scholarly journals Gross primary productivity and water use efficiency is increasing in a high rainfall tropical savanna

2021 ◽  
Author(s):  
L.B. Hutley ◽  
J. Beringer ◽  
S. Fatichi ◽  
S.J. Schymanski ◽  
M. Northwood
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Primary Productivity ◽  
Gross Primary Productivity ◽  
Tropical Savanna ◽  
High Rainfall ◽  
Use Efficiency

scholarly journals Global gross primary productivity and water use efficiency changes under drought stress

2017 ◽  
Vol 12 (1) ◽  
pp. 014016 ◽  
Author(s):  
Zhen Yu ◽  
Jingxin Wang ◽  
Shirong Liu ◽  
James S Rentch ◽  
Pengsen Sun ◽  
...  
Keyword(s):  
Drought Stress ◽  
Water Use Efficiency ◽  
Water Use ◽  
Primary Productivity ◽  
Gross Primary Productivity ◽  
Use Efficiency

scholarly journals Tree–grass phenology information improves light use efficiency modelling of gross primary productivity for an Australian tropical savanna

2017 ◽  
Vol 14 (1) ◽  
pp. 111-129 ◽  
Author(s):  
Caitlin E. Moore ◽  
Jason Beringer ◽  
Bradley Evans ◽  
Lindsay B. Hutley ◽  
Nigel J. Tapper
Keyword(s):  
Primary Productivity ◽  
Vegetation Index ◽  
Temporal Dynamics ◽  
Seasonal Pattern ◽  
Gross Primary Productivity ◽  
Perennial Grasses ◽  
Light Use Efficiency ◽  
Tropical Savanna ◽  
Flux Tower ◽  
Use Efficiency

Abstract. The coexistence of trees and grasses in savanna ecosystems results in marked phenological dynamics that vary spatially and temporally with climate. Australian savannas comprise a complex variety of life forms and phenologies, from evergreen trees to annual/perennial grasses, producing a boom–bust seasonal pattern of productivity that follows the wet–dry seasonal rainfall cycle. As the climate changes into the 21st century, modification to rainfall and temperature regimes in savannas is highly likely. There is a need to link phenology cycles of different species with productivity to understand how the tree–grass relationship may shift in response to climate change. This study investigated the relationship between productivity and phenology for trees and grasses in an Australian tropical savanna. Productivity, estimated from overstory (tree) and understory (grass) eddy covariance flux tower estimates of gross primary productivity (GPP), was compared against 2 years of repeat time-lapse digital photography (phenocams). We explored the phenology–productivity relationship at the ecosystem scale using Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices and flux tower GPP. These data were obtained from the Howard Springs OzFlux/Fluxnet site (AU-How) in northern Australia. Two greenness indices were calculated from the phenocam images: the green chromatic coordinate (GCC) and excess green index (ExG). These indices captured the temporal dynamics of the understory (grass) and overstory (trees) phenology and were correlated well with tower GPP for understory (r2 =  0.65 to 0.72) but less so for the overstory (r2 =  0.14 to 0.23). The MODIS enhanced vegetation index (EVI) correlated well with GPP at the ecosystem scale (r2 =  0.70). Lastly, we used GCC and EVI to parameterise a light use efficiency (LUE) model and found it to improve the estimates of GPP for the overstory, understory and ecosystem. We conclude that phenology is an important parameter to consider in estimating GPP from LUE models in savannas and that phenocams can provide important insights into the phenological variability of trees and grasses.

scholarly journals Water‐use efficiency in a semi‐arid woodland with high rainfall variability

2019 ◽  
Vol 26 (2) ◽  
pp. 496-508 ◽  
Author(s):  
Tonantzin Tarin ◽  
Rachael H. Nolan ◽  
Belinda E. Medlyn ◽  
James Cleverly ◽  
Derek Eamus
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Rainfall Variability ◽  
High Rainfall ◽  
Use Efficiency ◽  
Semi Arid

Yield and water-use efficiency of wheat in a high-rainfall environment

2015 ◽  
Vol 66 (5) ◽  
pp. 419 ◽  
Author(s):  
Tina Botwright Acuña ◽  
Shaun Lisson ◽  
Peter Johnson ◽  
Geoff Dean
Keyword(s):  
Grain Yield ◽  
Water Use Efficiency ◽  
Water Use ◽  
Production Systems ◽  
Management Practice ◽  
Low Cost ◽  
Yield Potential ◽  
High Rainfall ◽  
Modelling Studies ◽  
Use Efficiency

Yield, water use and water-use efficiency (WUE) in the high-rainfall zone of Tasmania are highly variable because of environmental and agronomic constraints to grain production that limit yield potential. The expansion of irrigation infrastructure in Tasmanian production systems with access to low-cost, plentiful irrigation sources will also influence these components in some areas. This paper reports on desktop modelling studies that aimed to benchmark wheat WUE and to explore the sensitivity of yield, water use and WUE to changes in management practice in a high-rainfall environment. Here, WUE was defined as: grain yield/(evapotranspiration + drainage + runoff). The crop simulation model APSIM-Wheat was used to quantify key water balance elements and estimate ‘attainable’ and ‘potential’ WUE and grain yield for 27 wheat trials. The upper limit for WUE was ~30 kg/ha.mm in excess of 180 mm evaporation, which is 16% higher than previous estimates at this southerly latitude for wheat. Attainable WUE ranged from 58% to 100% of potential WUE and was limited by nitrogen supply and water loss through evaporation, drainage and runoff. Model scenarios showed that co-limitation of inputs of nitrogen and irrigation was an important driver of grain yield and WUE. The implications of this research on crop management and production in temperate, high-rainfall environments are discussed.

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