scholarly journals Evidence for a non-linear carbon accumulation pattern along an Alpine glacier retreat chronosequence in Northern Italy

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7703 ◽  
Author(s):  
Leonardo Montagnani ◽  
Aysan Badraghi ◽  
Andrew Francis Speak ◽  
Camilla Wellstein ◽  
Luigimaria Borruso ◽  
...  
Keyword(s):  
Primary Succession ◽  
Ecosystem Respiration ◽  
Carbon Accumulation ◽  
Glacier Retreat ◽  
High Mountain ◽  
Total Biomass ◽  
Successional Stage ◽  
Accumulation Pattern ◽  
Glacier Forefield ◽  
Biomass Components

Background The glaciers in the Alps, as in other high mountain ranges and boreal zones, are generally retreating and leaving a wide surface of bare ground free from ice cover. This early stage soil is then colonized by microbes and vegetation in a process of primary succession. It is rarely experimentally examined whether this colonization process is linear or not at the ecosystem scale. Thus, to improve our understanding of the variables involved in the carbon accumulation in the different stages of primary succession, we conducted this research in three transects on the Matsch glacier forefield (Alps, N Italy) at an altitude between 2,350 and 2,800 m a.s.l. Methods In three field campaigns (July, August and September 2014) a closed transparent chamber was used to quantify the net ecosystem exchange (NEE) between the natural vegetation and the atmosphere. On the five plots established in each of the three transects, shading nets were used to determine ecosystem response function to variable light conditions. Ecosystem respiration (Reco) and gross ecosystem exchange (GEE) was partitioned from NEE. Following the final flux measurements, biometric sampling was conducted to establish soil carbon (C) and nitrogen (N) content and the biomass components for each transect. Results A clear difference was found between the earlier and the later successional stage. The older successional stages in the lower altitudes acted as a stronger C sink, where NEE, GEE and Reco were significantly higher than in the earlier successional stage. Of the two lower transects, the sink capacity of intermediate-succession plots exceeded that of the plots of older formation, in spite of the more developed soil. Total biomass (above- and belowground) approached its maximum value in the intermediate ecosystem, whilst the later stage of succession predominated in the corresponding belowground organic mass (biomass, N and C). Outlook We found that the process of carbon accumulation along a glacier retreat chronosequence is not linear, and after a quite rapid increase in carbon accumulation capacity in the first 150 years, in average 9 g C m−2 year−1, it slows down, taking place mainly in the belowground biomass components. Concurrently, the photosynthetic capacity peaks in the intermediate stage of ecosystem development. If confirmed by further studies on a larger scale, this study would provide evidence for a predominant effect of plant physiology over soil physical characteristics in the green-up phase after glacier retreat, which has to be taken into account in the creation of scenarios related to climate change and future land use.

scholarly journals Evidence for a non-linear carbon accumulation pattern along an Alpine glacier retreat chronosequence in Northern Italy

2019 ◽  
Author(s):  
Leonardo Montagnani ◽  
Aysan Badraghi ◽  
Andrew Francis Speak ◽  
Camilla Wellstein ◽  
Luigimaria Borruso ◽  
...  
Keyword(s):  
Primary Succession ◽  
Ecosystem Respiration ◽  
Carbon Accumulation ◽  
Glacier Retreat ◽  
High Mountain ◽  
Total Biomass ◽  
Successional Stage ◽  
Accumulation Pattern ◽  
Glacier Forefield ◽  
Biomass Components

Background. The glaciers in the Alps, as in other high mountain ranges and boreal zones, are generally retreating and leaving a wide surface of bare ground free from ice cover. This early stage soil is then colonized by microbes and vegetation in a process of primary succession. It is rarely experimentally examined whether this colonization process is linear or not at the ecosystem scale. Thus, to improve our understanding of the variables involved in the carbon accumulation in the different stages of primary succession, we conducted this research in three transects on the Matsch glacier forefield (Alps, N Italy) at an altitude between 2350 and 2800 m a.s.l. Methods. In three field campaigns (July, August and September 2014) a closed transparent chamber was used to quantify the net ecosystem exchange (NEE) between the natural vegetation and the atmosphere. On the five plots established in each of the three transects, shading nets were used to determine ecosystem response function to variable light conditions. Ecosystem respiration (Reco) and gross ecosystem exchange (GEE) was partitioned from NEE. Following the final flux measurements, biometric sampling was conducted to establish soil carbon (C) and nitrogen (N) content and the biomass components for each transect. Results. A clear difference was found between the earlier and the later successional stage. The older successional stages in the lower altitudes acted as a stronger C sink, where NEE, GEE, and Reco were significantly higher than in the earlier successional stage. Of the two lower transects, the sink capacity of intermediate-succession plots exceeded that of the plots of older formation, in spite of the more developed soil. Total biomass (above- and belowground) approached its maximum value in the intermediate ecosystem. Whilst, the later stage of succession predominated in the corresponding belowground organic mass (biomass, N and C). Outlook. We found that the process of carbon accumulation along a glacier retreat chronosequence is not linear, and after a quite rapid increase in carbon accumulation capacity in the first 150 years, in average 9 g C m-2 y-1, it slows down, taking place mainly in the belowground biomass components. Concurrently, the photosynthetic capacity peaks in the intermediate stage of ecosystem development. If confirmed by further studies on a larger scale, this study would provide evidence for a predominant effect of plant physiology over soil physical characteristics in the green-up phase after glacier retreat, which has to be taken into account in the creation of scenarios related to climate change and future land use.

scholarly journals Evidence for a non-linear carbon accumulation pattern along an Alpine glacier retreat chronosequence in Northern Italy

2019 ◽  
Author(s):  
Leonardo Montagnani ◽  
Aysan Badraghi ◽  
Andrew Francis Speak ◽  
Camilla Wellstein ◽  
Luigimaria Borruso ◽  
...  
Keyword(s):  
Primary Succession ◽  
Ecosystem Respiration ◽  
Carbon Accumulation ◽  
Glacier Retreat ◽  
High Mountain ◽  
Total Biomass ◽  
Successional Stage ◽  
Accumulation Pattern ◽  
Glacier Forefield ◽  
Biomass Components

Background. The glaciers in the Alps, as in other high mountain ranges and boreal zones, are generally retreating and leaving a wide surface of bare ground free from ice cover. This early stage soil is then colonized by microbes and vegetation in a process of primary succession. It is rarely experimentally examined whether this colonization process is linear or not at the ecosystem scale. Thus, to improve our understanding of the variables involved in the carbon accumulation in the different stages of primary succession, we conducted this research in three transects on the Matsch glacier forefield (Alps, N Italy) at an altitude between 2350 and 2800 m a.s.l. Methods. In three field campaigns (July, August and September 2014) a closed transparent chamber was used to quantify the net ecosystem exchange (NEE) between the natural vegetation and the atmosphere. On the five plots established in each of the three transects, shading nets were used to determine ecosystem response function to variable light conditions. Ecosystem respiration (Reco) and gross ecosystem exchange (GEE) was partitioned from NEE. Following the final flux measurements, biometric sampling was conducted to establish soil carbon (C) and nitrogen (N) content and the biomass components for each transect. Results. A clear difference was found between the earlier and the later successional stage. The older successional stages in the lower altitudes acted as a stronger C sink, where NEE, GEE, and Reco were significantly higher than in the earlier successional stage. Of the two lower transects, the sink capacity of intermediate-succession plots exceeded that of the plots of older formation, in spite of the more developed soil. Total biomass (above- and belowground) approached its maximum value in the intermediate ecosystem. Whilst, the later stage of succession predominated in the corresponding belowground organic mass (biomass, N and C). Outlook. We found that the process of carbon accumulation along a glacier retreat chronosequence is not linear, and after a quite rapid increase in carbon accumulation capacity in the first 150 years, in average 9 g C m-2 y-1, it slows down, taking place mainly in the belowground biomass components. Concurrently, the photosynthetic capacity peaks in the intermediate stage of ecosystem development. If confirmed by further studies on a larger scale, this study would provide evidence for a predominant effect of plant physiology over soil physical characteristics in the green-up phase after glacier retreat, which has to be taken into account in the creation of scenarios related to climate change and future land use.

Development of debris cover and changes in fluvial sediments at Eastern Alpine glaciers

2021 ◽  
Author(s):  
Kay Helfricht ◽  
Clemens Hiller ◽  
Severin Hohensinner ◽  
Gabriele Schwaizer ◽  
Florian Haas ◽  
...  
Keyword(s):  
Glacier Retreat ◽  
Bed Load ◽  
High Mountain ◽  
Fluvial Sediments ◽  
Glacier Forefield ◽  
The Past ◽  
Decadal Scale ◽  
Debris Cover ◽  
Load Transport ◽  
Bed Load Transport

<p>High mountain environments showed substantial geomorphological changes forced by rising temperatures over the past 150 years. Glacier retreat is the most visible manifestation of climate change in alpine areas and has a significant impact on glacier land systems, high mountain runoff and, thus, on sediment transport in headwaters. Downwasting glaciers face an increase debris cover due to sediment flux onto glacier surfaces and melt out of englacial debris. Continuous debris transport from the glacier to the glacier forefield enhances its sediment available for being mobilized in case of higher or extreme runoff events.</p><p>The presented results arise from the Hidden.Ice project, which serves to investigate the hydrological impact of supraglacial debris deposits in the transition zone from glacier ice to the proglacial area. A detailed study focusses on the debris connectivity to bed load transport at the LTER site Jamtalferner (Silvretta mountains, Austria) and the evolution of the debris cover on glaciers in Austria.</p><p>A first spatio-temporal analysis of the long-term land cover evolution along the river channel from historical maps and remote sensing data shows increasing shares of fluvial sediments to about 12% of the area deglaciated after the LIA glacier maximum until the 1920s. However, the ongoing exposure of additional sediment plains is compensated by sediment export and covering of former stream banks by vegetation at decadal scale. Vegetation developed on up to 20% of the area in a 50 m buffer around the present glacier stream. This complementary documentation increases our knowledge on the temporal evolution of the sediment-rich proglacial zone evolved with glacier retreat.</p><p>To tackle the present interaction of the debris-covered glacier tongue with the runoff, the connectivity of supraglacial debris to bed load transport is estimated based on multi-annual and sub-seasonal high-resolution surface information. The underlying point cloud analysis employs Structure-from-Motion photogrammetry from UAV surveys and airborne laser scanning acquisitions. The deposition and renewed movement of debris in the glacier forefield is calculated from sediment volume changes. Strong variations in the stream position suggest high connectivity of the entire proglacial sediment body to bed load transport, and considerable shifts of the main channel have been documented from year to year. Multi-spectral analysis of Landsat and Sentinel-2 optical satellite data time series from 1985 to 2020 show the development of debris cover on glaciers in the study region with increasing relative share of total glacier area over the past decades.</p>

Carbon accumulation rates recorded in the last 150 years in tropical high mountain peatlands of the Atlantic Rainforest, SE - Brazil

2017 ◽  
Vol 579 ◽  
pp. 439-446 ◽  
Author(s):  
Lúcio F. Lourençato ◽  
Pedro P. Caldeira ◽  
Marcelo C. Bernardes ◽  
Andressa C. Buch ◽  
Daniel C. Teixeira ◽  
...  
Keyword(s):  
Carbon Accumulation ◽  
Atlantic Rainforest ◽  
High Mountain ◽  
Accumulation Rates ◽  
Se Brazil ◽  
Carbon Accumulation Rates ◽  
Mountain Peatlands

scholarly journals Dynamics of apomictic and sexual reproduction during primary succession on a glacier forefield in the Swiss Alps

2019 ◽  
Author(s):  
Christian Sailer ◽  
Jürg Stöcklin ◽  
Ueli Grossniklaus
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Primary Succession ◽  
Swiss Alps ◽  
Reproductive Assurance ◽  
Glacier Forefield ◽  
Early Stages ◽  
Hieracium Pilosella ◽  
Baker’S Law ◽  
Successional Stages

AbstractApomixis, the asexual reproduction through seeds, is thought to provide reproductive assurance when ploidy is not even and/or when population density is low. Therefore, apomicts are expected to be more abundant, and the frequency of apomictic offspring higher, at early stages of primary succession when mates are rare.To test this hypothesis, we sampled facultative apomictic Hieracium pilosella L. along the successional gradient on a glacier forefield and determined their ploidy, the level of apomixis in their offspring, and the genetic diversity of the entire meta-population and within subpopulations.We found that apomixis is more common in odd- and aneuploid cytotypes, which are more frequent at early stages of primary succession. However, apomixis was uncommon at all successional stages and sexual hexaploids were dominating throughout. Reproductive assurance was reflected in the higher fertility of all odd-ploid apomictic plants (3x, 5x) by avoiding meiosis, illustrating that apomixis provides an escape from sterility, as proposed by Darlington. Odd-ploid plants are supposedly better colonizers (Baker’s law), which is supported by their higher occurrence close to the glacier snout. Independent of succession, we found gene flow between apomicts and sexuals, which allows for the continuous creation of new apomictic and sexual genotypes.We conclude that apomixis in H. pilosella does indeed provide an escape from sterility, and therefore reproductive assurance, in aneuploid cytotypes. We further propose that apomixis preserves beneficial combinations of unlinked alleles in every generation for as long as apomictic genotypes persist in the population.

scholarly journals Partitioning of canopy and soil CO<sub>2</sub> fluxes in a pine forest at the dry timberline across a 13-year observation period

2020 ◽  
Vol 17 (3) ◽  
pp. 699-714
Author(s):  
Rafat Qubaja ◽  
Fyodor Tatarinov ◽  
Eyal Rotenberg ◽  
Dan Yakir
Keyword(s):  
Soil Respiration ◽  
Primary Productivity ◽  
Pinus Halepensis ◽  
Ecosystem Respiration ◽  
Carbon Accumulation ◽  
Dry Forest ◽  
Mean Annual Precipitation ◽  
Co2 Uptake ◽  
Belowground Carbon Allocation ◽  
Observation Period

Abstract. Partitioning carbon fluxes is key to understanding the process underlying ecosystem response to change. This study used soil and canopy fluxes with stable isotopes (13C) and radiocarbon (14C) measurements in an 18 km2, 50-year-old, dry (287 mm mean annual precipitation; nonirrigated) Pinus halepensis forest plantation in Israel to partition the net ecosystem's CO2 flux into gross primary productivity (GPP) and ecosystem respiration (Re) and (with the aid of isotopic measurements) soil respiration flux (Rs) into autotrophic (Rsa), heterotrophic (Rh), and inorganic (Ri) components. On an annual scale, GPP and Re were 655 and 488 g C m−2, respectively, with a net primary productivity (NPP) of 282 g C m−2 and carbon-use efficiency (CUE = NPP ∕ GPP) of 0.43. Rs made up 60 % of the Re and comprised 24±4 %Rsa, 23±4 %Rh, and 13±1 %Ri. The contribution of root and microbial respiration to Re increased during high productivity periods, and inorganic sources were more significant components when the soil water content was low. Comparing the ratio of the respiration components to Re of our mean 2016 values to those of 2003 (mean for 2001–2006) at the same site indicated a decrease in the autotrophic components (roots, foliage, and wood) by about −13 % and an increase in the heterotrophic component (Rh∕Re) by about +18 %, with similar trends for soil respiration (Rsa∕Rs decreasing by −19 % and Rh∕Rs increasing by +8 %, respectively). The soil respiration sensitivity to temperature (Q10) decreased across the same observation period by 36 % and 9 % in the wet and dry periods, respectively. Low rates of soil carbon loss combined with relatively high belowground carbon allocation (i.e., 38 % of canopy CO2 uptake) and low sensitivity to temperature help explain the high soil organic carbon accumulation and the relatively high ecosystem CUE of the dry forest.

scholarly journals Responses of Carbon Dynamics to Nitrogen Deposition in Typical Freshwater Wetland of Sanjiang Plain

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yang Wang ◽  
Jingshuang Liu ◽  
Longxue He ◽  
Jingxin Dou ◽  
Hongmei Zhao
Keyword(s):  
Soil Carbon ◽  
Nitrogen Deposition ◽  
Carbon Dynamics ◽  
N Deposition ◽  
Sanjiang Plain ◽  
Carbon Accumulation ◽  
Total Biomass ◽  
Soil System ◽  
Carbon Fractions ◽  
Soil Carbon Fractions

The effects of nitrogen deposition (N-deposition) on the carbon dynamics in typicalCalamagrostis angustifoliawetland of Sanjiang Plain were studied by a pot-culture experiment during two continuous plant growing seasons. Elevated atmospheric N-deposition caused significant increases in the aboveground net primary production and root biomass; moreover, a preferential partition of carbon to root was also observed. Different soil carbon fractions gained due to elevated N-deposition and their response intensities followed the sequence of labile carbon > dissolved organic carbon > microbial biomass carbon, and the interaction between N-deposition and flooded condition facilitated the release of different carbon fractions. Positive correlations were found between CO2and CH4fluxes and liable carbon contents with N-deposition, and flooded condition also tended to facilitate CH4fluxes and to inhibit the CO2fluxes with N-deposition. The increases in soil carbon fractions occurring in the nitrogen treatments were significantly correlated with increases in root, aboveground parts, total biomass, and their carbon uptake. Our results suggested that N-deposition could enhance the contents of active carbon fractions in soil system and carbon accumulation in plant of the freshwater wetlands.

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