No beating around the bush: the impact of projected high‐latitude vegetation transitions on soil and ecosystem respiration

Release of heavy metals, salts and other toxic agents in the environment is of increasing concern in urban areas. Contaminants not solely decline the quality of the local environment and affect the health of human population and urban ecosystems but are also spread through runoff and leaching into non-contaminated areas. Urban lawns are the most distributed green infrastructure in the cities. Management of lawn system may either exacerbate the negative effects of contaminants on lawn functioning either help to withstand the toxic effects and maintain the lawn ecosystem health and the efficient release of ecosystem services. &#160;The aim of this study was to evaluate the interactions between the lawn management, the lawn functioning, and the release into the soil of typical urban contaminants. For this purpose, Festuca arundinacea grass was planted in a turf-sand mixture with and without amendment addition (zeolite + vermicompost). To reproduce the impact of traffic-related contaminants in proximity of the road, pots were treated with a solution containing de-icing salt (NaCl) and 6 heavy metals (Zn, Cd, Pb, Cr, Cu, Ni), imitating road runoff solution. After contamination, half of pots was maintained at optimum soil water content (Smart irrigation), another half was left to periodical drying in order to simulate conditions with discontinuous watering (Periodical irrigation). The same experimental scheme was reproduced for unplanted soil. CO2 net ecosystem exchange (NEE), soil and ecosystem respiration as well as flux from unplanted soil (heterotrophic respiration) were measured shortly after the treatment (short-term) and up 3 months since the treatment start (long-term).Soil amendment stimulated plant productivity and increased the efficiency of the system in C uptake (+56% NEE). A relevant reduction of NEE was observed from 14 to 40 days after the application of traffic-related contaminants in both amended and non amended pots. During this period the contaminants had the greatest impact on lawn NEE subjected to Periodic irrigation (-49% and -66% in amended and non amended pots, respectively), while lawn under Smart irrigation was less affected (-35% and -26% in amended and non amended pots, respectively). Different respiration sources (ecosystem respiration, soil respiration, heterotrophic respiration) were characterized by different sensitivity to management and contamination. Heterotrophic flux was not sensitive to soil amending but declined with contamination with enhanced negative effect under Smart irrigation. Response of ecosystem respiration to contamination was less pronounced in confront to soil respiration suggesting leaf-level buffering.&#160; &#160;&#160;Three months later,&#160; the effect of contaminants on lawn gas exchange ceased for all treated pots. Instead, the irrigation effect persisted depending on whether pots were amended or not. In non amended pots NEE was reduced by 18% under Periodic irrigation, while this effect was not present in amended pots. We conclude, that performance of such green infrastructure as lawns in terms of C sequestration under multiple anthropogenic stressors could be efficiently improved through soil amending and irrigation control.Current research was financially supported by RFBR No. 19-29-05187 and RSF No. 19-77-30012.

Download Full-text

Assessing the impact of exceptional inter-annual climatic variability on rates of net ecosystem carbon dioxide exchange at Clara bog.

10.5194/egusphere-egu21-13414 ◽

2021 ◽

Author(s):

Matthew Saunders ◽

Ruchita Ingle ◽

Shane Regan

Keyword(s):

Water Table ◽

Elevated Temperatures ◽

Ecosystem Respiration ◽

Anthropogenic Activities ◽

Climatic Variability ◽

Growing Season ◽

Carbon Dioxide Exchange ◽

Mean Annual Temperature ◽

Monitoring Networks ◽

The Impact

Peatland ecosystems are integral to the mitigation of climate change as they represent significant terrestrial carbon sinks. In Ireland, peatlands cover ~20% of the land area but hold up to 75% of the soil organic carbon stock however many of these ecosystems (~85% of the total area) have been degraded due to anthropogenic activities such as agriculture, forestry and extraction for horticulture or energy. Furthermore, the carbon stocks that remain in these systems are vulnerable to inter-annual variation in climate, such as changes in precipitation and temperature, which can alter the hydrological status of these systems leading to changes in key biogeochemical processes and carbon and greenhouse gas exchange.&#160; During 2018 exceptional drought and heatwave conditions were reported across Northwestern Europe, where reductions in precipitation coupled with elevated temperatures were observed. Exceptional inter-annual climatic variability was also observed at Clara bog, a near natural raised bog in the Irish midlands when data from 2018 and 2019 were compared. Precipitation in 2018 was ~300 mm lower than 2019 while the average mean annual temperature was 0.5&#176;C higher. The reduction in precipitation, particularly during the growing season in 2018, consistently lowered the water table where ~150 consecutive days where the water table was >5cm below the surface of the bog were observed at the central ecotope location. The differing hydrological conditions between years resulted in the study area, as determined by the flux footprint of the eddy covariance tower, acting as a net source of carbon of 53.5 g C m-2 in 2018 and a net sink of 125.2 g C m-2 in 2019. The differences in the carbon dynamics between years were primarily driven by enhanced ecosystem respiration (Reco) and lower rates of Gross Primary Productivity (GPP) in the drier year, where the maximum monthly ratio of GPP:Reco during the growing season was 0.96 g C m-2 month in 2018 and 1.14 g C m-2 month in 2019. This study highlights both the vulnerability and resilience of these ecosystems to exceptional inter-annual climatic variability and emphasises the need for long-term monitoring networks to enhance our understanding of the impacts of these events when they occur.

Download Full-text

The Impact of Freeze–thaw on the Stability of Soil Cut Slope in High-latitude Frozen Regions

Landslides in Cold Regions in the Context of Climate Change - Environmental Science and Engineering ◽

10.1007/978-3-319-00867-7_7 ◽

2013 ◽

pp. 85-98 ◽

Cited By ~ 1

Author(s):

Ying Guo ◽

Wei Shan ◽

Hua Jiang ◽

Yuying Sun ◽

Chengcheng Zhang

Keyword(s):

High Latitude ◽

Cut Slope ◽

Freeze Thaw ◽

The Stability ◽

The Impact

Download Full-text

CO2 uptake decreased and CH4 emissions increased in first two years of peatland seismic line restoration

10.21203/rs.3.rs-759056/v1 ◽

2021 ◽

Author(s):

Megan Schmidt ◽

Scott J. Davidson ◽

Maria Strack

Keyword(s):

Oil And Gas ◽

Ecosystem Respiration ◽

Tree Seedlings ◽

Co2 Uptake ◽

Seismic Line ◽

Oil And Gas Exploration ◽

Net Productivity ◽

The Impact ◽

Seismic Lines ◽

Reference Areas

Abstract Oil and gas exploration has resulted in over 300,000 km of linear disturbances known as seismic lines, throughout boreal peatlands across Canada. Sites are left with altered hydrologic and topographic conditions that prevent tree re-establishment. Restoration efforts have concentrated on tree recovery through mechanical mounding to re-create microtopography and support planted tree seedlings to block sightlines and deter predator use, but little is known about the impact of seismic line disturbance or restoration on peatland carbon cycling. This study looked at two mounding treatments and compared carbon dioxide and methane fluxes to untreated lines and natural reference areas in the first two years post-restoration. We found no significant differences in net ecosystem CO2 exchange, but untreated seismic lines were slightly more productive than natural reference areas and mounding treatments. Both restoration treatments increased ecosystem respiration, decreased net productivity by 6–21 gCO2m− 2d− 1, and created areas of increased methane emissions, including an increase in the contribution of ebullition, of up to 2000 mgCH4m− 2d− 1. Further research on this site to assess the longer-term impacts of restoration, as well as application on other sites with varied conditions, will help determine if these restoration practices are effective.

Download Full-text

Regional responses of surface ozone in Europe to the location of high-latitude blocks and subtropical ridges

10.5194/acp-2016-832 ◽

2016 ◽

Author(s):

Carlos Ordóñez ◽

David Barriopedro ◽

Ricardo García-Herrera ◽

Pedro M. Sousa ◽

Jordan L. Schnell

Keyword(s):

High Latitude ◽

Climate Models ◽

Surface Ozone ◽

Zonal Flow ◽

Near Surface ◽

Air Masses ◽

Anticyclonic Circulation ◽

The Uk ◽

The Impact ◽

First Time

Abstract. This paper analyses for the first time the impact of high-latitude blocks and subtropical ridges on near-surface ozone in Europe during a 15-year period. For this purpose, a catalogue of blocks and ridges over the Euro-Atlantic region is used together with a gridded dataset of maximum daily 8-hour running average ozone (MDA8 O3) covering the period 1998–2012. The response of ozone to the location of blocks and ridges with centres in three longitudinal sectors (Atlantic, ATL, 30º–0º W; European, EUR, 0º–30º E; Russian, RUS, 30º–60º E) is examined. The impact of blocks on ozone is regionally and seasonally dependent. In particular, blocks within the EUR sector yield positive ozone anomalies of ~ 5–10 ppb over large parts of central Europe in spring and northern Europe in summer. Over 20 % and 30 % of the days with blocks in that sector register exceedances of the 90th percentile of the seasonal ozone distribution at many European locations during spring and summer, respectively. The impacts of ridges during those seasons are subtle and more sensitive to their specific location, although they can trigger ozone anomalies of ~ 5–10 ppb in Italy and the surrounding countries in summer, eventually exceeding European air quality targets. During winter, surface ozone in the northwest of Europe presents completely opposite responses to blocks and ridges. The anticyclonic circulation associated with winter EUR blocking, and to a lesser extent with ATL blocking, yields negative ozone anomalies between −5 ppb and −10 ppb over the UK, Northern France and the Benelux. Conversely, the enhanced zonal flow around 50˚–60˚ N during the occurrence of ATL ridges favours the arrival of background air masses from the Atlantic and the ventilation of the boundary layer, producing positive ozone anomalies above 5 ppb in an area spanning from the British Isles to Germany. This work provides the first quantitative assessments of the remarkable but distinct impacts that the anticyclonic circulation and the diversion of the zonal flow associated with blocks and ridges exert on surface ozone in Europe. The findings reported here can be exploited in the future to evaluate the modelled responses of ozone to circulation changes within chemical transport models (CTMs) and chemistry-climate models (CCMs).

Download Full-text

Delayed responses of an Arctic ecosystem to an extreme summer: impacts on net ecosystem exchange and vegetation functioning

Biogeosciences ◽

10.5194/bg-11-5877-2014 ◽

2014 ◽

Vol 11 (20) ◽

pp. 5877-5888 ◽

Cited By ~ 16

Author(s):

D. Zona ◽

D. A. Lipson ◽

J. H. Richards ◽

G. K. Phoenix ◽

A. K. Liljedahl ◽

...

Keyword(s):

Extreme Events ◽

Extreme Event ◽

Ecosystem Respiration ◽

Gross Primary Production ◽

Net Ecosystem Exchange ◽

Co2 Uptake ◽

Lag Effects ◽

Tundra Ecosystem ◽

Co2 Sink ◽

The Impact

Abstract. The importance and consequences of extreme events on the global carbon budget are inadequately understood. This includes the differential impact of extreme events on various ecosystem components, lag effects, recovery times, and compensatory processes. In the summer of 2007 in Barrow, Arctic Alaska, there were unusually high air temperatures (the fifth warmest summer over a 65-year period) and record low precipitation (the lowest over a 65-year period). These abnormal conditions were associated with substantial desiccation of the Sphagnum layer and a reduced net Sphagnum CO2 sink but did not affect net ecosystem exchange (NEE) from this wet-sedge arctic tundra ecosystem. Microbial biomass, NH4+ availability, gross primary production (GPP), and ecosystem respiration (Reco) were generally greater during this extreme summer. The cumulative ecosystem CO2 sink in 2007 was similar to the previous summers, suggesting that vascular plants were able to compensate for Sphagnum CO2 uptake, despite the impact on other functions and structure such as desiccation of the Sphagnum layer. Surprisingly, the lowest ecosystem CO2 sink over a five summer record (2005–2009) was observed during the 2008 summer (~70% lower), directly following the unusually warm and dry summer, rather than during the extreme summer. This sink reduction cannot solely be attributed to the potential damage to mosses, which typically contribute ~40% of the entire ecosystem CO2 sink. Importantly, the return to a substantial cumulative CO2 sink occurred two summers after the extreme event, which suggests a substantial resilience of this tundra ecosystem to at least an isolated extreme event. Overall, these results show a complex response of the CO2 sink and its sub-components to atypically warm and dry conditions. The impact of multiple extreme events requires further investigation.

Download Full-text

Open water metabolism and dissolved organic carbon in response to environmental watering in a lowland river–floodplain complex

Marine and Freshwater Research ◽

10.1071/mf15318 ◽

2016 ◽

Vol 67 (9) ◽

pp. 1346 ◽

Cited By ~ 1

Author(s):

Todd A. Wallace ◽

Deborah Furst

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Food Webs ◽

Ecosystem Respiration ◽

Open Water ◽

Relative Role ◽

Eastern Australia ◽

Return Flows ◽

Receiving Waters ◽

The Impact

The relative importance of autochthonous and allochthonous organic material in fuelling ecosystem metabolism is increasingly understood for some river systems. However, in south-eastern Australia, the majority of studies have been conducted during low flows when the supply of allochthonous carbon was limited. Consequently, the importance of episodic inputs of terrestrially derived material in supporting these food webs remains poorly understood. We assessed the influence of return flows from two different scales of environmental watering actions on dissolved organic carbon and open-water productivity in receiving waters adjacent to the watered area. For the wetland-scale event, gross primary productivity and ecosystem respiration increased in the receiving waters during the period of return flows. During the floodplain-scale watering, differences were observed among sites. Within the managed inundation zone, values for net ecosystem productivity switched from near zero during the baseline to strongly negative during the impact period, whereas values at the river sites were either near zero or positive. The results contribute to our understanding of the relative role of allochthonous material in supporting aquatic food webs in lowland rivers, and demonstrate potential for watering actions to have a positive influence on riverine productivity during periods of low water availability.

Download Full-text

Precipitation legacy effects on dryland ecosystem carbon fluxes: direction, magnitude and biogeochemical carryovers

Biogeosciences ◽

10.5194/bg-13-425-2016 ◽

2016 ◽

Vol 13 (2) ◽

pp. 425-439 ◽

Cited By ~ 27

Author(s):

W. Shen ◽

G. D. Jenerette ◽

D. Hui ◽

R. L. Scott

Keyword(s):

Plant Biomass ◽

Net Primary Production ◽

Ecosystem Respiration ◽

Ecosystem Dynamics ◽

Legacy Effects ◽

Previous Period ◽

Legacy Effect ◽

Ecosystem Production ◽

Legacy Impacts ◽

The Impact

Abstract. The precipitation legacy effect, defined as the impact of historical precipitation (PPT) on extant ecosystem dynamics, has been recognized as an important driver in shaping the temporal variability of dryland aboveground net primary production (ANPP) and soil respiration. How the PPT legacy influences whole ecosystem-level carbon (C) fluxes has rarely been quantitatively assessed, particularly at longer temporal scales. We parameterized a process-based ecosystem model to a semiarid savanna ecosystem in the southwestern USA, calibrated and evaluated the model performance based on 7 years of eddy-covariance measurements, and conducted two sets of simulation experiments to assess interdecadal and interannual PPT legacy effects over a 30-year simulation period. The results showed that decreasing the previous period/year PPT (dry legacy) always increased subsequent net ecosystem production (NEP) whereas increasing the previous period/year PPT (wet legacy) decreased NEP. The simulated dry-legacy impacts mostly increased subsequent gross ecosystem production (GEP) and reduced ecosystem respiration (Re), but the wet legacy mostly reduced GEP and increased Re. Although the direction and magnitude of GEP and Re responses to the simulated dry and wet legacies were influenced by both the previous and current PPT conditions, the NEP responses were predominantly determined by the previous PPT characteristics including rainfall amount, seasonality and event size distribution. Larger PPT difference between periods/years resulted in larger legacy impacts, with dry legacies fostering more C sequestration and wet legacies more C release. The carryover of soil N between periods/years was mainly responsible for the GEP responses, while the carryovers of plant biomass, litter and soil organic matter were mainly responsible for the Re responses. These simulation results suggest that previous PPT conditions can exert substantial legacy impacts on current ecosystem C balance, which should be taken into account while assessing the response of dryland ecosystem C dynamics to future PPT regime changes.

Download Full-text

The impact of climate change on landslides in southeastern of high-latitude permafrost regions of China

Frontiers in Earth Science ◽

10.3389/feart.2015.00007 ◽

2015 ◽

Vol 3 ◽

Cited By ~ 10

Author(s):

Wei Shan ◽

Zhaoguang Hu ◽

Ying Guo ◽

Chengcheng Zhang ◽

Chuanjiao Wang ◽

...

Keyword(s):

Climate Change ◽

High Latitude ◽

Impact Of Climate Change ◽

The Impact ◽

Permafrost Regions

Download Full-text

Millennia-old carbon fluxes from degraded tropical peatland soils

10.5194/egusphere-egu2020-21851 ◽

2020 ◽

Author(s):

Stephanie Evers ◽

Thomas Smith ◽

Mark Garnett ◽

Selvakumar Dhandipani ◽

Massimo Lupascu

Keyword(s):

Land Use ◽

Organic Matter ◽

Land Use Change ◽

Ecosystem Respiration ◽

Critical Element ◽

Tropical Peatland ◽

Agricultural Conversion ◽

C Cycling ◽

The Impact ◽

Global Carbon

Assessing the flux of carbon (C) from terrestrial ecosystems to the atmosphere represents a critical element of global carbon budgeting. In tropical peatlands this has been a fundamental part of assessing the impact of land use change on an ecosystem that represents a significant global carbon store, with peat accumulation being often many meters deep. These systems have formed over thousands of years as a function of incomplete decomposition of organic matter from water-logged swamp forests. However, intact tropical peat swamp forests (PSFs) are under increasing threat from agricultural conversion, deforestation, drainage practices and fires. The resultant alteration of the peat soil results in peat oxidation, increased rates of organic matter decomposition and greenhouse gas (GHG) emissions. Consequently, these peats are reverting from C stores to sources.Radiocarbon (14C) abundance can be used to assess C cycling rates in varied ecosystems and identify rapid or slow C turnover rates from years to centuries, as well as shifts in cycling rates &#8211; for example with land use or hydrological alteration. Within intact peatlands, deep peats generally contain an increasing abundance of 14C depleted content due to radioactive decay, conversely, shallower peats are more abundant in recently produced organic litter enriched with &#8220;Bomb C&#8221;; derived from nuclear testing in the 1960s. Similarly, root derived organic matter and the associated root respiration (autotrophic respiration) also have signatures resembling recent atmospheres, whereas microbial respiration of soil organic matter (heterotrophic respiration) will resemble the mean age of the soil carbon being utilised by the microbial community, and as such can be a tracer for sources of carbon being decomposed.&#160;Yet while an increasing body of knowledge exists on tropical peatland carbon flux rates or net ecosystem respiration in association with land-use change, these approaches fail to delineate the sources of carbon being used within the soil profile and thus fully address questions linked to changing carbon cycling rates with land use change.Here we provide what we believe to be the first data on 14CO2 fluxes from tropical peatland soils in relation to varying land use classes with the aim of determining if peats which were previously long-terms C stores are being utilised within short, fast C cycles and thus contributing to modern GHG budgets. CO2 flux rates were measured using soil chambers and emitted CO2 was subsequently trapped on a zeolite molecular sieve cartridge. An aliquot of the recovered CO2 was graphitised and analysed for 14C by accelerator mass spectrometry. Associated soil age profiles were also determined.Results indicate significant fluxes of multi-millennia old carbon from peatlands under altered land use classes and clear evidence for a shift to C cycling speed, with previously long-term stored C contributing to modern C budgets. Result highlight the instability of the peat profile under altered land-use classes and minimal to no contribution of modern C from recently produced organic matter to these carbon budgets. Findings clearly indicate the unsustainability of these agricultural practices and the need for burn- and drain-free land-use strategies.

Download Full-text