Southern Boreal Region Research Articles

Description of a relict aspen parkland-associated grassland in the Peace River region of British Columbia, Canada

The aspen parkland-associated grasslands of the Peace River region, British Columbia (BC), have been severely reduced in area, primarily because of agricultural and urban development. In this region, the species composition of plant communities is similar to that of prairie grasslands and is topographically influenced, occurring primarily on warm-aspect slopes along the Peace River and some of its tributaries. Historical records show that non-forested grass- and sedge-dominated plant communities occurred on flat and gently rolling terrain in a parkland ecosystem near what are now the communities of Dawson Creek and Fort St. John. The Peace grasslands are not represented in BC’s biogeoclimatic ecosystem classification, perhaps leading to their neglect in regional natural resource management and conservation planning. Here, I describe the vascular plant community of a level-terrain relict aspen parkland-associated grassland in the Peace River region. Its species composition differs from nearby warm-aspect grasslands and includes provincially listed plant species. Increased awareness of grassland communities may support conservation, ecosystem restoration, and climate change adaptation in the southern boreal region of BC.

Conversion of boreal forests to agricultural systems: soil microbial responses along a land-conversion chronosequence

BackgroundBoreal regions are warming at more than double the global average, creating opportunities for the northward expansion of agriculture. Expanding agricultural production in these regions will involve the conversion of boreal forests to agricultural fields, with cumulative impacts on soil microbial communities and associated biogeochemical cycling processes. Understanding the magnitude or rate of change that will occur with these biological processes will provide information that will enable these regions to be developed in a more sustainable manner, including managing carbon and nitrogen losses. This study, based in the southern boreal region of Canada where agricultural expansion has been occurring for decades, used a paired forest-adjacent agricultural field approach to quantify how soil microbial communities and functions were altered at three different stages post-conversion (< 10, > 10 and < 50, and > 50 years). Soil microbial functional capacity was assessed by quantitative PCR of genes associated with carbon (C), nitrogen, and phosphorous (P) cycling; microbial taxonomic diversity and community structure was assessed by amplicon sequencing.ResultsFungal alpha diversity did not change, but communities shifted from Basidiomycota to Ascomycota dominant within the first decade. Bacterial alpha diversity increased, with Gemmatimonadota groups generally increasing and Actinomycetota groups generally decreasing in agricultural soils. These altered communities led to altered functional capacity. Functional genes associated with nitrification and low molecular weight C cycling potential increased after conversion, while those associated with organic P mineralization potential decreased. Stable increases in most N cycling functions occurred within the first decade, but C cycling functions were still changing 50 years post conversion.ConclusionsMicrobial communities underwent a rapid shift in the first decade, followed by several decades of slower transition until stabilizing 50 years post conversion. Understanding how the microbial communities respond at different stages post-conversion improves our ability to predict C and N losses from emerging boreal agricultural systems, and provides insight into how best to manage these soils in a way that is sustainable at the local level and within a global context.

The anthropogenic imprint on temperate and boreal forest demography and carbon turnover.

The sweeping transformation of the biosphere by humans over the last millennia leaves only limited windows into its natural state. Much of the forests that dominated temperate and southern boreal regions have been lost and those that remain typically bear a strong imprint of forestry activities and past land-use change, which have changed forest age structure and composition. Here, we ask how would the dynamics, structure and function of temperate and boreal forests differ in the absence of forestry and the legacies of land-use change? Global. 2001-2014, integrating over the legacy of disturbance events from 1875 to 2014. Trees. We constructed an empirical model of natural disturbance probability as a function of community traits and climate, based on observed disturbance rate and form across 77 protected forest landscapes distributed across three continents. Coupling this within a dynamic vegetation model simulating forest composition and structure, we generated estimates of stand-replacing disturbance return intervals in the absence of forestry for northern hemisphere temperate and boreal forests. We then applied this model to calculate forest stand age structure and carbon turnover rates. Comparison with observed disturbance rates revealed human activities to have almost halved the median return interval of stand-replacing disturbances across temperate forest, with more moderate changes in the boreal region. The resulting forests are typically much younger, especially in northern Europe and south-eastern North America, resulting in a 32% reduction in vegetation carbon turnover time across temperate forests and a 7% reduction for boreal forests. The current northern hemisphere temperate forest age structure is dramatically out of equilibrium with its natural disturbance regimes. Shifts towards more nature-based approaches to forest policy and management should more explicitly consider the current disturbance surplus, as it substantially impacts carbon dynamics and litter (including deadwood) stocks.

Amphibians and reptiles in North Sweden: distribution, habitat affinities, and abundance (Classes: Amphibia and Reptilia).

North Sweden ('Norrland' in Swedish) covers 243000 km2 and lies mainly in the boreal biome. The herpetofauna comprises five amphibian and four reptile species: Lissotriton vulgaris, Triturus cristatus, Bufo bufo, Rana temporaria, Rana arvalis, Zootoca vivipara, Anguis fragilis, Natrix natrix, and Vipera berus. Successful conservation and management of amphibians and reptiles depend on accurate information about distribution, habitat affinities, and abundance. Such knowledge is also essential as a benchmark to assess changes in distribution and abundance that may come about as a result of climate change and human habitat alteration. This paper aims to present accurate distribution maps, describe habitat affinities, and provide abundance estimates for the herpetofauna of North Sweden for the period 1970-2022. Distribution data are presented by traditional faunistic provinces, as well as by biotic regions and alpine life zones. Separate sections address post-glacial colonization and a herpetological perspective on anthropogenic changes in relation to species´ present status. Bufo bufo, Rana temporaria, Rana arvalis, Zootoca vivipara, and Vipera berus are widely distributed throughout the boreal sub-regions. Rana temporaria, Zootoca vivipara, and Vipera berus also extend into the alpine region. Triturus cristatus, Anguis fragilis, and Natrix natrix occur mainly in the coastal parts of the Southern Boreal region. There are no signs of recent changes in distribution range, but Lissotriton vulgaris, Triturus cristatus, and Rana arvalis have been largely overlooked in the past and have a much wider occurrence than previously recognized. Most species are found in habitats usually not described in all-European field guides. Nearly all anurans hibernate in water. Abundance estimates suggest that some species are more common in the boreal than thought, supporting the notion that a large share of their total European population occurs there. Although local extinctions and declines are known, there are no signs of widespread population decline for any species during the study period.

Distinct Climate Effects on Dahurian Larch Growth at an Asian Temperate-Boreal Forest Ecotone and Nearby Boreal Sites

Climate change is exerting profound impacts on the structure and function of global boreal forest. Compared with their northern counterparts, trees growing at the southern boreal forest and the temperate-boreal forest ecotone likely show distinct responses to climate change. Based on annual basal areal increment (BAI) of Dahurian larch (Larix gmelinii Rupr.) plantations with similar ages, tree densities and soil nutrient conditions, we investigated the tree growth responses to inter-annual climate variations at an Asian temperate-boreal forest ecotone and nearby boreal sites in northeast China. Annual BAI changed nonlinearly with cambial age in the form of a lognormal curve. The maximum annual BAI showed no significant difference between the two bioregions, while annual BAI peaked at an elder age at the boreal-temperate forest ecotone. After eliminating the age associated trend, conditional regression analyses indicate that residual BAI at the boreal sites increased significantly with higher growing-season mean nighttime minimum temperature and non-growing-season precipitation, but decreased significantly with higher growing-season mean daytime maximum temperature during the past three decades (1985–2015). In contrast, residual BAI at the boreal-temperate forest ecotone only showed a positive and weak response to inter-annual variations of growing-season precipitation. These findings suggest distinct effects of inter-annual climate variation on the growth of boreal trees at the temperate-boreal forest ecotone in comparison to the southern boreal regions, and highlight future efforts to elucidate the key factors that regulate the growth ofthe southernmost boreal trees.

Invertebrate colonization of a newly constructed diversion channel in the Canadian Shield

Construction of artificial channels to divert water is common in a variety of natural resource development projects; however, the length of time required for these stream channels to become productive fish habitat remains an understudied aspect. The creation of a bedrock channel (∼150 m) to drain a third-order boreal lake and its watershed (∼300 ha) offered the unique opportunity to study colonization by comparing habitat and invertebrate metrics with a reference stream. The amount of riparian vegetation on the banks of the diversion channel steadily increased, but remained much lower than the reference stream after 5 years. The channel was quickly colonized by benthic macroinvertebrates, which were of comparable abundance to the reference stream starting in the first year, and thereafter were greater in abundance. Taxa diversity and richness responded more slowly, becoming similar to the reference stream after 3 years. Results from this study suggest that newly created, lake-outlet channels can become productive small stream habitats in a relatively short time period (&lt;5 years) in southern boreal regions.

Heterogeneity in migration strategies of Whooping Cranes

AbstractMigratory birds use numerous strategies to successfully complete twice-annual movements between breeding and wintering sites. Context for conservation and management can be provided by characterizing these strategies. Variations in strategy among and within individuals support population persistence in response to changes in land use and climate. We used location data from 58 marked Whooping Cranes (Grus americana) from 2010 to 2016 to characterize migration strategies in the U.S. Great Plains and Canadian Prairies and southern boreal region, and to explore sources of heterogeneity in their migration strategy, including space use, timing, and performance. Whooping Cranes completed ~3,900-km migrations that averaged 29 days during spring and 45 days during autumn, while making 11–12 nighttime stops. At the scale of our analysis, individual Whooping Cranes showed little consistency in stopover sites used among migration seasons (i.e. low site fidelity). In contrast, individuals expressed a measure of consistency in timing, especially migration initiation dates. Whooping Cranes migrated at different times based on age and reproductive status, where adults with young initiated autumn migration after other birds, and adults with and without young initiated spring migration before subadult birds. Time spent at stopover sites was positively associated with migration bout length and negatively associated with time spent at previous stopover sites, indicating Whooping Cranes acquired energy resources at some stopover sites that they used to fuel migration. Whooping Cranes were faithful to a defined migration corridor but showed less fidelity in their selection of nighttime stopover sites; hence, spatial targeting of conservation actions may be better informed by associations with landscape and habitat features rather than documented past use at specific locations. The preservation of variation in migration strategies existing within this species that experienced a severe population bottleneck suggests that Whooping Cranes have maintained a capacity to adjust strategies when confronted with future changes in land use and climate.

Wildfire effects on BVOC emissions from boreal forest floor on permafrost soil in Siberia

One of the effects of climate change on boreal forest will be more frequent forest wildfires and permafrost thawing. These will increase the availability of soil organic matter (SOM) for microorganisms, change the ground vegetation composition and ultimately affect the emissions of biogenic volatile organic compounds (BVOCs), which impact atmospheric chemistry and climate. BVOC emissions from boreal forest floor have been little characterized in southern boreal region, and even less so in permafrost soil, which underlies most of the northern boreal region. Here, we report the long-term effects of wildfire on forest floor BVOC emission rates along a wildfire chronosequence in a Larix gmelinii forest in central Siberia. We determined forest floor BVOC emissions from forests exposed to wildfire 1, 23 and > 100 years ago. We studied how forest wildfires and the subsequent succession of ground vegetation, as well as changes in the availability of SOM along with the deepened and recovered active layer, influence BVOC emission rates. The forest floor acted as source of a large number of BVOCs in all forest age classes. Monoterpenes were the most abundant BVOC group in all age classes. The total BVOC emission rates measured from the 23- and >100-year-old areas were ca. 2.6 times higher than the emissions from the 1-year-old area. Lower emissions were related to a decrease in plant coverage and microbial decomposition of SOM after wildfire. Our results showed that forest wildfires play an important indirect role in regulating the amount and composition of BVOC emissions from post-fire originated boreal forest floor. This could have a substantial effect on BVOC emissions if the frequency of forest wildfires increases in the future as a result of climate warming.

Birds in boreal protected areas shift northwards in the warming climate but show different rates of population decline

Climate change has the potential to have wholesale impacts on species populations, driving them polewards and upwards, and even affecting populations occurring within protected area (PA) networks. We studied population changes in bird species in the boreal PA network of Finland based on extensive bird census data collected in the years 1981–1999 and in 2000–2017. Between these time periods, the mean annual temperature increased in Finland by 1.1 °C, and the mean weighted density of the species shifted 28.5 km (1.8 km/year) northwards in the PA network. However, the total bird population density simultaneously declined by approximately 10%. The decline was most pronounced in long-distance migrants, which showed strongest population contraction in southern boreal regions. In contrast, resident species increased between the two time slices, particularly in larger PAs. While the PA network of boreal native habitats appears to be successful in preserving resident species, climate-induced changes have also caused a decline in the populations of migrants in the PAs. Thus, life-history characteristics of species can significantly affect the success of conservation efforts in a warming climate. To enhance future survival of resident and migrant bird species moving to Finland and northwards, the PAs should be larger and the connectivity of the PA network improved in southern and central Finland. In addition, international actions are needed to enhance the survival of long-distance migrants during the migratory period and in overwintering grounds.

Early recruitment of boreal forest trees in hybrid poplar plantations of different densities on mine waste rock slopes

Mine wastes create harsh recruitment conditions for forest tree seedlings, especially waste rock piles where erodible slopes are prone to drought. Plantations using fast-growing tree species can potentially accelerate the conversion of degraded mine sites into forests through facilitation of tree recruitment, while contributing to the stability of slopes. In this study, hybrid poplars were tested as a means of achieving reclamation objectives by providing shelter for forest tree seedlings on waste rock slopes (3H:1V ratio) in the Canadian southern boreal region. Density effects of young hybrid poplars were assessed on the emergence and survival of early, mid and late successional species, naturally occurring or hand-seeded, and on the understory micro-environmental parameters in plantations of different spacings (1 × 1, 2 × 2, 4 × 4 m and control without planted trees). Results were also compared in 2 × 2-m plantations with and without a hydroseeded herbaceous cover, traditionally used to control erosion in slopes. During the 2nd growing season of the plantations, seedling emergence of naturally established Salicaceae (Populus and Salix) species followed a quadratic pattern along the density gradient, as emergence values were higher under an intermediary density. Nonetheless, decrease in light transmission emerged as a limiting factor of seedling survival for these early-successional, shade-intolerant species by the next summer. Following a spring sowing experiment in the 3rd growing season of the plantations, emergence rates for later-successional Picea glauca and Abies balsamea seedlings increased with hybrid poplar density. During their peak emergence period, in early season, higher soil moisture content was found under denser cover. However, at the end of the third year of the plantations, only A. balsamea showed moderate increase in early recruitment success rates under denser tree cover. In hydroseeded plots, a competitive effect of the herbaceous cover was observed on Salicaceae emergence and A. balsamea survival. These results suggest that planting of young plantations without a hydroseeded cover may offer a more suitable solution in order to quickly provide early recruitment opportunities for later-successional seedlings in waste rock slopes. Despite this, a significant decrease in moisture content recorded during the second half of the 3rd growing season under the 1 × 1-m cover, compared to the 2 × 2-m, likely signalled an increasing competitive effect from hybrid poplars, which may compromise their nursing potential in the longer term. Therefore, further monitoring is imperative for a better understanding of longer-term facilitation and competition interactions between nurse trees and understory seedlings in waste rock slopes, where competition for limited resources, such as water, may be severe.

Soil organic matter composition and quality across fire severity gradients in coniferous and deciduous forests of the southern boreal region

AbstractRecent patterns of prolonged regional drought in southern boreal forests of the Great Lakes region, USA, suggest that the ecological effects of disturbance by wildfire may become increasingly severe. Losses of forest soil organic matter (SOM) during fire can limit soil nutrient availability and forest regeneration. These processes are also influenced by the composition of postfire SOM. We sampled the forest floor layer (i.e., full organic horizon) and 0–10 cm mineral soil from stands dominated by coniferous (Pinus banksiana Lamb.) or deciduous (Populus tremuloides Michx.) species 1–2 months after the 2011 Pagami Creek wildfire in northern Minnesota. We used solid‐state 13C NMR to characterize SOM composition across a gradient of fire severity in both forest cover types. SOM composition was affected by fire, even when no statistically significant losses of total C stocks were evident. The most pronounced differences in SOM composition between burned and unburned reference areas occurred in the forest floor for both cover types. Carbohydrate stocks in forest floor and mineral horizons decreased with severity level in both cover types, whereas pyrogenic C stocks increased with severity in the coniferous forest floor and decreased in only the highest severity level in the deciduous forest floor. Loss of carbohydrate and lignin pools contributed to a decreased SOM stability index and increased decomposition index. Our results suggest that increases in fire severity expected to occur under future climate scenarios may lead to changes in SOM composition and dynamics with consequences for postfire forest recovery and C uptake.

Simulating impacts of water stress on woody biomass in the southern boreal region of western Canada using a dynamic vegetation model

Drought-related dieback of aspen-dominated woodland has been a persistent and possibly increasing phenomenon over recent decades in the southern boreal forests of western Canada. The Integrated BIosphere Simulator (IBIS) dynamic vegetation model was modified for Canadian ecosystems (hence “Can-IBIS”) and used to simulate effects of water stress on the woody biomass of aspen-dominated stands in the boreal mixedwood regions of Saskatchewan and Alberta. The modified model was evaluated using eddy-covariance measurements of CO2 and water vapor fluxes made at a forested site and a grassland site located in the study region. The tested model captured 74% of the variation in biomass growth trajectories at 13 boreal and 12 parkland field study sites; the mean difference between simulated and observed values was approximately 1100gCm−2. Under the combined influences of climatic variation and increasing atmospheric CO2 from 2000 to 2008, simulated values of net biomass growth were 544 and 240gCm−2 for the boreal and parkland study sites, respectively. Drought-induced biomass losses at the drier sites (in both boreal and parkland regions) were simulated to be 100–350gCm−2, corresponding to an annual modeled mortality rate of 5–7% during severe drought years. These results were consistent with field measurements and other statistical studies. Changes in biomass over the nine-year period varied with geographical location and corresponded to spatial variation in monthly values of the self-calibrated Palmer Drought Severity Index. We conclude that Can-IBIS can be used to investigate annual impacts of water stress on woody biomass growth, although cumulative physiological effects of multi-year droughts on tree mortality would benefit from improved simulation of subgrid-scale (soil texture-driven) processes. In particular, two areas for further development are: (1) calibration based on the results of soil surveys at fine spatial/temporal scales; and (2) biophysical experiments to refine the representation of water stress constraints on biomass turnover.

Anomalous earlywood vessel lumen area in black ash ( Fraxinus nigra Marsh.) tree rings as a potential indicator of forest fires

Earlywood, latewood, total ring width and cross-sectional earlywood vessel lumen areas were measured in twenty-one Fraxinus nigra trees located in the southern boreal region of Quebec, Canada. Two of the trees survived a severe fire in 1923 during which year almost no latewood was produced. In 1924 both trees produced rings with a strong decrease in the size of the largest earlywood vessels. This synchronized size decrease in cross-sectional earlywood vessel lumen area was not observed in other years and is likely a response of the trees to either direct injury or changes in environmental conditions associated with fire. Vessel characteristics in ring-porous species have the potential to be used in conjunction with other indicators of fire to extend fire history reconstructions on a spatial scale.

Plant community structure and functional differences between marshes and fens in the southern boreal region of Alberta, Canada

Abstract Despite visual similarities between marshes and moderate-rich fens in the southern part of the western boreal forest of Canada, there are ecological and functional differences between the two wetland classes. Western boreal marshes have received little attention and are often difficult to distinguish from moderate-rich fens in appearance, especially when both are located at the edges of ponds and small lakes. We examined species assemblages, net above-ground production, decomposition, nutrient cycling, and environmental characteristics in five wetlands, all with approximately 1 m of peat. Based on TWINSPAN and DCCA, both wetland classes contain Carex aquatilis, but marshes were characterized by Carex utriculata, Carex atherodes, Lemna minor, Typha latifolia, and no mosses. Fens were characterized by Carex lasiocarpa and various species of brown mosses, and overall, they were more variable in species composition. There were also functional differences between the classes, with net above-ground pro...

Plant diversity patterns in semi-natural grasslands along an elevational gradient in southern Norway

This paper examined vascular-plant and cryptogam speciesdiversity on different spatial scales in semi-natural grasslands alonganelevational gradient ranging from 530 m a.s.l. (southernboreal region) to 1230 m a.s.l. (low alpine region)in Vang, southern Norway. Species diversity of vascular-plants on asmallscale (0.25 m2) peaked atmid-elevations. Diversity at low elevations was not higher than that ofhigh elevations, but diversity on a large scale decreased continuously withelevation. Cryptogam diversity increased with elevation on all scales. Highsmall-scale vascular-plant diversity at high elevations waspositively related to species abundance which increased with elevation, andsuggests an area effect along the gradient. Most species atmid-elevational levels (750 and 915 m a.s.l.) didalso occur at other levels. Lowland vascular-plant species constituted50% of the species in the low alpine region. Collectively, these patternsreflect the importance of regional dynamics along the gradient. Environmentalvariables such as topography, biomass, soil variables were less important forexplaining variation in vascular plant diversity, and it is suggested thatland-use processes such as grazing, mowing, fuel-wood cuttinghavelevelled out the effects of other variables along the gradient.

Heterogeneity in semi‐natural grasslands: the importance of the elevational gradient

Heterogeneity patterns in semi‐natural grasslands were studied within 20 sites at 4 different elevational levels ranging from 530 m a.s.1. at level 1 (southern boreal region) to 1230 m a.s.1. at level 4 (low alpine region) in Vang, southern Norway. Vegetational heterogeneity decreased with elevation for vascular plants. Cryptogam species increased in heterogeneity at mid‐elevational levels (750 and 915 m a.s.1.), but heterogeneity decreased again at level 4. Mean values of soil nutrients and other soil variables (e.g. loss on ignition), and their heterogeneity increased with elevation, while pH showed a decrease for both parameters. The general increase in environmental heterogeneity in the soil was not reflected in vascular plant heterogeneity because soil variables explained 40 % variation at both level 1 and 4. However, the relative differences among levels suggest that vascular plant species patterns were more sensitive to soil heterogeneity at lower elevational levels. Soil variables were also relatively more important in structuring cryptogam species at higher elevations (level 3 and 4) compared to vascular plant species. The discrepancy between vascular plants and cryptogams are also shown in the relationship between heterogeneity and diversity. Gamma diversity decreased with decreasing heterogeneity of vascular plants, while the highest value of large scale cryptogam diversity corresponded with the lowest heterogeneity value at level 4. Alfa‐diversity peaked at an intermediate level of heterogeneity for vascular plants while alfa‐diversity of cryptogams decreased with increasing values of heterogeneity.

Spatial congruence between ecoregions and littoral macroinvertebrate assemblages

The usefulness of ecoregions for discriminating between littoral macroinvertebrate assemblages of 363 Swedish lakes was examined. A relatively good correspondence was found between ecoregion delineations and macroinvertebrate assemblages of the lake littoral zone. Variables describing macroinvertebrate assemblages (abundance, taxon richness, diversity, and Sørensen similarity) had significantly different values in the 6 ecoregions, but the most marked differences occurred between the middle and southern boreal regions, coinciding with the approximate location of the ecotone delineating the northern coniferous (taiga) and southern deciduous forests. Macroinvertebrate assemblages of lakes in the south were generally more diverse, having more taxa, whereas lakes in the north in general and in the arctic–alpine complex in particular were characterized by low richness and the presence of 2 plecopterans, namely Diura nanseni (Kempny) and Capnia atra Morton. Twenty-five variables made significant contributions to explaining the variance among species assemblages. In the constrained ordination of taxa and environmental factors by canonical correspondence analysis, variables indicative of geographic position (latitude and longitude), ecosystem type (water color and lake surface area), and habitat type (pebble substratum) were among the first 5 variables selected. Discriminant analysis of 25 environmental variables and 6 UPGMA (flexible β unweighted pair-group method using arithmetic averages) groups classified 64% of the sites to the correct group.

An attempt to explain the distribution of the tree species composing the riparian forests of Lake Duparquet, southern boreal region of Quebec, Canada

The objective of this study was to evaluate the most important environmental factors determining the distribution of tree species within the riparian zone of Lake Duparquet, located in the southern boreal region of Quebec, Canada. Occurrence and relative basal area of 10 species were recorded within an altitudinal range of 200 cm above mean water level along 95 transects. Stepwise logistic regression and canonical correspondence analyses were performed on the overall data set as well as separately for the five geomorphological shore types distinguished (depositional flats, floodplains, beaches, terraces, and rock outcrops). The elevation gradient, representing seasonal floodings, is the main factor determining the distribution of the species. The differences between the geomorphological shore types with respect to composition and arrangement of the arborescent vegetation along the elevation gradient are at least partially explained by surficial substratum, topography, aspect, and fire. Exposure to wave activity seems to be of minor importance only. However, since they are the driving force of erosion and sedimentation, the waves are to a great part responsible for the morphological differentiation of the shoreline. The distribution of the tree species along a characteristic physiographic cross-section is illustrated for each geomorphological shore type.

Diet, body condition, and reproduction of Eurasian pine martens Mantes martes during cycles in microtine density

Winter diet, body condition, growth, reproduction, and age structure of pine martens Martes martes were studied during cycles in microtine density in south‐central Sweden. I analysed 398 scats collected in winters 1988 89 to 1996‐97. and 483 carcasses from martens trapped in winters 1989‐90 to 1992‐93. Microtines were the single most frequent prey category in the winter diet, and the consumption of microtines was correlated with microtine density. In the absence of microtines. pine martens increased the relative consumption of some alternative prey, most notably hares. Among adults, total food consumption, body condition, and reproductive success did not follow microtine density. Among juveniles, there were indications of lower total food consumption, smaller fat deposits, and higher trapping vulnerability, and among juvenile females also of lower body growth, when microtines were scarce. The data were, however, not consistent in this respect. I suggest that pine martens in the southern boreal region do not suffer from food shortage at microtine lows, and accordingly, that the demography of pine martens is independent of microtine cycles.

An attempt to e×plain the distribution of the tree species composing the riparian forests of Lake Duparquet, southern boreal region of Quebec, Canada

An attempt to e×plain the distribution of the tree species composing the riparian forests of Lake Duparquet, southern boreal region of Quebec, Canada