Experimental warming differentially affects vegetative and reproductive phenology of tundra plants

AbstractRapid climate warming is altering Arctic and alpine tundra ecosystem structure and function, including shifts in plant phenology. While the advancement of green up and flowering are well-documented, it remains unclear whether all phenophases, particularly those later in the season, will shift in unison or respond divergently to warming. Here, we present the largest synthesis to our knowledge of experimental warming effects on tundra plant phenology from the International Tundra Experiment. We examine the effect of warming on a suite of season-wide plant phenophases. Results challenge the expectation that all phenophases will advance in unison to warming. Instead, we find that experimental warming caused: (1) larger phenological shifts in reproductive versus vegetative phenophases and (2) advanced reproductive phenophases and green up but delayed leaf senescence which translated to a lengthening of the growing season by approximately 3%. Patterns were consistent across sites, plant species and over time. The advancement of reproductive seasons and lengthening of growing seasons may have significant consequences for trophic interactions and ecosystem function across the tundra.

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Changes in the understory plant community and ecosystem properties along a shrub density gradient

Arctic Science ◽

10.1139/as-2017-0026 ◽

2018 ◽

Vol 4 (4) ◽

pp. 485-498 ◽

Cited By ~ 4

Author(s):

Anna L. Crofts ◽

Dennise O. Drury ◽

Jennie R. McLaren

Keyword(s):

Functional Group ◽

Ecosystem Structure ◽

Vegetation Community ◽

Ecosystem Properties ◽

Tundra Ecosystem ◽

Soil Temperatures ◽

Deciduous Shrubs ◽

Understory Plant ◽

And Function ◽

Ecosystem Structure And Function

Climate warming is projected to alter the vegetation community composition of arctic and alpine ecosystems including an increase in the relative abundance and cover of deciduous shrubs. This change in plant functional group dominance will likely alter tundra ecosystem structure and function. We conducted an observational study to quantify how the understory vegetation community and ecosystem properties varied along a shrub density and altitudinal gradient in a tundra alpine ecosystem in south-west Yukon. Although there was weak association between shrub density and species richness of understory community, there were large differences in functional group abundance between the different shrub densities; forb cover increased at lower elevations with higher shrub density at the expense of cryptogam and dwarf shrub cover. Litter mass, light interception, and soil carbon:nitrogen ratios all increased with shrub density. Sites with shrubs had higher summer soil temperatures, lower summer soil moisture, and lower percent soil nitrogen than the shrub-free site, although there was no difference in available nutrients among sites. This study presents findings from a nonmanipulated, model system where shrubification has been documented and suggests that direct and indirect effects of increasing shrub dominance are likely to affect the surrounding vegetation and abiotic environment controls.

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The effects of modern war and military activities on biodiversity and the environment

Environmental Reviews ◽

10.1139/er-2015-0039 ◽

2015 ◽

Vol 23 (4) ◽

pp. 443-460 ◽

Cited By ~ 46

Author(s):

Michael J. Lawrence ◽

Holly L.J. Stemberger ◽

Aaron J. Zolderdo ◽

Daniel P. Struthers ◽

Steven J. Cooke

Keyword(s):

Military Training ◽

Structure And Function ◽

Aquatic Systems ◽

Ecosystem Structure ◽

Population Declines ◽

Exclusion Zone ◽

Negative Effects ◽

And Function ◽

Ecosystem Structure And Function ◽

Modern War

War is an ever-present force that has the potential to alter the biosphere. Here we review the potential consequences of modern war and military activities on ecosystem structure and function. We focus on the effects of direct conflict, nuclear weapons, military training, and military produced contaminants. Overall, the aforementioned activities were found to have overwhelmingly negative effects on ecosystem structure and function. Dramatic habitat alteration, environmental pollution, and disturbance contributed to population declines and biodiversity losses arising from both acute and chronic effects in both terrestrial and aquatic systems. In some instances, even in the face of massive alterations to ecosystem structure, recovery was possible. Interestingly, military activity was beneficial under specific conditions, such as when an exclusion zone was generated that generally resulted in population increases and (or) population recovery; an observation noted in both terrestrial and aquatic systems. Additionally, military technological advances (e.g., GPS technology, drone technology, biotelemetry) have provided conservation scientists with novel tools for research. Because of the challenges associated with conducting research in areas with military activities (e.g., restricted access, hazardous conditions), information pertaining to military impacts on the environment are relatively scarce and are often studied years after military activities have ceased and with no knowledge of baseline conditions. Additional research would help to elucidate the environmental consequences (positive and negative) and thus reveal opportunities for mitigating negative effects while informing the development of optimal strategies for rehabilitation and recovery.

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Environmental ecology: The impacts of pollution and other stresses on ecosystem structure and function

Ecological Economics ◽

10.1016/0921-8009(91)90028-d ◽

1991 ◽

Vol 4 (2) ◽

pp. 168-169

Author(s):

Nils Kautsky

Keyword(s):

Structure And Function ◽

Ecosystem Structure ◽

And Function ◽

Ecosystem Structure And Function

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Interactions of Landuse and Ecosystem Structure and Function: A Case Study in the Central Great Plains

Integrated Regional Models ◽

10.1007/978-1-4684-6447-4_6 ◽

1994 ◽

pp. 79-95 ◽

Cited By ~ 12

Author(s):

Ingrid C. Burke ◽

William K. Lauenroth ◽

William J. Parton ◽

C. Vernon Cole

Keyword(s):

Great Plains ◽

Structure And Function ◽

Ecosystem Structure ◽

And Function ◽

Ecosystem Structure And Function

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Linking ocean biogeochemical cycles and ecosystem structure and function: results of the complex SWAMCO-4 model

Journal of Sea Research ◽

10.1016/j.seares.2004.07.001 ◽

2005 ◽

Vol 53 (1-2) ◽

pp. 93-108 ◽

Cited By ~ 22

Author(s):

Bénédicte Pasquer ◽

Goulven Laruelle ◽

Sylvie Becquevort ◽

Véronique Schoemann ◽

Hugues Goosse ◽

...

Keyword(s):

Biogeochemical Cycles ◽

Structure And Function ◽

Ecosystem Structure ◽

And Function ◽

Ecosystem Structure And Function

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Constraint of soil moisture on CO<sub>2</sub> efflux from tundra lichen, moss, and tussock in Council, Alaska, using a hierarchical Bayesian model

Biogeosciences ◽

10.5194/bg-11-5567-2014 ◽

2014 ◽

Vol 11 (19) ◽

pp. 5567-5579 ◽

Cited By ~ 9

Author(s):

Y. Kim ◽

K. Nishina ◽

N. Chae ◽

S. J. Park ◽

Y. J. Yoon ◽

...

Keyword(s):

Soil Moisture ◽

Environmental Factors ◽

Soil Temperature ◽

Co2 Emission ◽

Emission Rate ◽

Growing Season ◽

The Arctic ◽

Co2 Efflux ◽

Growing Seasons ◽

Tundra Ecosystem

Abstract. The tundra ecosystem is quite vulnerable to drastic climate change in the Arctic, and the quantification of carbon dynamics is of significant importance regarding thawing permafrost, changes to the snow-covered period and snow and shrub community extent, and the decline of sea ice in the Arctic. Here, CO2 efflux measurements using a manual chamber system within a 40 m × 40 m (5 m interval; 81 total points) plot were conducted within dominant tundra vegetation on the Seward Peninsula of Alaska, during the growing seasons of 2011 and 2012, for the assessment of driving parameters of CO2 efflux. We applied a hierarchical Bayesian (HB) model – a function of soil temperature, soil moisture, vegetation type, and thaw depth – to quantify the effects of environmental factors on CO2 efflux and to estimate growing season CO2 emissions. Our results showed that average CO2 efflux in 2011 was 1.4 times higher than in 2012, resulting from the distinct difference in soil moisture between the 2 years. Tussock-dominated CO2 efflux is 1.4 to 2.3 times higher than those measured in lichen and moss communities, revealing tussock as a significant CO2 source in the Arctic, with a wide area distribution on the circumpolar scale. CO2 efflux followed soil temperature nearly exponentially from both the observed data and the posterior medians of the HB model. This reveals that soil temperature regulates the seasonal variation of CO2 efflux and that soil moisture contributes to the interannual variation of CO2 efflux for the two growing seasons in question. Obvious changes in soil moisture during the growing seasons of 2011 and 2012 resulted in an explicit difference between CO2 effluxes – 742 and 539 g CO2 m−2 period−1 for 2011 and 2012, respectively, suggesting the 2012 CO2 emission rate was reduced to 27% (95% credible interval: 17–36%) of the 2011 emission, due to higher soil moisture from severe rain. The estimated growing season CO2 emission rate ranged from 0.86 Mg CO2 in 2012 to 1.20 Mg CO2 in 2011 within a 40 m × 40 m plot, corresponding to 86 and 80% of annual CO2 emission rates within the western Alaska tundra ecosystem, estimated from the temperature dependence of CO2 efflux. Therefore, this HB model can be readily applied to observed CO2 efflux, as it demands only four environmental factors and can also be effective for quantitatively assessing the driving parameters of CO2 efflux.

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