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Fire plays a major role in the structuring and functioning of boreal ecosystems. As peatlands are important components of boreal forests, the impact of fire upon these wetter ecosystems is increasingly studied, but with the focus on treed peatlands and Sphagnum-dominated bogs so far. Important fires occurring more frequently in the past decade in southern Northwest Territories (Canada) provide the opportunity to assess early post-fire vegetation regeneration in open rich fens (one, two, and five years post-fire) and to better understand early recovery succession. We aimed to (i) evaluate whether and how open rich fens are affected by fire, and (ii) describe short-term vegetation regeneration for both bryophytes and vascular species. A shift was observed between pioneer bryophytes and brown mosses between the second and fifth year post-fire. Vascular plants, especially slow-growing species and the ones reproducing mainly by seeds, recovered partially. The first bryophyte species recovering were pioneer species adapted to colonize burned environments such as Marchantia polymorpha L. or Ceratodon purpureus (Hedw.) Brid. For vascular plant species, the ones previously present and able to regrow rapidly from unburned plant structures (base of tussocks, rhizomes, roots) were represented by species like Betula glandulosa Michx. or Carex aquatilis Wahlenb. The wetter conditions and lower fuel availability of fen depressional biotopes were important factors controlling the resistance and regeneration of species associated with them. Key words: peatland, fen, fire, regeneration, vegetation, succession. Le feu joue un rôle majeur dans la structuration et le fonctionnement des écosystèmes boréaux. Comme les tourbières sont des composantes importantes des forêts boréales, l'impact du feu sur ces écosystèmes plus humides est de plus en plus étudié, mais jusqu'à présent, on s'est surtout concentré sur les tourbières boisées et les tourbières dominées par les sphaignes. Les incendies importants qui se sont produits plus fréquemment au cours de la dernière décennie dans le sud des Territoires du Nord-Ouest (Canada) offrent l'occasion d'évaluer la régénération de la végétation après un feu dans des fens riches ouverts (un, deux et cinq ans post-feu) et de mieux comprendre les processus de début de succession. Les objectifs de cette étude étaient les suivants : (i) évaluer si et comment les fens riches ouverts sont affectés par le feu et (ii) décrire la régénération de la végétation à court terme, tant pour les bryophytes que pour les espèces vasculaires. Un changement de dominance a été observé entre les bryophytes pionnières et les mousses brunes entre la deuxième et la cinquième année suivant le feu. Les plantes vasculaires, particulièrement les espèces à croissance lente et se reproduisant principalement par graines, se sont partiellement rétablies dans les fens brûlés étudiés. Les premières espèces qui se sont rétablies après le feu étaient soit des espèces pionnières adaptées à la colonisation d'environnements difficiles, comme le Marchantia polymorpha L. ou Ceratodon purpureus (Hedw.) Brid. Pour les espèces vasculaires, celles qui étaient déjà présentes et capables de repousser rapidement à partir de structures non brûlées (base de touradons, rhizomes, racines) étaient représentées par des espèces comme Betula glandulosa Michx. ou Carex aquatilis Wahlenb. Les conditions plus humides et la plus faible disponibilité en combustible des dépressions étaient des facteurs importants contrôlant la résistance et la régénération des espèces qui leur sont associées. Mots-clés : tourbière, fen, feu, régénération, végétation, succession., Introduction Fire is a key disturbance to boreal ecosystems, shaping their landscape diversity, energy flow, and biogeo-chemical cycle. It is estimated that around two million hectares (Mha) of forest burns [...]

As a rise in sea level is expected with climate change, peat-extracted peatlands located in coastal zones are more vulnerable to saltwater intrusion. Seawater contamination may prevent revegetation of typical bog species (e.g., Sphagnum, ericaceous shrubs) generally intolerant to saline conditions. Spontaneous revegetation was studied in a 27-year post-extracted bog that has been contaminated with seawater in New Brunswick (Eastern Canada). This study aimed (i) to evaluate spontaneous plant regeneration on saline but still acidic, organic soil; and (ii) to relate the recolonized vegetation patterns to the main environmental conditions. Of the seven plant communities found in the sea-contaminated bog, none were typical of bogs, and Sphagnum mosses were poorly represented. Plants communities and chemical properties were rather representative of salt marsh ecosystems (i.e., Carex paleacea, Sporobolus michauxianus, Empetrum nigrum, Myrica gale; neutral pH and nutrient-rich, namely P, Mg, and N[H.sup.+.sub.4]). Areas with low levels of spontaneous revegetation were associated with harsh chemical conditions (i.e., acid pH, high electrical conductivity, and nutrient-poor). Considering the aggravating factors that will persist with climate change, restoration of coastal bogs contaminated with seawater should aim to re-establish salt marsh ecosystems, given that spontaneous revegetation patterns and chemical conditions clearly do not allow the establishment of bog plant communities. Key words: peatland restoration, salt marsh, climate change, seawater contamination, spontaneous revegetation. Avec la montee du niveau des mers prevue avec les changements climatiques, les tourbieres extraites en zone cotiere sont vulnerables a l'intrusion d'eau salee. La contamination par l'eau salee peut nuire a la recolonisation par les plantes typiques des bogs (p. ex. : sphaignes, ericacees) generalement intolerantes aux conditions salines. La recolonisation vegetale spontanee a ete etudiee dans un bog ou les activites d'extraction de la tourbe ont cesse 27 ans auparavant et qui a ete contamine par l'eau de mer a travers le temps, au Nouveau-Brunswick (Est du Canada). Cette etude visait (i) a evaluer la regeneration vegetale sur des sols organiques sales, mais toujours acides; et (ii) a etablir un lien entre la recolonisation des plantes et les conditions environnementales, notamment les proprietes chimiques du sol. Des sept communautes de plantes retrouvees dans la tourbiere contaminee par l'eau de mer, aucune n'etait typique des bogs et les sphaignes y etaient peu presentes. Les communautes vegetales et les proprietes chimiques etaient plutot representatives d'un ecosysteme de marais sale (c.-a-d., Carex paleacea, Sporobolus michauxianus, Myrica gale; pH neutre et riche en elements nutritifs, notamment P, Mg et N[H.sup.+.sub.4]). Une faible recolonisation spontanee etait associee avec des conditions chimiques arides (c.-a-d., pH acide, conductivite electrique elevee, faible contenu en elements nutritifs). Considerant les facteurs aggravants qui persisteront avec les changements climatiques, la restauration des tourbieres cotieres contaminees par l'eau salee comme mesure de gestion adaptative devrait viser a retablir un marais sale, puisque la vegetalisation spontanee et les conditions chimiques ne permettent manifestement pas le retablissement de plantes typiques des tourbieres. Mots-cles: restauration de tourbieres, marais sale, changement climatique, contamination par l'eau de mer, vegetalisation spontanee., Introduction An increase in sea level and increased frequency and (or) intensity of extreme events, such as storm surges, are expected with climate change (IPCC 2014). These are recognized to [...]

Northern peatlands are sinks for atmospheric carbon (C), but peat extraction converts these ecosystems to C sources. Due to a dry regional climate, undisturbed bog peatlands in western Canada often have a tree cover of Picea mariana (Mill.) B.S.P. Thus, a coniferous forest plantation may be an appropriate land use for cutover peatlands. This study determined the effect of a 7-year-old P. mariana plantation on C balance of a cutover peatland. We measured C stored in P. mariana biomass and carbon dioxide (C[O.sub.2]) and methane (C[H.sub.4]) fluxes from bare peat at each of four fertilizer doses. Carbon stored in biomass of Betula papyrifera (Marsh.) that had spontaneously colonized the postfertilized site was also determined. Given that the water table remained very deep and that the sphagnum moss--ericaceous shrub peat- accumulating vegetation was not present, the site remained a source of C when only the planted P. mariana trees were considered, primarily in the form of C[O.sub.2] emissions by soil respiration. However, C accumulation in trees, including B. papyrifera biomass, resulted in a net C sink in fertilized plots. Results from this study indicate that tree plantations on cutover peatland may be a suitable land-management strategy on sites difficult to effectively rewet. Key words: carbon dioxide, peatland restoration, forest plantation, methane, soil organic matter. Les tourbieres nordiques sont des puits de carbone (C) atmospherique mais l'extraction de la tourbe convertit ces ecosystemes en source de C. A cause d'un climat regional sec, les tourbieres ombrotrophes non perturbees de l'ouest du Canada ont souvent un couvert arborescent de Picea mariana (Mill.) B.S.P. Par consequent, la plantation de forets de conifere peut constituer une utilisation appropriee des terres dans le cas des tourbieres qui ont subi une coupe. Cette etude a examine l'effet d'une plantation de P. mariana agee de 7 ans sur le bilan du C dans une tourbiere qui a ete coupee. Nous avons mesure le C emmagasine dans la biomasse de P. mariana ainsi que les flux de dioxyde de carbone (C[O.sub.2]) et de methane (C[H.sub.4]) dans la tourbe denudee pour chacune de quatre doses de fertilisant. Le carbone emmagasine dans la biomasse de Betula papyrifera Marsh., qui avait spontanement colonise le site apres une fertilisation, a egalement ete mesure. Etant donne que la nappe phreatique est demeuree tres profonde, et qu'il n'y avait pas de vegetation, mousse de sphaigne et ericacees arbustifs, qui permettait d'accumuler de la tourbe, le site est demeure une source de C lorsqu'on tenait compte seulement des tiges de P. mariana, surtout sous forme d'emissions de C[O.sub.2] provenant de la respiration du sol. Cependant, l'accumulation du C dans les arbres, incluant la biomasse de B. papyrifera, se traduisait par un puits net de C dans les places echantillons fertilisees. Les resultats de cette etude indiquent que la plantation d'arbres dans les tourbieres qui ont ete coupees peut constituer une strategie d'amenagement appropriee des terres pour les sites qui sont effectivement difficiles a rehumidifier. [Traduit par la Redaction] Mots-cles: dioxyde de carbone, restauration des tourbieres, plantation forestiere, methane, matiere organique du sol., Introduction When a peatland is used for commercial peat extraction, vegetation is removed and open ditches are installed to dry the land. Drainage of peatland and extraction of peat leads [...]

Abstract: Choosing past and present-day indicators could strengthen the reference ecosystem used for ecological restoration projects. Based on the paleoecological analysis of four peat cores and the characterization of 13 [...]

Abstract: We have developed an approach to restore bogs after peat extraction, but, when sedge-peat layers are exposed, the minerotrophic remnant peat conditions require restoration towards a fen ecosystem. Three [...]

Plant colonization after gravel extraction for road construction is slow and is often considered to be primary succession. The goal of this study was to identify the plant communities that spontaneously colonized borrow pits located in boreal climate zones and to assess how environmental variables influenced this colonization process. It also helped identifying potential combinations of plants to use as well as environmental factors to improve to restore borrow pits. A total of 505 plots were inventoried in 117 borrow pits located in the boreal forest highlands 120 km northeast of Quebec City, Quebec, Canada (Parc national des Grands Jardins). Species cover was visually estimated for different plant communities within each borrow pit where slope and soil characteristics were also evaluated. We used multivariate analyses, including clustering, redundancy, and regression tree analyses. The borrow pits studied were undergoing primary succession processes decades after abandonment. The main pioneer species were bryophytes and lichens. Soil water content and soil physicochemistry had the greatest influence on the natural colonization of borrow pits. We observed that, based on the prevailing conditions, the bryophytes Polytrichum piliferum Hedw. and Niphotrichum canescens (Hedw.) Bednarek-Ochyra & Ochyra, lichens of the genus Stereocaulon, and the lichen Trapeliopsis granulosa (Hoffm.) Lumbsch could potentially act as nurse species and could initiate the restoration of borrow pits located in boreal forests. Key words: roadside, road construction, site rehabilitation, spontaneous regeneration, restoration. Les processus de colonisation vegetale dans les sites utilises pour l'extraction du gravier pour la construction des routes est lent et ressemble a la succession primaire. Cette etude visait a identifier les communautes vegetales qui colonisaient spontanement les bancs d'emprunts soumis a un climat boreal et a evaluer le role des variables environnementales lors du processus de colonisation. Elle a aussi aide a identifier des combinaisons d'especes a utiliser et les contraintes a reprimer afin de restaurer les bancs d'emprunt. Un total de 505 releves de vegetation ont ete effectues dans 117 bancs d'emprunt situes dans les hauts plateaux de la foret boreale, a 120 km a au nord-est de Quebec, Quebec, Canada (Parc national des Grands Jardins). Le recouvrement de chaque espece a ete evalue visuellement pour toutes les communautes dans chacun des bancs d'emprunt. Les caracteristiques de la pente et du substrat ont ete evaluees. Des analyses de groupement, de redondance et d'arbre de regression multivariables ont ete effectuees. Nos resultats montrent que les bancs d'emprunt sont soumis a des processus de succession primaire plusieurs decennies apres leur abandon. Les principaux colonisateurs primaires des bancs d'emprunt sont les bryophytes et les lichens. La physicochimie et la quantite d'eau du sol sont les variables qui influencent le plus le processus de colonisation. Nous avons observe que, selon les conditions environnementales, les bryophytes Polytrichum piliferum Hedw. et Niphotrichum canescens (Hedw.) Bednarek-Ochyra & Ochyra, les lichens du genre Stereocaulon et le lichen Trapeliopsis granulosa (Hoffm.) Lumbsch pourraient potentiellement faciliter la succession afin d'initier la restauration des bancs d'emprunt situes dans les forets boreales. Mots-cles: bord de route, construction de route, rehabilitation, regeneration spontanee, restauration., Introduction Large quantities of gravel and sand are required for road construction. In many cases, these granulates are extracted from glacial deposits adjacent to future road courses, forming borrow pits. [...]

We conducted a fertilization experiment in polygon fens that were grazed by Greater Snow Geese on Bylot Is land (Canadian Arctic) to determine whether mosses can interfere with nutrient cycling and thereby prevent a direct fertilizing effect of herbivore faeces on vascular plants. We measured the effects of nitrogen (N), phosphorus (P), and faecal addition on growth parameters and nutrient content of graminoids and mosses over a 2 year period. Growth and nutrient content of graminoids were enhanced only for high levels of N addition (5 g x [m.sup.2] per season), and showed little response to P addition. Although the growth of mosses showed a slight response to N or P addition, it is primarily nutrient content that was generally enhanced at all levels of fertilization. In many cases, stronger responses were detected when N and P were applied in combination, rather than singly. Addition of goose droppings had no effect on any measured parameters. Our results suggest that bryophytes act as a natural barrier by absorbing nutrients from external additions, thus blocking the access of highly assimilable nutrients to graminoid plant roots. At increased levels of N addition, bryophytes were apparently saturated so the nutrient surplus leached down to roots and was thus available for graminoid plant growth. The presence of a thick moss layer likely explains why the deposition of faeces by herbivores such as geese has no effect on graminoid growth in arctic polygon fens. Key words: fertilization, moss carpet layer, nutrient cycling, plant-herbivore interactions, polygon fens, Snow Goose. Nous avons realise une experience de fertilisation dans les polygones de tourbe broutes par la Grande oie des neiges sur l'Ile Bylot (arctique canadien) pour determiner si les mousses prevent modifier le cycle des nutriments et ainsi empecher un effet fertilisant des herbivores sur les plantes vasculaires. Nous avons mesure les effecs d'ajouts d'azote, de phosphore et de feces d'oie sur les parameters de croissance et le contenu en nutriments des graminoides et des mousses apres 2 annees de fertilisation. La croissance et le contenu en nutriments des graminoides ont augmente seulement en re ponse aux ajouts eleves d'azote (5 g x [m.sup.2] par season) et ont montre une faible reponse aux ajouts de phosphore. Meme si la croissance des mousses a ete legerement influencee par les ajouts d'azote ou de phosphore, c'est surtout leur contenu en nutriments qui a generalement augmente sous tous les niveaux de fertilisation. Souvent, une reponse plus importante a ete detectee lorsque l'azote et le phosphore etaient ajoutes en combination. L'addition de feces n'a eu d'effet sur aucun para metre. Nos resultats suggerent que les bryophytes agissent comme une barriere naturelle en absorbant les nutriments prove nant de la fertilisation, bloquant ainsi l'acces des racines des plantes vasculaires a des nutriments tres assimilables. Sous des ajouts eleves d'azote, les bryophytes sont apparemment saturees et le surplus de nutriments peut etre lessive jusqu'aux racines et devenir disponible pour la croissance des graminoides. La presence d'un epais tapis de mousses peut expliquer pourquoi la deposition de feces par des herbivores comme les oies n'a pas d'effet sur la croissance des graminoides dans les polygones de tourbe de l'Arctique. Mots-cles : fertilisation, tapis de mousses, cycle des nutriments, interactions plantes-herbivores, polygones de tourbe, Oie des neiges., Introduction Plant growth in the Arctic is constrained by low radiation, precipitation, and nutrient availability, and by the short duration of the snow-free period. In turn, the low nutrient avail [...]

We examined the role of trophic interactions in structuring a high arctic tundra community characterized by a large breeding colony of greater snow geese (Chen caerulescens atlantica). According to the exploitation ecosystem hypothesis of Oksanen et al. (1981), food chains are controlled by top-down interactions. However, because the arctic primary productivity is low, herbivore populations are too small to support functional predator populations and these communities should thus be dominated by the plant/herbivore trophic-level interaction. Since 1990, we have been monitoring annual abundance and productivity of geese, the impact of goose grazing, predator abundance (mostly arctic foxes, Alopex lagopus) and the abundance of lemmings, the other significant herbivore in this community, on Bylot Island, Nunavut, Canada. Goose grazing consistently removed a significant proportion of the standing crop (~40%) in tundra wetlands every year. Grazing changed plant community composition and reduced the production of grasses and sedges to a low-level equilibrium compared to the situation where the presence of geese had been removed. Lemming cyclic fluctuations were strong and affected fox reproduction. Fox predation on goose eggs was severe and generated marked annual variation in goose productivity. Predation intensity on geese was closely related to the lemming cycle, a consequence of an indirect interaction between lemming and geese via shared predators. We conclude that, contrary to the exploitation ecosystem hypothesis, both the plant/herbivore and predator/prey interactions are significant in this arctic community.

Previous studies in tundra ecology provide evidence for sensitivity of the vegetation-soil complex to climate. Short-term experiments ([less than or equal to] 10 yr) suggest that climate change may have a decade-scale effect on soil moisture, decomposition and nutrient availability, plant phenology, and plant growth. In contrast, there exists little evidence to confirm or refute the role of climate in structuring tundra vegetation over longer time scales (10 to 1000 yr). This study accordingly examines ~1500 yr in the stratigraphy of two permafrost sediment cores from a High Arctic, polygon-patterned, graminoid-moss tundra. Present-day bryophyte-environment relationships are quantified, and the radiocarbon-dated macrofossil record of bryophytes is used to reconstruct past changes in soil moisture. The paleoecological record is characterized by pronounced variability during polygon development. As the hydrology of tundra polygons is controlled by known climatic and geomorphologic mechanisms, the recurrent development of polygon vegetation (cf. hydrologic change) is compared to an independent paleoclimatic proxy for net radiation ([R.sub.n]). Based on this comparison, the vegetation provides support for a pronounced shift to colder and wetter conditions during the Little Ice Age (~300-465 yr BP), though the long-term response to past climate change is otherwise equivocal. We suggest accordingly that autogenic geomorphologic-vegetation processes may have been generally more important than climate in the long-term development of the polygon-patterned wetland examined. A framework for such processes is presented. We caution that previous research to simulate and describe the effects of climate warming might not have properly accounted for the dynamic role of geomorphology in regulating tundra microclimate. Key words: bryophytes; climate change; High Arctic wetland; Little Ice Age; paleohydrology; tundra polygons.

1 The response of plants to herbivory usually varies with the grazing regime experienced. We investigated (i) if the timing and frequency of grazing affected plant growth, (ii) if faeces deposition by herbivores stimulated plant growth, and (iii) if grazing affected the total nonstructural carbohydrate (TNC) reserves in the below-ground vegetation of two arctic graminoids, Dupontia fisheri and Eriophorum scheuchzeri. 2 This study was conducted in polygon fens exposed to intense summer grazing by greater snow geese (Chen caerulescens atlantica) on Bylot Island (73 [degrees] N) in the Canadian High Arctic. We manipulated the frequency (once or three times) and the timing (early, mid or late in the season) of grazing and faeces deposition in controlled grazing trials using captive goslings. 3 Although ungrazed plants were taller than grazed ones at the end of the season, data on cumulative tiller elongation (net above-ground height production) showed that plants grazed once or three times produced new foliage after each defoliation in both species. However, neither grazing (presence or absence) nor its frequency affected the net above-ground primary production (NAPP) or the number of tillers at the end of the summer. Nitrogen concentration was highest in plants grazed three times, intermediate in those grazed once, and lowest in ungrazed plants. 4 Timing of grazing and presence of goose faeces with or without grazing had no effect on plant growth. 5 Eriophorum plants grazed three times had less TNC in their below-ground tissues than ungrazed plants, and the trend was similar in Dupontia. 6 Dupontia and Eriophorum were able to compensate for leaves lost to grazing and to maintain production at a level similar to ungrazed plants, but at some cost (reduced below-ground reserves). The absence of an effect of faeces on plant growth may explain the absence of a positive effect of grazing on NAPP (i.e. overcompensation) in this ecosystem. Keywords: Arctic, below-ground reserve, Dupontia, Eriophorum, production, snow geese

Annual linear growth, net primary production, and decomposition of Sphagnum fuscum, Sphagnum magellanicum, and Sphagnum angustifolium were measured under experimental acidification and natural conditions in a poor fen at the Experimental Lakes Area (ELA), Ontario, Canada. Acidification increased growth and production of most species (2 out of 3 in the oligotrophic zone, and 2 out of 3 in the minerotrophic zone) in the first 2 yr. After 2-3 yr of artificial acidification, growth and production were not stimulated to the same extent in experimental areas as in earlier years. After 4 yr, growth and production in the experimental area declined so that they were the same as controls for 4 of the 6 treatments. Therefore, the effect of the acid treatment changes over the years. With 4 yr of simulated 'acid rain,' decomposition was unaffected. Our results suggest that the fertilizing effect of [SO.sub.4.sup.2-] and [NO.sub.3.sup.-] in North American acid precipitation as suggested previously in the literature is a very short-term one, at least for this type of peatland. Under natural conditions, in the oligotrophic central zone of mire 239, production for hollow species was somewhat greater than for hummock species for the 4 yr studied. Since the decomposition rate ratio between hummock-top, mid-hummock, and hollow species is roughly in the ratio 7:9:13, the rate of peat accumulation should be higher in hummocks. Hence hummocks appear to be maintained in this poor fen due to low decomposition rates rather than relatively high production. For 3 of the 4 yr studied (1985-1987) in the minerotrophic edge zone, hummock production (303, 175, and 156 [g.m.sup.-2].[yr.sup.-1], respectively) was greater than hollow (198, 100, and 97 [g.m.sup.-2].[yr.sup.-1]) and mid-hummock production (103, 59, and 52 [g.m.sup.-2].[yr.sup.-1]). The relative decomposition rates of the species had the same ratio as in the oligotrophic zone. Thus hummocks appear to be expanding in this minerotrophic edge zone at a faster rate than in the oligotrophic zone.

1 The response of peat-rich permafrost soils to human-induced climate change may be especially important in modifying the global C-flux. We examined the Holocene developmental record of a High Arctic peat-forming wetland to investigate its sensitivity to past climate change and aid understanding of the likely effects of future climate warming on high-latitude ecosystems. 2 The microhabitat of mosses was quantified in the present-day polygon-complex at Bylot Island (73[degrees] N, 80[degrees] W) and used to interpret the radiocarbon-dated macrofossil record of three cores, comprising c. 3500 years of wetland development. Recurrent wet and dry phases in the reconstructed palaeohydrological record indicated pronounced temporal variability. Wet and dry phases were compared between cores and with palaeoclimatic proxy values, measured as percentage melt and ?18O in nearby ice cores. 3 Periodic wet and dry phases appear unrelated to past climate over c. 50% of the combined stratigraphic records, and are attributable instead to geomorphological mechanisms. At other times, association of wet and dry phases with significantly lower and higher values of percentage melt and ?18O indicate a possible effect of past climate change on polygon hydrology and vegetation, although inconsistencies between cores suggest that local geomorphological processes continued to modify a regional climatic effect. However, during a period incorporating the Little Ice Age (c. 305u530 cal. years bp), reconstructed moisture and vegetation change is pronounced and consistent among all three cores. 4 The results provide strong evidence for the sensitivity of a High Arctic terrestrial ecosystem to past climate change during the Holocene. The estimated magnitude of changes in soil moisture between wet and dry phases is sufficient to imply recurrent shifts in wetland function, periodically impacted upon by pronounced climatic variability, although controlled principally by autogenic processes. The structure and function of such wetlands may therefore be susceptible to predicted, human-induced climate warming.

Research is presented concerning the nutritional carrying capacity of wetland habitats on Bylot Island, Nunavut, Canada which are used as breeding grounds by the Greater Snow Goose. The growth in the birds' population is discussed.