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  • Wiley  (4)
  • Ciais, Philippe  (4)
  • Biodiversitätsforschung  (4)
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  • Wiley  (4)
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  • Biodiversitätsforschung  (4)
  • 1
    Online-Ressource
    Online-Ressource
    Global vegetation biomass production efficiency constrained by models and observations
    Wiley ; 2020
    In:  Global Change Biology Vol. 26, No. 3 ( 2020-03), p. 1474-1484
    Details
    In: Global Change Biology, Wiley, Vol. 26, No. 3 ( 2020-03), p. 1474-1484
    Kurzfassung: Plants use only a fraction of their photosynthetically derived carbon for biomass production (BP). The biomass production efficiency (BPE), defined as the ratio of BP to photosynthesis, and its variation across and within vegetation types is poorly understood, which hinders our capacity to accurately estimate carbon turnover times and carbon sinks. Here, we present a new global estimation of BPE obtained by combining field measurements from 113 sites with 14 carbon cycle models. Our best estimate of global BPE is 0.41 ± 0.05, excluding cropland. The largest BPE is found in boreal forests (0.48 ± 0.06) and the lowest in tropical forests (0.40 ± 0.04). Carbon cycle models overestimate BPE, although models with carbon–nitrogen interactions tend to be more realistic. Using observation‐based estimates of global photosynthesis, we quantify the global BP of non‐cropland ecosystems of 41 ± 6 Pg C/year. This flux is less than net primary production as it does not contain carbon allocated to symbionts, used for exudates or volatile carbon compound emissions to the atmosphere. Our study reveals a positive bias of 24 ± 11% in the model‐estimated BP (10 of 14 models). When correcting models for this bias while leaving modeled carbon turnover times unchanged, we found that the global ecosystem carbon storage change during the last century is decreased by 67% (or 58 Pg C).
    Materialart: Online-Ressource
    ISSN: 1354-1013 , 1365-2486
    URL: Issue
    URL: Article
    DOI: 10.1111/gcb.v26.3
    DOI: 10.1111/gcb.14816
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2020
    ZDB Id: 2020313-5
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
  • 2
    Online-Ressource
    Online-Ressource
    Rainfall manipulation experiments as simulated by terrestrial biosphere models: Where do we stand?
    Wiley ; 2020
    In:  Global Change Biology Vol. 26, No. 6 ( 2020-06), p. 3336-3355
    Details
    In: Global Change Biology, Wiley, Vol. 26, No. 6 ( 2020-06), p. 3336-3355
    Kurzfassung: Changes in rainfall amounts and patterns have been observed and are expected to continue in the near future with potentially significant ecological and societal consequences. Modelling vegetation responses to changes in rainfall is thus crucial to project water and carbon cycles in the future. In this study, we present the results of a new model‐data intercomparison project, where we tested the ability of 10 terrestrial biosphere models to reproduce the observed sensitivity of ecosystem productivity to rainfall changes at 10 sites across the globe, in nine of which, rainfall exclusion and/or irrigation experiments had been performed. The key results are as follows: (a) Inter‐model variation is generally large and model agreement varies with timescales. In severely water‐limited sites, models only agree on the interannual variability of evapotranspiration and to a smaller extent on gross primary productivity. In more mesic sites, model agreement for both water and carbon fluxes is typically higher on fine (daily–monthly) timescales and reduces on longer (seasonal–annual) scales. (b) Models on average overestimate the relationship between ecosystem productivity and mean rainfall amounts across sites (in space) and have a low capacity in reproducing the temporal (interannual) sensitivity of vegetation productivity to annual rainfall at a given site, even though observation uncertainty is comparable to inter‐model variability. (c) Most models reproduced the sign of the observed patterns in productivity changes in rainfall manipulation experiments but had a low capacity in reproducing the observed magnitude of productivity changes. Models better reproduced the observed productivity responses due to rainfall exclusion than addition. (d) All models attribute ecosystem productivity changes to the intensity of vegetation stress and peak leaf area, whereas the impact of the change in growing season length is negligible. The relative contribution of the peak leaf area and vegetation stress intensity was highly variable among models.
    Materialart: Online-Ressource
    ISSN: 1354-1013 , 1365-2486
    URL: Issue
    URL: Article
    DOI: 10.1111/gcb.v26.6
    DOI: 10.1111/gcb.15024
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2020
    ZDB Id: 2020313-5
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
  • 3
    Online-Ressource
    Online-Ressource
    Global patterns and climate drivers of water‐use efficiency in terrestrial ecosystems deduced from satellite‐based datasets and carbon cycle models
    Wiley ; 2016
    In:  Global Ecology and Biogeography Vol. 25, No. 3 ( 2016-03), p. 311-323
    Details
    In: Global Ecology and Biogeography, Wiley, Vol. 25, No. 3 ( 2016-03), p. 311-323
    Kurzfassung: To investigate how ecosystem water‐use efficiency ( WUE ) varies spatially under different climate conditions, and how spatial variations in WUE differ from those of transpiration‐based water‐use efficiency ( WUE t ) and transpiration‐based inherent water‐use efficiency ( IWUE t ). Location Global terrestrial ecosystems. Methods We investigated spatial patterns of WUE using two datasets of gross primary productivity ( GPP ) and evapotranspiration ( ET ) and four biosphere model estimates of GPP and ET . Spatial relationships between WUE and climate variables were further explored through regression analyses. Results Global WUE estimated by two satellite‐based datasets is 1.9 ± 0.1 and 1.8 ± 0.6 g C m −2  mm −1 lower than the simulations from four process‐based models (2.0 ± 0.3 g C m −2  mm −1 ) but comparable within the uncertainty of both approaches. In both satellite‐based datasets and process models, precipitation is more strongly associated with spatial gradients of WUE for temperate and tropical regions, but temperature dominates north of 50°  N . WUE also increases with increasing solar radiation at high latitudes. The values of WUE from datasets and process‐based models are systematically higher in wet regions (with higher GPP ) than in dry regions. WUE t shows a lower precipitation sensitivity than WUE , which is contrary to leaf‐ and plant‐level observations. IWUE t , the product of WUE t and water vapour deficit, is found to be rather conservative with spatially increasing precipitation, in agreement with leaf‐ and plant‐level measurements. Main conclusions WUE , WUE t and IWUE t produce different spatial relationships with climate variables. In dry ecosystems, water losses from evaporation from bare soil, uncorrelated with productivity, tend to make WUE lower than in wetter regions. Yet canopy conductance is intrinsically efficient in those ecosystems and maintains a higher IWUE t . This suggests that the responses of each component flux of evapotranspiration should be analysed separately when investigating regional gradients in WUE , its temporal variability and its trends.
    Materialart: Online-Ressource
    ISSN: 1466-822X , 1466-8238
    URL: Issue
    URL: Article
    DOI: 10.1111/geb.2016.25.issue-3
    DOI: 10.1111/geb.12411
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2016
    ZDB Id: 1479787-2
    ZDB Id: 2021283-5
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
  • 4
    Online-Ressource
    Online-Ressource
    Seasonal responses of terrestrial ecosystem water‐use efficiency to climate change
    Wiley ; 2016
    In:  Global Change Biology Vol. 22, No. 6 ( 2016-06), p. 2165-2177
    Details
    In: Global Change Biology, Wiley, Vol. 22, No. 6 ( 2016-06), p. 2165-2177
    Kurzfassung: Ecosystem water‐use efficiency ( EWUE ) is an indicator of carbon–water interactions and is defined as the ratio of carbon assimilation ( GPP ) to evapotranspiration ( ET ). Previous research suggests an increasing long‐term trend in annual EWUE over many regions and is largely attributed to the physiological effects of rising CO 2 . The seasonal trends in EWUE , however, have not yet been analyzed. In this study, we investigate seasonal EWUE trends and responses to various drivers during 1982–2008. The seasonal cycle for two variants of EWUE , water‐use efficiency ( WUE , GPP / ET ), and transpiration‐based WUE ( WUE t , the ratio of GPP and transpiration), is analyzed from 0.5° gridded fields from four process‐based models and satellite‐based products, as well as a network of 63 local flux tower observations. WUE derived from flux tower observations shows moderate seasonal variation for most latitude bands, which is in agreement with satellite‐based products. In contrast, the seasonal EWUE trends are not well captured by the same satellite‐based products. Trend analysis, based on process‐model factorial simulations separating effects of climate, CO 2 , and nitrogen deposition ( NDEP ), further suggests that the seasonal EWUE trends are mainly associated with seasonal trends of climate, whereas CO 2 and NDEP do not show obvious seasonal difference in EWUE trends. About 66% grid cells show positive annual WUE trends, mainly over mid‐ and high northern latitudes. In these regions, spring climate change has amplified the effect of CO 2 in increasing WUE by more than 0.005 gC m −2  mm −1  yr −1 for 41% pixels. Multiple regression analysis further shows that the increase in springtime WUE in the northern hemisphere is the result of GPP increasing faster than ET because of the higher temperature sensitivity of GPP relative to ET . The partitioning of annual EWUE to seasonal components provides new insight into the relative sensitivities of GPP and ET to climate, CO 2, and NDEP .
    Materialart: Online-Ressource
    ISSN: 1354-1013 , 1365-2486
    URL: Issue
    URL: Article
    DOI: 10.1111/gcb.2016.22.issue-6
    DOI: 10.1111/gcb.13180
    Sprache: Englisch
    Verlag: Wiley
    Publikationsdatum: 2016
    ZDB Id: 2020313-5
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
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