Integrated long-term responses of an arctic–alpine willow and associated ectomycorrhizal fungi to an altered environment

2006 ◽  
Vol 84 (5) ◽  
pp. 831-843 ◽  
Author(s):  
Karina E. Clemmensen ◽  
Anders Michelsen
Keyword(s):  
Community Composition ◽  
Field Experiments ◽  
Environmental Changes ◽  
Plant Biomass ◽  
The Arctic ◽  
Root Tip ◽  
Root Mass ◽  
Cenococcum Geophilum ◽  
Root Tips

We evaluated ectomycorrhizal (ECM) colonization and morphotype community composition together with growth response and biomass distribution in the arctic–alpine, prostrate willow Salix herbacea L. × Salix polaris Wahlenb. after 11 seasons of shading, warming, and fertilization at a fellfield in subarctic Sweden. The aim was to assess responses of the integrated plant–fungal system to long-term field experiments simulating expected environmental changes. Warming more than doubled aboveground S. herbacea × S. polaris biomass and shoot growth, whereas shading and nutrient addition had less influence on these variables. In shaded plants, adjustments at leaf level probably buffered major changes in plant biomass allocation. Fertilization increased the root mass fraction and changed root system morphology by decreasing the number of root tips per unit root mass. While no long-term changes in total ECM colonization (%ECM root tips) in response to the treatments were identified, ECM colonization in June just after snowmelt was positively correlated with root density. Changes in densities of potential host plants may therefore be of great importance for ECM colonization intensity in this ecosystem type. The ECM morphotype community changed through the season, and frequencies of some ECM morphotypes ( Cortinarius saturninus and Clavulina spp.) changed more with season than with the treatments. Warming only slightly affected ECM morphotype frequencies, which implies a balanced increase in root tip numbers of most ECM morphotypes in warmed plants. Fertilization changed ECM morphotype community composition mainly because of a decrease in Cenococcum geophilum frequency and an increase in Tomentella stuposa frequency. We hypothesize that a shift from drought stress-tolerant fungi towards a dominance of minerogenic fungi may take place if nutrient availability increases substantially because of anthropogenic disturbances.

scholarly journals Differential arthropod responses to warming are altering the structure of Arctic communities

2018 ◽  
Vol 5 (4) ◽  
pp. 171503 ◽  
Author(s):  
Amanda M. Koltz ◽  
Niels M. Schmidt ◽  
Toke T. Høye
Keyword(s):  
Community Composition ◽  
Primary Productivity ◽  
Species Interactions ◽  
Ecosystem Processes ◽  
The Arctic ◽  
Individual Species ◽  
Freeze Thaw ◽  
Compositional Changes ◽  
Arctic Communities

The Arctic is experiencing some of the fastest rates of warming on the planet. Although many studies have documented responses to such warming by individual species, the idiosyncratic nature of these findings has prevented us from extrapolating them to community-level predictions. Here, we leverage the availability of a long-term dataset from Zackenberg, Greenland (593 700 specimens collected between 1996 and 2014), to investigate how climate parameters influence the abundance of different arthropod groups and overall community composition. We find that variation in mean seasonal temperatures, winter duration and winter freeze–thaw events is correlated with taxon-specific and habitat-dependent changes in arthropod abundances. In addition, we find that arthropod communities have exhibited compositional changes consistent with the expected effects of recent shifts towards warmer active seasons and fewer freeze–thaw events in NE Greenland. Changes in community composition are up to five times more extreme in drier than wet habitats, with herbivores and parasitoids generally increasing in abundance, while the opposite is true for surface detritivores. These results suggest that species interactions and food web dynamics are changing in the Arctic, with potential implications for key ecosystem processes such as decomposition, nutrient cycling and primary productivity.

scholarly journals 40 years High Arctic climatological dataset of the Polish Polar Station Hornsund (SW Spitsbergen, Svalbard)

2019 ◽  
Author(s):  
Tomasz Wawrzyniak ◽  
Marzena Osuch
Keyword(s):  
Environmental Changes ◽  
High Arctic ◽  
The Arctic ◽  
Data Series ◽  
Annual Data ◽  
Climate Data ◽  
Atlantic Sector ◽  
Svalbard Archipelago

Abstract. The article presents the climatological dataset from the Polish Polar Station Hornsund located in the SW part of Spitsbergen - the biggest island of the Svalbard Archipelago. Due to a general lack of long-term in situ measurements and observations, the high Arctic remains one of the largest climate‐data deficient regions on the Earth, so described series is of unique value. To draw conclusions on the climatic changes in the Arctic, it is necessary to analyse the long-term series of continuous, systematic, in situ observations from different locations and comparing the corresponding data, rather than rely on the climatic simulations only. In recent decades, rapid environmental changes occurring in the Atlantic sector of the Arctic are reflected in the data series collected by the operational monitoring conducted at the Hornsund Station. We demonstrate the results of the 40 years-long series of observations. Climatological mean values or totals are given, and we also examined the variability of meteorological variables at monthly and annual scale using the modified Mann-Kendall test for trend and Sen’s method. The relevant daily, monthly, and annual data are provided on the PANGAEA repository (https://doi.org/10.1594/PANGAEA.909042, Wawrzyniak and Osuch, 2019).

scholarly journals Tundra Type Drives Distinct Trajectories of Functional and Taxonomic Composition of Arctic Fungal Communities in Response to Climate Change – Results From Long-Term Experimental Summer Warming and Increased Snow Depth

2021 ◽  
Vol 12 ◽  
Author(s):  
József Geml ◽  
Luis N. Morgado ◽  
Tatiana A. Semenova-Nelsen
Keyword(s):  
Climate Change ◽  
Community Composition ◽  
Fungal Community ◽  
Snow Depth ◽  
Fungal Communities ◽  
The Arctic ◽  
Fungal Community Composition ◽  
Summer Warming ◽  
Edaphic Variables

The arctic tundra is undergoing climate-driven changes and there are serious concerns related to the future of arctic biodiversity and altered ecological processes under possible climate change scenarios. Arctic land surface temperatures and precipitation are predicted to increase further, likely causing major transformation in terrestrial ecosystems. As a response to increasing temperatures, shifts in vegetation and soil fungal communities have already been observed. Little is known, however, how long-term experimental warming coupled with increased snow depth influence the trajectories of soil fungal communities in different tundra types. We compared edaphic variables and fungal community composition in experimental plots simulating the expected increase in summer warming and winter snow depth, based on DNA metabarcoding data. Fungal communities in the sampled dry and moist acidic tundra communities differed greatly, with tundra type explaining ca. one-third of compositional variation. Furthermore, dry and moist tundra appear to have different trajectories in response to climate change. Specifically, while both warming and increased snow depth had significant effects on fungal community composition and edaphic variables in dry tundra, the effect of increased snow was greater. However, in moist tundra, fungal communities mainly were affected by summer warming, while increased snow depth had a smaller effect and only on some functional groups. In dry tundra, microorganisms generally are limited by moisture in the summer and extremely low temperatures in winter, which is in agreement with the stronger effect of increased snow depth relative to warming. On the contrary, moist tundra soils generally are saturated with water, remain cold year-round and show relatively small seasonal fluctuations in temperature. The greater observed effect of warming on fungi in moist tundra may be explained by the narrower temperature optimum compared to those in dry tundra.

Sensor system development for low-damage sugar beet harvesting – state and perspectives

2020 ◽  
pp. 299-306
Author(s):  
Ulrike Wilczek ◽  
Boris Kulig ◽  
Heinz-Josef Koch ◽  
Roman Kälberloh ◽  
Oliver Hensel
Keyword(s):  
High Speed ◽  
Field Experiments ◽  
System Development ◽  
Pressure Sensors ◽  
Sensor System ◽  
Root Tip ◽  
Frequency Spectra ◽  
Long Term Storage ◽  
Term Storage

The SmartBeet project aimed to develop a sensor system feasible to detect beet damages occurring in the harvester cleaning system. Sensor information should allow to design driver assistance systems safeguarding low-damage beets most suitable for long-term storage. Long-term storage trials in climate containers revealed that root tip breakage caused by turbine cleaning correlated sufficiently close with sugar losses, and thus can serve as an overall damage indicator. In a systematic drop test, heavier beets (>700 g), beets impacting the ground with the root tip ahead and dropping from 2.5 m caused largest tip breakage. Field experiments were conducted with measuring bobs which were shaped like beets and equipped with accelerometers and surface pressure sensors. They showed that type and form of impacts affect damage severity in addition to impact intensity. Moreover, the turbines exerted less impact compared to the lifter, sieve conveyor and auger conveyor. Results imply that the beet throughput level through the cleaning section significantly affects the occurrence of damages. In addition, the structure-borne sound of the beet guiding grates of the turbines was recorded. Single beet damage events were identified from videos taken by high speed cameras and synchronized with the associated sound frequency spectra. In future, time segments and synchronized Fast-Fourier-transformed frequency spectra will be used to derive specific trait variables in order to develop a Machine-Learning-Model.

scholarly journals Long-term warming manipulations reveal complex decomposition responses across different tundra vegetation types

2021 ◽  
Author(s):  
Katrín Björnsdóttir ◽  
Isabel C Barrio ◽  
Ingibjörg Svala Jónsdóttir
Keyword(s):  
Mass Loss ◽  
Environmental Changes ◽  
Plant Litter ◽  
The Arctic ◽  
Vegetation Types ◽  
Positive Effects ◽  
Tundra Vegetation ◽  
Tea Bag Index ◽  
Induced Changes

In a rapidly warming tundra, ecosystems will undergo major environmental changes which are predicted to significantly alter below–ground processes, such as decomposition of plant litter. Making use of International Tundra Experiment sites (ITEX), established approximately two decades ago, we examined long–term impacts of warming on decomposition. We used the Tea Bag Index (TBI) methodology to measure the annual mass loss (%) of two tea types as a proxy for potential decomposition rates, across five tundra vegetation types. Direct effects of warming were assessed by comparing mass loss within and outside warming manipulations. Indirect effects of warming, such as those caused by warming–induced changes in plant community composition, were assessed through the relationship between mass loss of tea and biotic and abiotic local conditions. We found positive effects of warming on decomposition, although the responses varied between vegetation and tea types. Interestingly, we found support for the indirect influence of long–term warming on decomposition through warming–induced changes in the composition of plant communities. Our findings demonstrate the complexity in decomposition responses to warming across different vegetation types and highlight the importance of long–term legacies of warming in decomposition responses across the Arctic.

scholarly journals Growth Responses to Wind Differ among Papaya Roots, Leaves, and Stems

HortScience ◽  
2011 ◽  
Vol 46 (8) ◽  
pp. 1105-1109 ◽  
Author(s):  
Thomas E. Marler
Keyword(s):  
Field Experiments ◽  
Stem Growth ◽  
Dose Effect ◽  
Root Tip ◽  
Extension Rate ◽  
Adaptive Responses ◽  
Growth Responses ◽  
Root Responses ◽  
Leaf Expansion Rate

‘Sunrise’ and ‘Tainung 2’ papaya seedlings were subjected to 3 weeks of ambient winds in Guam during five experiments, and growth responses of roots, leaves, and stems were quantified to compare speed and extent of the plasticity among the organs. The cultivars responded similarly with 1 week eliciting stem growth responses and 2 weeks eliciting root responses. The timeframe of these studies was sufficient to enable adaptive responses in all three organs. Wind reduced stem and leaf expansion rate but not root extension rate, providing one example of how the form of response differed among the organs. A dose–effect was evident among the experiments with magnitude of response increasing with mean ambient wind speed. Asymmetric stem diameter and root tip density were examples of adaptive responses to directional wind load. These data on young papaya plants may be used to inform field experiments aiming to determine how chronic winds influence long-term growth and fitness.

scholarly journals Long-Term Adaptation of Acidophilic Archaeal Ammonia Oxidisers Following Different Soil Fertilisation Histories

2021 ◽  
Author(s):  
Jun Zhao ◽  
Baozhan Wang ◽  
Xue Zhou ◽  
Mohammad Saiful Alam ◽  
Jianbo Fan ◽  
...  
Keyword(s):  
Community Composition ◽  
High Throughput Sequencing ◽  
Environmental Changes ◽  
Agricultural Soils ◽  
Terrestrial Ecosystems ◽  
Low Ph ◽  
Ph Change ◽  
Monooxygenase Gene ◽  
Ammonia Oxidising Archaea

AbstractAmmonia oxidising archaea (AOA) are ecologically important nitrifiers in acidic agricultural soils. Two AOA phylogenetic clades, belonging to order-level lineages of Nitrososphaerales (clade C11; also classified as NS-Gamma-2.3.2) and family-level lineage of Candidatus Nitrosotaleaceae (clade C14; NT-Alpha-1.1.1), usually dominate AOA population in low pH soils. This study aimed to investigate the effect of different fertilisation histories on community composition and activity of acidophilic AOA in soils. High-throughput sequencing of ammonia monooxygenase gene (amoA) was performed on six low pH agricultural plots originating from the same soil but amended with different types of fertilisers for over 20 years and nitrification rates in those soils were measured. In these fertilised acidic soils, nitrification was likely dominated by Nitrososphaerales AOA and ammonia-oxidising bacteria, while Ca. Nitrosotaleaceae AOA activity was non-significant. Within Nitrososphaerales AOA, community composition differed based on the fertilisation history, with Nitrososphaerales C11 only representing a low proportion of the community. This study revealed that long-term soil fertilisation selects for different acidophilic nitrifier communities, potentially through soil pH change or through direct effect of nitrogen, potassium and phosphorus. Comparative community composition among the differently fertilised soils also highlighted the existence of AOA phylotypes with different levels of stability to environmental changes, contributing to the understanding of high AOA diversity maintenance in terrestrial ecosystems.

Long-Term Ecological Research in the Arctic: Where Science Never Sleeps

2016 ◽  
Author(s):  
John E. Hobbie
Keyword(s):  
Mycorrhizal Fungi ◽  
Field Experiments ◽  
The Arctic ◽  
Ecological Research ◽  
Nitrogen And Phosphorus ◽  
Long Term Ecological Research ◽  
Bacterial Uptake ◽  
Project Data ◽  
Kinetics Of Uptake

When the Arctic (ARC) Long-Term Ecological Research (LTER) project began, I was an aquatic ecologist with experience in managing large projects in freshwaters and estuaries and a specialization in microbes. This project, which studies lakes, streams, and tundras, has greatly increased my breadth as an ecologist and allowed me to take part in terrestrial modeling, microbial studies in streams, and the role of soil mycorrhizal fungi in providing nutrients to many species of plants. As a mentor to several postdoctoral fellows, my LTER research has enabled me to learn about other fields such as the application of molecular biology to microbial ecology. The Arctic LTER project data, the long-term field experiments, and the facilities available at the University of Alaska field station brought me in contact with ecologists from many countries. One result of this association with experts was my coauthorship of a book on Arctic natural history aimed at communicating scientific knowledge to scientists and the general public unfamiliar with the Arctic (Huryn and Hobbie 2012). I have always collaborated extensively with many scientists and encouraged collaboration as the best way to carry out ecosystem research. The Arctic LTER project brought many opportunities to broaden the scope of my collaboration to include terrestrial ecologists and microbiologists. My PhD research was about year-round primary productivity of an Arctic lake but while on a postdoctoral fellowship at Uppsala University, Sweden, I switched to an emphasis on bacterial uptake kinetics in lakes. The techniques I helped develop in freshwater worked in the ocean and estuaries too (Hobbie and Williams 1984). In addition we developed the epifluorescence method for quantifying the abundance of planktonic bacteria. Our paper (Hobbie, Daley, and Jasper 1977) finally convinced oceanographers that bacteria are abundant (at 10⁹ per liter) and important. Recently, I have used my understanding of kinetics of uptake to analyze microbial activity in the soil. My Arctic expertise led to leadership of the aquatic part of the International Biological Program (IBP) at Barrow, Alaska, beginning in 1970. We (28 scientists, graduate students, and postdoctoral fellows) studied shallow ponds to quantify the carbon, nitrogen, and phosphorus cycles.

Solid phase-solution-root interactions in soils subjected to acid deposition

1984 ◽  
Vol 305 (1124) ◽  
pp. 353-368 ◽  
Keyword(s):  
Field Experiments ◽  
Solid Phase ◽  
Primary Cell Wall ◽  
Root Decomposition ◽  
Root Tip ◽  
Silicate Weathering ◽  
Managed Forests ◽  
Root Tips ◽  
Root Interactions ◽  
Proton Production

In managed forests, biomass utilization means a discoupling of the otherwise closed ion-cycle. The rate of proton production caused by the utilization of the timber, however, is of the same magnitude as the rate of proton consumption during silicate weathering. Managed forests can thus be in a steady state and stable. The input of acidity in forest ecosystems due to air pollution will in most cases exceed the rate of proton consumption by silicate weathering and thus result in soil acidification. Acidity can be accumulated as organic acids (mainly phenoles) and as cationic acids, that is, ions of sparingly soluble oxides (Al, Fe, Mn and heavy metals). The lower the pH , the higher is the solubility and toxicity of the acids existing. Owing to its high concentration and solubility, AlOOH produces the most important cation acid. A soil is composed of microcompartments in which different reactions can occur at the same time. Also proton production can be spatially inhomogeneous for the following reasons: (i) a considerable fraction of the input of acidity due to dry deposition of SO 2 is buffered by the leaves of the trees. It reaches the soil via the roots during ion uptake and thus acidifies the soil close to the root tips. (ii) In acid soils, where the burrowing animals are missing, the soil organic matter formed from the root decomposition accumulates on the aggregate surfaces. It is thus in direct contact with the living roots. If during a temporal discoupling of the ion cycle (nitrification push) nitric acid is formed, this can acidify also, especially the soil close to the root surface. Thus in the direct vicinity of the roots, much higher Al-concentrations have to be expected than those which can be measured in equilibrium soil solution or in lysimeter solutions. A direct effect of Al-toxicity on the root system of trees is the die-back of the young roots, which has been shown both in vitro and in field experiments to be the result of action of Al ions. The mechanism of this action was found to be the inhibition of uptake of Ca ions into the matrix of the cell walls, which changes the macromolecular and physical properties of the pectin molecules which form the primary cell wall of meristemic and parenchymatic tissues in the root tip region.

scholarly journals A 40-year High Arctic climatological dataset of the Polish Polar Station Hornsund (SW Spitsbergen, Svalbard)

2020 ◽  
Vol 12 (2) ◽  
pp. 805-815 ◽  
Author(s):  
Tomasz Wawrzyniak ◽  
Marzena Osuch
Keyword(s):  
Environmental Changes ◽  
High Arctic ◽  
The Arctic ◽  
Data Series ◽  
Annual Data ◽  
Climate Data ◽  
Atlantic Sector ◽  
Svalbard Archipelago

Abstract. The article presents the climatological dataset from the Polish Polar Station Hornsund located in the southwest part of Spitsbergen – the biggest island of the Svalbard archipelago. Due to a general lack of long-term in situ measurements and observations, the High Arctic remains one of the largest climate-data-deficient regions on the Earth. Therefore, the described time series of observations in this paper are of unique value. To draw conclusions on the climatic changes in the Arctic, it is necessary to analyse and compare the long-term series of continuous, in situ observations from different locations, rather than relying on the climatic simulations only. In recent decades, rapid environmental changes occurring in the Atlantic sector of the Arctic are reflected in the data series collected by the operational monitoring conducted at the Hornsund station. We demonstrate the results of the 40-year-long series of observations. Climatological mean values or totals are given, and we also examined the variability of meteorological variables at monthly and annual scale using the modified Mann–Kendall test for trend and Sen's method. The relevant daily, monthly, and annual data are provided on the PANGAEA repository (https://doi.org/10.1594/PANGAEA.909042, Wawrzyniak and Osuch, 2019).

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