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The extend of North American boreal zone
Abstract
The circumpolar boreal zone is one of the world’s major biogeoclimatic zones, covering much of North America and Eurasia with forests, woodlands, wetlands, and lakes. It regulates climate, acts as a reservoir for biological and genetic diversity, plays a key role in biogeochemical cycles, and provides renewable resources, habitat, and recreational opportunities. Poor agreement exists amongst scientists regarding this zone’s delimitation and the areal extent of boreal forests, even though the zone has been well-studied. This paper reviews the literature on the phytogeography of the zone and makes use of a geographic information system (GIS) and published maps to delineate a current map of the North American boreal zone and the hemiboreal subzone, which is a transitional area lying immediately to the south of the boreal zone that is usually included in the boreal zone by Europeans but excluded by North Americans. On the basis of the map described here, the boreal zone covers about 627 million ha, or 29% of the North American continent north of Mexico. If the hemiboreal subzone, at 116 million ha, is included, then 34% of the same area is covered. Forests and other wooded land (362 million ha) cover 58% of the North American boreal zone on the basis of current forest inventory data. With forests and other wooded land of the hemiboreal subzone (68 million ha) factored in, this percentage remains basically unchanged. Values reported in this paper are compared with other published statistics. Important sources of error contributing to differences in areal statistics are discussed.
... These changes are projected to alter the distribution and availability of key habitat components such as vegetation types and food resources, alter species assemblages, and lead to the establishment of species outside their previous altitudinal [8,9] and latitudinal [10,11] range limits. One of the most apparent changes in eastern North America is likely to be the northward expansion of temperate and hemiboreal (sensu Brandt [12]) forests at the expense of boreal forests [13]. These changes are projected to cause wide-ranging impacts on associated ecosystems and biodiversity, including birds [14,15]. ...
... Hereford Forest (5,669 ha) is located in the Atlantic Maritime ecozone in the hemiboreal subzone, which is considered to be part of the temperate zone but transitional to the boreal ( [12], Fig 1). The vegetation is characteristic of the hemiboreal sugar maple (Acer saccharum) and yellow birch (Betula alleghaniensis) bioclimatic domain, which is mainly composed of those two species mixed with intolerant hardwoods, balsam fir and red spruce (Picea rubens). ...
... The vegetation is characteristic of the hemiboreal sugar maple (Acer saccharum) and yellow birch (Betula alleghaniensis) bioclimatic domain, which is mainly composed of those two species mixed with intolerant hardwoods, balsam fir and red spruce (Picea rubens). [12]. The percentage of coniferous is shown with a gradation of greens. ...
The combination of climate change and anthropogenic disturbance significantly impacts forest bird assemblages. Assessing the cumulative effects of forest management and climate change on biodiversity and ecosystem services, including carbon sequestration and storage and provisioning of wood products is key to informing forest management and conservation decision making. Specifically, we projected changes in forest composition and structure according to various forest management strategies under a changing climate using LANDIS-II for two case study areas of Quebec (Canada): a hemiboreal (Hereford Forest) and a boreal (Montmorency Forest) area. Then, we assessed projected bird assemblage changes, as well as sensitive and at-risk species. As part of an integrated assessment, we evaluated the best possible management measures aimed at preserving avian diversity and compared them with optimal options for mitigation of carbon emissions to the atmosphere. Forest management and climate change were projected to lead to significant changes in bird assemblages in both types of forest through changes in forest composition. We projected an increase in deciduous vegetation which favored species associated with mixed and deciduous stands to the detriment of species associated with older, coniferous forests. Changes were more pronounced in Hereford Forest than Montmorency Forest. In addition, Hereford’s bird assemblages were mainly affected by climate change, while those in Montmorency Forest were more impacted by forest management. We estimated that 25% of Hereford and 6% of Montmorency species will be sensitive to climate change, with projected abundance changes (positive or negative) exceeding 25%. According to the simulations, a decrease in the level of forest harvesting could benefit bird conservation and contribute to reduction of carbon emissions in the boreal forest area. Conversely, the hemiboreal forest area require trade-offs, as mitigation of carbon emissions is favored by more intensive forest management that stimulates the growth and carbon sequestration of otherwise stagnant stands.
... In the present study, we focus on the Inuvik to Tuktoyaktuk Highway (ITH) in Northwest Territories, Canada (NWT). The highway corridor traverses the ecoclimate gradient of the treeline characterized by a northward decrease in snow and permafrost temperatures (Kokelj et al., 2017) and is characterized by a heterogeneous topography and ice-rich permafrost, which is particularly vulnerable to climate change (Rampton, 1988;Burn and Kokelj, 2009). The recently constructed highway provides a unique opportunity to study the evolution of impacts through time. ...
... The region south of the treeline zone is characterized by open spruce woodlands and peat plateaus. Tree cover decreases northwards and transforms to tundra with tall shrubs at the southern edge of the treeline zone, while the northern edge is characterized by sedges and dwarf shrubs (Burn and Kokelj, 2009). Sedges, grasses, ericaceous shrubs and lichens dominate the low Arctic tundra north of the treeline zone (Burn and Kokelj, 2009). ...
... Tree cover decreases northwards and transforms to tundra with tall shrubs at the southern edge of the treeline zone, while the northern edge is characterized by sedges and dwarf shrubs (Burn and Kokelj, 2009). Sedges, grasses, ericaceous shrubs and lichens dominate the low Arctic tundra north of the treeline zone (Burn and Kokelj, 2009). The landscape is characterized by a lake-rich, hummocky and rolling terrain. ...
Roads constructed on permafrost can have a significant impact on the surrounding environment, potentially inducing permafrost degradation. These impacts arise from factors such as snow accumulation near the road, which affects the soil's thermal and hydrological regime, and road dust that decreases the snow's albedo, altering the timing of snowmelt. However, our current understanding of the magnitude and the spatial extent of these effects is limited. In this study we addressed this gap by using remote sensing techniques to assess the spatial effect of the Inuvik to Tuktoyaktuk Highway (ITH) in Northwest Territories, Canada, on snow accumulation, snow albedo and snowmelt patterns. With a new, high resolution snow depth raster from airborne laser scanning, we quantified the snow accumulation at road segments in the Trail Valley Creek area using digital elevation model differencing. We found increased snow accumulation up to 36 m from the road center. The magnitude of this snow accumulation was influenced by the prevailing wind direction and the embankment height. Furthermore, by analyzing 43 Sentinel-2 satellite images between February and May 2020, we observed reduced snow albedo values within 500 m of the road, resulting in a 12-days-earlier onset of snowmelt within 100 m from the road. We examined snowmelt patterns before, during and after the road construction using the normalized difference snow index from Landsat-7 and Landsat-8 imagery. Our analysis revealed that the road affected the snowmelt pattern up to 600 m from the road, even in areas which appeared undisturbed. In summary, our study improves our understanding of the spatial impact of gravel roads on permafrost due to enhanced snow accumulation, reduced snow albedo and earlier snowmelt. Our study underscores the important contribution that remote sensing can provide to improve our understanding of the effects of infrastructure development on permafrost environments.
... The forest understory includes shrubs like willows (Salix spp.), birch (Betula spp.), and alders (Alnus spp.), as well as herbaceous plants. [41]. ...
... For our study, we selected the 2019 data of the AYNWT, as it offers the most recent dataset. Then, we clipped these data to the boundaries of the North American boreal forest extent [41]. ...
... We used Sen's Slope because it is a non-parametric technique offering advantages of being robust to outliers, lacking normality, and heteroscedasticity [53]. [41] showing the approximately 70,000 sampling points of the study region in red. ...
The extrapolation of forest structural attributes from LiDAR has traditionally been restricted to local or regional scales, hindering a thorough assessment of single-year versus time series predictors across expansive spatial scales. We extrapolated the vertical complexity captured by the Land, Vegetation, and Ice Sensor (LVIS) full-wave form LiDAR of boreal forests in the Alaska–Yukon–Northwest Territories region, utilizing predictors from Landsat images from 1989 to 2019. This included both single-year and long-term estimates of vegetation indices, alongside constant factors like terrain slope and location. Random forest regression models comparing the single-year and 15-year and 30-year time series models were applied. Additionally, the potential of estimating horizontal forest complexity from vertical complexity was explored using a moving window approach in the Kluane Valley. While the extended time series marginally enhanced model accuracy, a fine-tuned single-year model proved superior (R2 = 0.84, relative RRMSE = 8.4%). In estimating the horizontal complexity, the variance in a 5 × 5 moving window displayed the most promising results, aligning with traditional horizontal structure measures. Single-year Landsat models could potentially surpass time series models in predicting forest vertical complexity, with the added capability to estimate horizontal complexity using variance in a moving window approach.
... The Boreal Zone (BZ) forms a ring around the North Pole and lies immediately south of the Arctic Circle, encircling the Northern Hemisphere (Brandt 2009;Gauthier et al. 2015). This region experiences long, cold winters and short, warm summers. ...
... The BZ is renowned for its abundant biodiversity, with its forests providing habitats for diverse fauna. The region includes not only forested areas but also other types of woodland and treeless regions, such as alpine regions on mountains, heathlands in maritime regions, grasslands in drier areas, and wetlands (Brandt 2009;Gauthier et al. 2015). The tree species composition of the BZ forests varies depending on the specific location within the zone. ...
... The tree species composition of the BZ forests varies depending on the specific location within the zone. In general, coniferous trees make up approximately 70% to 80% of the tree population (Brandt 2009;Gauthier et al. 2015). density. ...
Wood density is a crucial factor in determining the quality of wood in boreal ecosystems within the Northern Hemisphere. Climate variables play a significant role in shaping wood density, posing challenges for forest managers and stakeholders in the wood industry to adapt amidst climate change. However, our current understanding of these effects remains incomplete. This systematic literature review explores the multifaceted influences on wood density in the boreal zone, encompassing both climate-related and non-climatic factors. The findings demonstrate that warmer temperatures can cause both increases and decreases in wood density, primarily due to their impact on tracheid lignification and cell wall thickening. Nonetheless, the outcome depends on various factors, including species type, age, soil conditions, presence of pests and diseases, fire, windstorms, and silviculture practices. The quantification of complex relationships between these factors and wood density has been insufficient in existing literature. Understanding the impacts of both climate and non-climate factors on wood density is essential for fostering a sustainable wood industry, while effectively mitigating adverse effects and maximizing benefits. Forest managers can leverage this knowledge to optimize wood production strategies, ensuring long-term ecological resilience amidst the increasingly variable climate challenges.
... The boreal zone is a circumpolar region representing one of the world's largest biomes. The area lies south of the arctic zone and is principally defined by temperate ecological communities, primarily conifer-dominated forest (Brandt 2009). In North America, the boreal zone covers approximately 627 million ha extending from the east coast of Canada across all provinces and through Alaska. ...
... The boreal zone in North America is divided into several ecozones based on climate, physiography, and biota, the largest of which is the Boreal Shield (Ecological Stratification Working Group 1995). The boreal forest is dominated by approximately 20 cold-tolerant tree species in the genera Abies, Larix, Picea, Pinus, Populus, and Betula (Brandt 2009). The most common and economically important species are white spruce, black spruce, jack pine, tamarack, balsam fir, balsam poplar Populus balsamifera, white birch Betula papyrifera, and quaking aspen. ...
... In addition to being one of the world's largest intact forest regions, Canada's boreal zone contains the world's highest concentration of surface water. Almost half the area of Canada's boreal zone is comprised of wetlands, peatlands, and more than 71 million ha of open water (Brandt 2009). There are 600,000 lakes larger than 0.1 km 2 , which is more than a quarter of the global total (Minns et al. 2008) as well as some of the world's largest lakes. ...
... Our proposed systematic review, addressing the question: 'To what extent does surrounding landscape explain stand-level occurrence of conservation-relevant species in fragmented boreal and hemi-boreal forest? [58,[69][70][71][72], has potential to provide stakeholders with information directly relevant for such decision making and policy development. Specifically, we believe that the proposed review will allow stakeholders to better understand the premises for conservation success in fragmented landscapes; interpret post monitoring results (such as reasons for an observed decline in a species); optimise conservation strategy by, for instance, prioritise among interventions, stands, and sites to protect and restore; and plan for green infrastructure (i.e., reconstructed connectivity) in boreal and hemi-boreal forest. ...
... Population: Boreal and hemi-boreal forest, defined as any forest within the boreal zone and the hemi-boreal transition zone which cover all or parts of the following countries: Canada, Scotland, Iceland, Norway, Sweden, Finland, Estonia, Latvia, Lithuania, Belarus, Russia, Mongolia, Japan, and the American states Alaska, Maine, and Minnesota [58,[69][70][71][72]. ...
... Relevant population. Articles will be included if studies have been conducted in boreal forest or forest in the hemi-boreal (also sometimes referred as boreonemoral) transition zone [58,[69][70][71][72]. Consequently, studies from the following countries: Canada, Scotland, Iceland, Norway, Sweden, Finland, Estonia, Latvia, Lithuania, Belarus, Russia, Mongolia, Japan, and the American states Alaska, Maine, and Minnesota, will be included if the study location falls within the boreal or hemi-boreal zone at the discretion of the review authors, i.e., studies will be included or excluded primarily based on where they took place, rather than based on the classification by the study author. ...
Background
Silviculture and land-use change has reduced the amount of natural forest worldwide and left what remains confined to isolated fragments or stands. To understand processes governing species occurrence in such stands, much attention has been given to stand-level factors such as size, structure, and deadwood amount. However, the surrounding matrix will directly impact species dispersal and persistence, and the link between the surrounding landscape configuration, composition and history, and stand-level species occurrence has received insufficient attention. Thus, to facilitate optimisation of forest management and species conservation, we propose a review addressing ‘To what extent does surrounding landscape explain stand-level occurrence of conservation-relevant species in fragmented boreal and hemi-boreal forest?’.
Methods
The proposed systematic review will identify and synthesise relevant articles following the CEE guidelines for evidence synthesis and the ROSES standards. A search for peer-reviewed and grey literature will be conducted using four databases, two online search engines, and 36 specialist websites. Identified articles will be screened for eligibility in a two-step process; first on title and abstract, and second on the full text. Screening will be based on predefined eligibility criteria related to a PECO-model; population being boreal and hemi-boreal forest, exposure being fragmentation, comparator being landscapes with alternative composition, configuration, or history, and outcome being occurrence (i.e., presence and/or abundance) of conservation-relevant species. All articles that pass the full-text screening will go through study validity assessment and data extraction, and be part of a narrative review. If enough studies prove comparable, quantitative meta-analyses will also be performed. The objective of the narrative review and the meta-analyses will be to address the primary question as well as six secondary questions, and to identify important knowledge gaps.
... Here we investigated the reproductive size and age thresholds, and the environmental drivers of reproductive maturity of two widespread boreal conifers, the semi-serotinous black spruce [Picea mariana (Mill) BSP] and the serotinous jack pine (Pinus banksiana Lamb.). We used a large observational study combining older (19-275 years after the last fire) and recently burned stands (less than 5 years after the last recent fire) from two geomorphologically distinct terrestrial ecozones (Ecosystem Classification Group, 2008, 2009, Taiga Plains and Taiga Shield, in the boreal forest of Northwest Territories, Canada. Our dataset represents a snapshot of reproductive maturity across a latitudinal gradient that approaches the treeline and throughout in the Taiga Shield and includes stands growing on sites with and without permafrost (perennially cryotic ground) in both ecozones. ...
... The 30-year (1981The 30-year ( -2010 climates normal for mean annual temperature and precipitation were −5.4 • C (range: −7.4 to −4.5 • C) and 309 mm (range: 267-397 mm), respectively, on the Plains and -3.6 • C (range: −6.6 to −2.4 • C) and 272 mm (range: 265-282 mm), respectively, on the Shield (Wang et al., 2016). The Plains overlie sedimentary bedrock whereas the Shield is characterized by exposed granite bedrock (Ecosystem Classification Group, 2008, 2009. ...
... It tolerates poor drainage, shallow permafrost soils, and active (seasonally thawed) layers as thin as 0.25 m (Ritchie, 1987). The distribution of jack pine extends from the eastern slope of the Rocky Mountains to Nova Scotia, Canada (Brandt, 2009). In contrast to black spruce, jack pine grows poorly in peatlands (Viereck and Johnston, 1990) and its range is limited by seasonal heat sums (growing degree-days above 5 • C) and its intolerance of deep snow (McLeod and MacDonald, 1997). ...
In boreal North America, much of the landscape is covered by fire-adapted forests dominated by serotinous conifers. For these forests, reductions in fire return interval could limit reproductive success, owing to insufficient time for stands to reach reproductive maturity i.e., to initiate cone production. Improved understanding of the drivers of reproductive maturity can provide important information about the capacity of these forests to self-replace following fire. Here, we assessed the drivers of reproductive maturity in two dominant and widespread conifers, semi-serotinous black spruce and serotinous jack pine. Presence or absence of female cones were recorded in approximately 15,000 individuals within old and recently burned stands in two distinct ecozones of the Northwest Territories (NWT), Canada. Our results show that reproductive maturity was triggered by a minimum tree size threshold rather than an age threshold, with trees reaching reproductive maturity at smaller sizes where environmental conditions were more stressful. The number of reproductive trees per plot increased with stem density, basal area, and at higher latitudes (colder locations). The harsh climatic conditions present at these higher latitudes, however, limited the recruitment of jack pine at the treeline ecotone. The number of reproductive black spruce trees increased with deeper soils, whereas the number of reproductive jack pine trees increased where soils were shallower. We examined the reproductive efficiency i.e., the number of seedlings recruited per reproductive tree, linking pre-fire reproductive maturity of recently burned stands and post-fire seedling recruitment (recorded up to 4 years after the fires) and found that a reproductive jack pine can recruit on average three times more seedlings than a reproductive black spruce. We suggest that the higher reproductive efficiency of jack pine can explain the greater resilience of this species to wildfire compared with black spruce. Overall, these results help link life history characteristics, such as reproductive maturity, to variation in post-fire recruitment of dominant serotinous conifers.
... Our overall study area comprises the spatial extent of the boreal and boreal alpine regions of North America (Brandt, 2009). However, most of our analysis is focused on a large subset (86%) of the Canadian boreal region (Figure 1, black outline), representing the intersection of the intactness and human influence maps evaluated. ...
... Two broad disturbance types were mapped within each range: (1) linear disturbances such as roads, seismic cutlines, and pipelines, and (2) polygonal disturbances such as forest cutblocks, agricultural areas, and mining quarries. The dataset includes both buffered and unbuffered linear and polygonal disturbances, covering 4.4 FIGURE 1 | Extent of boreal region, including boreal and boreal alpine zones, in North America (Brandt, 2009). The solid black line indicates the area of intersection of the eight intactness and human influence maps while the crosshatch pattern indicates the limits of the 51 caribou ranges that make up the 2015 BEAD dataset (Pasher et al., 2013). ...
... All binary intactness maps except for the GIFL maps (GIFL2000-16) covered at least 98% of the boreal region of Canada (Brandt, 2009) (Table 3). The three GIFL maps covered 86% of the region. ...
North America’s boreal forest contains some of the largest remaining intact and wild ecosystems in the world. However, human activities are systematically reducing its extent. Consequently, forest intactness and human influence maps are increasingly used for monitoring and conservation planning in the boreal region. We evaluated nine national and global maps to determine how well they agreed with each other and how effectively they captured recent anthropogenic disturbances. As a function of each map’s spatial coverage in North America, the area identified as intact ranged from 55 to 79% in Canada and from 32 to 96% in Alaska. Likewise, the similarity between pairs of datasets in the Canadian boreal ranged from 0.58 to 0.86 on a scale of 0–1. In total, 45% of the region was identified as intact by the eight most recent datasets. There was also variation in the ability of the datasets to account for anthropogenic disturbances that are increasingly common in the boreal region, such as those associated with resource extraction. In comparison to the recently produced high resolution Boreal Ecosystem Anthropogenic Disturbance dataset, the four human influence datasets (Human Footprint, Global Human Modification, Large Intact Areas, and Anthropogenic Biomes) omitted 59–85% of all linear disturbances and 54–89% of all polygonal disturbances. In contrast, the global IFL, Canadian IFL, and Human Access maps omitted 2–7% of linear disturbances and 0.1–5% of polygonal disturbances. Several differences in map characteristics, including input datasets and methods used to develop the maps may help explain these differences. Ultimately, the decision on which dataset to use will depend on the objectives of specific conservation planning projects, but we recommend using datasets that (1) incorporate regional anthropogenic activities, (2) are updated regularly, (3) provide detailed information of the methods and input data used, and (4) can be replicated and adapted for local use. This is especially important in landscapes that are undergoing rapid change due to development and have an active natural disturbance regime, such as the boreal forest of North America.
... An important part of the boreal forest is composed of poorly drained landscapes called peatlands (Beaulne et al., 2021;Metcalfe and Buttle, 2001;Viereck et al., 1986). In Canada, nearly 25% of the boreal forest is classified as peatland (Brandt, 2009;Schwieger et al., 2021). A thick organic layer with high a water table is common for peatlands (Metcalfe and Buttle, 2001). ...
... Black spruce is a tree species well-adapted to grow under various climatic and edaphic conditions (Sims et al., 1990). It is endemic to North America and is the dominant tree species of the eastern boreal forest of Canada (Brandt, 2009;Vogel et al., 2008). Black spruce presents specific adaptations allowing it to live and grow in peatlands (Lavoie et al., 2005). ...
... A large 4 portion of the boreal biome is underlain by permafrost 5 (perennially frozen ground; Gruber, 2012), which increases 6 in areal extent from south to north, from isolated (≤10 %), 7 sporadic (>10 -50 %) and discontinuous (>50 -90 %), to 8 continuous permafrost (>90 %). In North America, forests 9 occupy about 60 % of the boreal biome along with lake, 10 river, and wetland ecosystems (Brandt, 2009 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 A c c e p t e d M a n u s c r i p t Table 1. Soil, permafrost, and vegetation characteristics. ...
... Locations of the study sites in the boreal biome(Brandt, 2009) and permafrost zone (Gruber, 2012) of North America . Permafrost is isolated (≤10 % in areal extent), sporadic (>10 -50 %), discontinuous (>50 -90 %), and continuous (>90 %). ...
Climate change is rapidly altering composition, structure, and functioning of the boreal biome, across North America often broadly categorized into ecoregions. The resulting complex changes in different ecoregions present a challenge for efforts to accurately simulate carbon dioxide (CO2) and energy exchanges between boreal forests and the atmosphere with terrestrial ecosystem models (TEMs). Eddy covariance measurements provide valuable information for evaluating the performance of TEMs and guiding their development. Here, we compiled a boreal forest model benchmarking dataset for North America by harmonizing eddy covariance and supporting measurements from eight black spruce (Picea mariana)-dominated, mature forest stands. The eight forest stands, locating in six boreal ecoregions of North America, differ in stand characteristics, disturbance history, climate, permafrost conditions and soil properties. By compiling various data streams, the benchmarking dataset comprises data to parameterize, force, and evaluate TEMs. Specifically, it includes half-hourly, gap-filled meteorological forcing data, ancillary data essential for model parameterization, and half-hourly, gap-filled or partitioned component flux data on CO2 (net ecosystem production [NEP], gross primary production [GPP], and ecosystem respiration [ER]) and energy (latent [LE] and sensible heat [H]) and their daily aggregates screened based on half-hourly gap-filling quality criteria. We present a case study with the Canadian Land Surface Scheme Including Biogeochemical Cycles (CLASSIC) to:(1) demonstrate the utility of our dataset to benchmark TEMs and (2) provide guidance for model development and refinement. Model skill was evaluated using several statistical metrics and further examined through the flux responses to their environmental controls. Our results suggest that CLASSIC tended to overestimate GPP and ER among all stands. Model performance regarding the energy fluxes (i.e., LE and H) varied greatly among the stands and exhibited a moderate correlation with latitude. We identified strong relationships between simulated fluxes and their environmental controls except for H, thus highlighting the present strengths and limitations of CLASSIC.
... The boreal forest in Krasnoyarsk Krai in central Russia, which is also located in the middle of Siberia (Fig. 1), was selected as the study area. This area extends from approximately 51 to 69 • N and from 84 to 110 • E. The climatic zones found in this area range from temperate in the south to frigid in the north (Brandt, 2009), which means that the latitude range was considered sufficiently large for an analysis of the sensitivity of the forest to climate change to be carried out. The climate in the study area is strongly continental with a large temperature gradient from south to north. ...
... Finally, a random forest (RF) algorithm was used to discriminate coniferous and broad-leaved forests from areas of vegetation (Breiman, 2001;Strobl et al., 2007;Cutler et al., 2008;Svetnik et al., 2003;Rodriguez-Galiano et al., 2013;Assiri, 2021;Climent et al., 2019). Representative training samples are one of the most critical components of the RF algorithm. ...
Climate change has been proven to be an indisputable fact and to be occurring at a faster rate (com-pared to the other regions at the same latitude of the world) in boreal forest areas. Climate change has been observed to have a strong influence on forests; however, until now, the amount of quantitative information on the climate drivers that are producing changes in boreal forest has been limited. The objectives of this work were to quantify the spatiotemporal characteristics of boreal forest and forest types and to find the significant climate drivers that are producing changes in boreal forest. The boreal forest in Krasnoyarsk Krai, Siberia, Rus-sia, which lies within the latitude range 51-69 • N, was selected as the study area. The distribution of the boreal forest and forest types in the years 1985, 1995, 2005 and 2015 were derived from a series of Landsat data. The spatiotemporal changes in the boreal forest and forest types that occurred over each 10-year period within each 2 • latitudinal zone between 51 and 69 • N from 1985 to 2015 were then comprehensively analyzed. The results show that the total area of forest increased over the study period and that the increase was fastest in the high-latitude zone between 63 and 69 • N. The increases in the areas of broad-leaved and coniferous forests were found to have different characteristics. In the medium-latitude zone between 57 and 63 • N in particular, the area of broad-leaved forest grew faster than that of coniferous forest. Finally, the influence of the climate factors of temperature and precipitation on changes in the forests was analyzed. The results indicate that temperature rather than precipitation is the main climate factor that is driving change.
... Summer-time gaseous elemental mercury (GEM) concentrations obtained from the passive air samplers deployments in Ontario and select sites in the United States. The extents of the Hudson Bay Lowlands (HBL) (MNR, 2012), boreal forest(Brandt, 2009) and the Ohio River Valley Basin are shown using different shading(USGS, 2012). No GEM concentrations between 2.7 and 12.9 ng/m 3 were observed. ...
... (b) Map of corrected MDF values from the PAS deployment. The extents of the Hudson Bay Lowlands (MNR, 2012), boreal forest(Brandt, 2009) and the Ohio River Valley Basin are shown using different shading(USGS, 2012). Basemap by Ontario Ministry of Natural Resources and Forestry (ESRI, 2020). ...
This study deployed 59 passive air samplers (PAS) across the province of Ontario, Canada (and eight additional deployments in bordering states of northern USA) to assess the influence of local/regional sources, temporal differences, and possible transformations in the atmospheric gaseous elemental mercury (GEM) pool. The spatial mapping achieved with the PASs allowed for the observation of differences in GEM and its isotopic composition over the region. Concentrations of GEM were higher with more negative δ²⁰²Hg values near urban/industrial areas and suspected emission sources in southern Ontario. In northern Ontario, far from industrial influences, lower concentrations of GEM with isotopically more positive δ²⁰²Hg values were found at the boreal forest sites compared to sites within the Hudson Bay Lowlands. The differences in northern Ontario may be from greater uptake of GEM by the boreal forest removing isotopically light Hg and lowering concentrations. Lower GEM and a shift toward more positive δ²⁰²Hg were also observed during the summer relative to other times of year supporting vegetation uptake as an important sink for GEM. PASs were also deployed along a transect of increasing distance from a Hg recycling facility. The Hg emissions from the facility had unique positive Δ¹⁹⁹Hg and Δ²⁰⁰Hg signatures, but GEM concentrations and isotopic compositions returned to background within 400 m of the facility. The province‐wide variations in atmospheric GEM and isotopic compositions show that both sources (e.g., urban/industrial emissions) and sinks (e.g., vegetation uptake) contribute to the spatial and temporal patterns of the residual atmosphere GEM pool.
... We simulated future growth (BAI, cm 2 ·y −1 ) of the study species within the five ecozones of Canada that encompass most of the boreal forest east of the Rocky Mountains, including the Taiga Plains, Boreal Plains, Western Boreal Shield, Eastern Boreal Shield, and Atlantic Maritime ecozones (115). To do so, we combined the tree lists from the most recent PSPs and NFI plots, excluding suppressed and damaged trees (Fig. 1A). ...
... Individual tree growth estimates were summed per plot and then scaled per hectare. Relative growth change under each climate change scenario was calculated at the plot-level relative to baseline climate conditions, then averaged per ecodistrict, which are ecologically homogeneous spatial units of 78 × 78-km area on average (115,116). Finally, the average change in growth per species was calculated as the mean in relative growth changes across all ecodistricts for the five studied ecozones. ...
Large projected increases in forest disturbance pose a major threat to future wood fiber supply and carbon sequestration in the cold-limited, Canadian boreal forest ecosystem. Given the large sensitivity of tree growth to temperature, warming-induced increases in forest productivity have the potential to reduce these threats, but research efforts to date have yielded contradictory results attributed to limited data availability, methodological biases, and regional variability in forest dynamics. Here, we apply a machine learning algorithm to an unprecedented network of over 1 million tree growth records (1958 to 2018) from 20,089 permanent sample plots distributed across both Canada and the United States, spanning a 16.5 °C climatic gradient. Fitted models were then used to project the near-term (2050 s time period) growth of the six most abundant tree species in the Canadian boreal forest. Our results reveal a large, positive effect of increasing thermal energy on tree growth for most of the target species, leading to 20.5 to 22.7% projected gains in growth with climate change under RCP 4.5 and 8.5. The magnitude of these gains, which peak in the colder and wetter regions of the boreal forest, suggests that warming-induced growth increases should no longer be considered marginal but may in fact significantly offset some of the negative impacts of projected increases in drought and wildfire on wood supply and carbon sequestration and have major implications on ecological forecasts and the global economy.
... There is currently no universally agreed upon value of H-statistic that signi es signi cant interaction, therefore we chose to investigate any 2-way interactions that resulted in an H-statistic > 0.1. We simulated the growth (BAI, cm 2 ·year -1 ) of inventory stems within the ve ecozones of Canada that encompass most of the boreal forest east of the Rocky Mountains, including the Taiga Plains, Boreal Plains, Western Boreal Shield, Eastern Boreal Shield, and Atlantic Maritime ecozones 110 . To do so, we combined the tree lists from the most recent PSPs and NFI plots (Fig. 1a). ...
... Relative growth change under each climate change scenario was calculated at the plot-level relative to baseline climate conditions. Growth changes were averaged over ecologically homogeneous spatial units nested within ecozones called ecodistricts, and across ecozones 110,111 . ...
Large projected increases in forest disturbance pose a major threat to future wood fibre supply and carbon sequestration in the cold-limited, Canadian boreal forest ecosystem 1–4 . Given the large sensitivity of tree growth to temperature, warming-induced increases in forest productivity have the potential to reduce these threats, but research efforts to date have yielded contradictory results attributed to limited data availability, methodological biases, and regional variability in forest dynamics 5–8 . Here we apply a novel machine-learning algorithm to an unprecedented network of over 1 million tree growth records from 18,715 permanent sample plots distributed across both Canada and the US, spanning a 16.5°C climatic gradient, and project the near-term (2050s time period) growth of the six most abundant tree species in the Canadian boreal forest. Our results reveal a large, positive effect of increasing thermal energy on tree growth for most of the target species, leading to 40-52% projected gains in growth with climate change under RCP 4.5 and 8.5. The magnitude of these gains, which peak in the colder and wetter regions of the boreal forest, suggests warming-induced growth increases should no longer be considered marginal, but may in fact significantly offset some of the negative impacts of projected increases in drought and wildfire on wood supply and carbon sequestration and have major implications on ecological forecasts and the global economy.
... For Labrador, Eastern Alpine Tundra includes Alpine polygons from Brandt (2009). ...
... Continental treeline is that of Brandt (2009); this is the northern boundary of Subarctic Woodland-Tundra. ...
... La limite continentale des arbres est celle de Brandt (2009) ...
... Les délimitations proviennent du projet Circumpolar Arctic Vegetation Map (CAVM)(Équipe CAVM, 2003). La limite continentale des arbres (et donc la limite sud de la zone de végétation de niveau 2 Toundras arbustives du Bas-Arctique) est celle deBrandt (2009), sauf pour le nord du Yukon et l'ouest du delta de Mackenzie où la limite des arbres de la classification bioclimatique du Yukon est retenue (Ecological and Landscape Classification Technical Working Group, 2017). ...
Le présent document Zones de végétation du Canada : une perspective biogéoclimatique cartographie la géographie du Canada en fonction des gradients du climat régional, révélés par la végétation potentielle des sites zonaux. Par rapport aux anciens produits similaires à l’échelle nationale, le document Zones de végétation du Canada tire parti des travaux menés par les programmes de classification écologique à
l’échelle provinciale et territoriale des 30 dernières années, en intégrant les connaissances régionales des gradients climatiques importants en matière d’écologie dans une carte nationale harmonisée. Cette nouvelle carte, qui reflète la végétation et les sols adaptés aux climats antérieurs à 1960, peut servir de référence géospatiale à une échelle générale (environ 1 : 5 000 000 à 1 : 10 000 000) pour le monitorage et la modélisation des effets des changements climatiques sur les écosystèmes au Canada.
Le document Zones de végétation du Canada : une perspective biogéoclimatique comprend une légende hiérarchique à deux niveaux. Les zones de végétation de niveau 1 expriment le gradient latitudinal du bilan radiatif annuel net à l’échelle mondiale, ainsi que les effets de la haute altitude et des variations biogéographiques et climatiques d’ouest en est au Canada. Au sein des zones de végétation de niveau 1, les zones de niveau 2 distinguent des variations à une échelle plus fine dans la végétation zonale, en particulier en réaction aux gradients climatiques arctiques et d’altitude, à la diversité floristique et physionomique liée au climat dans les Grandes plaines, et aux influences maritimes du climat sur les côtes est et ouest.
... Seasonally snow-covered forests of the northern temperate and boreal regions are an important component of the global carbon (C) cycle (Friedlingstein et al., 2022;Luyssaert et al., 2007). These forested regions span hundreds of millions of hectares (Brandt, 2009;Keenan et al., 2015), and contain substantial C reservoirs (Kurz et al., 2013). Currently they are a significant sink for C (Pan et al., 2011), but the future of that sink is highly uncertain (Friedlingstein et al., 2014) and reliant on forest response to environmental change. ...
We examined the seasonality of photosynthesis in 46 evergreen needleleaf (evergreen needleleaf forests (ENF)) and deciduous broadleaf (deciduous broadleaf forests (DBF)) forests across North America and Eurasia. We quantified the onset and end (StartGPP and EndGPP) of photosynthesis in spring and autumn based on the response of net ecosystem exchange of CO2 to sunlight. To test the hypothesis that snowmelt is required for photosynthesis to begin, these were compared with end of snowmelt derived from soil temperature. ENF forests achieved 10% of summer photosynthetic capacity ∼3 weeks before end of snowmelt, while DBF forests achieved that capacity ∼4 weeks afterward. DBF forests increased photosynthetic capacity in spring faster (1.95% d⁻¹) than ENF (1.10% d⁻¹), and their active season length (EndGPP–StartGPP) was ∼50 days shorter. We hypothesized that warming has influenced timing of the photosynthesis season. We found minimal evidence for long‐term change in StartGPP, EndGPP, or air temperature, but their interannual anomalies were significantly correlated. Warmer weather was associated with earlier StartGPP (1.3–2.5 days °C⁻¹) or later EndGPP (1.5–1.8 days °C⁻¹, depending on forest type and month). Finally, we tested whether existing phenological models could predict StartGPP and EndGPP. For ENF forests, air temperature‐ and daylength‐based models provided best predictions for StartGPP, while a chilling‐degree‐day model was best for EndGPP. The root mean square errors (RMSE) between predicted and observed StartGPP and EndGPP were 11.7 and 11.3 days, respectively. For DBF forests, temperature‐ and daylength‐based models yielded the best results (RMSE 6.3 and 10.5 days).
... Furthermore, within these subcontinental climatic gradients are regional to local variations that result from the effects of lakes and elevational gradients (Cullen & Marshall, 2011;Eichenlaub, 1987). Together with fire, insects, diseases and their interactions, the climatic characteristics of the last millennia have played an important role in the formation of the country's landscape variability in terms of composition and structuring of tree species populations, rejuvenation of terrestrial ecosystems, biogeochemical cycling and maintenance of productivity (Brandt, 2009). ...
The evolutionary dynamics of tree species are influenced by their specific climatic environments, and their ability to persist is determined by adaptive strategies such as broad climate tolerance, phenotypic plasticity or genetic differentiation. Biogeographical predictions indicate that populations located at the edges of their ranges are more likely to experience heightened vulnerability to climatic fluctuations due to approaching tolerance limits. However, if local phenotypic acclimation or genetic adaptation has taken place, trees near the edge of their range could demonstrate comparable sensitivity to freeze and drought as the rest of the sampled population. Nevertheless, there remains uncertainty regarding the extent of developmental and evolutionary adjustments in climate sensitivity across the entire ranges of many tree species.
Here, we document the biogeography of tree growth sensitivity to freeze and soil water and vapour pressure deficits during 1950–2018 using an extensive multi‐species tree‐ring dataset of 35,784 trees at 4535 sites covering boreal, temperate conifer and temperate deciduous forests of Canada. We quantify the relationships between tree radial growth increment and seasonal climate variables and explore factors driving the observed patterns of annual growth and climate sensitivity such as species, regional climate and local site conditions, and tree age and size.
Freeze and drought had widespread impacts on tree growth that were contingent on the presence of focal species in interaction with tree size. An indirect growth thermal limitation towards cold/wet edges, occurring through the site moisture conditions, was observed in seven widespread species (e.g. Picea glauca, Picea mariana and Larix laricina). Moreover, six species had negative drought impacts more strongly expressed towards their warm/dry edges (e.g. Abies balsamea, Betula papyrifera and Pseudotsuga menziesii). However, widespread Picea, Pinus and Populus species showed no indication of increased sensitivity to soil water conditions at these edges.
Synthesis. Our findings support the idea of evolutionary or acclimatization adjustments in the development of populations in response to long‐term climate conditions experienced in their respective locations. This underscores the importance of incorporating phenotypic and genomic data into future analyses of climate change impacts, which would enhance our ability to predict potential ecological shifts.
... Within this vast expanse, the hemi-boreal zone occupies a critical ecological area in North America. This transitional zone marks the southern limit of closed boreal forest and is home to mixed forests with a high diversity of tree species and communities including savannas, grasslands, and wetlands [1][2][3] . Towards the interior of the North American continent, at the prairie-forest ecotone, woody and herbaceous vegetation intermingle at many different scales 4 . ...
The hemi-boreal zone, marking North America’s southern boreal forest boundary, has evolved post-glaciation, hosting diverse ecosystems including mixed forests with savannas, grasslands, and wetlands. While human, climate, and fire interactions shape vegetation dynamics therein, specific influences remain unclear. Here we unveil 12,000 years of hemi-boreal zone dynamics, exploring wildfire, vegetation, climate, and human population size interactions at such long time scales. Postglacial biomass burning exhibited episodes of persistent elevated activity, and a pivotal shift around 7000 years ago saw the boreal forest transition to an oak-pine barren ecosystem for about 2000 years before reverting. This mid-Holocene shift occurred during a period of more frequent burning and a sudden uptick in mean annual temperatures. Population size of Indigenous peoples mirrored wildfire fluctuations, decreasing with more frequent burning. Anticipated increases of fire activity with climate change are expected to echo transformations observed 7000 years ago, reducing boreal forest extent, and impacting land use.
... This finding contradicts our expectations as, according to the literature, black spruce is characterized by a broad ecological distribution and marked ecotypic differentiation (Rossi and Bousquet, 2014), which should lead to a weaker sensitivity to temperature. Compared with spruce, balsam fir has a smaller and more southern distribution, restricted to mid-eastern North America (Brandt, 2009), and no ecotypic differentiation in phenology ; thus, the buds of balsam fir should exhibit a higher sensitivity to warming. However, warming will be heterogeneous across Canada (IPCC, 2022). ...
Budburst is a pivotal event in plant life, representing a crucial response to seasonal meteorological shifts. Boreal tree species exhibit species-specific phenologies, and the rate of phenological changes under warming conditions may differ among these species. In this study we aim to investigate the timing of budburst in three coniferous species [Balsam fir (Abies balsamea), black spruce (Picea mariana) and white spruce (Picea glauca) (Pinaceae)]; identify the main drivers of budburst, its rate of advance and the spatiotemporal patterns of budburst in relation to climate across Canada using a time period of 1980–2021. The timing of budburst was observed at 2839 locations stretching from Alberta to Newfoundland. We developed response functions between budburst and climate (air temperature, precipitation and solar radiation) and used the strongest correlations to test their effect on budburst using species, time and the ecoclimatic framework of Canadian ecoprovinces. We applied spatially constrained multivariate clustering and identified natural budburst clustering across Canada. We found a baseline difference of 17 days in the budburst of black spruce relative to that of balsam fir and white spruce. Mean minimum temperature of May was negatively correlated with budburst date. Black spruce advanced budburst at a rate of change per degree of temperature (- 3.33 days °C-1), twice that of balsam fir and white spruce (-1.53 and -1.27 days °C-1, respectively). Cluster distribution of budburst timing matched well with the distribution of Canadian ecoprovinces. Budburst within the clusters followed clinal patterns in temperature across Canada. Mean minimum temperature in May is the main factor driving budburst in northern tree species. Under a warmer spring, we project an earlier budburst, with black spruce being the species expected to show the greatest rate of change. The identified clustering patterns did not vary with precipitation, which represents the primary longitudinal gradient across Canada.
... Wildlife Conservation Society Canada (WCS Canada) conducted a wolverine GPS collaring project near Red Lake, Ontario, Canada (51 • N, 93 • W) during winter months (Dec-Apr) of 2018-2022. The larger Red Lake area is boreal forest [45], with an active forestry and mining industry [46]. WCS Canada established 30 wooden live traps [47] in Red Lake over a 5740 km 2 area (100 % minimum convex polygon surrounding live traps). ...
... This embankment included the 8 m to Fig. 6a-b. The treeline zone (Brandt, 2009) is shown as white dashed line. Base map: Sentinel-2 cloudless data by EOX IT Services GmbH. ...
Roads constructed on permafrost can have a significant impact on the surrounding environment, potentially inducing permafrost degradation. These impacts arise from factors such as snow accumulation near the road, which affects the soil’s thermal and hydrological regime and road dust that decreases the snow’s albedo, altering the timing of snowmelt. However, our current understanding of the magnitude and the spatial extent of these effects is limited. In this study we addressed this gap by usingremote sensing techniques to assess the spatial effect of the Inuvik to Tuktoyaktuk Highway (ITH) in Northwest Territories, Canada, on snow accumulation, snow albedo and snowmelt patterns. We quantified the snow accumulation at road segments in the Trail Valley Creek area using digital elevation model differencing. We found increased snow accumulation up to 36 m from the road center. The magnitude of this snow accumulation was influenced by the prevailing wind direction and the height of the embankment. Furthermore, by analysing 43 Sentinel-2 satellite images between February and May 2020 we observed reduced snow albedo values within 500 m of the road, resulting in a twelve days earlier onset of snowmelt within 100 m from the road. We examined snowmelt patterns before, during and after the road construction using the normalized difference snow index from Landsat-7 and Landsat-8 imagery. Our analysis revealed that the road affected the snowmelt pattern up to 600 m from the road, even in areas which appeared undisturbed. In summary, our study improves our understanding of the spatial impact of gravel roads on permafrost on snow cover accumulation, snow albedo and snowmelt patterns. Our study underscores important contribution that remote sensing can provide to improve our understanding of the effects of infrastructure development on permafrost environments.
... The boreal forest consists of multiple land cover types including lakes, wetlands, shrubs and trees. Forested areal fractions can exceed 60% in many locations (Brandt, 2009), and are dominated by species of white and black spruce, aspen, jack and lodgepole pine, balsam fir and poplar (Luke et al., 2007;Matasci et al. 2018). Thus, tree canopy plays a critical role in the partitioning of water and energy in the boreal forest (Pomeroy et al., 1999). ...
... While the boundaries likely do not impose undue error on our methods, as plant vegetation adheres to sharp polygon boundaries, thus supporting ecoregionalization as a useful technique for summarizing vegetation properties (Smith et al 2018, Martins et al 2022, there remains a significant loss of understanding of vegetation patterns on the landscape. Still, the results capture growth dynamics within areas of similar biogeography and climate, and reproduce a gradient of growth that is consistent with widely recognized forest structure and environmental gradients in the North American boreal domain (Brandt 2009). Each model aggregates growth across many site conditions that include variations from topography, plant functional type, soil characteristics, and disturbance return intervals. ...
Forest structure - the height, cover, vertical complexity, and spatial patterns of trees - is a key indicator of productivity variation across forested extents. During the 2017 and 2019 growing seasons, NASA’s Arctic-Boreal Vulnerability Experiment collected full-waveform airborne LiDAR using the Land, Vegetation and Imaging Sensor, sampling boreal and tundra landscapes across a variety of ecological regions from central Canada westward through Alaska. Here, we compile and archive a geo-referenced gridded suite of these data that include vertical structure estimates and novel horizontal cover estimates of vegetation canopy cover derived from vegetation’s vertical lidar profile. We validate these gridded estimates with small footprint airborne lidar, and link > 36 million of them with stand age estimates from a Landsat time-series of tree-canopy cover that we confirm with plot-level disturbance year data. We quantify the regional magnitude and variability in site index, the age-dependent rates of forest growth, across 15 boreal ecoregions in North America. With this open archive suite of forest structure data linked to stand age, we bound current forest productivity estimates across a boreal structure gradient whose response to key bioclimatic drivers may change with stand age. These results, derived from a reduction of a large archive of airborne lidar and a Landsat time series, quantify forest productivity bounds for input into forest and ecosystem growth models, to update forecasts of changes in North America’s boreal forests by improving the regional parametrization of forest growth rates.
... Caract erisation des esp eces d'arbres dans les forêts bor eales nordiques a l'aide de l'analyse de m elanges spectraux a composantes multiples et de l'imagerie satellitaire multitemporelle Introduction In Canada, the boreal zone occupies 552 million ha, within which 309 million ha consists of forests and woodlands (Brandt 2009). Its forests are ecosystems that host high levels of biodiversity, influence biogeochemical cycles, provide a wide range of ecosystem services, and have commercial, economic, and cultural value (Kimmins 1996;Brandt et al. 2013). ...
Northern boreal forests are characterized by open stands whereby trees, understory background, and shadow are all significant components of the spectral response within a pixels’ spatial footprint. To overcome this mixed pixel problem, accurate spectral characterization of these (endmember) components is necessary for spectral mixture analysis (SMA) to generate forest classifications at the species level. Obtaining these endmember spectra in the field, however, can be difficult or impossible. This study examined whether image endmember spectra can be identified using forest inventory information to derive dominant tree species classifications. This was tested using multiple-endmember SMA (MESMA) and single- and multi-date Landsat imagery of a forested area in the Northwest Territories, Canada. Image classifications (n = 80) were generated based on 20 image-date combinations and four unmixing models. Accuracies of 80% and 82% were achieved for open and medium dense forest stands, respectively using multi-date imagery, which outperformed single-date imagery acquired at peak phenology. The overall accuracy is 72%; lower due to challenges in very open stands. The multi-date MESMA approach was robust for both compositionally pure and mixed stands. The approach merits further investigation, particularly within the context of the increasing availability of regional-scale satellite imagery enabling composite time-series and spectral-temporal image features.
... The first sub-region includes Alaska and the northern part of the Canadian boreal region and is bounded at the upper right corner of the map at 72.5°N, 168.5°W and the bottom left corner at 60°N 43.5°W. The North American sub-region contains approximately one-third of the entire boreal region of this continent based on the map described by Brandt (2009). The second region stretches from Scandinavia to the Pacific coasts of Siberia and is limited at the upper right corner at 72.5°N 5°E and the bottom left corner at 60°N 180°E. ...
Background. Fires in the boreal forest occur with natural frequencies and patterns. Burned area (BA) is an essential variable in assessing the impact of climate change in boreal regions. Aims. Spatial wildfire occurrence data since the 1950s are available for North America. However, there are no reliable data for Eurasia, mainly for Siberia, during the 1980s and 1990s. Methods. A Bayesian-network algorithm was applied to the Long-Term Data Record (LTDR) Version 5 to generate a BA DataSet (BA-LTDR-DS) for the Boreal region from 1982 to 2020, validated using official reference data and compared with the MODIS MCD64A1 product. Key results. A high correlation (>93%) with all the reference BA datasets was found. BA-LTDR-DS data grouped by decades estimated a linear increase in BA of 4.47 million ha/decade. This trend provides evidence of how global warming affects fire activity in these boreal forests. Conclusions. BA-LTDR-DS constitutes a unique data source for the pre-MODIS era, and becomes a reliable source when other products with higher spatial/spectral resolution are not available. Implications. The BA-LTDR-DS dataset constitutes the longest time series developed for the boreal region at this spatial resolution. BA-LTDR-DS could be used as input in global climate models, helping improve wildfire prediction capabilities and understand the interactions between fire, climate and vegetation dynamics.
... Boreal forests contain a complex assemblage of trees, other wooded lands, and naturally non-treed areas (e.g. wetlands) and is the biome with the most surface freshwater (Brandt 2009, Burton et al. 2010. These forests are dominated by cold-tolerant and fire-adapted tree species such as white spruce (Picea glauca), black spruce (Picea mariana), balsam fir (Abies balsamea), jack pine (Pinus banksiana), trembling aspen (Populus tremuloides), and balsam poplar (Populus balsamifera). ...
Wildfire is a key driver of forest dynamics in boreal forests; however, the annual area burned in boreal forests is highly variable, with increasing wildfire activity documented over the past half century. Post-fire recovery has important implications for carbon balance, and for the wide range of ecosystem goods and services provisioned by the boreal forest. Monitoring post-fire recovery is challenging given the vast and often inaccessible areas impacted, coupled with the marked variability in post-fire conditions and recovery processes. Field assessments of recovery are constrained in space and time, whereas remotely sensed data are spatially explicit, cover large areas, and can retrospectively provide assessments of pre- and post-fire conditions and establish spectral recovery baselines. However, there is a need to link spectral measures of recovery to manifestations of post-fire forest recovery on the ground. Understanding how different forest characteristics influence spectral recovery is key to the successful application of spectral recovery metrics for forest management applications in different forest environments. Herein, using a synthesis of plot data for the North American boreal forest, we assess the influence of pre- and post-fire field-measured characteristics on spectral recovery rates, with a focus on stem density and composition in Canadian boreal forests. Plots that experienced rapid spectral recovery (as measured using Landsat-derived NBR time series data) were associated with a transition from conifer to broadleaf or were broadleaf pre-fire. Plots that experienced a decrease in stem density took significantly longer to spectrally recover than plots that experienced no change in stem density. Plots that had not yet spectrally recovered by the end of the time series were associated with higher elevations, drier sites, greater pre-fire basal area, and had the greatest change magnitude. Our results emphasize that recovery is a process that is highly variable and that knowledge of pre-fire condition is important for characterizing and interpreting measures of post-fire spectral recovery for forest management applications. Remotely sensed time series data are uniquely able to provide information on both pre- and post-fire condition. Our analysis of pre- and post-fire field measures provided novel insights regarding the influence of forest composition and changes in stem density on measures of post-fire spectral recovery in boreal forests.
... This region is characterized by warm summers and cold winters [40]. In terms of its eco-climates [41], much of it is within the Prairie grasslands, but the southern part of the boreal forest [42] cuts through it as well. There is a small area on the southeastern corner, which is part of the Great Lakes-St. ...
Solid precipitation falling near 0 °C, mainly snow, can adhere to surface features and produce major impacts. This study is concerned with characterizing this precipitation over the Canadian Prairie provinces of Manitoba and Saskatchewan in the current (2000–2013) and pseudo-global warming future climate, with an average 5.9 °C temperature increase, through the use of high resolution (4 km) model simulations. On average, simulations in the current climate suggest that this precipitation occurs within 11 events per year, lasting 33.6 h in total and producing 27.5 mm melted equivalent, but there are wide spatial variations that are partly due to enhancements arising from its relatively low terrain. Within the warmer climate, average values generally increase, and spatial patterns shift somewhat. This precipitation consists of four categories covering its occurrence just below and just above a wet-bulb temperature of 0 °C, and with or without liquid precipitation. It generally peaks in March or April, as well as in October, and these peaks move towards mid-winter by approximately one month within the warmer climate. Storms producing this precipitation generally produce winds with a northerly component during or shortly after the precipitation; these winds contribute to further damage. Overall, this study has determined the features of and expected changes to adhering precipitation across this region.
... The land area of Canada's boreal forests (including other wooded land types) covers 309 Mha (Brandt et al., 2013), nearly 30% of the global boreal forested area (Brandt, 2009); thus, these forests play critical roles in Earth's surface albedo effect (Bonan, 2008) and global C cycle (Kurz et al., 2008). However, evidence suggested that Canada's boreal forests are believed to be more sensitive and vulnerable to drought than other forests, possibly due to the unique climate, soil conditions, and stand structure of Canada's boreal forests (Dial et al., 2022;Lenton et al., 2008;Michaelian et al., 2011;Peng et al., 2011), and even low-intensity droughts can significantly impact these forests (Sánchez-Pinillos et al., 2022). ...
Canada's boreal forests, which occupy approximately 30% of boreal forests worldwide, play an important role in the global carbon budget. However, there is little quantitative information available regarding the spatiotemporal changes in the drought‐induced tree mortality of Canada's boreal forests overall and their associated impacts on biomass carbon dynamics. Here, we develop spatiotemporally explicit estimates of drought‐induced tree mortality and corresponding biomass carbon sink capacity changes in Canada's boreal forests from 1970 to 2020. We show that the average annual tree mortality rate is approximately 2.7%. Approximately 43% of Canada's boreal forests have experienced significantly increasing tree mortality trends (71% of which are located in the western region of the country), and these trends have accelerated since 2002. This increase in tree mortality has resulted in significant biomass carbon losses at an approximate rate of 1.51±0.29 MgC ha‐1 year‐1 (95% confidence interval) with an approximate total loss of 0.46±0.09 PgC year‐1 (95% confidence interval). Under the drought condition increases predicted for this century, the capacity of Canada's boreal forests to act as a carbon sink will be further reduced, potentially leading to a significant positive climate feedback effect.
... The temperate-boreal ecotone (TBE), at the southern edge of the biome or occasionally in interspersed climatic microniches, has litter that reflects the mix of coniferous and deciduous trees (Brandt, 2009) and thus has more accelerated decomposition (Wardle et al., 2003) than is found in the boreal biome. As climate change (CC) advances, the TBE shifts northward (Gonzalez et al., 2010) affecting C speciation pathways. ...
Food webs and the functional status of soils are governed primarily by microbial carbon and nitrogen fluxes as determined by ecosystem type and management. In boreal regions, expanding and intensifying agriculture affects the functional status of soils due to biodiversity, carbon, and nitrogen losses. The status of northern soils must be monitored using informative, standardised methods that are comparable across land uses, managements, and scales. Food web nodes sensitive to complex changes in the soil environment, such as free-living nematodes, can be utilised to monitor alterations in the functional state of natural systems and inform management decisions to ensure that new and established agriculture is environmentally sustainable. The objectives of this a-priori review were to 1) describe the likely impacts of land use and land use change on nematode communities and indices in boreal regions, 2) determine if nematodes respond differently to land use and land use change in the global biomes, and 3) identify literature gaps related to nematodes in the boreal biome to draw attention to future research needs. Soil quality bioindicators were compared and 31 published, peer-reviewed, in-situ studies found in Web of Science and Scopus databases in March 2020 that assessed the impacts of land use and land use change on free-living nematode parameters across global biomes were systematically summarised. While the northern biomes have greater abundances of nematodes than other biomes, the literature search found zero articles pertaining to nematodes in boreal or Arctic agricultural systems highlighting the need for future work. Given the key roles that free-living nematodes have in the food web, their longer and more stable generation times than microbes, and relatively well-known taxonomy, life history traits, and feeding habits, the authors propose that nematodes could and ought to be employed as indicators of functional changes in boreal agricultural soils.
... Forested ecosystems of Canada comprise not only trees, but also wetlands and lakes, occupying an area of ~650 million ha [59] widespread across the country in 15 ecozones with different climatic, topographic, and vegetation types [60]. Here, we focused our prediction on treed vegetation and other wooded land in Canada, involving an area of 347 million ha [61]. ...
Continuous large-scale mapping of forest canopy height is crucial for estimating and reporting forest carbon content, analyzing forest degradation and restoration, or to model ecosystem variables such as aboveground biomass. Over the last years, the spaceborne Light Detection and Ranging (LiDAR) sensor specifically designed to acquire forest structure information, Global Ecosystem Dynamics Investigation (GEDI), has been used to extract forest canopy height information over large areas. Yet, GEDI has no spatial coverage for most forested areas in Canada and other high latitude regions. On the other hand, the spaceborne LiDAR called Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) provides a global coverage but was not specially developed to study forested ecosystems. Nonetheless, both spaceborne LiDAR sensors obtain point-based information, making spatially continuous forest canopy height estimation very challenging. This study compared the performance of both spaceborne LiDAR, GEDI and ICESat-2, combined with ALOS-2/PALSAR-2 and Sentinel-1 and-2 data to produce continuous canopy height maps in Canada for the year 2020. A set-aside dataset and airborne LiDAR (ALS) from a national LiDAR campaign were used for accuracy assessment. Both maps overestimated canopy height in relation to ALS data, but GEDI had a better performance than ICESat-2 with a mean difference (MD) of 0.9 m and 2.9 m, and a root mean square error (RMSE) of 4.2 m and 5.2 m, respectively. However, as both GEDI and ALS have no coverage in most of the hemi-boreal forests, ICESat-2 captures the tall canopy heights expected for these forests better than GEDI. PALSAR-2 HV polarization was the most important covariate to predict canopy height, showing the great potential of L-band in comparison to C-band from Senti-nel-1 or optical data from Sentinel-2. The approach proposed here can be used operationally to produce annual canopy height maps for areas that lack GEDI and ICESat-2 coverage.
... We recognize that tropical ecosystems, for example, present a higher diversity and larger number of tree species, and obtaining pure samples using methods defined in this study might be challenging. Boreal forests, however, are one of the largest relatively intact ecosystems globally (Brandt, 2009) and where sustainable forest management is on-going, thereby necessitating the need for detailed maps of predicted species. Likewise, temperate forests contain globally significant reserves of forest biomass (Pan et al., 2013), and also require species information (Evans and Brown, 2017;Wulder et al., 2020). ...
Knowledge of tree species is required to inform management, planning, and monitoring of forests as well as to characterize habitat and ecosystem function. Remotely sensed data and spatial modeling enable mapping of tree species presence and distribution. Following an assessment of tree species identified in the sample-based National Forest Inventory (NFI), we mapped 37 tree species over the 650-Mha, forest-dominated ecosystems of Canada representing 2019 conditions. Landsat imagery and related spectral indices, geographic and climate data, elevation derivatives, and remote sensing-derived phenology are used as predictor variables trained with calibration samples from Canada's NFI using the Random Forests machine learning algorithm. Based upon prior knowledge of tree species distributions, classification models were implemented on a regional basis, meaning only the tree species that are expected in a given mapping region were modeled using local calibration samples. Modeling resulted in class membership probabilities values for each regionally eligible tree species for all treed pixels as well as an indicator of attribution confidence derived from the distance in feature space between the two leading classes. Accuracy assessment was conducted using independent validation data also drawn from the NFI following the same selection rules and indicated an overall accuracy of 93.1% ± 0.1% (95%-confidence interval). Predictor variables informing on geographic, climatic and topographic conditions had the largest importance on the classification models. Nationally, the most common leading tree species were black spruce (Picea mariana; 203 Mha or 57.3% of the treed area), trembling aspen (Populus tremuloides; 34.7 Mha, 9.8%), and lodgepole pine (Pinus contorta; 21.1 Mha, 5.9%). Regionally, there was ecozone-level dominance of other tree species, including subalpine fir (Abies lasiocarpa; Montane Cordillera), western hemlock (Tsuga heterophylla; Pacific Maritime), and balsam fir (Abies balsamea; Atlantic Maritime). Based upon the per-pixel class membership probabilities, species assemblages akin to those in forest inventories can also be produced. Further, given the calibrated reflectance of Landsat imagery, the methods presented herein can be implemented over a time series of images. The approach uses open data as predictor variables, making the method portable to other areas given availability of tree species training data.
... To assess analogues for late Pleistocene and Holocene subfossil assemblages in Greenland, and to evaluate temperature reconstructions based upon the new calibration dataset, we utilized new late glacial and Holocene subfossil assemblage data from Lake N14 in southernmost Greenland (Fig. 1) and published Holocene subfossil assemblage data from four lakes representing three , Fishtote Lake, North Lake, Lake N14, and Deltasø), to which the temperature-inference model presented here is applied, are shown as triangles ( ). The extent of the North American Boreal Zone is outlined (Brandt, 2009) and the settlements of Narsarsuaq, Nuuk, and Kangerlussuaq are shown ( ). additional geographically and climatically distinct regions of Greenland: Fishtote Lake and North Lake in the west near Disko Bugt ( Fig. 1; Axford et al., 2013), Deltasø in the northwest near Qaanaaq and Pituffik/Thule Air Base (Axford et al., 2019), and Last Chance Lake in the east inboard of Scoresby Sund (Axford et al., 2017). For the four published sites, detailed site geography and sediment chronologies are presented in the respective original publications. ...
We present chironomid species assemblage data from 402 lakes across northern North America, Greenland, Iceland, and Svalbard to inform interpretations of Holocene subfossil chironomid assemblages used in paleolimnological reconstruction. This calibration-set was developed by re-identifying and taxonomically harmonizing chironomids in previously described surface sediment samples, with identifications made at finer taxonomic resolution than in original publications. The large geographic coverage of this dataset is intended to provide climatic analogues for a wide range of Holocene climates in the northwest North Atlantic region and North American Arctic, including Greenland. For many of these regions, modern calibration data are sparse despite keen interest in paleoclimate reconstructions from high latitudes. A suite of chironomid-based temperature models based upon this training set are evaluated here and the best statistical model is used to reconstruct late glacial (Allerød and Younger Dryas) and Holocene paleotemperatures at five non-glacial lakes representing a wide range of climate zones across Greenland. The new continent-scale training set offers more analogues for the majority of Greenland subfossil assemblages than existing smaller training sets, with many in Iceland and northern Canada. We find strong agreement between chironomid-based reconstructions derived from the new model and independent glacier-based evidence for multi-millennial Holocene temperature trends. Some of the new Holocene reconstructions are very similar to published data, but at a subset of sites and time periods we find improved paleotemperature reconstructions attributable both to the new model's finer taxonomic resolution and to its expanded geographic/climatic coverage, which resulted in improved characterization of species optima. In the late glacial, the new model's finer taxonomic resolution yields a unique ability to resolve temperatures of the Allerød from colder temperatures of the Younger Dryas, although the magnitude of that temperature difference may be underestimated. This study demonstrates the value of geographically and climatically broad paleoecological training sets. The large, taxonomically harmonized dataset presented here should be useful for a wide range of future investigations, including but not limited to paleotemperature reconstructions across the Arctic.
... Short group meetings were held afterwards at each step of the research (i.e. data F I G U R E 1 The boreal zone in Canada (Brandt, 2009) and Quebec (light green) and the hunting grounds of the Abitibiwinni and Ouje-Bougoumou first nations. Boreal landscapes are affected by forestry south of the northern limit of commercial forests (Ministère des Forêts de la Faune et des Parcs du Québec, 2018), mining (Ministère de l'Énergie et des Ressources naturelles du Québec, 2018), hydro-electric development (Hydro-Québec, 2015) and climate change (Ouranos, 2015). ...
1. Major environmental changes affect the health and capacity of ecosystems to
sustain Indigenous people's well-being
in boreal landscapes. Collaboration between
Indigenous communities and researchers could help assessing and mitigating
the consequences of environmental changes.
2. We used Driver Pressure State Impact (DPSI) conceptual models to compare
the perspectives of Indigenous and scientific communities on environmental
changes in boreal landscapes of Quebec, Canada.
3. The Indigenous DPSI model emerged from interviews with local land-use
experts
from two Indigenous communities. The scientific model was informed by
the publication topics of expert researchers.
4. We compared the Indigenous and scientific models and exposed convergences
and divergences between perspectives. Forestry was identified as a major driver
of change in both models. Most issues related to mining, hydro-power
and forest road development were specific to the Indigenous model. Climate change and
wildfires were of greater interest in the scientific model.
5. Convergences between the perspectives of Indigenous and scientific communities
are conducive to collaborative research. Divergences could be addressed
through reciprocal knowledge transfer activities, which would lead to research
that better aligns with the concerns and needs of Indigenous communities.
... Our study focused on Facebook groups to communicate about wildlife sightings in Victoria Beach, Manitoba (50.709 • N, 96.540 • W, elev. 237 m.), a WUI community located along the southern extent of the boreal forest (Brandt, 2009) on a peninsula that reaches out into the south basin of Lake Winnipeg (Fig. 1). Because of its placement on a peninsula and thus controlled environment from larger macroscale processes, Victoria Beach has been used by Manitoba's Model Forest for longitudinal case studies (Kaczanowski, 2010). ...
Understanding human reactions to potentially dangerous wildlife at the wildland-urban interface is central to mitigating human-wildlife conflicts. Social media is increasingly used to share information about wildlife among residents living in the interface. We used an online survey distributed on community Facebook groups in Victoria Beach, Manitoba — an area experiencing increasing wildlife sightings — to examine whether posts to the groups resulted in people using avoidance tactics to reduce human-wildlife interactions or conflicts. The results indicate that the majority of respondents used Facebook posts to change their behaviour to avoid potential encounters with black bears, wolves, and coyotes. Despite few respondents having wildlife safety training, most respondents taught their children wildlife safety. Most respondents would not phone the local conservation authority, for reasons including distrust and concerns about lethal control. Coexistence attitudes towards wildlife management were dominant and respondents recognized the importance of protecting wildlife in the community.
... The boreal zone is one the world's largest biomes, spanning 1.89 billion ha across the northern hemisphere (Brandt et al. 2013). This zone consists of forests of cold-tolerant tree species, lakes, rivers, wetlands, and naturally treeless areas, such as shrublands and grasslands (Brandt 2009). ...
Increasing fire frequency in some biomes is leading to fires burning in close succession, triggering rapid vegetation change and altering soil properties. We studied the effects of short-interval reburns on soil bacterial communities of the boreal forest of northwestern Canada using paired sites (n = 44). Both sites in each pair had burned in a recent fire; one site had burned within the previous 20 years before the recent fire (short interval reburn) and the other had not. Paired sites were closely matched in pre-fire ecosite characteristics, pre-fire tree species composition, and stand structure. We hypothesized that there would be a significant effect of short vs. long fire-free intervals on community composition and that richness would not be consistently different between paired sites. We found that Blastococcus sp. was consistently enriched in short-interval reburns, indicating its role as a strongly ‘pyrophilous’ bacterium. Caballeronia sordidicola was consistently depleted in short-interval reburns. The depletion of this endophytic diazotroph raises questions about whether this is contributing to—or merely reflects—poor conifer seedling recolonization post-fire at short-interval reburns. While short-interval reburns had no significant effect on richness, dissimilarity between short- and long-interval pairs was significantly correlated with difference in soil pH, and there were small significant changes in overall community composition.
... We conducted an exhaustive literature review to compile all available data on exotic species of earthworms in the Canadian boreal forest. We used the map of Brandt (2009) to show the extent of their expansion in the Canadian boreal zone. Also, observations were made in Quebec by J.D. Moore during fishing expeditions. ...
In the last decades, concerns have emerged that boreal forests could convert from a carbon sink to a carbon source, thus accentuating climate change. Although forest fire is generally mentioned as the main factor that could cause the boreal forest to transition to a carbon source, other factors, such as exotic earthworm activity, could also play an important role. Invasive exotic earthworms can also affect nutrient cycling, biodiversity and forest dynamics. In this context, a better knowledge of the distribution of exotic earthworms can help understand the likely changes in the ecosystems that they have colonized. Here we report the results of an exhaustive literature review of the presence of exotic earthworms in the Canadian boreal forest and taiga zones. We identified 230 sectors containing 14 earthworm species (11 exotic, 2 native and 1 putative native) in 6 provinces and 3 territories across Canada’s boreal forest and taiga zone. We also report 23 as-yet unpublished observations from the province of Quebec. We note the presence of earthworms in environments (acid soils, harsh climate) that were historically considered inadequate for their survival. This suggests that the portion of Canada’s boreal forests suitable for their presence or colonization is larger than what was previously believed. This study represents the first compilation of exotic earthworm presence in this large northern area. Factors that could affect their distribution and potential effects on boreal ecosystems are also discussed. Globally, several earthworm species seem to be overcoming the previously assumed limitation by temperature and pH.
... Lakes for this study were selected based on location, accessibility, lack of disturbance, and comparable environmental conditions. The lakes are located within the boreal and discontinuous permafrost zones of Alaska (Brandt 2009;Wang et al. 2018) and situated on unconsolidated Quaternary surficial deposits . The lakes have experienced climatic warming ( Fig. 2B) with comparable rates of change (Supporting Information Fig. S2) and trends during the last c. 100 yr. ...
By understanding lake ecosystem resilience in the face of increasing environmental and anthropogenic stress, we can hope to anticipate future ecosystem instability. We assess recent historic ecosystem resilience using composition and network analyses of empirical zoobenthos chironomid (Diptera: Chironomidae; non-biting midges) reconstructions from three Subarctic Alaskan lakes, spanning the last c. 200 years. We measured community richness, turnover and structure using taxon richness, beta diversity and network skewness respectively. Simulated taxonomic networks were created to establish the sensitivity of these metrics to changes in taxon connectivity, and to inform the interpretation of empirical chironomid records. The models indicated that beta diversity was more sensitive to taxon loss, while skewness was more sensitive to taxon gain. Both beta diversity and skewness were required to understand structural change under taxon replacement. The simulated arrival of strongly connected taxa caused a greater decrease in skewness than the arrival of weakly connected taxa. The empirical datasets indicated a rise in taxon richness (measured as rarefaction) and beta diversity in the recent samples. Changes in chironomid composition were associated with climate warming (replacement of cold taxa with temperate taxa) and increased lake biological productivity (the arrival of macrophyte-associated taxa). Skewness was predominantly negative across the lakes, indicating high taxon connectivity and structural stress. However, little directional change in the skewness trends suggests some resilience within the chironomid community structures in relation to the current levels of climate and environmental stress. Continued climatic warming, and associated rises in nutrient levels, may cause further structural stress and ecological degradation.
... Canadian Forest Inventory. Canada encompasses 223 million hectares of continuous boreal forest, representing 20% of the world's boreal forest biome, in addition to 45 million hectares of cool temperate forests (Brandt 2009). Boreal forests, in particular, have been identified as an important terrestrial carbon pool (Pan et al. 2011) and tipping point in the Earth's climate system (Lenton et al. 2008). ...
Tree-ring time series provide long-term, annually resolved information on the growth of trees. When sampled in a systematic context, tree-ring data can be scaled to estimate the forest carbon capture and storage of landscapes, biomes, and-ultimately-the globe. A systematic effort to sample tree rings in national forest inventories would yield unprecedented temporal and spatial resolution of forest carbon dynamics and help resolve key scientific uncertainties, which we highlight in terms of evidence for forest greening (enhanced growth) versus browning (reduced growth, increased mortality). We describe jump-starting a tree-ring collection across the continent of North America, given the commitments of Canada, the United States, and Mexico to visit forest inventory plots, along with existing legacy collections. Failing to do so would be a missed opportunity to help chart an evidence-based path toward meeting national commitments to reduce net greenhouse gas emissions, urgently needed for climate stabilization and repair.
... Located in northern Labrador, the Inuit territory of Nunatsiavut is unique in Inuit Nunangat due to its location in the ecological transition zone between arctic tundra and open boreal forest (Lopoukhine et al. 1978;Brandt 2009). Traditionally hunter-fisher-gatherers, Inuit of Nunatsiavut have occupied the northern coast of Labrador for at least the last 400 years (Richling 2000). ...
For Inuit in the subarctic transition zone of northeastern Canada, an intimate knowledge of the environment and local biodiversity is crucial for successful traditional activities. This study examines what kinds of landscape features and habitats Inuit of Nunatsiavut recognize and name. During interviews, community members (mostly Elders) were shown photographs from the region, and were asked to describe and name salient types of places in Labrador Inuttitut. The most frequently reported geographical units dealt with the region’s topography (e.g., ‘mountain’, ‘island’, ‘flat-place’), hydrology (e.g., ‘river’, ‘bay’), and superficial characteristics (e.g., ‘bedrock’, ‘permanent snow patch’). Ecological considerations were also prominent, such as plant associations and animal habitats (e.g., ‘shrubby-place’, wetland’, ‘caribou-return-to-place’). Areas were often characterized by a dominant species or substrate type, being named using the plural form of the species/substrate (e.g., napâttuk ‘tree’/ napâttuit ‘forest’, siugak ‘sand’/siugalak ‘sandy-area’). Some types of places reported by Inuit were significant mainly for traditional activities (e.g., ‘berry-patch’, ‘seal-place’, ‘dry-wood-place’, ‘danger-place’), aiding navigation and resource finding. Integrating Inuit conceptions of ecosystems and their component landscape units with those of contemporary science can improve our understanding of subarctic ecology, benefit climate change adaptation strategies and Inuit language/culture conservation initiatives.
The carbon (C) dynamics of boreal coniferous swamps are a largely understudied component of wetland carbon cycling. We investigated the above- and below-ground carbon stocks and growing season carbon dioxide (CO2) and methane (CH4) fluxes from a representative wooded coniferous swamp in northern Alberta, Canada in 2022. Tree inventories, understory vegetation biomass and peat cores were collected across three sub-sites within the broader swamp, with gas flux collars placed in the dominant plant communities present. Alongside the C flux measurements, environmental variables such as water table depth, soil temperature and growing season understory green leaf phenology were measured. Our results show that these wooded coniferous swamps store large volumes of organic C in their biomass and soil (134 kg C m-2), comparable with other wetland and forest types, although 95% of the total C stock at our site was within the soil organic carbon. We also found that understory CO2 and CH4 fluxes indicated that the ground layer of the site is a source of greenhouse gases (GHG) to the atmosphere across the growing season. However, we did not measure litterfall input, tree GHG fluxes or net primary productivity of the overstory, therefore we are not able to say whether the site is an overall source of C to the atmosphere. This study provides a much-needed insight into the C dynamics of these under-valued wetland ecosystems and we highlight the need for a coordinated effort across boreal regions to try to improve inventories of C stocks and fluxes.
Covering 55% of Canada’s total surface area and stretching from coast to coast to coast, the Canadian boreal zone is crucial to the nation’s economic and ecological integrity. Although often viewed as relatively underdeveloped, it is vulnerable to numerous stressors such as mining, forestry, and anthropogenic climate change. Natural archives preserved in lake sediments can provide key insights by quantifying pre-disturbance conditions (pre-1850 CE) and the nature, magnitude, direction, and speed of environmental change induced by anthropogenic stressors over the past ~150 years. Here, we paired a review of paleolimnological literature of the Canadian boreal zone with analyses of published sediment core data to highlight the effects of climate change, catchment disturbances, and atmospheric deposition on boreal lakes. Specifically, we conducted quantitative syntheses of two lake health indicators: elemental lead (Pb) and chlorophyll a . Segmented regressions and Mann-Kendall trend analysis revealed a generally increasing trend in elemental Pb across the boreal zone until ~1970 CE, followed by a generally decreasing trend to the present. Snapshot comparisons of sedimentary chlorophyll a from recent and pre-industrial sediments (i.e., top-bottom sediment core design) revealed that a majority of sites have increased over time, suggesting a general enhancement in lake primary production across the boreal zone. Collectively, this body of work demonstrates that long-term sediment records offer a critical perspective on ecosystem change not accessible through routine monitoring programs. We advocate using modern datasets in tandem with paleolimnology to establish baseline conditions, measure ecosystem changes, and set meaningful management targets.
Background Drivers of fire regimes vary among spatial scales, and fire history reconstructions are often limited to stand scales, making it difficult to partition effects of regional climate forcing versus individual site histories. Aims To evaluate regional-scale historical fire regimes over 350 years, we analysed an extensive fire-scar network, spanning 240 km across the upper Great Lakes Region in North America. Methods We estimated fire frequency, identified regionally widespread fire years (based on the fraction of fire-scarred tree samples, fire extent index (FEI), and synchronicity of fire years), and evaluated fire seasonality and climate–fire relationships. Key results Historically, fire frequency and seasonality were variable within and among Great Lakes’ ecoregions. Climate forcing at regional scales resulted in synchronised fires, primarily during the late growing season, which were ubiquitous across the upper Great Lakes Region. Regionally significant fire years included 1689, 1752, 1754, 1791, and 1891. Conclusions We found significant climate forcing of region-wide fire regimes in the upper Great Lakes Region. Implications Historically, reoccurring fires in the upper Great Lakes Region were instrumental for shaping and maintaining forest resilience. The climate conditions that helped promote widespread fire years historically may be consistent with anticipated climate–fire interactions due to climate change.
Holocene fire records from charcoal are critical to understand linkages between regional climate and fire regime and to create effective fire management plans. The Hudson Bay Lowlands (HBL) of Canada is one of the largest continuous peatland complexes in the world and is predicted to be increasingly impacted by wildfire. We present three charcoal records from a bog in the western HBL and demonstrate that median fire frequency was higher in the Middle Holocene, related to warmer regional temperatures and higher evaporative demand. Holocene fire frequencies are lower than in western Canadian peatlands, supporting that the HBL lies in the transition between continental and humid boreal fire regimes. Apparent carbon accumulation rates at the site were not significantly different between the Middle and Late Holocene, suggesting that higher fire frequency and enhanced decomposition offset the potential for higher rates of biomass production. We compile records from the boreal region and demonstrate that increasing fire frequency is significantly correlated with diminishing long-term carbon accumulation rates, despite large variation in response of peatlands to fire frequency changes. Therefore, the paleo-record supports that higher fire frequencies will likely weaken the capacity of some northern peatlands to be net carbon sinks in the future.
Amplified climate warming in high latitudes is expected to affect growing season timing of the vast boreal biome. It is unclear whether the presence of permafrost (perennially frozen ground) might have an influence on changes in growing season timing. This study examined how different environmental variables explained, either directly or indirectly, the variation in growing season timing of boreal forest stands with and without permafrost. We expected that environmental variables explaining the variation in growing season timing differed or had different explanatory power depending on permafrost presence or absence. The growing season was delineated from daily gross primary productivity (GPP) time series derived from 40 site-year data of net ecosystem carbon dioxide exchange measured with eddy covariance techniques over five black spruce (Picea mariana [Mill.])-dominated boreal forest stands in North America. In permafrost-free forest stands, a combination of start in canopy ‘green-up’ in spring and the timing of air and soil temperature increasing above freezing explained the start-of-season (SOSGPP). Results from commonality analysis and structural equation modeling suggest that canopy ‘green-up’ and air temperature directly affected SOSGPP in permafrost-free forest stands. In addition, soil temperature acted as mediator for an indirect effect of air temperature on SOSGPP. In contrast, none of the environmental variables, or their combination, explained the variation in SOSGPP in forest stands with permafrost. The explanatory power of environmental variables was more consistent regarding the end-of-season (EOSGPP). In both, forest stands with and without permafrost, EOSGPP was directly explained by mean soil water content in the fall and the first day of continuous snowpack formation. A better understanding how environmental variables control SOSGPP and EOSGPP in forest stands with and without permafrost will help to refine parameterizations of the boreal biome in Earth system models.
Pipelines carrying diluted bitumen (dilbit) traverse North America and may result in dilbit release into sensitive freshwater ecosystems. To better understand potential effects of a freshwater oil release, the Boreal-lake Oil Release Experiment by Additions to Limnocorrals (BOREAL) project at the IISD-Experimental Lakes Area (Ontario, Canada) modelled seven dilbit spills contained within 10 m diameter littoral limnocorrals in a boreal lake. Wild finescale dace (Phoxinus neogaeus) were released in the limnocorrals 21 days after oil addition and remained there for 70 days. Dilbit volumes covered a large range representing a regression of real spill sizes and total polycyclic aromatic compounds (TPACs) between 167 ng L-1 d-1 and 1989 ng L-1 d-1 . Here we report the effects of chronic exposure on reproductive potential as well as physiological responses in the gallbladder and liver. In exposures greater than 1000 ng L-1 d-1 there was a significant decrease in fish retrieval culminating in zero recapture from the three highest treatments. Among the fish from the limnocorrals with lower levels of TPACs (<500 ng L-1 d-1 ) effects were inconsistent. Gallbladder bile fluorescence for a naphthalene metabolite were significantly different in fish from the oil exposed limnocorrals when compared to the lake and reference corral indicating that fish in these lower exposures were interacting with dilbit-derived PACs. There were no significant differences in condition factor, somatic indices, or hepatocyte volume indices. There were also no significant changes in the development of testes or ovaries of exposed dace. The results from this study may serve to orient policy makers and emergency responders to the range of TPAC exposure that may not significantly affect wild fish. This article is protected by copyright. All rights reserved. © 2022 SETAC.
North American waterfowl conservation, management, and harvest regulation are delegated across administrative flyways and primarily guided by breeding population estimates. The Ring-necked Duck (Aythya collaris) is a late-nesting migratory species that winters and breeds across all of the United States Fish and Wildlife Service administrative flyways. We used satellite telemetry to characterize the spring migration and breeding distribution of 25 female Ring-necked Ducks marked in the southern Atlantic Flyway, USA in the winters of 2017-2018 and 2018-2019. Mean migratory initiation date was 17 March (range: 24 Feb - 5 April) and mean migratory completion date (i.e., arrival to a suspected breeding site) was 16 May (range: 17 April - 27 June), with migratory duration averaging 61.1 days (95% CI: 53.6 - 68.6 days). Total migratory distance averaged 3,409.6 km (95% CI: 2,956.7 - 3,862.6 km). Individuals took, on average, 3.3 stopovers (95% CI: 2.7 - 4.0 stopovers) that lasted an average of 13.5 days (95% CI: 13.3 - 13.8 days). The majority of individuals migrated northwestward and primarily traveled within the Mississippi Flyway prior to reaching Canada. Ten of 25 marked birds migrated through but did not settle in the Prairie Pothole Region (PPR) during the time when the Waterfowl Breeding Population and Habitat Survey (WBPHS) was conducted. Total indicated bird population estimates could be inflated if individuals are counted in multiple WBPHS strata. We also note that 24 of 25 marked birds bred outside of strata comprising the WBPHS eastern survey area, which suggests that more Ring-necked Ducks wintering in the Atlantic Flyway breed outside of the WBPHS eastern survey area than is currently assumed by a scaling parameter incorporated in Atlantic Flyway models used to estimate population size. Individuals from a single wintering site in the southern Atlantic Flyway dispersed widely across two states (USA), five provinces, and one territory (CAN) during the breeding season. Our results support concerns over the efficacy of the WBPHS for Ring-necked Ducks and other late-nesting waterfowl and suggest that the bounds of the scaling parameter incorporated in the Atlantic Flyway multi-stock population model may need to be widened to more accurately account for individuals breeding outside of the Flyway.
The biodiversity and climate change crises have led countries—including Canada—to commit to protect more land and inland waters and to stabilize greenhouse gas concentrations. Canada is also obligated to recover populations of at-risk species, including boreal caribou. Canada has the opportunity to expand its protected areas network to protect hotspots of high value for biodiversity and climate mitigation. However, co-occurrence of hotspots is rare. Here we ask: is it possible to expand the network to simultaneously protect areas important for boreal caribou, other species at risk, climate refugia, and carbon stores? We used linear programming to prioritize areas for protection based on these conservation objectives, and assessed how prioritization for multiple, competing objectives affected the outcome for each individual objective. Our multi-objective approach produced reasonably strong representation of value across objectives. Although trade-offs were required, the multi-objective outcome was almost always better than when we ignored one objective to maximize value for another, highlighting the risk of assuming that a plan based on one objective will also result in strong outcomes for others. Multi-objective optimization approaches could be used to plan for protected areas networks that address biodiversity and climate change objectives, even when hotspots do not co-occur.
Remote sensing data are increasingly used, particularly through inversion methods, for vegetation monitoring due to its improved measurement accuracy and spatial/spectral/temporal resolution and the advances in remote sensing data interpretation methods. Traditional one-dimensional radiative transfer models are often inaccurate when simulating the reflectance of vegetation, which translates into inaccurate inversion of remote sensing observations in terms of bio-optical parameters. Three-dimensional radiative transfer models are usually much more accurate because they consider a realistic architecture of foliage coverage (FC). However, the application of 3D radiative transfer simulation and inversion encounters three major problems. (1) Existing simulation models do not have continuous-time phase simulation capability due to the lack of knowledge of the spatial and temporal variation of key ground parameters. However, remote sensing images are mostly time series data, making it difficult to use together with time series of remote sensing data. (2) Existing leaf spectral inversion methods are mainly applicable to densely vegetated areas. However, in scenes with complex components and many mixed pixels, such as cities, the inversion accuracy of leaf optical properties is seriously degraded. (3) Existing vegetation indices are easy to saturate in high FC areas, severely limiting their inversion capability. The problems mentioned above are addressed with the coupling of the Discrete Anisotropic Radiative Transfer (DART) model and a growth model. Also, the accurately inverting of the spectral signatures of leaves in urban areas is achieved by introducing an innovative calibration of DART. Finally, we analyze the vegetation isolines behaviours and propose the intersection point right shift phenomenon based on the DART simulation data to mitigate the soil-adjusted vegetation index (SAVI) saturation effect in high FC areas. In this thesis, vegetation reflectance simulation and bio-optical property inversion based on a three-dimensional radiative transfer model is the research object in terms of both simulation and inversion. The first half of this thesis focuses on the modelling and reflectance simulation of a 3D vegetation scene with a coupled growth model. The second half focuses on the inversion of vegetation bio-optical parameters using the 3D radiative transfer model. Potential applications include providing high-quality analytical validation data for sensor design and adequate data support for quantitative remote sensing inversion modelling, spatial and temporal scale conversion.
Présentation des régions écologiques du Québec méridional (3e édition) et du système hiérarchique de classification écologique du territoire mis au point par le ministère des Ressources naturelles du Québec (définitions, critères distinctifs, échelles de perceptions, nomenclature, exemples de descriptions) .
Samples from birch populations were collected in Qingua-dalen and Narssarssuaq during the excursion of SBP (the Subarctic Birch Project) to SW Greenland 1984. In Qingua-dalen, where the environmental conditions are more favourable, the stems of the Mountain birch (Betula pubescens ssp. tortuosa) are taller and thicker and the leaf size is larger than in populations at Narssarssuaq. Intermediate forms – probably introgressions - between B. pubescens and B. glandulosa were found in both populations. According to cytological investigations of Qingua-dalen populations, the putative hybrids between B. glandulosa (2n = 28) and B. pubescens (2n = 56) were found to be triploids (2n = 42). Seeds collected from hybrids did not germinate but the germination of the Mountain birch was also extremely low in 1984. In the same year, B. glandulosa produced abundantly seeds with high germination percentage. Germination experiments with seeds collected in 1982 and 1985 indicated that under climatically favourable conditions Mountain birch produces viable seeds. Reproduction through vegetative means was found to be strong in all birch taxa. Considerable differences have been found between the provenances of birches from SW Greenland and Finland in cultivation experiments carried out since 1976 in South and North Finland. The clones of B. pubescens and B. glandulosa, originating from Kangerdluarssuk , mature very late in autumn and the shoots above snow level were badly frostdamaged during the winter. This was particularly noticeable for B. pubescens in test fields in Lapland. The plants have survived, however, by means of re-suckering and started flowering at an early stage producing viable seeds. Probably no reproductive barriers between birches of the two geographically isolated areas, SW Greenland and Finland, have developed.
South Greenland, extending from 59° 45' to 62° 20' N., is considered a botanical province ranking with those of West, North and East Greenland. The province is divided into six vegetational zones, based on the distribution of selected taxa. A phytogeographical analysis grouped the 346 taxa into eleven distribution types, each with two to seven subtypes. Each taxon is characterized further by a map of its distribution in South Greenland, by its holarctic distribution type (HOT) and climatic distribution type (CDT), and by a chorological index value (CI). The flora of South Greenland is compared with that of adjacent areas in Greenland, and its affinities to the floras of Europe and North America shows a slight predominance of the American elements. The following new combinations are proposed: Elymus violaceus (Hornem.) J. Feilberg, Lychnis alpina L. ssp. americana (Fern.) J. Feilberg and Vaccinium oxycoccos L. ssp. microphyllum (Lange) J. Feilberg.
The immigration and present distribution of the Greenland "trees": Abus crispa (Ait.) Pursh, Betula pubescens Ehrh. s.l. and Sorbus groenlandica (Schneid.) Love & Love is summarized. As a consequence of a very limited knowledge of the ecological conditions in this zone, the Nordic Subarctic Birch Project (SBP) organized a field trip to S Greenland in 1984 followed by a symposium in Copenhagen in 1988. The present volume of Meddr Grønland brings the results of these two events.
Preface Acknowledgements 1. Introduction 2. The biogeographical setting 3. Autecology and pollen representation 4. Full-glacial refugia 5. Eastern Canada - fossil record and reconstruction 6. The Western interior 7. Pacific-Cordilleran region 8. Vegetation reconstruction and palaeoenvironments Appendix References Index.
Production ecology and nutrient budgets Faecal analysis and exclosure studies Water relations and stress Mineral nutrition Site and soils Chemical analysis Data analysis Plant population biology Description and analysis of vegetation Site history.
Aims to provide a better spatial view of the distibution of different forest types and other major vegetation types and of their relationship to the landscape. The study is based on new topographic maps, interpretation of Landsat-1 imagery, aerial photographs and field controls. A new four-colour vegetation map on a scale of 1:200 00 has been produced. Special attention has been given to the vast damage to birch forests caused by the butterfly larvae of Oporinia autumnata. The total mapped area is 13 207 km² and the damaged area 1 210 km². Reafforestation of the damaged areas has been hampered so badly that to some extent they may form new treeless tundra areas. The most important factors affecting the formation of forest limits are different climatic and biotic hazards that occur occasionally. -Authors
Ground temperature studies, begun in 1977, revealed the presence of permafrost at the summit of Mont Jacques-Cartier (1270m), in Gaspesie. Temperature profile data to a depth of 30m in a drill hole indicates an active layer slightly thicker than 5.75m, overlying a permafrost body extending beyond the base of the hole to 45-60m . A mean annual ground surface temperature of -1oC to 01.5oC is estimated for the site. -from Authors
Mild, moist maritime conditions characterise a region of forest with Pseudotsuga menziesii, Tsuga heterophylla, Thuja plicata, Picea sitchensis and Sequoia sempervirens. These dominant conifers are the largest and longest-lived representatives of their genera, and the forests provide the greatest biomass accumulations of some of the highest productivity levels of any in the world. Disturbance regimes are characterised by infrequent catastropic events, eg fire, at intervals of several hundreds of years. Major forest types are described: Douglas-fir/western hemlock; Sitka spruce/western hemlock; coast redwood; Klamath Mountains mixed evergreen forests (primarily Douglas-fir plus evergreen hardwoods, eg Lithocarpus densiflorus, Quercus chrysolepis, Arbutus menziesii and Castanopsis chrysophylla); and Sierran type mixed conifer forest. Other vegetation types include subalpine forests (with Abies amabilis, A. magnifica var. shastensis, Tsuga heterophylla and T. mertensiana) and parklands. -P.J.Jarvis
Of the numerous hypotheses that have been proposed to explain the reported reduction in vigor, biomass, and regeneration of red spruce (Picea rubens Sarg.) throughout various parts of eastern North America, those related to winter injury are particularly noteworthy because winter injury has been documented in red spruce forests for many years, and red spruce appears to be uniquely susceptible. That is, species sympatric with red spruce are often uninjured, or only slightly injured, by environmental conditions that result in severe winter injury to red spruce foliage. Undoubtedly, the repeated loss of current-year foliage due to winter injury, as frequently as 3 or 4 years per decade, has had a negative impact on the subsequent growth and vigor of injured trees. This chapter represents a comprehensive summary of the current state of knowledge regarding winter injury and cold tolerance in red spruce. It includes discussion of the nature, extent, and probable cause(s) of winter injury to red spruce, descriptions of unique aspects of developmental cold tolerance for this species, and evidence that certain perturbations, including atmospheric pollutants, have contributed directly to the recent high frequency of winter injury and indirectly to the decline of red spruce throughout the northern montane forests of eastern North America.
Temperatures across the northern regions of North America have been increasing for 150 years, and forests have responded to this increase. In the Noatak National Preserve in Alaska, white spruce (Picea glauca [Moench] Voss) forests reach their northern limit, occurring primarily on well-drained sites and as gallery forests along streams. Rolling plateaus of tundra separate the white spruce forests into disjunct stands. We examined patterns of tree age, tree growth, and tree encroachment into tundra ecosystems in six stands along the Agashashok River. Warming over the past 150 years appears to have increased tree growth and resulted in forest expansion into adjacent tundra ecosystems. The forest/tundra ecotone shifted by about 80 to 100 m into the tundra in the past 200 years, as evidenced by declining maximum tree age with distance towards the tundra. The decadal-scale pattern of tree establishment at the farthest extent of trees into the tundra (the tundra-forest ecotone) correlated with the detrended growth index for trees within the forests; climate conditions that led to higher tree growth appeared to foster tree establishment in the tundra. This recent forest expansion has occurred across topographic boundaries, from well-drained soils on slopes onto poorly drained, flatter areas of tundra. Further expansion of the forests may be limited by more severe wind exposure and poor drainage that make the majority of tundra less suitable for trees.
We documented seasonal food habits of grizzly bears (Ursus arctos) in the Firth River Valley, Ivvavik National Park (INP), northern Yukon, Canada, 1993-1995 using: (1) analysis of 176 scats, (2) 222 hours of direct observation, and (3) 99 feeding site investigations. In spring, the primary grizzly bear food plants were alpine hedysarum (Hedysarum aìpinum) roots and over-wintered berries such as crowberry (Empetrum nigrum). The main food plants in summer were common horsetail (Equisetum an'ense) and bearflower (ßoykinia richardsonii). Bears fed primarily on bog blueberries (Vaccinium uliginosum), crowberries, horsetail, and bearflower in fall. When blueberries were not available, grizzly bears dug for alpine hedysarum roots. In addition to eating plants, grizzly bears killed or scavenged caribou (Rangifer tarandus) and hunted Arctic ground squirrels (Spermophilus parryií) and microtines when available. Well used grizzly bear food plants in INP have similar nutritional quality as food plants from southern Canada. However, the northern growing season is short, and suitable growing sites and diversity of major foods are generally less than in the south, so food plant availability is lower.
I determined the activity of 5 radiocollared grizzly bears (Ursus arctos) in the Firth River Valley, Iwavik National Park, Yukon, Canada, based on 574 hours of direct observation during 1994 and 1995. Radiocollared grizzly bears that were feeding primarily on caribou (Rangifer tarandus) tended to spend less time feeding and more time traveling or resting than bears that were feeding primarily on plants. During most observations bears fed primarily on plants. All bears spent a similar amount of time active (mean 66%, range 59-81%), during which they were primarily feeding or foraging (mean 56%, range 48-62%). For most behaviors, there was no difference among seasons; however, there was a difference for intraspecific behavior. Grizzly bear feeding bouts were longer in summer than fall or spring. In summer with 24 hours of daylight, grizzly bears tended to be most active in the evening and least active when the sun was lowest on the horizon. During fall, with increasing hours of darkness, grizzly bears were least active at night and had peaks of activity in the morning and evening. Grizzly bears in the Firth River Valley were not active more, relative to southern areas, to compensate for their short growing season, despite having more hours of daylight and not being constrained by human disturbance. Bears appeared to meet their energy requirements by acquiring protein and fat from caribou, Artic ground squirrels (spermophi Ius parryii), and other small mammals. Grizzly bears in the Firth River Valley currently appear to be able to effectively exploit available resources; however, repeated disruptions from human activity have the potential to adversely affect the time available for the acquisition of necessary energy.
A preliminary map of the latitudinal, transcontinental subzones of the Eurasian and North American circumboreal vegetation zone is presented. The recognized subzones are called herniboreal, southern boreal, middle boreal and northern boreal. Along the humidity ‑ aridity gradient the zone may be divided into several sectors (not mapped). The highly humid sectors may be characterized by treeless heaths, and birch and/or alder woods or ‘krummholz’ thickets, while moderately humid sectors are primarily dominated by coniferous forests. In the arid sectors there are areas of aspen and larch woods and even boreal steppe vegetation.
Equations given by W. Zenker in the last decade of the Nineteenth Century and later modified by other authors, characterizing the degree of continentality at a given place have the general form:
k = mA/sin ϕ + n:
where k = the continentality coefficient in per cent, A = average annual range of temperature at a given place, ϕ = geographical latitude, and m and n are constants.
Existing vegetation maps of the Korean Peninslla were compared to reveal the common features involved. The thermal climates of the five representative forest types were determined in terms of the warmth and the coldness indices, based on the most detailed maps, those by Ueki (1933), Lautensach (1935) and Yim (1968). The northern boundary of the warm-temperate evergreen lucidophyll forest zone was examined in detail with reference to the distribution of its component species. Taking the results of the three preceding papers and those of Japanese studies into consideration, it was concluded that the four principal forest zones and two subzones more or less commonly recognized by the preceding authors were-distributed-in the Peninsula in close correlation with the distribution of thermal climate.
The vegetation of the earth is characterized by distinct zones which have a rather uniform physiognomical appearance or structure even though they may be composed of many different plant species, genera, and families and may have a very different evolutionary history. The classic example of such “convergence” of morphological structure in a plant community is the evergreen sclerophyllous vegetation of the mediterranean-type climates (Grisebach 1872), but also the rain forest, the tropical and temperate grasslands, the savannahs or boreal forests and other formation types (Whittaker 1973) may be considered.
