Benoît Jobin

EFFECTS OF AGRICULTURAL PRACTICES ON THE FLORA OF HEDGEROWS AND WOODLAND EDGES IN SOUTHERN QUEBEC

The structure and distribution of herbaceous species were examined in cultivated fields and in adjacent habitats in light of herbicide use and tillage. The diversity and vegetation cover of the herbaceous layer of hedgerows and woodland edges were lower on sites at which herbicides had been sprayed in recent years, probably due to herbicide drift during application on adjacent fields. Herbicide use and tillage had an impact on the species composition of the cultivated fields: there was a higher proportion of annual and introduced species in cultivated fields subjected to herbicide use and tillage than in fields that were not regularly treated or tilled. The species that were found only in non-crop habitats were primarily native and perennials, few of which were weed species, whereas a high proportion of the species found only in cultivated fields were annual and introduced species, several of which were considered weeds. Key words: Woodland edge, hedgerow, herbicide, tillage, weeds, life span

Plant diversity in three types of hedgerows adjacent to cropfields

The farming landscape of eastern Canada is dotted with three main types of hedgerows: (1) natural woody, (2) planted woody and (3) herbaceous. The objective of this study was to compare the value of these habitats as a repository of plant biodiversity in agricultural areas of southern Quebec. The overall plant diversity was higher in natural hedgerows and they contained more plant species of conservation values than other hedgerow types. Plant species richness per quadrat was, however, higher in planted woody hedgerows, and together with the species composition, lead to the conclusion that planted hedgerows in their entirety consisted of an ecotone type of vegetation such as is found in field edges which usually support high plant diversity and productivity but where transient plant species predominate. Consequently, this study indicated that natural hedgerows fare better than planted hedgerows in terms of diversity of plants of conservation interest. In spite of that, planted woody hedgerows contained plant (and bird) species of some interest and should be favoured over more desolate herbaceous hedgerows. In areas where hedgerows were removed and are not re-establishing naturally, a mixture of deciduous trees and conifers should be encouraged in further windbreak planting programs so as to conciliate both the conservation and agronomic objectives. Furthermore, management practices should optimise the growth of establishing plants of conservation values.

Population trends in selected species of farmland birds in relation to recent developments in agriculture in the St. Lawrence Valley

Abstract Changes in the populations of 28 species of birds typical of farmland habitats were assessed using data from seven Breeding Bird Survey (BBS) routes surveyed in southern Quebec over the last 25 years. Aerial photographs taken in the 1960s and 1980s covering 82 stops along these routes were interpreted to evaluate changes in the rural landscape. Based on the crops grown at these stops in 1992, four types of agricultural landscapes were identified: cash crops, forage crops and pastureland, crops and livestock raising, and heterogeneous landscape. An intensive bird census of these stops in June 1992 showed that species richness and abundance are greater at stops with a heterogeneous landscape than at those characterized mainly by cash crops. Cash crops (corn, wheat, soybean) now cover more surface area than in the 1960s, whereas numerous dairy farms have disappeared over the past 25 years because of abandonment, urbanization and industrialization. These changes in the crops grown in the most productive agricultural regions of Quebec appear to be responsible for fluctuations in populations of a number of farmland species in the St. Lawrence Lowland. Many species associated with dairy farming, such as the Savannah Sparrow, Bobolink, Brown-headed Cowbird and Eastern Meadowlark, show decreasing population abundance, while other species such as the Ring-billed Gull and Rock Dove appear to be benefiting from the introduction of intensive agriculture.

Landscape changes and ecological studies in agricultural regions, Quebec, Canada

Most landscape definitions in the western world are based on soil, climatic, or physiographic features and do not integrate humans as an integral part of the landscape. We present an approach where landscape types have been delineated in southern Québec, Canada based on current land use where anthropogenic and agricultural activities are concentrated as a practical application of the holistic approach in landscape definition. Landsat-TM satellite images were classified and the 27 habitat classes were regrouped into 5 general land cover classes (cash crop, dairy farming, forest, anthropogenic, wetlands) and overlaid onto soil landscape polygons to characterize natural boundary units. Cluster analyses were used to aggregate these polygons into seven agricultural types of land scape forming a gradient from urban and high-intensity cash crop farming activities to landscapes dominated by a mosaic of agriculture and forested areas. Multivariate analyses of raw data and of socio-economic and farming practices variables were used to describe the defined types of landscape and these were projected over three established land classification systems of southern Québec (Canadian ecoregions, North American Bird Conservation Initiative regions and Corn Heat Unit regions) to compare their similarity in terms of land cover and for planning of future ecological studies. Because agricultural landscapes are highly dynamic, they are bound to undergo changes in the near future. Our landscape delineation may serve as an experimental setup where land scape dynamics and wildlife populations and community structures could be monitored. Because the information we used to delineate and characterize agricultural landscape types is readily available in other countries, our approach could easily be adapted to similar data sources under and a wide variety of landscape types.

Factors affecting predation on artificial nests in marshes

Artificial waterfowl and passerine nests containing chicken or quail eggs were used to examine the effects of breeding season date, nest concealment, and surrounding upland habitat type (high density urban, agricultural, and natural areas) on nest predation in 8 marshes in 1989 and 1990. Predation on waterfowl nests was lower than on passerine nests in agricultural marshes. Predation on waterfowl nests consistently increased seasonally in all marshes in both years, in spite of the increase in nest concealment resulting from growing vegetation. The increasing predation was likely a result of decreasing water depth that increased accessibility of waterfowl nests to terrestrial predators such as raccoons (Procyon lotor). Predation on passerine nests was generally high throughout the 2 seasons in agricultural marshes but increased seasonally in urban and natural marshes. We argue that this pattern was caused by predation by marsh wrens (Cistothorus palustris) that were breeding mostly in agricultural marshes throughout both seasons. In the natural marshes, the pattern of predation on passerine nests reflected increasing effect of mammalian predators, presumably resulting from decreasing water depth. Our results support the view that water depth plays the key role in reproductive success of marsh-nesting birds. Successful management of marsh-nesting birds thus requires maintenance of high water levels throughout the breeding season.

American Black Duck and Mallard Breeding Distribution and Habitat Relationships along a Forest-Agriculture Gradient in Southern Québec

Abstract Although the American black duck (Anas rubripes) has been designated a priority species in eastern North America, no systematic survey has been done in the agricultural lowlands of southern Québec, where the species is suspected to be relatively abundant and cohabits with the mallard (Anas platyrhynchos), often considered as a competing species. During the spring of 1998 and 1999, we surveyed breeding waterfowl in 343 4-km2 plots distributed in the lowlands of the St. Lawrence Valley and Lac-Saint-Jean, Canada, and in agricultural areas of Abitibi-Témiscamingue, Canada. American black duck densities were higher in dairy farm and forested landscapes (>39 indicated breeding pairs [IBPs]/100 km2) than in cropland landscapes (8 IBPs/100 km2). Mallard densities were similar across all landscape types (30–43 IBPs/100 km2). Habitat modeling using data derived from satellite imagery indicated that the presence of black ducks decreased with increasing areas of corn, ploughed fields, and deciduous forests, whereas it was favored in areas where topography was undulating with slopes of 10–15%. The same parameters had the opposite effect on mallard presence. The odds of black ducks being present were doubled where mallards were present, indicating that both species seem to be attracted to areas supporting adequate habitats, which contradicts the hypothesis of competition between these 2 species to explain for recent declines in the black duck population. Results of our habitat analyses support the hypothesis that habitat changes may be a primary factor leading to these declines. Dairy farm landscapes are of great importance for black ducks, and the conversion of this type of landscape toward a cropland landscape represents a threat to an important portion of the population of this species.

Using satellite imagery to assess breeding habitat availability of the endangered loggerhead shrike in Quebec

The loggerhead shrike (Lanius ludovicianus) is a grassland bird species whose preferred nesting habitat in eastern Canada is pastureland. This species has been extirpated from much of its historical range in this region, and breeding habitat loss is suspected to be an important cause of this decline. We evaluated the availability of suitable breeding habitats in Québec using satellite imagery. Because this species no longer breeds in Québec, we established habitat selection criteria from known nesting sites in the adjacent province of Ontario, from analysis of a Landsat-TM satellite image, and applied these criteria to Landsat-TM images covering southern Québec. We developed regional landscape criteria in 100 km2 plots and patch indices criteria at the pasture level. Spatial analyses were conducted to characterize plots and pastures on the basis of pasture availability and spatial distribution. Pastures suitable for nesting loggerhead shrikes were those fulfilling patch criteria at the pasture level and located in plots fulfilling regional landscape criteria. Overall, 310 out of 1700 plots located in the historical breeding range of the loggerhead shrike in Québec fulfilled landscape criteria, supporting 3988 pastures that fulfilled patch criteria. More than 500 of these pastures were visited to validate their current status. The Outaouais region would be the most suitable region for nesting loggerhead shrikes in southern Québec, where suitable breeding habitat still remains because more than two-thirds of visited sites were still pastureland, hawthorns were well-distributed in the region, and pastureland fragmentation was lowest. We conclude that the availability of breeding habitat does not limit the establishment of a breeding population of loggerhead shrike in southern Québec, as we estimated that thousands of hectares of suitable habitat still remain in that province.

Comparing weed composition in natural and planted hedgerows and in herbaceous field margins adjacent to crop fields

Hedgerows and field margins are common features of the agricultural landscape in southern Quebec. In the last decade, hedgerow establishment has been encouraged primarily for the prevention of soil erosion, though many farmers view them as reservoirs of invasive weeds and pests. In this study, we compared weed assemblages of several hedgerow types and herbaceous field margins. Ranking that takes into consideration weed abundance was clearly demonstrated: planted hedgerows > herbaceous field margins > natural woody hedgerows. The latter harboured many perennial plant species of less weedy propensity than planted hedgerows, which accommodated a larger number of weedy species. In planted hedgerows close to 50% of plants were weeds, even in their central position, although planted and natural hedgerows sheltered similar weed composition in their central parts. Likewise, most species inventoried in adjacent fields were weeds. Weeds characterising the central position of hedgerows/field margins were often speci...

Knowing, Mapping and Understanding st. Lawrence Biodiversity, with Special Emphasis on Bird Assemblages

Environment Canada and the Québec Department of the Environment, partners in the St Lawrence Vision 2000 Action Plan, set out to prepare a compendium of knowledge of the flora and fauna of the St Lawrence and to identify potential conservation sites. The resulting Portrait is an Internet site that presents the current knowledge base of the rivers ecological and biological diversity (http://lavoieverte.qc.ec.gc.ca/faune/biodiv/index.html). The Portrait provides information on over 5,000 species of flora and fauna. On the website, you will find a detailed ecological analysis of the richness, rarity and vulnerability of several broad groups of plant and animal species. Furthermore, you will find a list of species for each of the 700 survey units and a distribution map for 2,500 species recorded along the St Lawrence., in atlas form, along with a detailed conservation plan. The plan encompasses the most unique and heterogeneous landscapes of the St Lawrence, some of which have no protection at present. The Portrait provides an overview of the sites that are currently protected by public agencies and private-sector organisations and identifies new sites of interest for conserving biodiversity and protecting species at risk. This paper exposes the content of this extensive compendium on the biodiversity of the St. Lawrence. For conciseness, it presents some of the analyses conducted on birds to illustrate a few of the analytical approaches that were used. Then, the information on species richness and concentration areas for priority species of vascular plants, breeding birds and herpetofauna will serve to identify the terrestrial sites of significance for biodiversity. Finally, a similar approach having been applied to the aquatic environnement, we will conclude with a conservation plan that identifies the terrestrial and aquatic ecosystems, and the geographic sites where the most important elements of St. Lawrence biodiversity are concentrated. Our analysis of the biodiversity of the most thoroughly studied taxa of the St. Lawrence clearly shows the importance of wetlands, particularly those located at the mouths of rivers or within archipelagos or delta complexes, such as the groups of islands and channels found at both ends of the Montréal Archipelago. These aquatic landscapes are sites of intense biological production, combining in a small geographical area spawning, nursery and feeding grounds for a large number of fish species and breeding, rearing and foraging areas for aquatic birds. Variable flooding conditions, associated with seasonal flooding or daily tidal fluctuations, create a complex mosaic of wetland and aquatic habitats. Although wetlands occupy only a small area in comparison with terrestrial habitats, they support a large number of rare plant and animal species in relation to their size. At present, 10% of the vascular flora and 27% of the herpetofauna of the St. Lawrence are at risk. In the case of reptiles and amphibians, the situation is especially worrisome because nearly all of the most threatened species live in a narrow band along the river corridor. Not only is this the sector that is under the greatest pressure from human development, very little public land remains here, making it difficult to create protected areas. Increased participation by non-governmental organisations and individuals, through private stewardship arrangements, is an essential precondition for completing the network of conservation areas in this part of the St. Lawrence. Along the estuary and the Gulf, habitat integrity has not been affected as much by the expansion of Québecs human population. This is a vast territory, and sites have been identified with a view to making up for the deficiencies in the present network of protected sites in terms of representing biodiversity.

Predation on Artificial Nests in Upland Habitats Adjacent to Freshwater Marshes

Abstract Predation patterns on artificial waterfowl and passerine nests were studied in upland habitats adjacent to freshwater marshes located in urban, agricultural and natural habitats, near Ottawa, Ontario in 1989 and 1990. Nest predation on waterfowl nests did not change during the breeding season in urban and in agricultural habitats but it increased significantly in natural habitats. There were no significant differences over time of year in predation on passerine nests in any of the three types of habitats. Nest camouflage was not a factor in preventing nest destruction. Nest predation was higher on passerine nests than on waterfowl nests in urban and natural habitats but was similar in agricultural habitats. Losses of waterfowl nests were similar among habitats in both years. Passerine nests were more frequently destroyed in natural habitats than in urban and agricultural habitats. Small predators such as the blue jay (Cyanocitta cristata) and red squirrel (Tamiasciurus hudsonicus), more commonly observed in urban and natural habitats compared to agricultural habitats, would most likely explain differences in nest predation among habitats as well as differences between nest types.