Foraging characteristics of Canada geese on the Nisutlin River delta, Yukon

1987 ◽  
Vol 65 (10) ◽  
pp. 2358-2361 ◽  
Author(s):  
T. S. Coleman ◽  
D. A. Boag
Keyword(s):  
Dominant Species ◽  
Food Selection ◽  
Yukon Territory ◽  
Water Levels ◽  
River Delta ◽  
Intermediate Water ◽  
Canada Geese ◽  
Plant Associations ◽  
South Central ◽  
Eleocharis Palustris

Food selection by Canada geese (Branta canadensis), staging in the autumn on the Nisutlin River delta in the south central Yukon Territory, was investigated between August and October of 1981, 1982, and 1983. Three distinct plant associations were used by the foraging geese: an aquatic association in which rhizomes of Potamogeton richardsonii, the dominant species, were eaten; a terrestrial and more vegetatively complex association in which Equisetum palustre was the main plant taken; and an association of almost pure stands of Equisetum fluviatile in wet depressions behind old river levees. Availability of these feeding zones depended on water levels on the delta. When water levels were low (October 1982), all feeding zones were available, yet the geese fed almost entirely in the Potamogeton zone, indicating a preference for that zone. At intermediate water levels, Potamogeton richardsonii was no longer available and the geese grazed on the complex vegetative zone, taking Equisetum palustre, Ranunculus reptans, and Eleocharis palustris in the ratio of their relative availability (85:10:5). Only when water levels were high did the geese graze exclusively in the Equisetum fluviatile zone, the least preferred.

Numerical classification of French vegetation of Carici caryophylleae – Genistetea lobelii J.-C. Klein 1972

2021 ◽  
Vol 42 ◽  
pp. e68062
Author(s):  
Pauline Delbosc ◽  
Mathieu Le Dez ◽  
Jean-Bernard Bouzillé ◽  
Kevin Cianfaglione ◽  
Frédéric Bioret
Keyword(s):  
Expert System ◽  
Dominant Species ◽  
Numerical Classification ◽  
Distribution Map ◽  
Diagnostic Species ◽  
Plant Associations ◽  
Formal Definitions ◽  
Twinspan Classification ◽  
New Association

Carici-Genistetea lobelii Klein 1972 corresponds to cyrno-sardinian oromediterranean cushion scrub and related grasslands. In France, this class is only present in Corsica and the syntaxonomic scheme is debated among phytosociologists. The aim of this paper is to highlight the main plant associations of Carici-Genistetea lobelii Klein 1972 and to define the diagnostic species for each phytosociological unit. We compiled 519 vegetation plots and we applied EuropeanVegetationChecklist expert system for the classes of European vegetation to retain only vegetation plots belonging to Carici-Genistetea lobelii. We obtained a dataset with 189 vegetation plots and we classified them with Modified TWINSPAN classification. Our analyses recognized 6 plant associations and 3 sub-associations already described in the literature; and to describe a new alliance corresponding to the supra-mediterranean vegetations (Genistion salzmannii), a new association (Brimeuro fastigiatae-Juniperetum nanae) and its sub-association (alnetosum suaveolentis). For each of them, we identified diagnostic, constant and dominant species and produced their distribution map. Formal definitions were then written for each phytosociological unit (from subassociation to class) and grouped in an expert system to automatically classify the vegetations of Carici-Genistetea lobelii.

scholarly journals Partitioning CO<sub>2</sub> net ecosystem exchange fluxes on the microsite scale in the Lena River Delta, Siberia

2018 ◽  
Author(s):  
Tim Eckhardt ◽  
Christian Knoblauch ◽  
Lars Kutzbach ◽  
Gillian Simpson ◽  
Evgeny Abakumov ◽  
...  
Keyword(s):  
Water Table ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Arctic Tundra ◽  
High Water ◽  
Water Levels ◽  
River Delta ◽  
Lena River ◽  
Hydrological Conditions ◽  
Lena River Delta

Abstract. Arctic tundra ecosystems are currently facing rates of amplified climate change. This is critical as these ecosystems store significant amounts of carbon in their soils, which can be mineralized to CO2 and CH4 and released to the atmosphere. To understand how the CO2 net ecosystem exchange (NEE) fluxes will react to changing climatic conditions, it is necessary to understand the individual responses of the physiological processes contributing to CO2 NEE. Therefore, this study aimed: (i) to partition NEE fluxes at the soil-plant-atmosphere interface in an arctic tundra ecosystem; and (ii) to identify the main environmental drivers of these fluxes. Hereby, the NEE fluxes were partitioned into gross primary productivity (GPP) and ecosystem respiration (Reco) and further into autotrophic (RA) and heterotrophic respiration (RH). The study examined flux data collected during the growing season in 2015 using closed chamber measurements in a polygonal tundra landscape in the Lena River Delta, northeastern Siberia. The measured fluxes on the microscale (1 m–10 m) were used to model the NEE, GPP, Reco, RH, RA and net ecosystem production (NPP) over the growing season. Here, for the first time, the differing response of in situ measured RA and RH fluxes from permafrost-affected soils to hydrological conditions have been examined. It was shown that low RA fluxes are associated to a high water table, most likely due to the submersion of mosses, while an effect of water table fluctuations on RH fluxes was not observed. Furthermore, this work found the polygonal tundra in the Lena River Delta to be a sink for atmospheric CO2 during the growing season. Spatial heterogeneity was apparent with the net CO2 uptake at a wet, depressed polygon center being more than twice as high as that measured at a drier polygon rim. In addition to higher GPP fluxes, the differences in NEE between the two microsites were caused by lower Reco fluxes at the center compared to the rim. Here, the contrasting hydrological conditions caused the CO2 flux differences between the microsites, where high water levels lad to lower decomposition rates due to anoxic conditions.

scholarly journals Eco-epidemiological and pathological features of wildlife mortality events related to cyanobacterial bio-intoxication in the Kruger National Park, South Africa

2016 ◽  
Vol 87 (1) ◽  
Author(s):  
Roy Bengis ◽  
Danny Govender ◽  
Emily Lane ◽  
Jan Myburgh ◽  
Paul Oberholster ◽  
...  
Keyword(s):  
South Africa ◽  
National Park ◽  
Field Investigation ◽  
Water Levels ◽  
Kruger National Park ◽  
Cyanobacterial Blooms ◽  
Toxicity Tests ◽  
Management Options ◽  
South Central ◽  
Wildlife Mortality

Over the past decade, several clustered, multispecies, wildlife mortality events occurred in the vicinity of two man-made earthen dams in the southern and south central regions of the Kruger National Park, South Africa. On field investigation, heavy cyanobacterial blooms were visible in these impoundments and analysis of water samples showed the dominance of Microcystis spp. (probably Microcystis aeruginosa). Macroscopic lesions seen at necropsy and histopathological lesions were compatible with a diagnosis of cyanobacterial intoxication. Laboratory toxicity tests and assays also confirmed the presence of significant levels of microcystins in water from the two dams. These outbreaks occurred during the dry autumn and early winter seasons when water levels in these dams were dropping, and a common feature was that all the affected dams were supporting a large number of hippopotamuses (Hippopotamus amphibius). It is hypothesised that hippopotamus’ urine and faeces, together with agitation of the sediments, significantly contributed to internal loading of phosphates and nitrogen – leading to eutrophication of the water in these impoundments and subsequent cyanobacterial blooms. A major cause for concern was that a number of white rhinoceros (Ceratotherium simum) were amongst the victims of these bio-intoxication events. This publication discusses the eco-epidemiology and pathology of these clustered mortalities, as well as the management options considered and eventually used to address the problem.

A study of Canada geese, Branta canadensis, nesting on islands in southeastern Alberta

1970 ◽  
Vol 48 (2) ◽  
pp. 235-240 ◽  
Author(s):  
Kees Vermeer
Keyword(s):  
Egg Laying ◽  
Water Levels ◽  
Branta Canadensis ◽  
Canada Goose ◽  
Canada Geese ◽  
Uniform Spacing ◽  
Incubation Periods

Canada goose clutches situated on islands in Dowling Lake and Lake Newell, Alberta, were checked from laying to hatching. Egg-laying intervals averaged 1.87 days and incubation periods 26.8 days. The distribution of nests showed a significant deviation from randomness in the direction of uniform spacing. Causes of extensive hatching failure at Dowling Lake were predation and desertion. Predation by coyotes was facilitated by low water levels. A preference for nesting on islands appears to be a mechanism to counteract mammalian predation.

Flake Tools in the American Arctic: Some Speculations

1964 ◽  
Vol 29 (3) ◽  
pp. 338-344 ◽  
Author(s):  
Edwin N. Wilmsen
Keyword(s):  
North America ◽  
Central Asia ◽  
New World ◽  
Yukon Territory ◽  
River Delta ◽  
The Arctic ◽  
Land Bridge ◽  
Bering Land Bridge

AbstractTwo sites, Kogruk (at the summit of Anaktuvuk Pass, Alaska) and Engigstciak (at the head of the Firth River delta, Yukon Territory, Canada), have recently yielded flake-tool assemblages which show striking resemblances to a Eurasiatic flake-blade tradition based on a Levallois-Mousterian stone-chipping technique, and to the Clovis flake-blade tradition of America which appears to be based on a similar chipping technique. It is suggested that these traditions are historically related and that the Arctic sites provide a possible link between the two. The presence of incipient fluting in Siberia and at Engigstciak may prove significant. Dating is discussed in terms of the ecology and geology of the sites and is correlated with the probable periods of availability of the Bering land bridge. An upland-foothills zone is seen to be essentially continuous from central Asia to central North America. It is suggested that this zone provided the only environmentally compatible link between the two continents, and that it was therefore the most probable route of early hunting peoples into the New World.

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