Climate change promotes transitions to tall evergreen vegetation in tropical Asia

Scheiter, Simon; Kumar, Dushyant; Corlett, Richard T.; Gaillard, Camille; Langan, Liam; Lapuz, R. Sedricke; Martens, Carola; Pfeiffer, Mirjam; Tomlinson, Kyle W.

doi:10.1111/gcb.15217

Cited by 45 publications

(34 citation statements)

References 92 publications

(209 reference statements)

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“…A study by Chaturvedi et al (2011) using the IBIS model also predicted transitions toward evergreen forest. Woody encroachment in many ecosystems is attributed to rising CO 2 , and this is supported by studies based on both field observations (e.g., FACE experiments) and satellite data (Brienen et al, 2015;Fischlin et al, 2007;Piao et al, 2006;Schimel et al, 2015;Archer et al, 2017;Stevens et al, 2017). The aDGVM2 also supports these findings, i.e., increasing canopy cover and woody biomass under the eCO 2 condition, and agrees with the reported greening trend in South Asia during the last three decades (Wang et al, 2017).…”

Section: Impact Of Climate Change and Elevated Co 2 On Biomes And Biomasssupporting

confidence: 80%

Climate change and elevated CO<sub>2</sub> favor forest over savanna under different future scenarios in South Asia

et al. 2021

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Abstract. South Asian vegetation provides essential ecosystem services to the 1.7 billion inhabitants living in the region. However, biodiversity and ecosystem services are threatened by climate and land-use change. Understanding and assessing how ecosystems respond to simultaneous increases in atmospheric CO2 and future climate change is of vital importance to avoid undesired ecosystem change. Failed reaction to increasing CO2 and climate change will likely have severe consequences for biodiversity and humankind. Here, we used the adaptive dynamic global vegetation model version 2 (aDGVM2) to simulate vegetation dynamics in South Asia under RCP4.5 and RCP8.5, and we explored how the presence or absence of CO2 fertilization influences vegetation responses to climate change. Simulated vegetation under both representative concentration pathways (RCPs) without CO2 fertilization effects showed a decrease in tree dominance and biomass, whereas simulations with CO2 fertilization showed an increase in biomass, canopy cover, and tree height and a decrease in biome-specific evapotranspiration by the end of the 21st century. The predicted changes in aboveground biomass and canopy cover triggered transition towards tree-dominated biomes. We found that savanna regions are at high risk of woody encroachment and transitioning into forest. We also found transitions of deciduous forest to evergreen forest in the mountain regions. Vegetation types using C3 photosynthetic pathway were not saturated at current CO2 concentrations, and the model simulated a strong CO2 fertilization effect with the rising CO2. Hence, vegetation in the region has the potential to remain a carbon sink. Projections showed that the bioclimatic envelopes of biomes need adjustments to account for shifts caused by climate change and elevated CO2. The results of our study help to understand the regional climate–vegetation interactions and can support the development of regional strategies to preserve ecosystem services and biodiversity under elevated CO2 and climate change.

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Section: Impact Of Climate Change and Elevated Co 2 On Biomes And Biomasssupporting

confidence: 80%

Climate change and elevated CO<sub>2</sub> favor forest over savanna under different future scenarios in South Asia

et al. 2021

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“…GCM data or interpolated data such as ISIMIP instead of RCM data), different DGVMs (Doherty et al., 2010; Gonzalez et al., 2010) and that precipitation changes until 2100 were not accounted for (Higgins & Scheiter, 2012). In addition, utilization of different biome classification schemes can influence if and where vegetation changes are simulated (Scheiter et al., 2020) and create mismatches between different vegetation models that impede comparison of simulated biomes. Nonetheless, the different studies agree on a potential increase in the area covered by woody biomes under future climatic conditions.…”

Section: Discussionmentioning

confidence: 99%

“…Fire has been shown to influence and delay projected biome changes and can delay transitions to woody biomes and thus stabilization of ecosystem states after changes in environmental drivers stabilized (e.g. [CO 2 ], Scheiter et al., 2020). Even when ecophysiological processes have already saturated (e.g.…”

Section: Discussionmentioning

confidence: 99%

Large uncertainties in future biome changes in Africa call for flexible climate adaptation strategies

Martens

Hickler

Davis-Reddy

et al. 2020

Global Change Biology

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Anthropogenic climate change is expected to impact ecosystem structure, biodiversity and ecosystem services in Africa profoundly. We used the adaptive Dynamic Global Vegetation Model (aDGVM), which was originally developed and tested for Africa, to quantify sources of uncertainties in simulated African potential natural vegetation towards the end of the 21st century. We forced the aDGVM with regionally downscaled high‐resolution climate scenarios based on an ensemble of six general circulation models (GCMs) under two representative concentration pathways (RCPs 4.5 and 8.5). Our study assessed the direct effects of climate change and elevated CO2 on vegetation change and its plant‐physiological drivers. Total increase in carbon in aboveground biomass in Africa until the end of the century was between 18% to 43% (RCP4.5) and 37% to 61% (RCP8.5) and was associated with woody encroachment into grasslands and increased woody cover in savannas. When direct effects of CO2 on plants were omitted, woody encroachment was muted and carbon in aboveground vegetation changed between –8 to 11% (RCP 4.5) and –22 to –6% (RCP8.5). Simulated biome changes lacked consistent large‐scale geographical patterns of change across scenarios. In Ethiopia and the Sahara/Sahel transition zone, the biome changes forecast by the aDGVM were consistent across GCMs and RCPs. Direct effects from elevated CO2 were associated with substantial increases in water use efficiency, primarily driven by photosynthesis enhancement, which may relieve soil moisture limitations to plant productivity. At the ecosystem level, interactions between fire and woody plant demography further promoted woody encroachment. We conclude that substantial future biome changes due to climate and CO2 changes are likely across Africa. Because of the large uncertainties in future projections, adaptation strategies must be highly flexible. Focused research on CO2 effects, and improved model representations of these effects will be necessary to reduce these uncertainties.

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“…Despite numerous past studies such as those of Boit et al (2016), Clark et al (2001), Erfanian et al (2016), Harrison and Prentice (2003), Levy et al (2004), Liu et al (2015), Ostendorf et al(2001), andHiggins (2009), focusing on the global change impact on vegetation in the tropical region, South and Southeast Asia remain poorly explored in such studies (Scheiter, Kumar, et al, 2020).…”

Section: Climate-vegetation Interaction In Tropical Asia: Reviewmentioning

confidence: 99%

“…I have used aDGVM2 (Scheiter et al, 2013;Langan et al, 2017;Gaillard et al, 2018) for studies conducted for this thesis. In Chapter 3 I have described in detail the changes made in aDGVM2 for South Asia (Kumar et al, 2020b) to assess the impact of climate change on vegetation distribution (Chapter 3; Kumar et al, 2020b), structure, phenology (Chapter 4, Scheiter, Kumar et al, 2020) and threatened biomes (Chapter 5; Kumar et al, 2020a).…”

Section: The Adgvm2mentioning

confidence: 99%

Modelling vegetation-climate interactions in South and Southeast Asia using a trait-based dynamic vegetation model

Kumar¹

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Climate controls the broad-scale distribution of vegetation and change in climate will alter the vegetation distribution, biome boundaries, biodiversity, phenology and supply of ecosystem services. A better understanding of the consequences of climate change is required, particularly in under-investigated regions such as tropical Asia, i.e., South and South-east Asia, which is a host to 7 of the 36 global biodiversity hotspots. Conservation strategies would also require an in-depth understanding of the response of vegetation to climate change. Therefore, the main objective of this thesis was to investigate the impact of climate change and rising CO2 vegetation in tropical Asia. Dynamic global vegetation model (DGVMs) are the well-known tools to investigate vegetation-climate interactions and climate change impacts on ecosystems. In this thesis, I used a complex trait-based DGVM called adaptive dynamic vegetation model version 2 (aDGVM2). In Chapter 1, I presented a brief background of the phytogeography and discussed the exiting knowledge gap on vegetation-climate interactions in the region. One major disadvantage for available DGVMs studies for the tropical Asia is that most of them have used fixed plant functional types (PFTs) and do not explicitly represent the distinct varieties of vegetation type of the region such as Asian savannas. In Chapter 2, I discussed at great length to improve DGVMs for South Asia and discussed ways to include them in the model for better representation of region vegetation-climate interaction. I upgraded the current version of aDGVM2 and added a new vegetation type i.e., C3 grasses, and modified the sub-module to simulate photosynthesis for each individual plants to aDGVM2. In chapter 3, I used this updated version of aDGVM2 to simulate the current and future vegetation distribution in South Asia under RCP4.5 and RCP8.5 (RCP: representative concentration pathway). The model predicted an increase in biomass, canopy cover, and tree height under the presence of CO2 fertilization, which triggered transitions towards tree-dominated biomes by the end of the 21st century under both RCPs. I found that vegetation along the Western Ghats and the Himalayas are more susceptible to change due to climate change and open biomes such as grassland and savanna are prone to woody encroachment. In Chapter 4, the study domain was extended to include South-east Asia to verify if the model configuration used in Chapter 3 can also simulate vegetation patterns in tropical Asia. The aDGVM2 simulations showed a robust trend of increasing vegetation biomass and transitions from small deciduous vegetation to taller evergreen vegetation across most of tropical Asia. Shifts in plant phenology also affect ecosystem carbon cycles and ecosystem feedback to climate, yet the quantification of such impacts remains challenging. The study showed increased biomass due to CO2 fertilization, indicates that the region can remain a carbon sink given there is no other resource limitation. However, nutrient limitations on CO2 fertilization effects were not included in the study, and carbon sink potential has to be seen with caution. In Chapter 5, I focused on Asian savannas, which have been mismanaged since the colonial era due to misinterpretation as a degraded forest. I proposed a biome classification scheme to distinguish between degraded forest or woodland and savanna based on the abundance of grass biomass and canopy cover. I found that considering vegetation systems as woodland or degraded forest could easily be mistaken as a potential for forest restoration within a tree-centric perspective. This would put approximately 35% to 40% of a unique savanna biome at risk. Although projected woody encroachments may imply a transition toward the forest that benefits climate mitigation. This raises potential conflicts of interest between biodiversity conservation in open ecosystems, i.e., savanna and active afforestation, to enhance carbon sequestration. Proper management strategies should be taken into account to maintain a balance for both objective In conclusion, the model predicted that vegetation in South and South-East Asia would significantly shift towards tree-dominated biomes due to CO2-induced fertilization of C3-photosynthesis. The simulation under fixed CO2 and rising CO2 scenarios clearly showed that rising level of atmospheric CO2 is responsible for most of the predicted change in biome properties. This study is an important step towards understanding ecosystems of South and Southeast Asia, specifically savannas. The aDGVM2 can serve as tools to inform decision making for climate adaptation and mitigation for savanna. The thesis, thus contributes to our ability to improve conservation strategies to mitigate the consequences of climate change.

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Climate change promotes transitions to tall evergreen vegetation in tropical Asia

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 45 publications

References 92 publications

Climate change and elevated CO<sub>2</sub> favor forest over savanna under different future scenarios in South Asia

Climate change and elevated CO<sub>2</sub> favor forest over savanna under different future scenarios in South Asia

Large uncertainties in future biome changes in Africa call for flexible climate adaptation strategies

Modelling vegetation-climate interactions in South and Southeast Asia using a trait-based dynamic vegetation model

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Climate change promotes transitions to tall evergreen vegetation in tropical Asia

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 45 publications

References 92 publications

Climate change and elevated CO&lt;sub&gt;2&lt;/sub&gt; favor forest over savanna under different future scenarios in South Asia

Climate change and elevated CO&lt;sub&gt;2&lt;/sub&gt; favor forest over savanna under different future scenarios in South Asia

Large uncertainties in future biome changes in Africa call for flexible climate adaptation strategies

Modelling vegetation-climate interactions in South and Southeast Asia using a trait-based dynamic vegetation model

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Product

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Climate change and elevated CO<sub>2</sub> favor forest over savanna under different future scenarios in South Asia

Climate change and elevated CO<sub>2</sub> favor forest over savanna under different future scenarios in South Asia