Variable tree rooting strategies improve tropical productivity and evapotranspiration in a dynamic global vegetation model

Sakschewski, Boris; Bloh, Werner von; Drüke, Markus; Sörensson, Anna A.; Ruscica, Romina; Langerwisch, Fanny; Billing, Maik; Bereswill, Sarah; Hirota, Marina; Oliveira, Rafael S.; Heinke, Jens; Thonicke, Kirsten

doi:10.5194/bg-2020-97

Cited by 12 publications

(17 citation statements)

References 61 publications

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“…and by increasing the tropical rooting depths and hence, the soil water access of the trees (Sakschewski et al, 2020). Global biomass patterns are now also comparable with the stand-alone LPJmL5 version (Fig.…”

Section: Challenges Of Coupling Lpjml5 Into Cm2mcsupporting

confidence: 52%

“…The key advantages of CM2Mc-LPJmL are the relatively fast and computational inexpensive atmosphere-ocean general circulation model (due to its relatively low spatial resolution) and the ability to investigate detailed feedbacks of the biosphere using the state-of-the-art DGVM LPJmL5. While LPJmL5 is constantly improved, recent new features such as a process-based nitrogen cycle (Von Bloh et al, 2018), a tillage system for land use (Lutz et al, 2019) or variable root growth (Sakschewski et al, 2020) can be integrated in the modelling framework consecutively and tested in the Earth system model. The coupled model also remains flexible for new model compartments such as a new atmosphere or a new ocean model, which are compatible with FMS.…”

Section: Climate and Land-use Change In Cm2mc-lpjmlmentioning

confidence: 99%

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CM2Mc-LPJmL v1.0: Biophysical coupling of a process-based dynamic vegetation model with managed land to a general circulation model

Drüke¹,

Bloh²,

Petri³

et al. 2021

Preprint

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Abstract. The terrestrial biosphere is exposed to land-use and climate change, which not only affects vegetation dynamics, but also changes land-atmosphere feedbacks. Specifically, changes in land-cover affect biophysical feedbacks of water and energy, therefore contributing to climate change. In this study, we couple the well established and comprehensively validated Dynamic Global Vegetation Model LPJmL5 to the coupled climate model CM2Mc, which is based on the atmosphere model AM2 and the ocean model MOM5 (CM2Mc-LPJmL). In CM2Mc, we replace the simple land surface model LaD (where vegetation is static and prescribed) with LPJmL5 and fully couple the water and energy cycles using the Geophysical Fluid Dynamics Laboratory (GFDL) Flexible Modeling System (FMS). Several improvements to LPJmL5 were implemented to allow a fully functional biophysical coupling. These include a sub-daily cycle for calculating energy and water fluxes, a conductance of the soil evaporation and plant interception, a canopy-layer humidity, and the surface energy balance in order to calculate the surface and canopy layer temperature within LPJmL5. Exchanging LaD by LPJmL5, and therefore switching from a static and prescribed vegetation to a dynamic vegetation, allows us to model important biosphere processes, including fire, mortality, permafrost, hydrological cycling, and the impacts of managed land (crop growth and irrigation). Our results show that CM2Mc-LPJmL has similar temperature and precipitation biases as the original CM2Mc model with LaD. Performance of LPJmL5 in the coupled system compared to Earth observation data and to LPJmL offline simulation results is within acceptable error margins. The historic global mean temperature evolution of our model setup is within the range of CMIP5 models. The comparison of model runs with and without land-use change shows a partially warmer and drier climate state across the global land surface. CM2Mc-LPJmL opens new opportunities to investigate important biophysical vegetation-climate feedbacks with a state-of-the-art and process-based dynamic vegetation model.

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Section: Challenges Of Coupling Lpjml5 Into Cm2mcsupporting

confidence: 52%

Section: Climate and Land-use Change In Cm2mc-lpjmlmentioning

confidence: 99%

CM2Mc-LPJmL v1.0: Biophysical coupling of a process-based dynamic vegetation model with managed land to a general circulation model

Drüke¹,

Bloh²,

Petri³

et al. 2021

Preprint

Self Cite

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“…These Savanna ecosystem cover around 20% of the Australian landscape, but as this study implies (see fig. 6), progress has been limited, although recent model developments incorporating competing rooting strategies and dynamic root growth (Sakschewski et al, 2020) may help this process. Australia has a high fraction of endemic vegetation (>90%; Chapman, 2006), structurally distinct vegetation including open canopy forests and woodlands (predominately Eucalyptus) and hummock grasslands and a dominance of Sclerophyll leaves (Box, 1996).…”

Section: Future Directionsmentioning

confidence: 99%

Assessing the representation of the Australian carbon cycle in global vegetation models

Teckentrup

Kauwe

Pitman

et al. 2021

Preprint

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Abstract. Australia plays an important role in the global terrestrial carbon cycle on inter-annual timescales. While the Australian continent is included in global assessments of the carbon cycle such as the global carbon budget, the performance of dynamic global vegetation models (DGVMs) over Australia has rarely been evaluated. We assessed simulations of net biome production (NBP) and the carbon stored in vegetation between 1901 to 2018 from 13 DGVMs (TRENDY v8 ensemble). We focused our analysis on both Australia's short-term (inter-annual) and long-term (decadal to centennial) terrestrial carbon dynamics. The TRENDY models simulated differing magnitudes of NBP on inter-annual timescales, and these differences contributed to carbon accumulation in the vegetation on decadal to centennial timescales (−4.7–9.5 PgC). We compared the TRENDY ensemble to several satellite-derived datasets and showed that the spread in the models' simulated carbon storage resulted from varying changes in carbon residence time rather than differences in net carbon uptake. Differences in simulated long-term accumulated NBP between models were mostly due to model responses to land-use change. The DGVMs also simulated different sensitivities to atmospheric carbon dioxide (CO2) concentration, although notably, the models with nutrient cycles did not simulate the smallest NBP response to CO2. Our results suggest that a change in the climate forcing did not have a large impact on the carbon cycle on long timescales. However, the inter-annual variability in precipitation drives the year-to-year variability in NBP. We analysed the impact of key modes of climate variability, including the El Nino Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on NBP. While the DGVMs agreed on sign of the response of NBP to El Nino and La Nina, and to positive and negative IOD events, the magnitude of inter-annual variability in NBP differed strongly between models. In addition, we identified differences in the timing of simulated phenology and fire dynamics associated with differences in simulated/prescribed vegetation composition and process representation. Model disagreement in simulated vegetation carbon, phenology and apparent carbon residence time, indicates the models have different types of vegetation cover across Australia (whether prescribed or emergent). Our study highlights the need to evaluate parameter assumptions and the key processes that drive vegetation dynamics, such as phenology, mortality and fire, in an Australian context to reduce uncertainty across models.

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“…The Amazon is not a uniform forest as trees can adapt to local climatic conditions, for instance through variable rooting strategies 24,25 . This can lead to different absolute forest mortality thresholds with respect to precipitation and drought conditions on local to regional scales.…”

Section: Forestmentioning

confidence: 99%

Network dynamics of drought-induced tipping cascades in the Amazon rainforest

Wunderling

Staal

Sakschewski

et al. 2020

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Tipping elements are nonlinear subsystems of the Earth system that can potentially abruptly and irreversibly shift if environmental change occurs. Among these tipping elements is the Amazon rainforest, which is threatened by anthropogenic activities and increasingly frequent droughts. Here, we assess how extreme deviations from climatological rainfall regimes may cause local forest-savanna transitions that cascade through the coupled forest-climate system. We develop a dynamical network model to uncover the role of atmospheric moisture recycling in such tipping cascades. We account for the heterogeneity in critical thresholds of the forest caused by adaptation to local climatic conditions. Our results reveal that, despite this adaptation, increased dry-season intensity may trigger tipping events particularly in the southeastern Amazon. Moisture recycling is responsible for one-fourth of the tipping events. If the rate of climate change exceeds the adaptive capacity of some parts of the forest, secondary effects through moisture recycling may exceed this capacity in other regions, increasing the overall risk of tipping across the Amazon rainforest.

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Variable tree rooting strategies improve tropical productivity and evapotranspiration in a dynamic global vegetation model

Cited by 12 publications

References 61 publications

CM2Mc-LPJmL v1.0: Biophysical coupling of a process-based dynamic vegetation model with managed land to a general circulation model

CM2Mc-LPJmL v1.0: Biophysical coupling of a process-based dynamic vegetation model with managed land to a general circulation model

Assessing the representation of the Australian carbon cycle in global vegetation models

Network dynamics of drought-induced tipping cascades in the Amazon rainforest

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