scholarly journals Ecosystem effects of CO<sub>2</sub> concentration: evidence from past climates

2009 ◽  
Vol 5 (2) ◽  
pp. 937-963 ◽  
Author(s):  
I. C. Prentice ◽  
S. P. Harrison
Keyword(s):  
Forest Cover ◽  
Dissolved Inorganic Carbon ◽  
Net Primary Production ◽  
Isotope Composition ◽  
Late Quaternary ◽  
Co2 Concentration ◽  
C3 Plants ◽  
Sea Level Changes ◽  
Co2 Effects ◽  
Concentration Changes

Abstract. Atmospheric CO2 concentration has varied from minima of 170–200 ppm in glacials to maxima of 280–300 ppm in the recent interglacials. Photosynthesis by C3 plants is highly sensitive to CO2 concentration variations in this range. Physiological consequences of the CO2 changes should therefore be discernible in palaeodata. Several lines of evidence support this expectation. Reduced terrestrial carbon storage during glacials, indicated by the shift in stable isotope composition of dissolved inorganic carbon in the ocean, cannot be explained by climate or sea-level changes. It is however consistent with predictions of current process-based models that propagate known physiological CO2 effects into net primary production at the ecosystem scale. Restricted forest cover during glacial periods, indicated by pollen assemblages dominated by non-arboreal taxa, cannot be reproduced accurately by palaeoclimate models unless CO2 effects on C3-C4 plant competition are also modelled. It follows that methods to reconstruct climate from palaeodata should account for CO2 concentration changes. When they do so, they yield results more consistent with palaeoclimate models. In conclusion, the palaeorecord of the Late Quaternary, interpreted with the help of climate and ecosystem models, provides evidence that CO2 effects at the ecosystem scale are neither trivial nor transient.

scholarly journals Ecosystem effects of CO<sub>2</sub> concentration: evidence from past climates

2009 ◽  
Vol 5 (3) ◽  
pp. 297-307 ◽  
Author(s):  
I. C. Prentice ◽  
S. P. Harrison
Keyword(s):  
Forest Cover ◽  
Dissolved Inorganic Carbon ◽  
Net Primary Production ◽  
Isotope Composition ◽  
Late Quaternary ◽  
Co2 Concentration ◽  
C3 Plants ◽  
Sea Level Changes ◽  
Co2 Effects ◽  
Concentration Changes

Abstract. Atmospheric CO2 concentration has varied from minima of 170–200 ppm in glacials to maxima of 280–300 ppm in the recent interglacials. Photosynthesis by C3 plants is highly sensitive to CO2 concentration variations in this range. Physiological consequences of the CO2 changes should therefore be discernible in palaeodata. Several lines of evidence support this expectation. Reduced terrestrial carbon storage during glacials, indicated by the shift in stable isotope composition of dissolved inorganic carbon in the ocean, cannot be explained by climate or sea-level changes. It is however consistent with predictions of current process-based models that propagate known physiological CO2 effects into net primary production at the ecosystem scale. Restricted forest cover during glacial periods, indicated by pollen assemblages dominated by non-arboreal taxa, cannot be reproduced accurately by palaeoclimate models unless CO2 effects on C3-C4 plant competition are also modelled. It follows that methods to reconstruct climate from palaeodata should account for CO2 concentration changes. When they do so, they yield results more consistent with palaeoclimate models. In conclusion, the palaeorecord of the Late Quaternary, interpreted with the help of climate and ecosystem models, provides evidence that CO2 effects at the ecosystem scale are neither trivial nor transient.

Recent and future productivity of Russian forests under climate change

2020 ◽  
Author(s):  
Anatoly Shvidenko ◽  
Dmitry Schepaschenko ◽  
Sergey Bartalev ◽  
Andrey Krasovskii ◽  
Anton Platov
Keyword(s):  
Remote Sensing ◽  
Forest Inventory ◽  
Carbon Budget ◽  
Forest Cover ◽  
Net Primary Production ◽  
Co2 Concentration ◽  
Growing Stock ◽  
Distributed Modelling ◽  
Live Biomass ◽  
Russian Forests

&lt;p&gt;Knowledge of dynamics of forest productivity, expressed in terms of Growing Stock Volume (GSV), Net Primary Production (NPP), such derivatives like current increments (net and gross growth), is crucial for understanding the impacts of forest ecosystems on the major global biogeochemical cycles and eventually &amp;#8211; on the Earth climate system. This knowledge is not satisfactory in Russia currently (the country&amp;#8217;s forests cover &gt;20% of the global forest area) because 1) data of official forest inventory are obsolete and substantially biased due to the fact that about 50% of Russian forests were inventoried more than 30 years ago; 2) of the above indicators, Russian forest inventory directly defines only GSV, but by the methods, which have substantial systematic errors of unknown size; 3) remote sensing methods themselves still cannot reliably provide some necessary details, like species composition, age and age structure of stands, below ground live biomass etc. In this presentation, we attempted to provide a systematic reanalysis of the estimates of the above indicators. To this end, a special system was developed to update the data of forest inventory for periods after the latest inventory by forest enterprises (about 1700) based on all available ground-based information and a multi-sensor concept of remote sensing. Hybrid forest cover was presented as an aggregation of 12 satellite products at spatial resolution of 150m. The updating of the main biometric indicators of Russian forests was based on the models of the growth and bioproductivity of modal stands. The results of the actualization have showed substantial overestimation of areas by official inventory and underestimation (up to 20%) of GSV. Comparison of obtained results with an independent assessment of the dynamics of areas and GSV, which was made by the Space Research Institute of the Russian Academy of Sciences for the period 2000-2017, showed a high level of compatibility. Using the results of actualization, live biomass was assessed based on a new system of conversion coefficients (Schepaschenko et al. 2018), NPP - on a method described in Shvidenko et al. (2007); and current increments &amp;#8211; using a regionally distributed modelling system on increment dynamics of modal stands. Climate were analyzed for 3 periods: &amp;#8220;historical&amp;#8221; (1948-1975), &amp;#8220;current&amp;#8221;(1975-2017) and &amp;#8220;future&amp;#8221; (using all 4 scenarios RCP (2020-2100)). NPP and increments were estimated for the two last periods using a model, which takes into account selected climatic indicators and fertilization effect of enhanced CO2 concentration. It is shown that use of the obtained results presents substantial possibility for improvement of estimates of the carbon budget of Russian forests, particularly those received by inventory methods, and eliminate the existing discrepancies in estimates of the carbon budget of Russian forests reported in different publications. Projections for future suppose that significant part of Russian forests under &amp;#8220;critical&amp;#8221; scenarios (RCP6.0 and RCP 8.5) have a high probability to reach the tipping point by end of this century.&lt;/p&gt;

scholarly journals Geographic Aspects of Temperature and Concentration Feedbacks in the Carbon Budget

2010 ◽  
Vol 23 (3) ◽  
pp. 775-784 ◽  
Author(s):  
G. J. Boer ◽  
V. Arora
Keyword(s):  
Negative Feedback ◽  
Carbon Concentration ◽  
Carbon Budget ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Climate Feedback ◽  
Climate Modelling ◽  
Emission Scenarios ◽  
Temperature Feedback ◽  
Concentration Changes

Abstract The geographical distribution of feedback processes in the carbon budget is investigated in a manner that parallels that for climate feedback/sensitivity in the energy budget. Simulations for a range of emission scenarios, made with the Canadian Centre for Climate Modelling and Analysis (CCCma) earth system model (CanESM1), are the basis of the analysis. Anthropogenic CO2 emissions are concentrated in the Northern Hemisphere and provide the forcing for changes to the atmospheric carbon budget. Transports redistribute the emitted CO2 globally where local feedback processes act to enhance (positive feedback) or suppress (negative feedback) local CO2 amounts in response to changes in CO2 concentration and temperature. An increased uptake of CO2 by the land and ocean acts to counteract increased atmospheric CO2 concentrations so that “carbon–concentration” feedbacks are broadly negative over the twenty-first century. Largest values are found over land and particularly in tropical regions where CO2 acts to fertilize plant growth. Extratropical land also takes up CO2 but here the effect is limited by cooler temperatures. Oceans play a lesser negative feedback role with comparatively weak uptake associated with an increase in the atmosphere–ocean CO2 gradient rather than with oceanic biological activity. The effect of CO2-induced temperature increase is, by contrast, to increase atmospheric CO2 on average and so represents an overall positive “carbon–temperature” feedback. Although the average is positive, local regions of both positive and negative carbon–temperature feedback are seen over land as a consequence of the competition between changes in biological productivity and respiration. Positive carbon–temperature feedback is found over most tropical land while mid–high-latitude land exhibits negative feedback. There are also regions of positive and negative oceanic carbon–temperature feedback in the eastern tropical Pacific. The geographical patterns of carbon–concentration and carbon–temperature feedbacks are comparatively robust across the range of emission scenarios used, although their magnitudes are somewhat less robust and scale nonlinearly as a consequence of the large CO2 concentration changes engendered by the scenarios. The feedback patterns deduced nevertheless serve to illustrate the localized carbon feedback processes in the climate system.

Palaeoecological evidences from foraminifers and ostracods on Late Quaternary sea-level changes in the Ombrone river plain (central Tyrrhenian coast, Italy)

Geobios ◽  
2002 ◽  
Vol 35 ◽  
pp. 40-50 ◽  
Author(s):  
M Gabriella Carboni ◽  
Luisa Bergamin ◽  
Letizia Di Bella ◽  
Fabrizia Iamundo ◽  
Nevio Pugliese
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Sea Level Changes ◽  
River Plain

Grass phytoliths in surface sediments of the Sunderbans, India and their implications in reconstructing past deltaic environmental changes

The Holocene ◽  
2021 ◽  
pp. 095968362110417
Author(s):  
Madhab Naskar ◽  
Ruby Ghosh ◽  
Sayantani Das ◽  
Dipak Kumar Paruya ◽  
Binod Saradar ◽  
...  
Keyword(s):  
Surface Sediments ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Salinity Gradient ◽  
Detrended Correspondence Analysis ◽  
Mangrove Ecosystem ◽  
Sea Level Changes ◽  
Tidal Influence ◽  
Mangrove Environment ◽  
Mangrove Associate

Reliability of grass phytoliths for discriminating different deltaic sub-environments has been assessed on the modern surface sediments collected along the salinity gradient of the Sunderbans delta, India. It has been observed that grass phytolith assemblages can successfully distinguish different deltaic sub-environments especially the true mangrove zones from the mangrove associate and non-mangrove zones with minor overlaps, which further corroborated with the results of discriminant analysis (DA). Detrended correspondence analysis (DCA) and redundancy analysis (RDA) performed on the surface grass phytolith data show that salinity is the most crucial environmental parameter influencing grass phytolith distribution in the deltaic sub-environments. The potential of modern grass phytolith data in reconstructing past deltaic environmental changes has been further assessed on a late Quaternary fossil phytolith spectra from the Sunderbans spanning a sedimentary record for the last ~13.6 ka. A true mangrove environment with discernible tidal influence has been revealed between 13.6 and 3.9 ka. Absence of true mangrove–indicator grass phytoliths between ~3.9 and 2.2 ka further suggests disappearance of mangrove vegetation from this part of the Sunderbans which might have recolonized during ~2.2–0.8 ka. A mangrove associated or non-mangrove environment with little or no tidal influence came into existence in the study area since 0.8 ka onwards. A comparison with some earlier records suggests that the present grass phytolith-based palaeoenvironmental data shows conformity with the past dynamics in mangrove ecosystem in the east coast of India in respect to relative sea level changes.

scholarly journals Late Quaternary drainage dynamics in northern Brazil based on the study of a large paleochannel from southwestern Marajó Island

2008 ◽  
Vol 80 (3) ◽  
pp. 579-593 ◽  
Author(s):  
Dilce F. Rossetti ◽  
Ana M. Góes
Keyword(s):  
Remote Sensing ◽  
Forest Cover ◽  
Late Quaternary ◽  
Drainage System ◽  
Perfect Agreement ◽  
Marajó Island ◽  
Northern Brazil ◽  
Remote Sensing Mapping ◽  
The Town ◽  
Tectonic Origin

Marajó Island shows an abundance of paleochannels easily mapped in its eastern portion, where vegetation consists mostly of savannas. SRTM data make possible to recognize paleochannels also in western Marajó, even considering the dense forest cover. A well preserved paleodrainage network from the adjacency of the town of Breves (southwestern Marajó Island) was investigated in this work combining remote sensing and sedimentological studies. The palimpsest drainage system consists of a large meander connected to narrower tributaries. Sedimentological studies revealed mostly sharp-based, fining upward sands for the channelized features, and interbedded muds and sands for floodplain areas. The sedimentary structures and facies successions are in perfect agreement with deposition in channelized and floodplain environments, as suggested by remote sensing mapping. The present study shows that this paleodrainage was abandoned during Late Pleistocene, slightly earlier than the Holocene paleochannel systems from the east part of the island. Integration of previous studies with the data available herein supports a tectonic origin, related to the opening of the Pará River along fault lineaments. This would explain the disappearance of large, north to northeastward migrating channel systems in southwestern Marajó Island, which were replaced by the much narrower, south to southeastward flowing modern channels.

scholarly journals Assessment of NTSG MODIS NPP product for forests in Kurzeme region, Latvia / Kuramaa metsade primaarproduktsiooni hindamisest NTSG MODIS NPP andmestiku abil

2013 ◽  
Vol 58 (1) ◽  
pp. 26-36
Author(s):  
Mait Lang ◽  
Agris Traškovs ◽  
Linda Gulbe
Keyword(s):  
Baltic Sea ◽  
Forest Cover ◽  
Net Primary Production ◽  
Growth Potential ◽  
Stem Biomass ◽  
Biomass Increment ◽  
Potential Estimate ◽  
Site Fertility ◽  
The Baltic ◽  
Sea Coast

Abstract The space-borne Moderate Resolution Imaging Spectroradiometer (MODIS) data based net primary production (NPP) product from Numerical Terradynamic Simulation Group (NTSG) was tested in the Kurzeme region, Latvia using a stand-wise forest inventory database. The NPP product has been validated globally and found to have no overall bias. In this study the NPP product was compared with stem biomass increment and soil fertility in respect to distance from the Baltic Sea coast. For each MODIS NPP product pixel we calculated forest cover, share of coniferous trees, average stem biomass increment and average site fertility (growth potential estimate). Then, 2432 pixels with a forest cover over 75% were selected for analysis. The results indicated that MODIS NPP decreased with distance from Baltic Sea coast but stem biomass increment and site fertility indicated a trend of increase. There was no functional relationship between MODIS NPP and stem biomass increment. Analysis of the landcover map used by NTSG for MODIS NPP product showed that the classes “Evergreen needleleaf” and “Mixed forests” differentiated only 10% by mode value of coniferous proportions in species composition. A non-natural jump was detected in the MODIS NPP values at a longitude of 22.5 degrees east corresponding to the border of the coarse scale meteorological dataset (NCEP Reanalysis (R2)) data representation unit. According to the results the MODIS NPP product is not applicable for regional level planning but can probably provide only rough average estimates of NPP for the Baltic region

scholarly journals Modeling Climate Change Impacts on Rangeland Productivity and Livestock Population Dynamics in Nkayi District, Zimbabwe

2020 ◽  
Vol 10 (7) ◽  
pp. 2330
Author(s):  
Trinity S. Senda ◽  
Gregory A. Kiker ◽  
Patricia Masikati ◽  
Albert Chirima ◽  
Johan van Niekerk
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Population Dynamics ◽  
C3 Plants ◽  
Climate Scenarios ◽  
Herbaceous Layer ◽  
Livestock Population ◽  
Co2 Effects ◽  
Forested Areas ◽  
Carbon Dioxide Co2

Smallholder farmers in semi-arid areas depend on both cropping and livestock as the main sources of livelihoods. Rangeland productivity varies on both spatial and temporal scales and provides the major source of feed for livestock. Rangeland productivity is expected to decline with climate change thereby reducing livestock feed availability and consequently livelihoods that depend on livestock. This study was carried out to assess the impacts of climate change on rangeland productivity and consequently livestock population dynamics using a 30-year simulation modeling approach. The climate scenarios used in the simulations are built from the localized predictions by General Circulation Models (GCMs). The primary climate variables under consideration are rainfall (+/−7% change), carbon dioxide (CO2 up to 650 ppm) and temperature (+4 °C change). This was done by applying the SAVANNA ecosystem model which simulates rangeland processes and demographic responses of herbivores on a temporal and spatial scale using a weekly internal time step and monthly spatial and temporal outputs. The results show that rainfall levels of less than 600 mm/year have the largest negative effect on herbaceous biomass production. The amount of biomass from the woody layer does not change much during the year. The carbon dioxide (CO2) effects are more influential on the tree and shrub layers (C3 plants) than the herbaceous layer (C4 grasses). The CO2 effect was more dominant than the effects of rainfall and temperature. In the baseline simulations, the shrub plant layer increased significantly over 30 years while there is a three-fold increase in the woody plant layer (trees and shrubs) where biomass increased from a 1980 production to that of 2010. The biomass of the herbaceous layer was stable over the historical period (1980 to 2010) with values fluctuating between 200 and 400 g/m2. Grass green biomass has a variable distribution where most production occurred in the fields and cleared areas while lower levels of production were found in the forested areas. The spatial distribution of shrub green biomass was less directly linked to yearly rainfall. Shrub biomass was mostly found in forested areas, and it showed a steady increase in production. Cattle, donkey, and goat populations rose slowly from 1980 but the rise was disrupted by a dry period during the late 1980s to the early 1990s causing a decline in all populations primarily due to grass unavailability. The populations of cattle goats and donkeys started to rise again from 1995 onwards due to improvements in rainfall. Cattle and donkey populations were rising faster than that of goats while sheep population was not changing much for most of the simulation period, otherwise they declined significantly during the drought of 2002. Similar changes in simulated grass biomass (g/m2) were observed in almost all climate scenarios, except for the peak and low years. The livestock population simulation showed few variations in livestock population under all scenarios. The main conclusion from the study is that CO2 effects on rangeland productivity are much more dominant than the localized effects of rainfall and temperature. This has implications of favoring the growth of the tree and shrub layers over herbaceous layer, which meant that in the long run, the species that are able to use tree and shrub layers may be kept as a livelihood source as they will have a feed source.

scholarly journals Biophsyical constraints on gross primary production by the terrestrial biosphere

2014 ◽  
Vol 11 (20) ◽  
pp. 5987-6001 ◽  
Author(s):  
H. Wang ◽  
I. C. Prentice ◽  
T. W. Davis
Keyword(s):  
Primary Production ◽  
Optimality Theory ◽  
Vegetation Cover ◽  
Gross Primary Production ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Water Shortage ◽  
C3 Plants ◽  
Environmental Controls ◽  
Green Vegetation

Abstract. Persistent divergences among the predictions of complex carbon-cycle models include differences in the sign as well as the magnitude of the response of global terrestrial primary production to climate change. Such problems with current models indicate an urgent need to reassess the principles underlying the environmental controls of primary production. The global patterns of annual and maximum monthly terrestrial gross primary production (GPP) by C3 plants are explored here using a simple first-principles model based on the light-use efficiency formalism and the Farquhar model for C3 photosynthesis. The model is driven by incident photosynthetically active radiation (PAR) and remotely sensed green-vegetation cover, with additional constraints imposed by low-temperature inhibition and CO2 limitation. The ratio of leaf-internal to ambient CO2 concentration in the model responds to growing-season mean temperature, atmospheric dryness (indexed by the cumulative water deficit, Δ E) and elevation, based on an optimality theory. The greatest annual GPP is predicted for tropical moist forests, but the maximum (summer) monthly GPP can be as high, or higher, in boreal or temperate forests. These findings are supported by a new analysis of CO2 flux measurements. The explanation is simply based on the seasonal and latitudinal distribution of PAR combined with the physiology of photosynthesis. By successively imposing biophysical constraints, it is shown that partial vegetation cover – driven primarily by water shortage – represents the largest constraint on global GPP.

Sign in / Sign up

Export Citation Format

Share Document