bird communities in three replicate stands in each of 1, 13-15, and 22-28 yr old forests following wildfire and harvest in north-central Alberta, Canada. Stands were chosen from old (>120 yr) boreal mixedwood forests having -95% of the canopy trees killed during fire, and harvested sites retaining an average of 6% of the pre-harvest canopy trees. For all age classes, postharvest sites tended to have greater bird abundance. Species composition also differed between these treatment types. Two-Way Indicator Spe- cies Analysis (TWINSPAN) identified five major ecological groupings of species that dif- fered between wildfire and harvest, and among stand ages. Correspondence analysis (CA) identified similar bird communities. Greatest differences between bird communities oc- curred immediately following disturbance, and gradual convergence of communities oc- curred throughout the first 28 yr after disturbance. Species associated with open shrub and grassland or riparian habitats were associated primarily with 1-yr postharvest stands. Three- toed Woodpeckers (Picoides tridactyla) and Black-backed Woodpeckers (P. arcticus), to- gether with other species that use snags for foraging or nesting, occurred primarily in 1- yr postwildfire stands. Convergence in avian communities was correlated with the loss of standing snags on postwildfire sites. However, differences in bird communities were ap- parent up to 28 yr following disturbance, and this lack of complete convergence has im- portant consequences for sustainable forestry practices designed to maintain biodiversity in the boreal mixedwood forest. Notably, Connecticut Warbler (Oporornis agilis), Brown Creeper (Certhia americana), Winter Wren (Troglodytes troglodytes), and American Robin (Turdus migratorius) had higher densities on postwildfire than on postharvest stands. Lin- colns Sparrow (Melospiza georgiana), Alder Flycatcher (Empidonax alnorum), Tennessee Warbler (Vermivora peregrina), Black-and-white Warbler (Mniotilta varia), American Red- start (Setophaga ruticilla), Mourning Warbler (Oporornis philadelphia), Rose-breasted Grosbeak (Pheucticus ludoviciana), Canada Warbler (Wilsonia canadensis), and Pine Siskin (Carduelis pinus) had higher densities on postharvest stands, possibly due to the greater abundance, after harvest, of larger live residual trees and a taller and more dense shrub layer. Harvest designed to approximate stand-replacing fires may require the retention of more snags than is currently practiced. New approaches to fire salvage logging are also required to ensure adequate retention of standing dead trees on the landscape.

Bird communities are affected by amount and dispersion of vegetation retained in mixedwood boreal forest harvest areas

Abstract We evaluated bird community response to type, amount, and dispersion of trees, snags, and shrubs that were retained at harvest in mixedwood boreal forests of Alberta, Canada. We also evaluated whether the degree of similarity between bird communities in harvest and old-growth areas was related to the type and amount of materials retained at harvest. We combined data from three separate studies to generate a large data set covering a wide range of cut-block structures. Birds were surveyed using point counts and line transects. Residual vegetation was surveyed partially on the ground, and partially from aerial photographs. Bird species commonly associated with parkland and open country habitats had high densities in harvest areas that contained abundant shrubs and few residual trees or snags. Within harvest areas where more trees, particularly large deciduous trees, were retained, and when those trees were retained in clumps, bird communities were more similar to those found in old-growth forests. Thus, by retaining clumps of large trees and snags in harvest areas managers may be able to create habitats that are used by old-growth forest bird species. However, for many forest birds, density was lower in cut-blocks with residual trees and snags than it was in old-growth forest. Results should be interpreted cautiously because survival and reproductive success of forest birds in cut-blocks with residual trees and snags was not determined.

Planning forwards: biodiversity research and monitoring systems for better management.

The world is currently facing a suite of complex and dynamic issues that threaten the diversity and processes sustaining humanity. Ecologists have long debated how to best study these issues, resulting in ‘friendly fire’ between different camps of thought. The most recent casualties, the Alberta Biodiversity Monitoring Institute (http://www.abmi.ca), and the PPBio Program in Brazil (http://ppbio.inpa.gov.br/Eng/public/) and Australia (http://www.griffith.edu.au/ppbio), results from Lindenmayer and Likens’ [1] supposition that these programs lack rigorous questions, a factor that has ‘undermined the credibility of long-term research and monitoring’.

A framework for adaptive monitoring of the cumulative effects of human footprint on biodiversity

Effective ecological monitoring is imperative in a human-dominated world, as our ability to manage functioning ecosystems will depend on understanding biodiversity responses to anthropogenic impacts. Yet, most monitoring efforts have either been narrowly focused on particular sites, species and stressors — thus inadequately considering the cumulative effects of multiple, interacting impacts at scales of management relevance — or too unfocused to provide specific guidance. We propose a cumulative effects monitoring framework that integrates multi-scaled surveillance of trends in biodiversity and land cover with targeted evaluation of hypothesized drivers of change. The framework is grounded in a flexible conceptual model and uses monitoring to generate and test empirical models that relate the status of diverse taxonomic groups to the nature and extent of human “footprint” and other landscape attributes. An adaptive cycle of standardized sampling, model development, and model evaluation provides a means to learn about the system and guide management. Additional benefits of the framework include standardized data on status and trend for a wide variety of biodiversity elements, spatially explicit models for regional planning and scenario evaluation, and identification of knowledge gaps for complementary research. We describe efforts to implement the framework in Alberta, Canada, through the Alberta Biodiversity Monitoring Institute, and identify key challenges to be addressed.

Completion and Updating of a Landsat-Based Land Cover Polygon Layer for Alberta, Canada

Abstract We describe the creation of a GIS vector layer of land cover polygons for the entire province of Alberta, Canada, based upon preexisting, Landsat-derived, land cover raster datasets circa 2000 that were produced by the Canadian federal government. Our novel spatial and semantic generalization algorithm begins with a morphological segmentation of the original Landsat imagery used in the classification, and then assigns classes to the segments based on the land cover labels of pixels inside the segments, using sequential rules that account for contextual and size factors in addition to class preponderance. An object-based accuracy assessment followed, which allowed us to correct issues and refine the polygon map. The enhanced map, which was later updated to circa 2010 conditions using Landsat imagery from that time period and ancillary GIS information on natural and anthropogenic disturbances, consists of 1 million land cover polygons belonging to 11 classes and has an overall accuracy of 75%. This methodology could be employed in other jurisdictions with similar raster datasets to create a more intense spatial generalization than that provided by a conventional raster to vector conversion. Résumé . Nous décrivons la création d’une couche vectorielle SIG de polygones de couverture terrestre pour toute la province de l’Alberta, au Canada, sur la base d’ensembles de données raster de la couverture terrestre produits par le gouvernement fédéral canadien et dérivés de données Landsat acquises vers l’an 2000. Notre nouvel algorithme de généralisation (spatial et sémantique) commence par une segmentation morphologique de l’imagerie Landsat originale utilisée dans le classement. Ensuite, il attribue des classes aux segments basées sur les étiquettes de couverture terrestre des pixels à l’intérieur des segments à l’aide de règles séquentielles qui tiennent compte des facteurs contextuels et des facteurs de taille, en plus de la prépondérance de la classe. Par la suite, une évaluation de la précision basée sur les objets nous a permis de corriger des problèmes et d’affiner la carte de polygones. La carte améliorée, qui a ensuite été mise à jour pour les conditions observées vers 2010 en utilisant l’imagerie Landsat de cette période et des informations connexes du SIG sur les perturbations naturelles et anthropiques, se compose d’un million de polygones de la couverture terrestre appartenant à 11 classes et elle a une précision globale de 75 %. Cette méthode pourrait être utilisée dans d’autres régions avec des jeux de données raster similaires pour créer une généralisation spatiale plus intense que celle fournie par une conversion classique raster-à-vecteur.