Aquatic macroinvertebrate communities and diversity patterns in the Northern Prairie Pothole Region

The Northern Prairie Pothole Region (NPPR) of Alberta, Canada contains numerous shallow marshes that serve as important habitat for wildlife and provide many essential ecosystem services. Many of these pothole wetlands have been destroyed or degraded by agricultural activity, prompting research into their condition and management. Aquatic macroinvertebrates are frequently used as indicators of environmental condition in rivers and lakes, but their effectiveness as indicators in prairie pothole marshes is not clear. I discovered that, contrary to my predictions, macroinvertebrate richness and community composition at family-level resolution do not respond to land use. Instead, macroinvertebrate community composition in pothole marshes is structured primarily by hydroperiod, which ranges from temporary, through seasonal and semi-permanent, to permanent marsh classes. I discovered that the macroinvertebrate abundance, diversity and community composition differed significantly among wetland permanence classes, and that macroinvertebrates exhibited a nested community composition along this hydrological gradient. In other words, macroinvertebrates in temporary wetlands were not unique, but rather subsets of the taxa occupying more permanent wetlands. I also looked at macroinvertebrate functional groups (desiccation strategies, functional feeding groups and behavioural guilds). I discovered that the subset of taxa occupying temporary marshes were those that possess strategies for surviving the drawdown period, such as drought resistant stages or the ability to disperse to larger water bodies. Most functional feeding groups and behavioural guilds were more abundant in permanent wetlands; however, variation existed that was unrelated to hydroperiod and might be due to differences in aquatic vegetation. Like abundance, both alpha and gamma diversity were highest in permanent marshes; however, beta diversity was highest in temporary mashes. This suggests that alpha and gamma diversities are constrained in pothole marshes by the tolerance of taxa to periodic desiccation, in keeping with the species-sorting model of community assembly. However, in temporary marshes the assembly process is reinitiated frequently, and is therefore more strongly influenced by the stochastic aspects of dispersal. This yields a higher beta diversity or taxon turnover among temporary marshes and is in line with neutral theory. This stresses the importance of both local and regional factors in shaping biodiversity and provides insight into the community ecology of wetland macroinvertebrates and their associations with environmental variables

Assessing the Effectiveness of Tradable Landuse Rights for Biodiversity Conservation: An Application to Canada's Boreal Mixedwood Forest

Ecological reserve networks are an important strategy for conserving biodiversity. One approach to selecting reserves is to use optimization algorithms that maximize an ecological objective function subject to a total reserve area constraint. Under this approach, economic factors such as potential land values and tenure arrangements are often ignored. Tradable landuse rights are proposed as an alternative economic mechanism for selecting reserves. Under this approach economic considerations determine the spatial distribution of development and reserves are allocated to sites with the lowest development value, minimizing the cost of the reserve network. The configuration of the reserve network as well as the biodiversity outcome is determined as a residual. However cost savings can be used to increase the total amount of area in reserve and improve biodiversity outcomes. The appropriateness of this approach for regional planning is discussed in light of key uncertainties associated with biodiversity protection. A comparison of biodiversity outcomes and costs under ecological versus economic approaches is undertaken for the Boreal Forest Natural Region of Alberta, Canada. We find a significant increase in total area protected and an increase in species representation under the TLR approach.Biodiversity conservation, Reserve design, Tradable landuse rights

Caractéristiques de la forêt boréale de l'Est du Québec en relation avec la faune aviaire

Les objectifs de ce projet étaient, en premier lieu, de comprendre l’effet d’une perturbation naturelle (le feu) sur la disponibilité et l’abondance des arbres morts sur pied et sur les oiseaux résidant dans la forêt boréale non-aménagée de l’Est du Québec. En deuxième lieu, j’ai voulu comprendre l’effet des changements de structure et de composition des forêts boréales sur les communautés d’oiseaux en général et ce, le long de deux chronoséquences couvrant plus de 200 ans après feu. Mes résultats montrent que le taux de mortalité des arbres forme un patron en U caractérisé par une forte abondance de chicots dans les jeunes peuplements et dans les peuplements âgés. Ces peuplements sont caractérisés par un plus grand nombre de cavités et de signes d’alimentation de la part des oiseaux résidents. Toutefois, la richesse en espèces des oiseaux n’a que très peu varié en fonction des classes d’âge des peuplements, mais plusieurs espèces sont disparues et d’autres ont été recrutées en fonction des stades de succession. Cette étude souligne l’attention qu’il faut porter à tous les stades de succession de la forêt boréale, spécialement aux vieilles forêts qui procurent un environnement hétérogène requis par un grand nombre d’espèces.The first objective of this project was to understand the effect of natural fire disturbance on the availability and abundance of dead trees (snags) and their use by cavity-nesting birds in the northeastern part of Quebec’s unmanaged boreal forest stands. Secondly, I aimed to understand the effects of the structure and composition of the boreal forest on bird species communities along two long-term chronosequences after fire (0 to > 200 years postfire). Results show that tree mortality follow a U-shape pattern, with more snags in young and old-growth forests, where I also found more nest cavities and foraging signs. Although bird species richness did not vary greatly according to the different age classes, many species were lost and others recruited following succession stages. This study highlights the need to protect the forest at all stages, especially old-growth, which provides a heterogeneous environment suitable for several bird species

Fire, humans, and climate: modeling distribution dynamics of boreal forest waterbirds

Understanding the effects of landscape change and environmental variability on ecological processes is important for evaluating resource management policies, such as the emulation of natural forest disturbances. We analyzed time-series of detection/nondetection data using hierarchical models in a Bayesian multi-model inference framework to decompose the dynamics of species distributions into responses to environmental variability, spatial variation in habitat conditions, and population dynamics and interspecific interactions, while correcting for observation errors and variation in sampling regimes. We modeled distribution dynamics of 14 waterbird species (broadly defined, including wetland and riparian species) using data from two different breeding bird surveys collected in the Boreal Shield ecozone within Ontario, Canada. Temporal variation in species occupancy (2000 - 2006) was primarily driven by climatic variability. Only two species showed evidence of consistent temporal trends in distribution: ring-necked duck (Aythya collaris) decreased and red-winged blackbird (Agelaius phoeniceus) increased. The models had good predictive ability on independent data over time (1997 - 1999). Spatial variation in species occupancy was strongly related to the distribution of specific land cover types and habitat disturbance: fire and forest harvesting influenced occupancy more than did roads, settlements or mines. Bioclimatic and habitat heterogeneity indices and geographic coordinates exerted negligible influence on most species distributions. Estimated habitat suitability indices had good predictive ability on spatially independent data (Hudson Bay Lowlands ecozone). Additionally, we detected effects of interspecific interactions. Species responses to fire and forest harvesting were similar for 13 of 14 species; thus, forest harvesting practices in Ontario generally appeared to emulate the effects of fire for waterbirds over time scales of 10-20 years. Extrapolating to all 84 waterbird species breeding on the Ontario shield, however, suggested that up to 30 species may instead have altered (short-term) distribution dynamics due to forestry practices. Hence, natural disturbances are critical components of the ecology of the boreal forest and forest practices which aim to approximate them may succeed in allowing the maintenance of the associated species, but improved monitoring and modeling of large-scale boreal forest bird distribution dynamics is necessary to resolve existing uncertainties, especially on less-common species

Avian species richness elevational patterns in mountain peatlands

Avian research and elevation gradients have been studied extensively in the last century but there is a lack of understanding of the patterns and underlying mechanisms that drive avian species richness in mountain peatlands. This project examined the richness-elevation pattern and possible underlying mechanisms driving this pattern and the accuracy of avian species richness observed when collecting richness estimates from ARUs. Avian species richness was recorded using ARUs at 24 mountain peatland sites in the Upper Bow Basin for one hour during the dawn chorus on four days spread out between May 22nd and June 12th during the breeding season. Avian species richness in mountain peatlands displayed a plateauing pattern, cubic model, much like the plateauing patterns described by McCain in 2009 and it was determined that this pattern was a result of the effect of area on richness and the effect of Natural Subregion, a proxy variable for climate, temperature, soil and vegetation community, on richness. Also, the methods chosen to survey avian species richness provided accurate estimates of avian species richness but to get accurate estimates each survey required a larger survey effort than suggested by the literature

Cumulative Effects of Habitat Change: American Marten Habitat Selection and 30 Years of Forest Harvesting in Maine

Wildlife habitat conservation in landscapes where human activities cause chronic habitat disturbance is contingent upon developing land management strategies that minimize the effects of future habitat changes on wildlife populations. Long term studies can provide unique opportunities to understand how species respond to progressive habitat change, and such an understanding can reveal ways in which the often conflicting objectives of wildlife habitat conservation and human land use can be reconciled. Characterizing how animals respond behaviorally to habitat conditions may be a useful tool for identifying potential negative effects of disturbance before such effects impact rates of species occurrence, population demography, or other metrics indicative of population viability. The composition and configuration of Maine’s forests have been progressively and drastically altered by forest harvesting, and behavioral responses displayed by forest-associated species to the temporally cumulative effects of forest harvesting can inform forest management strategies for the conservation of Maine’s forest-associated wildlife. I evaluated the effects of forest composition and patch configuration on patterns of patch-scale habitat selection displayed by American marten (Martes americana) to identify marten responses to the cumulative and multidimensional effects of forest harvesting across a 30-year period (1989-2019). I used a spatially-explicit time series of forest harvesting and forest inventory data to classify forest types that were ecologically distinct to marten and were easily interpretable from a forest management perspective. I coupled marten habitat maps with a telemetry dataset collected from resident, non-juvenile marten to estimate patterns of marten habitat selection as they related to forest height and harvest history, the availability of different forest types within marten home ranges, and forest patch configuration using resource selection functions within an information-theoretic framework. Tall well-stocked forests (TWF) \u3e12m in height, whether mature, uncut forest or originating from previously clearcut forest, received similar selection, and selection by marten for TWF increased relative to other forest types as TWF availability decreased as a result of forest harvesting. Decreased TWF availability within marten home ranges was also associated with an increase in the relative preference marten displayed for less isolated and smaller patches of TWF. The negative effect of patch area suggests that marten increasingly utilized all available TWF patches, regardless of patch size, as this forest type became less abundant. These results indicate that marten require extensive use of TWF, which is limited when forest harvesting results in a scarcity of sparsely distributed TWF patches, and that regenerating clearcuts regain the structural characteristics selected by marten when trees reach 12m. Relative avoidance of scrub and early-successional clearcuts (height) was stronger among marten occupying home ranges where these forest types were abundant, indicating a risk or cost associated with individuals increasing their use of early-successional forest in proportion to increased availability. Partial harvests and mid-successional forest types (9m-12m tree height) received similar selection as well as extensive use by marten. These forest types were preferred relative to unforested areas, forested road edges, and scrub and early-successional clearcuts, suggesting that some harvested forest types constitute a hospitable matrix for marten. Marten responses in selection to the shape and area of hospitable matrix patches were consistent with marten use of hospitable matrix being primarily associated with movement between TWF patches, which indicates that marten selection of partial harvests and mid-successional forest is dependent on the selection of adjacent TWF patches. Patterns of marten habitat selection I documented suggest that the effects of forest harvesting on marten may be reduced if harvests are 1) positioned adjacent to multiple TWF patches, 2) do not separate TWF patches by more than 300m, and 3) are located within female marten home range sized areas (~2.5km2) with high proportions of TWF relative to the surrounding landscape. Small patches of TWF within occupied areas should not be preferentially harvested unless they are highly isolated, especially in areas with low relative TWF abundance. Additionally, minimizing road construction within areas occupied by marten, decommissioning established roads wherever future access is not an immediate management priority, and reducing the intensity of road edge maintenance will diminish the impacts of logging roads on marten. This research illustrates how animal location data collected across periods of habitat change can be used to precisely characterize species’ responses to the interrelated components of that change. Further, this study demonstrates how the components of habitat change can be quantified in ecologically meaningful ways that are also easily interpretable from a land management perspective, ensuring the translatability of results to readily implementable recommendations for habitat conservation

Development of integrated ecological standards of sustainable forest management at an operational scale

Within Canada, and internationally, an increasing demand that forests be managed to maintain all resources has led to the development of criteria and indicators of sustainable forest management. There is, however, a lack of understanding, at an operational scale, how to evaluate and compare forest management activities to ensure the sustainability of all resources. For example, nationally, many of the existing indicators are too broad to be used directly at a local scale of forest management; provincially, regulations are often too prescriptive and rigid to allow for adaptive management; and forest certification programs, often based largely on public or stake-holder opinion instead of scientific understanding, may be too local in nature to permit a comparison of operations across a biome. At an operational scale indicators must be relevant to forest activities and ecologically integrated. In order to aid decision-makers in the adaptive management necessary for sustainable forest management, two types of indicators are identified: those that are prescriptive to aid in planning forest management and those that are evaluative to be used in monitoring and suggesting improvements. An integrated approach to developing standards based on an ecosystem management paradigm is outlined for the boreal forest where the variability inherent in natural systems is used to define the limits within which forest management is ecologically sustainable. Sustainability thresholds are thus defined by ecosystem response after natural disturbances. For this exercise, standards are proposed for biodiversity, forest productivity via regeneration, soil conservation and aquatic resources. For each of these standards, planning indicators are developed for managing forest conditions while forest values are evaluated by environmental indicators, thus leading to a continuous cycle of improvement. Approaches to developing critical thresholds and corresponding prescriptions are also outlined. In all cases, the scale of evaluation is clearly related to the landscape (or FMU) level while the stand level is used for measurement purposes. In this view the forest should be managed as a whole even though forest interventions are usually undertaken at the stand level