Seasonal, interannual and decadal drivers of tree and grass productivity in an Australian tropical savanna

Moore, Caitlin E.; Beringer, Jason; Donohue, Randall J.; Evans, Bradley J.; Exbrayat, Jean‐François; Hutley, Lindsay B.; Tapper, Nigel

doi:10.1111/gcb.14072

Cited by 31 publications

(19 citation statements)

References 107 publications

(227 reference statements)

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“…In this study, a marked inter-annual variation of NPP was observed in the savanna ecosystem ( Fig. 3) consistent with the findings from other savannas (Moore et al, 2018a;Räsänen et al, 2017) and biomes (Knapp and Smith, 2001;Yang et al, 2011a). These results suggest that carbon accumulation fluctuates with annual precipitation.…”

Section: Inter-annual Variation Of Nppsupporting

confidence: 91%

Response of net primary productivity to precipitation exclusion in a savanna ecosystem

Jin

Liu

et al. 2018

Forest Ecology and Management

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Declines in precipitation are expected to affect plant performance and ecosystem carbon uptake. The response of ecosystem productivity to declines in precipitation and potential underlying mechanisms have been well studied in many biomes; however, little is known about the role of declines in precipitation and the involved mechanisms in savanna ecosystems. In a 4-year field precipitation manipulation experiment, we simulated four levels of precipitation exclusion (control, 30%, 50% and 70%) to assess the effects of declines in precipitation on net primary productivity (NPP) in a savanna ecosystem in southwestern China. NPP was strongly correlated with soil water content during the experimental period. Precipitation exclusion significantly decreased the NPP of the entire vegetation including trees, shrubs, perennials and litterfall but significantly increased the NPP of annuals. Our results suggested that precipitation exclusion can reduce the productivity of savannas and that plant functional types differ in sensitivity to precipitation exclusion. These findings imply that future declines in precipitation in savanna regions may negatively impact carbon accumulation and may induce shifts in plant functional types to buffer the effects of declines in precipitation on productivity and stabilize ecosystem function in savannas.

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Section: Inter-annual Variation Of Nppsupporting

confidence: 91%

Response of net primary productivity to precipitation exclusion in a savanna ecosystem

Jin

Liu

et al. 2018

Forest Ecology and Management

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“…The Howard River catchment (~140 km 2 ) is located in the wet–dry tropics of the Northern Territory, Australia. The low‐relief landscape supports savanna woodlands (~35% of the catchment area) as well as permanent wetlands and seasonally inundated floodplains (~23%; Hutley, Beringer, Isaac, Hacker, & Cernusak, 2011; Moore et al., 2018). A zone of peri‐urban, rural development occupies the remaining area (~42%) and is dominated by relatively large land parcels (2–5 ha) covered by native savanna vegetation.…”

Section: Methodsmentioning

confidence: 99%

Net landscape carbon balance of a tropical savanna: Relative importance of fire and aquatic export in offsetting terrestrial production

Duvert

Hutley

Beringer

et al. 2020

Global Change Biology

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The magnitude of the terrestrial carbon (C) sink may be overestimated globally due to the difficulty of accounting for all C losses across heterogeneous landscapes. More complete assessments of net landscape C balances (NLCB) are needed that integrate both emissions by fire and transfer to aquatic systems, two key loss pathways of terrestrial C. These pathways can be particularly significant in the wet–dry tropics, where fire plays a fundamental part in ecosystems and where intense rainfall and seasonal flooding can result in considerable aquatic C export (ΣFaq). Here, we determined the NLCB of a lowland catchment (~140 km2) in tropical Australia over 2 years by evaluating net terrestrial productivity (NEP), fire‐related C emissions and ΣFaq (comprising both downstream transport and gaseous evasion) for the two main landscape components, that is, savanna woodland and seasonal wetlands. We found that the catchment was a large C sink (NLCB 334 Mg C km−2 year−1), and that savanna and wetland areas contributed 84% and 16% to this sink, respectively. Annually, fire emissions (−56 Mg C km−2 year−1) and ΣFaq (−28 Mg C km−2 year−1) reduced NEP by 13% and 7%, respectively. Savanna burning shifted the catchment to a net C source for several months during the dry season, while ΣFaq significantly offset NEP during the wet season, with a disproportionate contribution by single major monsoonal events—up to 39% of annual ΣFaq was exported in one event. We hypothesize that wetter and hotter conditions in the wet–dry tropics in the future will increase ΣFaq and fire emissions, potentially further reducing the current C sink in the region. More long‐term studies are needed to upscale this first NLCB estimate to less productive, yet hydrologically dynamic regions of the wet–dry tropics where our result indicating a significant C sink may not hold.

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“…However, the heterogeneous relationships between climate variability induced by ENSO and terrestrial ecosystem productivity, especially regarding the extent, amplitude, and underlying mechanisms, are still not well understood (Gonsamo et al, ; Wang et al, ; Zhu et al, ). Previous studies have been largely conducted at regional (Dannenberg et al, ; Moore et al, ; Parazoo et al, ) or continental scales (Baker et al, ; Ciais et al, ; Zhang et al, ). Global‐scale studies were mainly based on the short MODIS record (Bastos et al, ; Luo et al, ), only normalized difference vegetation index rather than estimated GPP (Gonsamo et al, ; Kogan & Guo, ), or solely based on modeled results with no remote sensing inputs (Ahlström et al, ; Zhu et al, ).…”

Section: Introductionmentioning

confidence: 99%

El Niño‐Southern Oscillation‐Induced Variability of Terrestrial Gross Primary Production During the Satellite Era

et al. 2019

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Terrestrial gross primary production (GPP) is the largest carbon flux entering the biosphere from the atmosphere, which serves as a key driver of global carbon cycle and provides essential matter and energy for life on land. However, terrestrial GPP variability is still poorly understood and difficult to predict, especially at the annual scale. As a major internal climate oscillation, El Niño-Southern Oscillation (ENSO) influences global climate patterns and thus may strongly alter interannual terrestrial GPP variation. Using a remote sensing-driven ecosystem model with long-term satellite and climate data, we comprehensively examined the impacts of ENSO on global GPP dynamics from 1982 to 2016, focusing on lag effects of ENSO and their spatial heterogeneity. We found a clear seasonal lag effect of previous-year ENSO indices on current-year global GPP variability. The composite Oceanic Niño Index in the previous-year's August-October showed the strongest correlation with global annual GPP (R = −0.51, p < 0.01). Spatially, 20.1% and 11.7% of vegetated land area showed significant negative and positive correlations with the ENSO cycle, respectively. ENSO effects on annual GPP exhibited diverse seasonal evolutions, and the timings of peak ENSO influences were heterogeneous across the globe. Annual GPP from TRENDY land surface model ensemble did not capture the major lag effects of ENSO identified in the satellite-derived GPP and top-down-based land sink. Despite the complexity of the climate system, our efforts linking ENSO with global GPP dynamics provide a simple framework to understand and project climatic influences on the terrestrial carbon cycle.

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Seasonal, interannual and decadal drivers of tree and grass productivity in an Australian tropical savanna

Cited by 31 publications

References 107 publications

Response of net primary productivity to precipitation exclusion in a savanna ecosystem

Response of net primary productivity to precipitation exclusion in a savanna ecosystem

Net landscape carbon balance of a tropical savanna: Relative importance of fire and aquatic export in offsetting terrestrial production

El Niño‐Southern Oscillation‐Induced Variability of Terrestrial Gross Primary Production During the Satellite Era

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