scholarly journals Use of an acoustic location system to understand how presence of conspecifics and canopy cover influence Ovenbird (Seiurus aurocapilla) space use near reclaimed wellsites in the boreal forest of Alberta

2018 ◽  
Vol 13 (2) ◽  
Author(s):  
Scott J. Wilson ◽  
Erin M. Bayne
Keyword(s):  
Boreal Forest ◽  
Canopy Cover ◽  
Space Use ◽  
Location System ◽  
Seiurus Aurocapilla

Temporal changes in boreal forest tree canopy cover along a gradient of gamma radiation

1985 ◽  
Vol 63 (1) ◽  
pp. 15-20 ◽  
Author(s):  
B. D. Amiro ◽  
J. R. Dugle
Keyword(s):  
Gamma Radiation ◽  
Boreal Forest ◽  
Gamma Rays ◽  
Forest Canopy ◽  
Canopy Cover ◽  
Woody Species ◽  
Tree Canopy ◽  
Forest Site ◽  
Dose Rates ◽  
Tree Canopy Cover

A forest site in southeastern Manitoba has been irradiated by a point source of gamma rays continuously since 1973, and measurements have been made yearly to study the change in boreal forest canopy cover along the radiation gradient. After 10 years of chronic irradiation, a zone of total tree death has resulted from mean dose rates between 25 and 62 mGy h−1. Tree canopy cover was reduced at mean dose rates exceeding ~ 4.5 mGy h−1 and the largest reduction occurred in the first 2 years of irradiation. The temporal responses of seven woody species to gamma radiation are presented. Bebb's willow, trembling aspen, speckled alder, and paper birch were less sensitive to radiation than black spruce, balsam fir, and jack pine. The results confirm that gymnosperms are more sensitive to gamma rays than angiosperms.

Gradient analysis of Larix laricina dominated wetlands in Canada's southeastern boreal forest

2001 ◽  
Vol 79 (4) ◽  
pp. 444-456 ◽  
Author(s):  
Martin-Philippe Girardin ◽  
Jacques Tardif ◽  
Yves Bergeron
Keyword(s):  
Boreal Forest ◽  
Abies Balsamea ◽  
Hierarchical Classification ◽  
Canopy Cover ◽  
Larix Laricina ◽  
Betula Papyrifera ◽  
Kalmia Angustifolia ◽  
Fraxinus Nigra ◽  
Hierarchical Classification Analysis ◽  
Substrate Ph

With the objective of understanding how vegetation was structured in four Larix laricina (Du Roi) K. Koch dominated wetlands in north-western Quebec, 186 point-centred quarters were sampled in four stands. For each point, both biotic and abiotic variables were collected and species cover was recorded. Divisive hierarchical classification analysis (Twinspan) identified nine vegetation clusters: i) Larix laricina & Spiraea alba, ii) Larix laricina & Kalmia angustifolia, iii) Larix laricina, Picea mariana & Alnus rugosa, iv) Larix laricina & Betula pumila, v) Thuja occidentalis & Trientalis borealis, vi) Abies balsamea & Betula papyrifera, vii) Fraxinus nigra & Onoclea sensibilis, viii) Alnus rugosa, and ix) Eleocharis smallii. Results of the canonical correspondence analyses indicated that the distribution of these clusters was mainly related to (i) distance from shore, (ii) shade (canopy cover), (iii) substrate nitrate concentration (in relation to the abundance of Kalmia angustifolia and Alnus rugosa), (iv) substrate pH (in relation to the abundance of Sphagnum spp.), and (v) substrate conductivity. Several characteristics of the water table also affected species distribution, including pH, depth, and carbon concentration. Further studies should address the effect of the presence of Kalmia angustifolia and Alnus rugosa on larch growth.Key words: larch, wetland, vegetation analysis, flooding, boreal forest.

scholarly journals Spatial variability in pollen and resource limitation for fruit production of two species in interior Alaska: Vaccinium uliginosum and V. vitis-idaea

2019 ◽  
Author(s):  
Lindsey Viann Parkinson ◽  
Christa P.H. Mulder
Keyword(s):  
Soil Moisture ◽  
Boreal Forest ◽  
Resource Availability ◽  
Pollen Limitation ◽  
Canopy Cover ◽  
Fruit Production ◽  
Floral Resources ◽  
Soil Conditions ◽  
Vaccinium Uliginosum ◽  
Interior Alaska

AbstractMany recent studies assessing fruit productivity of plants in the boreal forest focus on interannual variability across a forested region, rather than on environmental variability within the forest. Frequency and severity of wildfires in the boreal forest affect soil moisture, canopy, and community structure at the landscape level, all of which may influence overall fruit production at a site directly (through resource availability) or indirectly (through impacts on pollinators). We evaluated how fruit production in two boreal shrubs, Vaccinium uliginosum (blueberry) and V. vitis-idaea (lingonberry), was explained by factors associated with resource availability (such as canopy cover and soil conditions) and pollen limitation (such as floral resources for pollinators and pollen deposition) across boreal forest sites of Interior Alaska. We classified our study sites into upland and lowland sites, which differed in elevation, soil moisture (lower in upland sites), and active layer (deeper in upland sites). We found that resource and pollen limitation differed between the two species and between uplands and lowlands. Lingonberry was more pollen limited than blueberry, and plants in lowland sites were more pollen limited relative to other sites while plants in upland sites were relatively more resource limited. Additionally, canopy cover had a significant negative effect in upland sites on a ramet’s investment in reproductive tissues and leaves versus structural growth, but little effect in lowland sites. These results point to importance of including pollinator abundance as well as resource availability in predictions for changes in berry abundance.

scholarly journals How to Calibrate Historical Aerial Photographs: A Change Analysis of Naturally Dynamic Boreal Forest Landscapes

Forests ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 631 ◽  
Author(s):  
Niko Kulha ◽  
Leena Pasanen ◽  
Tuomas Aakala
Keyword(s):  
Bayesian Inference ◽  
Boreal Forest ◽  
Tree Ring ◽  
Canopy Cover ◽  
Aerial Photographs ◽  
Time Interval ◽  
Calibration Data ◽  
Forest Change ◽  
Change Analysis ◽  
Percentage Points

Time series of repeat aerial photographs currently span decades in many regions. However, the lack of calibration data limits their use in forest change analysis. We propose an approach where we combine repeat aerial photography, tree-ring reconstructions, and Bayesian inference to study changes in forests. Using stereopairs of aerial photographs from five boreal forest landscapes, we visually interpreted canopy cover in contiguous 0.1-ha cells at three time points during 1959–2011. We used tree-ring measurements to produce calibration data for the interpretation, and to quantify the bias and error associated with the interpretation. Then, we discerned credible canopy cover changes from the interpretation error noise using Bayesian inference. We underestimated canopy cover using the historical low-quality photographs, and overestimated it using the recent high-quality photographs. Further, due to differences in tree species composition and canopy cover in the cells, the interpretation bias varied between the landscapes. In addition, the random interpretation error varied between and within the landscapes. Due to the varying bias and error, the magnitude of credibly detectable canopy cover change in the 0.1-ha cells depended on the studied time interval and landscape, ranging from −10 to −18 percentage points (decrease), and from +10 to +19 percentage points (increase). Hence, changes occurring at stand scales were detectable, but smaller scale changes could not be separated from the error noise. Besides the abrupt changes, also slow continuous canopy cover changes could be detected with the proposed approach. Given the wide availability of historical aerial photographs, the proposed approach can be applied for forest change analysis in biomes where tree-rings form, while accounting for the bias and error in aerial photo interpretation.

scholarly journals Stand-level Attributes of Snowshoe Hare (Lepus americanus) Habitat in a Post-Fire Trembling Aspen (Populus tremuloides) Chronosequence in Central Yukon

2013 ◽  
Vol 126 (4) ◽  
pp. 295 ◽  
Author(s):  
Wayne L. Strong ◽  
Thomas S. Jung
Keyword(s):  
Boreal Forest ◽  
Populus Tremuloides ◽  
Large Scale ◽  
Global Climate ◽  
Canopy Cover ◽  
White Spruce ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Trembling Aspen ◽  
Understory Shrubs

Large-scale fires are anticipated to increase in frequency in the boreal forest under global climate warming scenarios. To understand concomitant responses by wildlife to fire-induced habitat changes, fecal pellet counts were used to assess Snowshoe Hare (Lepus americanus) use of four age-classes of boreal forest after fire in central Yukon, Canada. Use of stands across a chronosequence of 8–177 years was bimodal. Post-fire Trembling Aspen (Populus tremuloides) stands ≤20 years old had greater densities of Snowshoe Hare pellets (median 156 pellets/dam2) than Trembling Aspen stands 21–70 years old, mixedwood stands 71–120 years old (<17 pellets/dam2), or Western White Spruce (Picea albertiana) -dominated stands 121–170 years old (71 pellets/dam2). Forty stand-level compositional and structural variables were assessed as possible predictors of Snowshoe Hare pellet densities. Multidimensional scaling was used to identify variables (n = 10) that were most strongly related to pellet densities and was followed by multiple regression. Canopy cover of Trembling Aspen <50 cm tall and Western White Spruce ≤1 m tall, and deadfall depth, in combination, were the best estimators of Snowshoe Hare pellet densities among stands in the chronosequence (P <0.001, 64.5% variance explained). Although Trembling Aspen <50 cm tall explained the most variance, its canopy cover did not exceed 10%. More Trembling Aspen cover <50 cm tall and greater deadfall depths within the chronosequence were associated with stands ≤20 years old. Peak Snowshoe Hare use occurred in early (≤20 years old) rather than mid-successional (21–120 years old) stands, contrary to use patterns reported elsewhere. The lack of tall understory shrubs likely limited the use of mid-successional stands.

scholarly journals Songbird community response to regeneration of reclaimed wellsites in the boreal forest of Alberta

2019 ◽  
Vol 3 (1) ◽  
pp. 1-1 ◽  
Author(s):  
Scott J. Wilson ◽  
Erin M. Bayne
Keyword(s):  
Boreal Forest ◽  
Oil And Gas ◽  
Canopy Cover ◽  
Community Response ◽  
Breeding Habitat ◽  
Time Of Arrival ◽  
Limited Information ◽  
Acoustic Localization ◽  
Mature Forest ◽  
Forest Sites

The boreal forest of Alberta, Canada is important breeding habitat for North American songbirds. Thousands of oil and gas wellsites exist in this region that have been actively reclaimed since the 1960s. Limited information exists on how songbirds respond to regeneration of wellsites following reclamation. Methods that provide spatially accurate data are required to determine impacts of these small disturbances characteristic of energy sector on songbirds. Acoustic localization can be used to determine singing locations, based on time of arrival differences of songs to an array of microphones. We used acoustic localization to determine the assemblage of songbirds on 12 reclaimed wellsites ranging from 7 to 49 years since reclamation, and how the similarity of this assemblage to 12 control mature forest sites (greater than 80 years old) changed with increasing canopy cover on the wellsite. Songbird community composition became more similar to mature forest as canopy cover increased on reclaimed wellsites. Results from this study suggest that wellsite reclamation practices are allowing for initial suitable vegetation recovery, however more research on the effectiveness of different strategies at promoting regeneration of wellsites and subsequent impact on songbird communities is required.

scholarly journals Comparison of LiDAR and Digital Aerial Photogrammetry for Characterizing Canopy Openings in the Boreal Forest of Northern Alberta

2019 ◽  
Vol 11 (16) ◽  
pp. 1919 ◽  
Author(s):  
Annette Dietmaier ◽  
Gregory J. McDermid ◽  
Mir Mustafizur Rahman ◽  
Julia Linke ◽  
Ralf Ludwig
Keyword(s):  
Boreal Forest ◽  
Forest Structure ◽  
Forest Canopy ◽  
Canopy Structure ◽  
Three Dimensional ◽  
Canopy Cover ◽  
Aerial Photogrammetry ◽  
Northern Alberta ◽  
Height Model ◽  
Economical Alternative

Forest canopy openings are a key element of forest structure, influencing a host of ecological dynamics. Light detection and ranging (LiDAR) is the de-facto standard for measuring three-dimensional forest structure, but digital aerial photogrammetry (DAP) has emerged as a viable and economical alternative. We compared the performance of LiDAR and DAP data for characterizing canopy openings and no-openings across a 1-km2 expanse of boreal forest in northern Alberta, Canada. Structural openings in canopy cover were delineated using three canopy height model (CHM) alternatives, from (i) LiDAR, (ii) DAP, and (iii) a LiDAR/DAP hybrid. From a point-based detectability perspective, the LiDAR CHM produced the best results (87% overall accuracy), followed by the hybrid and DAP models (47% and 46%, respectively). The hybrid and DAP CHMs experienced large errors of omission (9–53%), particularly with small openings up to 20m2, which are an important element of boreal forest structure. By missing these, DAP and hybrid datasets substantially under-reported the total area of openings across our site (152,470 m2 and 159,848 m2, respectively) compared to LiDAR (245,920 m2). Our results illustrate DAP’s sensitivity to occlusions, mismatched tie points, and other optical challenges inherent to using structure-from-motion workflows in complex forest scenes. These under-documented constraints currently limit the technology’s capacity to fully characterize canopy structure. For now, we recommend that operational use of DAP in forests be limited to mapping large canopy openings, and area-based attributes that are well-documented in the literature.

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