Pollen productivity estimates from the forest—tundra ecotone in west-central Sweden: implications for vegetation reconstruction at the limits of the boreal forest

The Holocene ◽  
2008 ◽  
Vol 18 (2) ◽  
pp. 323-332 ◽  
Author(s):  
Henrik von Stedingk ◽  
Ralph M. Fyfe ◽  
Anna Allard
Keyword(s):  
Boreal Forest ◽  
Forest Tundra ◽  
Vegetation Reconstruction ◽  
West Central ◽  
Pollen Productivity

Pollen deposition in the boreal forest of west-central Canada

1996 ◽  
Vol 74 (8) ◽  
pp. 1265-1272 ◽  
Author(s):  
Eun Ju Lee ◽  
Norm C. Kenkel ◽  
Thomas Booth
Keyword(s):  
Boreal Forest ◽  
Species Abundance ◽  
Jack Pine ◽  
Flowering Plant ◽  
Pollen Deposition ◽  
West Central ◽  
General Flowering ◽  
Pine Pollen ◽  
Pollen Rain ◽  
Pollen Release

Deposition of tree and tall shrub pollen was examined along a 5.5-km transect in mixed boreal forest in west-central Manitoba, Canada. Annual pollen deposition averaged ca. 6850 grains/cm2 in 1992, with jack pine contributing 67.3% and spruce 24.5% of the total. In general, flowering plant species released their pollen in early to late May, while conifer (spruce and pine) pollen release occurred in early to mid-June. Pollen deposition was poorly correlated with relative species abundance in the community, with some species (e.g., jack pine) being over-represented in the pollen rain and others (e.g., aspen poplar) being under-represented. In 1993, spruce pollen deposition was 63% of that in 1992. By contrast, total pollen deposition by jack pine showed little variation from 1991 to 1993. However, pollen release dates varied between years, occurring earlier in years with warmer spring temperatures. Jack pine pollen release exhibited diurnal variation, with the majority of pollen being released during daylight hours on warm, sunny days. Keywords: Manitoba, jack pine, black spruce, boreal forest, pollen rain, palynology.

Ultra-high resolution assessment of potential impacts of vegetation shadows on satellite-derived spectral signals from small thermokarst lakes in the boreal forest-tundra transition zone (subarctic Canada)

2021 ◽  
Author(s):  
Pedro Freitas ◽  
Gonçalo Vieira ◽  
Carla Mora ◽  
João Canário ◽  
Diogo Folhas ◽  
...  
Keyword(s):  
High Resolution ◽  
Boreal Forest ◽  
Transition Zone ◽  
Satellite Data ◽  
Thermokarst Lakes ◽  
Forest Tundra ◽  
Permafrost Thaw ◽  
Spectral Signal ◽  
Tree Communities ◽  
Additional Support

<p>Warming of the circumpolar north is accelerating permafrost thaw, with implications for landscapes, hydrology, ecosystems and the global carbon cycle. In subarctic Canada, abrupt permafrost thaw is creating widespread thermokarst lakes. Little attention has been given to small waterbodies with area less than 10,000 m<sup>2</sup>, yet these are biogeochemically more active than larger lakes. Additionally, the landscapes where they develop show intense shrubification and terrestrialization processes, with increases in area and height of shrub and tree communities. Tall vegetation that is colonizing waterbody margins can cast shadows that impact productivity, thermal regime and the water spectral signal, which in satellite data generates pixels with mixed signatures between sunlit and shaded surfaces. We undertook UAV surveys using optical and multispectral sensors at long-term monitoring sites of the Center for Northern Studies (CEN) in subarctic Canada, from the sporadic (SAS/KWAK) to the discontinuous (BGR) permafrost zones in the boreal forest-tundra transition zone. This ultra-high spatial resolution data enabled spectral characterization and 3D reconstruction of the study areas. Ultra-high resolution digital surface models were produced to model shadowing at satellite overpass time (WorldView, PlanetScope and Sentinel-2). We then analyzed the impacts of surrounding vegetation and cast shadows on lake surface spectral reflectance derived from satellite imagery. Ultra-high resolution UAV data allows generating accurate shadow models and can be used to improve the assessment of errors and accuracy of satellite data analysis. Particularly, we identify different spectral signal impacts of cast shadows according to lake color, which highlight the need for special attention of this issue onto lakes with more turbidity.</p><p>This research is funded by the Portuguese Foundation for Science and Technology (FCT) under the project THAWPOND (PROPOLAR), by the Centre of Geographical Studies (FCT I.P. UIDB/00295/2020 and UIDP/00295/2020), with additional support from ArcticNet (NCE), Sentinel North (CFREF) and CEN and is a contribution to T-MOSAiC. PF is funded by FCT (SFRH/BD/145278/2019).</p>

Winter habitat use by ptarmigan, snowshoe hares, red foxes, and river otters in the boreal forest – tundra transition zone of western Quebec

1995 ◽  
Vol 73 (4) ◽  
pp. 755-764 ◽  
Author(s):  
Mario St-Georges ◽  
Simon Nadeau ◽  
Daniel Lambert ◽  
Robert Décarie
Keyword(s):  
Boreal Forest ◽  
Transition Zone ◽  
Species Abundance ◽  
Habitat Type ◽  
Riparian Habitat ◽  
Red Foxes ◽  
Winter Habitat ◽  
Forest Tundra ◽  
River Otters ◽  
Snowshoe Hares

We investigated species–habitat relationships of the midsized fauna inhabiting the transition zone between the boreal forest and forest tundra of subarctic Quebec. Data were collected during a winter aerial track survey of 46 randomly selected 25-km2 plots. The presence of species tracks and habitat variables were recorded for each 1-km section of riparian edge habitat within a plot. Sections of non-riparian habitat were also surveyed. Logistic regression was used to construct habitat models for ptarmigan (Lagopus spp.), snowshoe hares (Lepus americanus), red foxes (Vulpes vulpes), and river otters (Lutra canadensis). Species' habitat type selection was studied by comparing use and availability. Kendall's correlation coefficients were computed to analyze interrelations between variables. Significant logistic regressions were obtained for each species. The index of rank correlation between the observed responses and predicted probabilities for all pairs of observations ranged from 0.67 for ptarmigan to 0.84 for river otters. Species abundance was negatively associated with latitude except for that of snowshoe hare, which showed a stronger negative link with open habitat. For all species, distribution was not proportional to the frequency of occurrence of habitat types. Non-riparian habitat was either avoided or not significantly preferred by all species. Herbivorous species and river otter selected edge habitats along watercourses. Our study suggests that differences presented by the forest tundra and boreal forest are of importance for wildlife.

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