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Taiga experiments : 12 science experiments in one hour or less
\"A variety of science projects related to the taiga biome that can be done in under an hour, plus a few that take longer for interested students.\"-- Provided by publisher.
BOOK
Even modest climate change may lead to major transitions in boreal forests
The sensitivity of forests to near-term warming and associated precipitation shifts remains uncertain
1
–
9
. Herein, using a 5-year open-air experiment in southern boreal forest, we show divergent responses to modest climate alteration among juveniles of nine co-occurring North American tree species. Warming alone (+1.6 °C or +3.1 °C above ambient temperature) or combined with reduced rainfall increased the juvenile mortality of all species, especially boreal conifers. Species differed in growth responses to warming, ranging from enhanced growth in
Acer rubrum
and
Acer saccharum
to severe growth reductions in
Abies balsamea
,
Picea glauca
and
Pinus strobus
. Moreover, treatment-induced changes in both photosynthesis and growth help explain treatment-driven changes in survival. Treatments in which species experienced conditions warmer or drier than at their range margins resulted in the most adverse impacts on growth and survival. Species abundant in southern boreal forests had the largest reductions in growth and survival due to climate manipulations. By contrast, temperate species that experienced little mortality and substantial growth enhancement in response to warming are rare throughout southern boreal forest and unlikely to rapidly expand their density and distribution. Therefore, projected climate change will probably cause regeneration failure of currently dominant southern boreal species and, coupled with their slow replacement by temperate species, lead to tree regeneration shortfalls with potential adverse impacts on the health, diversity and ecosystem services of regional forests.
The survival of southern boreal tree saplings decreases in response to even modest warming and reduced rainfall, which,together with species-specific growth responses, could lead to regeneration failure of currently dominant tree species.
Journal Article
Phytotoxic Effects of Kerosene on Plants of Forest and Bog Phytocenoses of Southern Taiga
One of the most important problems of environmental sciences is to determine limits for the sustainable functioning of affected ecosystems. The effects of volatile hydrocarbons (such as gasoline and kerosene) on plants in natural ecosystems have been poorly studied to date. The present work outlines the data of a field experiment on the effects of kerosene on the plants of forest and bog communities in Central Russia. In this paper, we model the influence of kerosene spillage on plants growing in a coniferous broad-leaved (aspen–spruce) forest and a raised bog with a subshrub–sphagnum pine forest. We used TS-1 kerosene, which is the most commonly used fuel for commercial aviation in Russia. The applied pollutant (loads of 1 to 100 g/kg) had a significant impact on herbaceous plants, leading to the death of individuals even at minimal doses. The shrubs of the bog community as well as the mosses of both communities were more resistant to kerosene. The recovery processes of plant communities were clearly pronounced as early as 2 years after the application of the pollutant. The level of kerosene threshold exposure, which significantly affects the dominant plants of the herb–shrub layer, can be defined as 1–5 g/kg for the forest community and 5–10 g/kg for the bog community.
Journal Article
Agricultural Crops Grown in Laboratory Conditions on Chernevaya Taiga Soil Demonstrate Unique Composition of the Rhizosphere Microbiota
Chernevaya taiga in West Siberia is a unique environment, with gigantism of grasses and shrubs. Exceptionally high productivity of plants is determined by the synergistic interaction of various factors, with a special role belonging to microorganisms colonizing the plant roots. This research explored whether agricultural plants can recruit specific microorganisms from within virgin Chernevaya Umbrisol and thus increase their productivity. Radish and wheat plants were grown on the Umbrisol (T1) and control Retisol of Scotch pine forest stand (T3) soils in the phytotron, and then a bacterial community analysis of the rhizosphere was performed using high-throughput sequencing of the 16S rRNA genes. In laboratory experiments, the plant physiological parameters were significantly higher when growing on the Umbrisol as compared to the Retisol. Bacterial diversity in T1 soil was considerably higher than in the control sample, and the principal coordinate analysis demonstrated apparent differences in the bacterial communities associated with the plants. Agricultural plants growing in the T1 soil form specific prokaryotic communities, with dominant genera Chthoniobacter, Pseudomonas, Burkholderia, and Massilia. These communities also include less abundant but essential for plant growth nitrifiers Cand. Nitrosocosmius and Nitrospira, and representatives of Proteobacteria, Bacilli, and Actinobacteria, known to be gibberellin-producers.
Journal Article
Environmental drivers of increased ecosystem respiration in a warming tundra
Arctic and alpine tundra ecosystems are large reservoirs of organic carbon
1
,
2
. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere
3
,
4
. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain
5
–
7
. This hampers the accuracy of global land carbon–climate feedback projections
7
,
8
. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9–2.0 °C] in air and 0.4 °C [CI 0.2–0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22–38%] (
n
= 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (
n
= 9) and continued for at least 25 years (
n
= 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration.
Datasets from in situ warming experiments across 28 arctic and alpine tundra sites covering a span of less than 1 year up to 25 years show the importance of local soil conditions and warming-induced changes therein for future climatic impacts on ecosystem respiration.
Journal Article
Tundra soil carbon is vulnerable to rapid microbial decomposition under climate warming
Release of carbon previously locked in permafrost is a potentially important positive climate feedback. Now metagenomics reveal the vulnerability of active-layer soil carbon to warming-induced microbial decomposition in Alaskan tundra.
Microbial decomposition of soil carbon in high-latitude tundra underlain with permafrost is one of the most important, but poorly understood, potential positive feedbacks of greenhouse gas emissions from terrestrial ecosystems into the atmosphere in a warmer world
1
,
2
,
3
,
4
. Using integrated metagenomic technologies, we showed that the microbial functional community structure in the active layer of tundra soil was significantly altered after only 1.5 years of warming, a rapid response demonstrating the high sensitivity of this ecosystem to warming. The abundances of microbial functional genes involved in both aerobic and anaerobic carbon decomposition were also markedly increased by this short-term warming. Consistent with this, ecosystem respiration (
R
eco
) increased up to 38%. In addition, warming enhanced genes involved in nutrient cycling, which very likely contributed to an observed increase (30%) in gross primary productivity (GPP). However, the GPP increase did not offset the extra
R
eco
, resulting in significantly more net carbon loss in warmed plots compared with control plots. Altogether, our results demonstrate the vulnerability of active-layer soil carbon in this permafrost-based tundra ecosystem to climate warming and the importance of microbial communities in mediating such vulnerability.
Journal Article
The role of highly oxygenated organic molecules in the Boreal aerosol-cloud-climate system
Over Boreal regions, monoterpenes emitted from the forest are the main precursors for secondary organic aerosol (SOA) formation and the primary driver of the growth of new aerosol particles to climatically important cloud condensation nuclei (CCN). Autoxidation of monoterpenes leads to rapid formation of Highly Oxygenated organic Molecules (HOM). We have developed the first model with near-explicit representation of atmospheric new particle formation (NPF) and HOM formation. The model can reproduce the observed NPF, HOM gas-phase composition and SOA formation over the Boreal forest. During the spring, HOM SOA formation increases the CCN concentration by ~10 % and causes a direct aerosol radiative forcing of −0.10 W/m
2
. In contrast, NPF reduces the number of CCN at updraft velocities < 0.2 m/s, and causes a direct aerosol radiative forcing of +0.15 W/m
2
. Hence, while HOM SOA contributes to climate cooling, NPF can result in climate warming over the Boreal forest.
Forests emit compounds into the atmosphere that are oxidized into highly oxygenated molecules that serve as precursors for cloud condensation nuclei–a process that impacts the climate, but is poorly represented in models. Here the authors create a new model that accurately depicts highly oxygenated molecule and climate dynamics over Boreal forests.
Journal Article
Origins of abrupt change? Postfire subalpine conifer regeneration declines nonlinearly with warming and drying
Robust tree regeneration following high-severity wildfire is key to the resilience of subalpine and boreal forests, and 21st century climate could initiate abrupt change in forests if postfire temperature and soil moisture become less suitable for tree seedling establishment. Using two widespread conifer species, lodgepole pine (Pinus contorta var. latifolia) and Douglas-fir (Pseudotsuga menziesii var. glauca), we conducted complementary experiments to ask (1) How will projected early-to mid-21st-century warming and drying affect postfire tree seedling establishment and mortality? (2) How does early seedling growth differ between species and vary with warming and drying? With a four-year in situ seed-planting experiment and a one growing season controlled-environment experiment, we explored effects of climate on tree seedling establishment, growth, and survival and identified nonlinear responses to temperature and soil moisture. In our field experiment, warmer and drier conditions, consistent with mid-21ˢᵗ-century projections, led to a 92% and 76% reduction in establishment of lodgepole pine and Douglas-fir. Within three years, all seedlings that established under warmer conditions died, as might be expected at lower elevations and lower latitudes of species' ranges. Seedling establishment and mortality also varied with aspect; approximately 1.7 times more seedlings established on mesic vs. xeric aspects, and fewer seedlings died. In the controlled-environment experiment, soil temperatures were 2.0°–5.5°C cooler than the field experiment, and warming led to increased tree seedling establishment, as might be expected at upper treeline or higher latitudes. Lodgepole pine grew taller than Douglas-fir and produced more needles with warming. Douglas-fir grew longer roots relative to shoots, compared with lodgepole pine, particularly in dry soils. Differences in early growth between species may mediate climate change effects on competitive interactions, successional trajectories, and species distributions. This study demonstrates that climate following high-severity fire exerts strong control over postfire tree regeneration in subalpine conifer forests. Climate change experiments, such as those reported here, hold great potential for identifying mechanisms that could underpin fundamental ecological change in 21st-century ecosystems.
Journal Article
Bioassay of Virulence of Some Entomopathogenic Ascomycetous Anamorphic Fungi to Adult Ixodes persulcatus Ticks under Cool Conditions
Entomopathogenic fungi (EPF) play an important role in the density control of many arthropods in nature. The lethal effects of EPF on ixodid ticks (Ixodidae) have been mainly described for the warm-loving southern species that are mostly absent in Europe. We have performed a laboratory assessment of the virulence of 9 psychrotolerant EPF isolates of
Beauveria bassiana
s. l. (6),
Akanthomyces
cf.
muscarius
(2), and
Metarhizium anisopliae
s. l. (1) at a moderate mean daily temperature of +14°C against the overwintered adult taiga ticks
Ixodes persulcatus
, collected at the end of May in Kondopoga Province of the Republic of Karelia. All the tested isolates caused mortality in ticks at this temperature after infection with a concentration of 3 × 10
7
infectious spores per 1 mL. The most virulent and rapidly acting isolate was
B. bassiana
s. l. CCi-Ar (SI)14 from Arkhangelsk Province, Bolshoy Solovetsky Island (65°N, 35°E), killing 70% of the ticks in 9 days and 95% in 11 days. Male ticks had a slightly higher death rate from fungal infections. The potential suitability of some EPF isolates for biological control of
I. persulcatus
at low temperatures, demonstrated in our study, requires confirmation in further tests under real conditions of recreational areas actively visited by humans.
Journal Article