Nitrogen cycling in undisturbed and manipulated boreal forest

1982 ◽  
Vol 296 (1082) ◽  
pp. 419-425 ◽  
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Forest Canopy ◽  
Mineral Soil ◽  
Terrestrial Ecosystems ◽  
Ecosystem Functions ◽  
Managed Forests ◽  
Available N ◽  
Humus Layer

Like most forests and several other natural terrestrial ecosystems, the boreal forest accumulates N in biomass and soil organic matter, even although measured rates of biological N 2 fixation are normally low. The accumulation of N is disrupted if the forest canopy is removed by natural causes (fire, wind-felling or insect outbreaks) or by cutting. During the period after such a ‘catastrophe’ (in fact a common event in boreal forests, considered in a long-term perspective), the accumulation is discontinued or even changed into a loss of N from the site. Some losses are caused directly by fire or, in managed forests, by removal of biomass. These losses are usually small, except with whole-tree utilization. Nitrogen losses associated with nitrification processes (both leaching and denitrification) may be more serious on a cleared area, where uptake by vegetation is inconsiderable for some period. Nitrate formation may then take place both in the humus layer (the mor) and in the mineral soil, although the pH may be well below 4.5 in the mor layer. Scarcity of available N in the soil is a common cause of slow growth. Effects of fertilization on ecosystem functions are discussed.

scholarly journals Resilience of the boreal forest in response to Holocene fire-frequency changes assessed by pollen diversity and population dynamics

2010 ◽  
Vol 19 (8) ◽  
pp. 1026 ◽  
Author(s):  
Christopher Carcaillet ◽  
Pierre J. H. Richard ◽  
Yves Bergeron ◽  
Bianca Fréchette ◽  
Adam A. Ali
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Frequency Control ◽  
Regional Scale ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Frequency Changes ◽  
Fire Intervals ◽  
In Fire

The hypothesis that changes in fire frequency control the long-term dynamics of boreal forests is tested on the basis of paleodata. Sites with different wildfire histories at the regional scale should exhibit different vegetation trajectories. Mean fire intervals and vegetation reconstructions are based respectively on sedimentary charcoal and pollen from two small lakes, one in the Mixedwood boreal forests and the second in the Coniferous boreal forests. The pollen-inferred vegetation exhibits different trajectories of boreal forest dynamics after afforestation, whereas mean fire intervals have no significant or a delayed impact on the pollen data, either in terms of diversity or trajectories. These boreal forests appear resilient to changes in fire regimes, although subtle modifications can be highlighted. Vegetation compositions have converged during the last 1200 years with the decrease in mean fire intervals, owing to an increasing abundance of boreal species at the southern site (Mixedwood), whereas changes are less pronounced at the northern site (Coniferous). Although wildfire is a natural property of boreal ecosystems, this study does not support the hypothesis that changes in mean fire intervals are the key process controlling long-term vegetation transformation. Fluctuations in mean fire intervals alone do not explain the historical and current distribution of vegetation, but they may have accelerated the climatic process of borealisation, likely resulting from orbital forcing.

scholarly journals Impacts of forest management on soil properties: a fundamental research topic for Mexico

2020 ◽  
Vol 27 (1) ◽  
pp. 33-52 ◽  
Author(s):  
Karla Valladares-Samperio ◽  
◽  
Leopoldo Galicia-Sarmiento ◽  
Keyword(s):  
Forest Management ◽  
Boreal Forests ◽  
Negative Influence ◽  
Biological Properties ◽  
Ecosystem Functions ◽  
Functional Changes ◽  
Wood Harvesting ◽  
Intensive Forest Management ◽  
The Impact

Introduction: The increase in the intensity of wood harvesting has a negative influence on ecosystem functions of soils in temperate and boreal forests. Objective: To understand the impacts of intensive and extensive forest management methods on the physical, chemical and biological properties of soils, and consequences on nutrient availability and stabilization processes in temperate and boreal forests. Results and discussion: Intensive forest management methods can generate greater imbalance in the processes of availability and stabilization of nutrients, compared to selective methods. The impact is reflected in the deterioration of soil structure and the decrease of nutrient reserves and microbial communities. These damages affect fertility and functionality of soil, decreasing long-term productivity. Affectations depend on the intensity of biomass extracted, environmental conditions and site preparation. This makes evident the need to monitor forest management and its impact on soil ecology in temperate forests, which maintains long-term productivity and ensures the availability of wood volumes. Conclusion: In Mexico, the impact of forest management has been scarcely analyzed and it is indispensable to understand the functional changes in the processes that determine soil fertility and forest productivity.

scholarly journals Long-term fungus-plant co-variation from multi-site sedimentary ancient DNA metabarcoding in Siberia

2021 ◽  
Author(s):  
Barbara von Hippel ◽  
Kathleen R. Stoof-Leichsenring ◽  
Luise Schulte ◽  
Peter Seeber ◽  
Laura S. Epp ◽  
...  
Keyword(s):  
Ancient Dna ◽  
Boreal Forests ◽  
Mycorrhizal Fungus ◽  
Terrestrial Ecosystems ◽  
Dry Forest ◽  
Operational Taxonomic Units ◽  
Arctic Regions ◽  
Southern Tundra ◽  
Dna Metabarcoding

Climate change has a major impact on arctic and boreal terrestrial ecosystems as warming leads to northward treeline shifts, inducing consequences for heterotrophic organisms associated with the plant taxa. To unravel ecological dependencies, we address how long-term climatic changes have shaped the palaeo-ecosystems at selected sites in Siberia. We investigated sedimentary ancient DNA from five lakes spanning the last 47,000 years, using the ITS1 marker for fungi and the chloroplast P6 loop marker for vegetation metabarcoding. After bioinformatic processing with the OBItools pipeline, we obtained 706 unique fungal operational taxonomic units (OTUs) and 243 amplicon sequence variants (ASVs) for the plants. We show higher OTU numbers in dry forest tundra as well as boreal forests compared to wet southern tundra. The most abundant fungal taxa in our dataset are Pseudeurotiaceae, Mortierella, Sordariomyceta, Exophiala, Oidiodendron, Protoventuria, Candida vartiovaarae, Pseudeurotium, Gryganskiella fimbricystis, and Trichosporiella cerebriformis. The overall fungal composition is explained by the plant composition as revealed by redundancy analysis. The fungal functional groups show antagonistic relationships in their climate susceptibility. The advance of woody taxa in response to past warming led to an increase in the abundance of mycorrhizae, lichens, and parasites, while yeast and saprotroph distribution declined. We also show co-occurrences between Salicaceae, Larix, and Alnus and their associated pathogens and detect higher mycorrhizal fungus diversity with the presence of Pinaceae. Under future warming, we can expect feedback between fungus compositional and plant diversity changes which will affect forest advance and stability in arctic regions.

scholarly journals Relationships between low-temperature fires, climate and vegetation during three late glacials and interglacials of the last 430 kyr in northeastern Siberia reconstructed from monosaccharide anhydrides in Lake El'gygytgyn sediments

2020 ◽  
Vol 16 (2) ◽  
pp. 799-818 ◽  
Author(s):  
Elisabeth Dietze ◽  
Kai Mangelsdorf ◽  
Andrei Andreev ◽  
Cornelia Karger ◽  
Laura T. Schreuder ◽  
...  
Keyword(s):  
Low Temperature ◽  
Boreal Forest ◽  
Biomass Burning ◽  
Boreal Forests ◽  
Vegetation Shifts ◽  
Low Intensity ◽  
Northern Latitudes ◽  
Lake El’Gygytgyn ◽  
Monosaccharide Anhydrides

Abstract. Landscapes in high northern latitudes are assumed to be highly sensitive to future global change, but the rates and long-term trajectories of changes are rather uncertain. In the boreal zone, fires are an important factor in climate–vegetation interactions and biogeochemical cycles. Fire regimes are characterized by small, frequent, low-intensity fires within summergreen boreal forests dominated by larch, whereas evergreen boreal forests dominated by spruce and pine burn large areas less frequently but at higher intensities. Here, we explore the potential of the monosaccharide anhydrides (MA) levoglucosan, mannosan and galactosan to serve as proxies of low-intensity biomass burning in glacial-to-interglacial lake sediments from the high northern latitudes. We use sediments from Lake El'gygytgyn (cores PG 1351 and ICDP 5011-1), located in the far north-east of Russia, and study glacial and interglacial samples of the last 430 kyr (marine isotope stages 5e, 6, 7e, 8, 11c and 12) that had different climate and biome configurations. Combined with pollen and non-pollen palynomorph records from the same samples, we assess how far the modern relationships between fire, climate and vegetation persisted during the past, on orbital to centennial timescales. We find that MAs attached to particulates were well-preserved in up to 430 kyr old sediments with higher influxes from low-intensity biomass burning in interglacials compared to glacials. MA influxes significantly increase when summergreen boreal forest spreads closer to the lake, whereas they decrease when tundra-steppe environments and, especially, Sphagnum peatlands spread. This suggests that low-temperature fires are a typical characteristic of Siberian larch forests also on long timescales. The results also suggest that low-intensity fires would be reduced by vegetation shifts towards very dry environments due to reduced biomass availability, as well as by shifts towards peatlands, which limits fuel dryness. In addition, we observed very low MA ratios, which we interpret as high contributions of galactosan and mannosan from biomass sources other than those currently monitored, such as the moss–lichen mats in the understorey of the summergreen boreal forest. Overall, sedimentary MAs can provide a powerful proxy for fire regime reconstructions and extend our knowledge of long-term natural fire–climate–vegetation feedbacks in the high northern latitudes.

Seed banks in five boreal forest stands originating between 1810 and 1963

1982 ◽  
Vol 60 (9) ◽  
pp. 1815-1821 ◽  
Author(s):  
Anders Granström
Keyword(s):  
Boreal Forest ◽  
Plant Species ◽  
Mineral Soil ◽  
Coniferous Forest ◽  
Soil Samples ◽  
Distribution Data ◽  
Forest Stands ◽  
Humus Layer ◽  
Seed Content ◽  
Organic Horizons

The viable seed content of soil samples from five coniferous forest stands in northern Sweden, aged 16–169 years, was determined by means of germination trials. The soil samples were separated into five fractions: three organic horizons and two mineral soil horizons. Seedlings of 15 phanerogam species emerged, representing densities of 239–763 seeds/m2 in the soils from the different stands. The depth distributions of the seeds varied with both plant species and forest stand. Most seeds were found at various depths in the humus layer, but in one stand an appreciable seed density of Luzula pilosa was present in the mineral soil. Most of the seedlings belonged to plant species present in the vegetation or with good means of dispersal. The depth distribution data, however, suggest that Luzula pilosa in particular may have a persistent seed bank. The role of persistent seeds in the vegetational composition of the boreal forest is discussed.

Effect of temperature on soil organic matter decomposition in three forest biomes of eastern Canada

2006 ◽  
Vol 86 (Special Issue) ◽  
pp. 247-256 ◽  
Author(s):  
D. Paré ◽  
R. Boutin ◽  
G. R. Larocque ◽  
F. Raulier
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Sugar Maple ◽  
Mineral Soil ◽  
Organic Matter Decomposition ◽  
Effect Of Temperature ◽  
Organic Matter Quality ◽  
Soil Organic Matter Decomposition ◽  
Humus Layer

The sensitivity of soil organic matter decomposition to temperature change is critical tothe global carbon balance and to whether soils will respond with positive feedback to climate change. Forest cover determines litter composition, which controls to a large extent soil organic matter quality and its sensitivity to temperature. The effect of temperature on soil organic matter decomposition was studied along a latitudinal gradient encompassing sugar maple, balsam fir and black spruce forest types. Long-term laboratory soil incubations conducted at four different temperatures were used to discriminate the effect of temperature from that of organic matter quality on decomposition rates. The specific C mineralization rate of the humus layer was highest for balsam fir sites, intermediate for one sugar maple site and lowest for black spruce sites and the other sugar maple site. However, considering the total C pools of the FH layer and of the top 20 cm of mineral soil, it was estimated that coniferous sites exhibit a higher C efflux than sugar maple soils at any given temperature. Estimated C mineralization rates in the field using the temperature records for each individual site showed the same trends despite cooler temperature regimes for the coniferous sites. The Q10 respiration rates of the humus layer of all sites increased as the temperature got warmer. A significant effect of temperature on the pool size of labile C in the mineral soil was detected for some sites suggesting a potential long-term loss of C upon warming. The low estimated C evolution rates of sugar maple soils were perhaps due to the greater decomposition activity within the L layer, before the litter C enters underlying soil pools. These observations suggest that coniferous soils are not more resistant than deciduous forests to increasing their specific rates of soil heterotrophic respiration upon warming. Key words: Soil organic carbon, forest type, forest composition, warming, long-term incubation, labile carbon

Long-term effects of nitrogen fertilization on soil chemistry in three Scots pine stands in Sweden

2011 ◽  
Vol 41 (2) ◽  
pp. 279-288 ◽  
Author(s):  
Eva Ring ◽  
Staffan Jacobson ◽  
Lars Högbom
Keyword(s):  
Scots Pine ◽  
Nitrogen Fertilization ◽  
Boreal Forests ◽  
Soil Chemistry ◽  
Mineral Soil ◽  
Long Term Effects ◽  
Stem Wood ◽  
Mineral Soils ◽  
Major Nutrients

Adding nitrogen to coniferous forests on mineral soils will increase stem-wood growth in most boreal forests. The addition of nitrogen affects soils and waters as well. This investigation was conducted to evaluate the long-term effects of nitrogen fertilization at different intensities on soil chemistry in nitrogen-limited ecosystems. The study was performed at three experimental sites that were originally established around 1980 in Scots pine ( Pinus sylvestris L.) stands. Fertilization regimes with applications ranging from conceivable commercial rates to very intensive rates (3× 150 kg N·ha–1 up to 12× 150 kg N·ha–1) had been applied. Samples were collected from the FH horizon at all sites and 0–20 cm in the mineral soil at two sites and analyzed for pH and major nutrients. The carbon to nitrogen ratio in the FH horizon decreased with increasing total nitrogen application, while the concentrations and contents of nitrogen and exchangeable magnesium and phosphorus increased. The concentration and contents of exchangeable potassium decreased in both the FH horizon and the mineral soil. In general, larger effects on soil chemistry were observed with increasing fertilization intensity.

scholarly journals Long-Term Nitrogen Deposition Alters Ectomycorrhizal Community Composition and Function in a Poplar Plantation

2021 ◽  
Vol 7 (10) ◽  
pp. 791
Author(s):  
Nan Yang ◽  
Bo Wang ◽  
Dong Liu ◽  
Xuan Wang ◽  
Xiuxiu Li ◽  
...  
Keyword(s):  
Community Structure ◽  
Eastern China ◽  
Mineral Soil ◽  
Total Carbon ◽  
N Addition ◽  
Poplar Plantation ◽  
Total Carbon Content ◽  
Humus Layer ◽  
And Function

The continuous upsurge in soil nitrogen (N) enrichment has had strong impacts on the structure and function of ecosystems. Elucidating how plant ectomycorrhizal fungi (EMF) mutualists respond to this additional N will facilitate the rapid development and implementation of more broadly applicable management and remediation strategies. For this study, we investigated the responses of EMF communities to increased N, and how other abiotic environmental factors impacted them. Consequently, we conducted an eight-year N addition experiment in a poplar plantation in coastal eastern China that included five N addition levels: 0 (N0), 50 (N1), 100 (N2), 150 (N3), and 300 (N4) kg N ha−1 yr−1. We observed that excessive N inputs reduced the colonization rate and species richness of EMF, and altered its community structure and functional traits. The total carbon content of the humus layer and available phosphorus in the mineral soil were important drivers of EMF abundance, while the content of ammonium in the humus layer and mineral soil determined the variations in the EMF community structure and mycelium foraging type. Our findings indicated that long-term N addition induced soil nutrient imbalances that resulted in a severe decline in EMF abundance and loss of functional diversity in poplar plantations.

The demographic structure of European aspen (Populus tremula) populations in managed and old-growth boreal forests in eastern Finland

2007 ◽  
Vol 37 (6) ◽  
pp. 1070-1081 ◽  
Author(s):  
Tarja Latva-Karjanmaa ◽  
Reijo Penttilä ◽  
Juha Siitonen
Keyword(s):  
Protected Areas ◽  
Boreal Forests ◽  
Large Scale ◽  
Populus Tremula ◽  
Managed Forests ◽  
Mature Trees ◽  
Old Growth ◽  
European Aspen ◽  
Eastern Finland

European aspen ( Populus tremula L.) is a keystone species for biodiversity in boreal forests. However, large aspen have largely been removed from managed forests, whereas regeneration and the long-term persistence of mature trees in protected areas are matters of concern. We recorded the numbers of mature (≥20 cm diameter) aspen in old-growth and managed forests in eastern Finland, based on a large-scale inventory (11 400 ha, 36 000 living and dead trees). In addition, saplings and small aspen trees were surveyed on thirty-six 1 ha sample plots. The average volumes of mature living and dead aspen were 4.0 and 1.3 m3/ha in continuous old-growth forests and 0.2 and 0.6 m3/ha in managed forests, respectively. These results indicate that large aspen trees in managed forests are a legacy of the past, when forest landscapes were less intensively managed. We conclude that the long-term persistence of aspen in protected areas can only be secured by means of restoration measures that create gaps large enough for regeneration to occur. More emphasis should be given to sparing aspen during thinning and to retaining mature aspen during regeneration cutting in managed forests.

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