Sedge Meadow Research Articles

Wetland types and wetland maps differ in ability to predict dissolved organic carbon concentrations in streams

Three categories of digital wetland maps widely available in the United States were used to develop models relating wetlands to DOC: (1) wetlands mapped by the U.S. National Wetlands Inventory (NWI) (2) wetland vegetation cover mapped by the U.S. National Land Cover Dataset (NLCD), and (3) maps of hydric soils. Data extracted from these maps for 27 headwater catchments of the Ontonagon River in northern Michigan, USA were used with DOC concentrations measured in catchment streams to develop stepwise multiple regressions based on wetland area and type. The catchments of the 27 tributaries ranged in area from 2 to 66 km 2 and wetlands constituted 10 to 53% of their area. Although all three databases provided regressions that were highly significant ( p < 0.001), the variance explained was greater for NWI maps ( R 2 = 0.75) than for NLCD ( R 2 = 0.61) or soil maps ( R 2 = 0.60). Wetland–stream relationships were strongest during September 2002, but were significant for nine out of ten dates sampled during subsequent seasons. The individual wetland type most highly correlated ( r > 0.62) with stream DOC concentrations was conifer peatland, represented on the NWI maps as Palustrine Needle-leaved Forest, the NLCD maps as woody wetland, and the soil maps as organic soils. For the NWI dataset, DOC was negatively correlated with area of palustrine emergent wetlands (i.e., sedge meadows and graminoid fens) and bog shrubs, inferring that these wetland types may be sinks for DOC. Because of the different effects of wetland vegetation types on DOC, a GIS data source such as the NWI which depicts those wetland types is superior for predicting landscape contributions to stream DOC concentrations.

THE EFFECTS OF LIVESTOCK GRAZING ON THE BOG TURTLE [GLYPTEMYS ( = CLEMMYS) MUHLENBERGII

The bog turtle Glyptemys ( = Clemmys) muhlenbergii is an inhabitant of groundwater-fed sedge meadows in the northeastern and southeastern United States. Observations of bog turtle habitats throughout the species' range demonstrate that livestock grazing has been an important factor in staving off successional processes and abating large-scale invasions by tall-growing, competitively dominant plants—many of which are exotic in origin. The demise of small-scale dairy farming over the past three decades has led to the pastoral abandonment of the majority of bog turtle habitats in the Northeast. As a consequence, habitats are being degraded by the growth of invasive flora, changes in hydrology, and loss of turtle microhabitats created by livestock. In this study we compared the number of bog turtle captures, bog turtle demographic parameters, bog turtle densities, and vegetation at sites that are currently grazed (n = 12) and at sites in which grazing had recently ceased (n = 12). This analysis demonstra...

Distribution and Habitat Use of Ross's and Lesser Snow Geese During Late Brood Rearing

ABSTRACT We assessed spatial distribution and habitat use by Ross's and lesser snow geese (Chen rossii and C. caerulescens caerulescens) during late brood rearing to begin understanding goose‐habitat interactions and monitoring key habitats around a rapidly growing nesting colony located at Karrak Lake, Nunavut, Canada. We conducted aerial surveys to count geese and georeference locations, then used Landsat Thematic Mapper satellite imagery to identify habitats associated with each flock. We observed 435 and 407 flocks and 36,287 and 32,745 birds in 1994 and 1995, respectively. Birds were somewhat uniformly distributed over the 5,000‐km2 study area, with larger aggregations occurring closer to the coast, about 70 km from the colony. We assessed habitat use using Bonferroni intervals at both the flock and individual scales. At the flock level, birds avoided lichen‐heath, used other terrestrial habitats as available, and selected freshwater. At the individual level, geese selected lowland habitats: wet sedge meadow, hummock graminoid tundra, and freshwater, which accounted for about 70% of the birds observed, and avoided upland habitats. Selection of lowland habitats is likely due to greater availability of food and easier predator avoidance compared to drier upland areas. Because most geese in our study used freshwater habitats, our results demonstrate that assessment of carrying capacity, at least in the central Arctic, must be expanded beyond the coastal salt marshes traditionally considered by researchers and managers as primary brood‐rearing habitat for mid‐continent light geese.

Assessing the potential of ammonia oxidizing bacteria to produce nitrous oxide in soils of a high arctic lowland ecosystem on Devon Island, Canada

The contribution of nitrifiers (ammonia-oxidizing bacteria (AOB)) and denitrifiers to nitrous oxide (N 2O) emission from arctic soils remains inconclusive. Based on preliminary experiments, we hypothesized that AOB are the primary producers of N 2O in a high arctic lowland ecosystem on Devon Island, Nunavut, Canada. In part 1 of the study, flux chambers were installed in a catena to determine in situ fluxes of gases (N 2O and carbon dioxide (CO 2)) from 16 June to 13 July 2004. Although fluxes were low, N 2O production occurred in the wettest area of the landscape when ammonium levels were high. As ammonium, but not nitrate, levels declined in the wet sedge meadow, N 2O emissions correspondingly decreased. In part 2, the contribution of nitrification and denitrification to N 2O production was assessed by Acetylene Inhibition Assay and 15N isotopically enriched incubations. Ammonium fertilization stimulated N 2O emissions to a greater extent than nitrate, and acetylene had a greater impact on N 2O emissions in ammonium-fertilized soils than in nitrate-amended soils. Stable isotope analysis indicated that at 50–55% water filled pore space, nitrification was the dominant (>80%) N 2O emitting process. In part 3, molecular analyses of the two N 2O producing groups indicated the both nitrifiers and denitrifiers did not differ between landforms. Our results suggest nitrifier denitrification is the dominant process occurring in these arctic soils and that the role of denitrifiers in N 2O release from arctic soils needs to be re-evaluated.

The Prairie-Wetland Vegetation Continuum in the Chicago Region of Northeastern Illinois

We conducted a floristic ordination and gradient analysis of plant communities extending from prairie through graminoid-dominated wetlands in the Chicago region of northeastern Illinois. Data represented about 450 species from 103 stands sampled across a gradient of six soil moisture classes ranging from dry to hydric, and included sand, gravel, dolomite and loam prairies, as well as fen, sedge meadow, floating mat, marsh, and bog. As found in other midwestern grassland studies, vegetation aligned most strongly along a soil moisture gradient, with individualistic species distributions forming a hierarchical continuum, and lower species richness at the dry and wet extremes of the moisture gradient. Most species were infrequent, with about 70% occurring at less than 20% frequency and present in less than five communities. Species that were more frequent within communities were also more widespread among communities, fitting the niche-based model of species distribution. Moreover, less than 20% of all species sampled were significant indicators of soil moisture gradient classes, with most representing mesic and hydric habitats. Dominant prairie grasses extended from dry to wet habitats, merging with wetland species in graminoid fen, calcareous seep and sedge meadow habitats. Hydric habitat, represented by calcareous floating mat, marsh and bog, had fewer dominant prairie species and was dominated by a wetland flora. These results provide compositional and structural models for managing and restoring vegetation across the prairie-wetland vegetation gradient of the Chicago region.

Tools for Carex revegetation in freshwater wetlands: understanding dormancy loss and germination temperature requirements

Carex is a globally distributed genus with more than 2000 species worldwide and Carex species are the characteristic vegetation of sedge meadow wetlands. In the mid-continental United States, Carex species are dominant in natural freshwater wetlands yet are slow to recolonize hydrologically restored wetlands. To aid in Carex revegetation efforts, we determined the dormancy breaking and temperature germination requirements of 12 Carex species. Seeds were cold stratified at 5/1°C for 0–6 months and then incubated in light at 5/1°C, 14/1°C, 22/8°C, 27/15°C, or 35/30°C. We found that all Carex species produced conditionally dormant seeds. The optimal temperature for germination for all but three species was 27/15°C. As is the case in other species with physiological dormancy, cold stratification increased germination percentages, broadened the temperature range suitable for germination, and increased germination rates for most species, but the magnitude of the effects varied among species. Many species germinated to 80% at 27/15°C without cold stratification and at 22/8°C with ≤1 month of stratification but required much longer stratification (up to 6 months depending on the species) to germinate to 80% at 14/1°C and 35/30°C. Our findings illustrate how a stratification pretreatment can greatly benefit Carex seed sowing efforts by triggering rapid germination to higher percentages. We recommend that cold stratification be targeted towards species with strong dormancy or used across a wider range of species when seed supplies for restoration are limiting. For Carex revegetation, establishing Carex canopies rapidly may help to prevent the invasion of undesirable species such as Phalaris arundinacea.

The importance of subsurface geology for water source and vegetation communities in Cherokee Marsh, Wisconsin

Restoration of disturbed wetland systems is an important component of wetland mitigation, yet uncertainty remains about how hydrologic processes affect biologic processes and wetlands patterns. To design more effective restoration strategies and re-establish native plant communities in disturbed wetlands, it is imperative to understand undisturbed systems. A site within Cherokee Marsh located in Madison, Wisconsin, USA, contains a relatively undisturbed area of wetland consisting of plant communities common within the prairie landscape including a fen, sedge meadow, and shallow marsh. These distinct communities are found within an area of minimal topographic relief, yet transitions from one community to the next occur over short distances. This study sought to characterize the geologic, hydrologic, and chemical gradients associated with these shifts in vegetation to gain insight into the factors controlling the spatial differences in dominant plant species, which could be critical for restoration success. Vegetation analyses revealed a transition of dominant sedge species, which appeared to correspond to changes in hydrology from a ground-water dominated to a surface-water dominated system (as determined by water isotopes). Along the same vegetation transect, subsurface coring results show a heterogeneous composition of peat and till with lateral and vertical variations in stratigraphy, which relates to variability in ground-water discharge as evidenced by hydroperiods and stable isotope composition. Applications of this type of approach throughout the glaciated terrains of the midwestern and northeastern United States and Canada can improve future wetland restoration and management.

Inspiration in Unexpected Ways

Inspiration in Unexpected Ways

Perceived Conflicts Between Pastoralism and Conservation of the Kiang Equus kiang in the Ladakh Trans-Himalaya, India

An emerging conflict with Trans-Himalayan pastoral communities in Ladakh’s Changthang Plateau threatens the conservation prospects of the kiang (Equus kiang) in India. It is locally believed that Changthang’s rangelands are overstocked with kiang, resulting in forage competition with livestock. Here, we provide a review and preliminary data on the causes of this conflict. Erosion of people’s tolerance of the kiang can be attributed to factors such as the loss of traditional pastures during an Indo-Chinese war fought in 1962, immigration of refugees from Tibet, doubling of the livestock population in about 20 years, and increasing commercialization of cashmere (pashmina) production. The perception of kiang overstocking appears misplaced, because our range-wide density estimate of 0.24 kiang km−2 (± 0.44, 95% CL) is comparable to kiang densities reported from Tibet. A catastrophic decline during the war and subsequent recovery of the kiang population apparently led to the overstocking perception in Ladakh. In the Hanle Valley, an important area for the kiang, its density was higher (0.56 km−2) although even here, we estimated the total forage consumed by kiang to be only 3–4% compared to 96–97% consumed by the large livestock population (78 km−2). Our analysis nevertheless suggests that at a localized scale, some herders do face serious forage competition from kiang in key areas such as moist sedge meadows, and thus management strategies also need to be devised at this scale. In-depth socioeconomic surveys are needed to understand the full extent of the conflicts, and herder-centered participatory resolution needs to be facilitated to ensure that a sustainable solution for livelihoods and kiang conservation is achieved.

Effect of Light on Seed Germination of Eight Wetland Carex Species

In wetland plant communities, species-specific responses to pulses of white light and to red : far-red light ratios can vary widely and influence plant emergence from the seed bank. Carex species are the characteristic plants of sedge meadows of natural prairie wetlands in mid-continental USA but are not returning to restored wetlands. Little is known about how light affects seed germination in these species-information which is necessary to predict seed bank emergence and to develop optimal revegetation practices. The effects of light on germination in eight Carex species from prairie wetlands were investigated. Non-dormant seeds of eight Carex species were used to determine the influence of light on germination by examining: (a) the ability of Carex seeds to germinate in the dark; (b) the effect of different lengths of exposures to white light on germination; (c) whether the effect of white light can be replaced by red light; and (d) whether the germination response of Carex seeds to white or red light is photoreversible by far-red light. Seeds of C. brevior and C. stipata germinated >25 % in continuous darkness. Germination responses after exposure to different lengths of white light varied widely across the eight species. Carex brevior required <15 min of white light for > or =50 % germination, while C. hystericina, C. comosa, C. granularis and C. vulpinoidea required > or =8 h. The effect of white light was replaced by red light in all species. The induction of germination after exposure to white or red light was reversed by far-red light in all species, except C. stipata. The species-specific responses to simulated field light conditions suggest that (a) the light requirements for germination contribute to the formation of persistent seed banks in these species and (b) in revegetation efforts, timing seed sowing to plant community development and avoiding cover crops will improve Carex seed germination.

How tussocks structure sedge meadow vegetation

Carex stricta dominates sedge meadows in southern Wisconsin, USA. In contrast with invasive species that dominate as monotypes, C. stricta supports a diversity of co-occurring species by forming tussocks. Concerns about diversity loss and the potential to restore species-rich tussocks led us to ask how tussocks foster high species richness and affect composition. Our study of 181 tussocks at three sites showed that tussocks structure sedge meadow vegetation by adding both surface area and micro-habitats. Tussocks, which average 15–25 cm tall, increase surface area of an otherwise flat plot by 40%. Species richness was positively correlated with tussock size, but the patterns differed among sites. At a site where water was deep, tussock height was the best predictor of richness; at two other sites, surface area and circumference were the best predictors. Micro-habitats differed in conditions and species composition: tussock tops were high in light, variable in temperature, and high in litter cover. Tussock sides had less litter but more moss; off-tussock areas tended to be aquatic. Of the 56 taxa found, 34 showed significant affinities for one or more micro-habitats. Of these, four species occurred primarily on tops, several extended from tops to lower levels, seven aquatic taxa preferred areas off-tussocks, and one species specialized in tussock sides. Over the 2004 growing season, species richness increased in an additive process, from 35 species in May to 56 in September 2004. Cover of litter and moss increased and bare surface decreased with season, but only seven of the 34 taxa with micro-site preferences expanded their distributions as the September drawdown exposed the off-tussock micro-habitat. We conclude that tussocks enhance species richness in three ways, by increasing surface area, by providing multiple micro-habitats, and by undergoing seasonal changes in composition. Our detailed data on plant-diversity support by large tussocks form a benchmark for tussock meadow conservation, as well as a target for restoration of degraded meadows.

Soil microbial and nutrient dynamics in a wet Arctic sedge meadow in late winter and early spring

Microbial activity is known to continue during the winter months in cold alpine and Arctic soils often resulting in high microbial biomass. Complex soil nutrient dynamics characterize the transition when soil temperatures approach and exceed 0 °C in spring. At the time of this transition in alphine soils microbial biomass declines dramatically together with soil pools of available nutrients. This pattern of change characterizes alpine soils at the winter–spring transition but whether a similar pattern occurs in Arctic soils, which are colder, is unclear. In this study amounts of microbial biomass and the availability of carbon (C), nitrogen (N) and phosphorus (P) for microbial and plant growth in wet peaty soils of an Arctic sedge meadow have been determined across the winter–spring boundary. The objective was to determine the likely causes of the decline in microbial biomass in relation to temperature change and nutrient availability. The pattern of soil temperature at depths of 5–15 cm can be divided into three phases: below −10 °C in late winter, from −7 to 0 °C for 7 weeks during a period of freeze–thaw cycles and above 0 °C in early spring. Peak microbial biomass and nutrient availability occurred early in the freeze–thaw phase. Subsequently, a steady decrease in inorganic N occurred, so that when soil temperatures rose above 0 °C, pools of inorganic nutrients in soils were very low. In contrast, amounts of microbial C and soluble organic C and N remained high until the end of the period of freeze–thaw cycles, when a sudden collapse occurred in soluble organic C and N and in phosphatase activity, followed by a crash in microbial biomass just prior to soil temperatures rising consistently above 0 °C. Following this, there was no large pulse of available nutrients, implying that competition for nutrients from roots results in the collapse of the microbial pool.

Light competition for invasive species control: A model of cover crop–weed competition and implications for Phalaris arundinacea control in sedge meadow wetlands

Since resource competition plays a critical role in many plant invasions, controlling invasive vegetation may require managing the supply of limiting resources. For example, lowering light availability with a cover crop might prevent invasions during community establishment in light-limited restored ecosystems. However, most cover crops evaluated for invasive species control either do not adequately suppress invasives or equally suppress desired species. To improve our ability to predict cover crop effectiveness, we use a theoretical model of plant competition to identify potential mechanisms by which cover crops might favor desired species over invasives. In addition, we consider the model's implications for controlling an invasive forage, Phalarisarundinacea, in restored sedge meadows. The model suggests that cover crops will improve the outcome of competition between desired and invasive species only when (1) desired species have lower minimum light requirements than invasive species and (2) invasive species dominance results from rapid establishment and resource preemption. Cover crops in the model favor desired species over faster-growing invasives because faster-growing invasives are positioned higher in the canopy. Invasive species higher in the canopy shade desired species more than desired species shade invasives. Consequently, by reducing invasive species biomass, cover crops give desired species a competitive advantage. The simple requirements for cover crop success in the model suggest that cover crops may be effective for invasive species control in light-limited restored ecosystems. The available information on P. arundinacea responses to shade suggests, however, that cover crops are unlikely to favor sedge meadow species over P. arundinacea.

Quantifying Early Indicators of Global Climate Change

One of the more significant voids remaining in our scientific understanding of global climate change is the relationship between climate change and the resulting changes expected in ecological communities. Because a large proportion of the North American landscape has been modified by human activities, it is difficult to assess whether ecological changes are being caused by human activities or climate change. Thus, we must look to landscapes where the modification has been less severe. One of the most pristine landscapes in North America where scientists can study natural processes is that of the Greater Yellowstone Ecosystem. Within this system some of the more sensitive habitats are the montane meadows. These habitats exist along a continuum from very dry (xeric) sagebrush meadows, to flowering (mesic) meadows, to wet (hydric) sedge meadows. Because of the relatively short growing season, species in these meadows can exhibit quick changes in distribution and abundance relative to climatic changes. My research uses satellite images and field surveys to evaluate how meadow habitats and their associated species respond to interannual changes in precipitation and soil moisture. I am examining the plant and butterfly communities to measure the response. Over 100 species of butterflies occur in this area and many are closely associated with specific types of meadows. This research is significant because it will provide an early warning system for assessing the effects of climate change. Documenting changes in montane meadows will assist in understanding how climate change may affect more highly managed areas of the globe.

Controlling Speckled Alder (Alnus incana ssp. rugosa) Invasion in a Wetland Reserve of Southern Québec

Abstract Managing invasive species in natural areas of high ecological value generally involves the selection of an appropriate control method that is cost effective while minimizing the secondary impacts of the control operation on the ecosystem. During the last decades, speckled alder (Alnus incana ssp. rugosa) has been invading wet sedge meadows of the Lac Saint-Francois National Wildlife Area (NWA), Quebec, Canada. This invasion threatens the habitat of several bird and plant species considered rare at the national and provincial levels. We evaluated effectiveness and impacts of four methods for controlling alder invasion in the wetland. As a short-term control method, controlled fire appears to be ineffective in the context of the Lac Saint-Francois NWA, as suggested by the high survival of alders in a zone previously burnt on our study site. Double-cut of the shoots aims at killing the shrubs by depleting nutrient reserves in the roots using two successive cuts during the same growing season. This m...

Relationships Between Soil Characteristics, Distribution and Restoration Potential of The Federal Threatened Eastern Prairie Fringed Orchid, Platanthera leucophaea (Nutt.) Lindl

The Federal threatened eastern prairie fringed orchid (Platanthera leucophaea) occupies prairies, sedge meadows, bogs and fens, primarily north of the Wisconsinan glacial boundary. In the Midwest, where restoration is a recovery objective, its southern distribution is thought to be limited by the transition from nutrient-rich Wisconsinan-aged soils to more acidic nutrient poor soils of Illinoian-aged glacial drift. To better understand edaphic factors affecting its distribution and potential for establishment of new populations, we analyzed soil characteristics across the range of habitats occupied by this species, as well as from unoccupied habitats on the Illinoian Till Plain. We found that P. leucophaea occupies a complex edaphic gradient in variation of % organic matter, base content and soil texture. On Wisconsinan-aged substrates, it occurs in circum-neutral base-rich organic prairie soils in Illinois and Wisconsin and in less calcareous soils with slightly higher pH and lower organic matter content in Michigan lake plain prairies. Eastern sand prairie and sedge meadow habitats on Wisconsinan-aged drift and on unglaciated soils are moderately acid and nutrient poor, while bog and fen habitats are more strongly acidic and highly organic, with no evidence for an underlying calcareous substrate. In comparison, unoccupied prairie soils on the Illinoian till plain have lower pH, % organic matter and base concentrations. These soils also have relatively high % silt content which results in comparatively low available soil moisture holding capacity. This combination of soil conditions may exceed the tolerance limits of P. leucophaea and prevent this species from occurring south of the Wisconsin glacial boundary in the Midwest. On the other extreme, calcareous fens have high pH levels as well as extremely high calcium concentrations, which may exceed the tolerance limits of this species. These findings have implications for guiding efforts to establish P. leucophaea into habitats that should be suitable for this species.

Relationships among environmental factors, vegetation zones, and species richness in a North American calcareous prairie fen

Pattern and zonation of peatland vegetation are regulated by environmental gradients, as well as by effects of biomass and competitive exclusion on distribution of species richness. The interplay of these factors has not been closely examined in calcareous prairie fens, which are isolated, species rich, calcareous peatlands in the Prairie Peninsula region of North America. We used multivariate analyses to classify vegetation and to quantify species richness in relation to substrate conditions and vegetation structure in a 23-ha calcareous prairie fen in northeast Illinois, USA. Plant assemblages formed a floristic continuum across sedge meadow, graminoid fen, calcareous seep, marl flat, and spring run vegetation, with complete dissimilarity between spring run and sedge meadow. These vegetation zones corresponded to gradients of decreasing organic content and cation exchange capacity, and increasing pH, Na, Mg, and total Ca concentrations, which reach extremes in spring run and marl flats. Species richness was unimodal across the fen gradient, fitting an expected model of low richness in vegetation either with large biomass (as shown by low light penetration in tall sedge meadow) or with environmentally harsh conditions and low biomass (shown by high light penetration in short marl flat and spring run vegetation). These biotic and abiotic factors, as well as hydrology, mediate vegetation pattern across the fen.

Pollen records and time scale for the RM core of the Zoige Basin, northeastern Qinghai-Tibetan Plateau

A continuous pollen record from the Zoige Basin in the northeastern Qinghai-Tibetan Plateau not only provides information on the vegetation and climate changes during the last two glacial/interglacial cycles, but also gives proof to establish the time scale of the upper 60 m of the RM core. Subalpine spruce-fir forests colonized the Zoige Basin during the interglacials and interstadials, implying warm and wet climate conditions. Alpine periglacial desert or dry desert may have existed during the penultimate glacial and the last glacial maxima, respectively. Alpine sedge meadow dominated the landscape during MIS 4. The MIS 3 is punctuated by a number of stadials similar to those documented in the Guliya and GISP2 ice cores, as indicated by repeated rise and fall of subalpine spruce-fir forests. Our pollen record reveals a regional climate history similar to those from the neighboring sites, including the Arabian Sea and the Guliya ice core, and thus supports the notion that the Qinghai-Tibetan Plateau acts as an important link between climatic events in the North Atlantic realm and the Asian monsoon domain.

Habitat Use by the Federally Endangered Mitchell's Satyr Butterfly (Neonympha mitchellii mitchellii) in a Michigan Prairie Fen

Mitchell's satyr (Neonympha mitchellii mitchellii) is a restricted fen species currently listed as endangered by the U.S. Fish and Wildlife Service and is considered one of the rarest butterflies in North America. The objectives of this study were to estimate population size, determine distribution within the study site and characterize habitat use for this important species. A mark-release-recapture study conducted at a prairie fen in Jackson County, Michigan, yielded a total population estimate of 1106 individuals. Most N. m. mitchellii were captured at the interface of open fen or sedge meadow and tamarack/hardwood forest within 3 m of woody vegetation. Distribution of N. m. mitchellii within the fen was clumped. The longest distances flown by males and females were 511.8 m and 344.8 m, respectively. Minimum home range values were 0.22 ha for males and 0.07 ha for females. Compared with prior studies on two populations in southwestern Michigan, these individuals flew significantly farther and had much larger population and home range sizes. This new information is critical for the conservation of the species and provides evidence that individuals may be capable of dispersing to new areas if linkages exist between isolated colonies.

FEEDING ECOLOGY OF CANADA GEESE (BRANTA CANADENSIS INTERIOR) IN SUB-ARCTIC INLAND TUNDRA DURING BROOD-REARING

Abstract The diet of adult Canada Geese (Branta canadensis interior) and their goslings was determined during the brood-rearing season in a freshwater tundra habitat using esophageal contents from 25 adult females, 27 adult males, and 59 goslings. Habitat use by geese and the availability and quality of aboveground biomass in wet sedge meadows and around ponds in lichen-heath tundra were also evaluated throughout the summer. During the first four weeks of brood-rearing, adult Canada Geese ate primarily graminoids (>65%), especially leaves of the short form of Carex aquatilis and Eriophorum spp., which had the highest nitrogen concentration (2.5–3.5%). Although graminoids were also important for goslings, they consumed a greater variety of other plant species (68%) than adults, especially in the first two weeks, possibly because of their inexperience. Late in the brood-rearing period, as the nitrogen concentration of graminoid plants declined, adults shifted to a diet composed mainly of berries (>40%, most...