Abstract
Despite occupying one-third of the terrestrial surface and being highly sensitive to changes in
hydrology, agricultural ecosystems are under-represented in flux studies of water and carbon cycles across the
globe. Australia and New Zealand are no different, where only 16% of OzFlux sites are located in
predominately agricultural landscapes. Consequently, the primary objective of this study was to investigate
and compare the responses of agricultural fluxes of surface energy (sensible heat flux), water
(evapotranspiration, ET) and carbon (net ecosystem exchange, NEE) to eight meteorological and edaphic
drivers (net radiation, atmospheric specific humidity, vapour pressure deficit, net radiation, air temperature,
ground heat flux, soil temperature and soil water content). Three levels of management intensity were
considered, including minimal management (e.g. grazed rangelands); moderate management (e.g. dryland
agriculture and pasturelands); and irrigated or other intensively managed agricultural systems (e.g. dense
grazing in fertilised and irrigated paddocks). The responses of sensible heat flux, ET and NEE to meteorological
and edaphic drivers were investigated on a daily timescale using a novel statistical approach based upon
wavelet theory (wavelet-based canonical correlation analysis, wCCA). The approach consisted of (i) waveletbased principal components analysis (wPCA) to reduce the number of driving variables and to separately
identify dependencies amongst fluxes or drivers, followed by (ii) wavelet-based multiple linear regression
(wMLR) to infer relationships between drivers and fluxes. We found that irrigation of crops released NEE and
ET from dependence upon all meteorological and edaphic drivers, except in extreme conditions such as
inundation (rice) or high heat (almonds). By contrast, moderate intensity agriculture and pasture (along with
high intensity grazing in the energy-limited environments of NZ) were most closely coupled to these drivers,
especially vapour pressure deficit, available energy and air temperature. Low intensity grazed rangelands were
most strongly coupled to the large fluctuations in available energy and atmospheric humidity which
characterise the summer wet season across northern and much of central Australia. Results from this study
provide a consistent, detailed understanding of factors related to optimisation of water use and crop and forage
production across a variety of conditions.
hydrology, agricultural ecosystems are under-represented in flux studies of water and carbon cycles across the
globe. Australia and New Zealand are no different, where only 16% of OzFlux sites are located in
predominately agricultural landscapes. Consequently, the primary objective of this study was to investigate
and compare the responses of agricultural fluxes of surface energy (sensible heat flux), water
(evapotranspiration, ET) and carbon (net ecosystem exchange, NEE) to eight meteorological and edaphic
drivers (net radiation, atmospheric specific humidity, vapour pressure deficit, net radiation, air temperature,
ground heat flux, soil temperature and soil water content). Three levels of management intensity were
considered, including minimal management (e.g. grazed rangelands); moderate management (e.g. dryland
agriculture and pasturelands); and irrigated or other intensively managed agricultural systems (e.g. dense
grazing in fertilised and irrigated paddocks). The responses of sensible heat flux, ET and NEE to meteorological
and edaphic drivers were investigated on a daily timescale using a novel statistical approach based upon
wavelet theory (wavelet-based canonical correlation analysis, wCCA). The approach consisted of (i) waveletbased principal components analysis (wPCA) to reduce the number of driving variables and to separately
identify dependencies amongst fluxes or drivers, followed by (ii) wavelet-based multiple linear regression
(wMLR) to infer relationships between drivers and fluxes. We found that irrigation of crops released NEE and
ET from dependence upon all meteorological and edaphic drivers, except in extreme conditions such as
inundation (rice) or high heat (almonds). By contrast, moderate intensity agriculture and pasture (along with
high intensity grazing in the energy-limited environments of NZ) were most closely coupled to these drivers,
especially vapour pressure deficit, available energy and air temperature. Low intensity grazed rangelands were
most strongly coupled to the large fluctuations in available energy and atmospheric humidity which
characterise the summer wet season across northern and much of central Australia. Results from this study
provide a consistent, detailed understanding of factors related to optimisation of water use and crop and forage
production across a variety of conditions.
| Original language | English |
|---|---|
| Pages | 117-118 |
| Number of pages | 2 |
| Publication status | Published - Feb 2018 |
| Event | Joint 25th AMOS National Conference and 12th International Conference for Southern Hemisphere Meteorology and Oceanography: AMOS-ICSHMO 2018 - Univeristy of New South Wales, Sydney, Australia Duration: 05 Feb 2018 → 09 Feb 2018 https://www.amos-icshmo2018.com.au/ |
Conference
| Conference | Joint 25th AMOS National Conference and 12th International Conference for Southern Hemisphere Meteorology and Oceanography |
|---|---|
| Abbreviated title | Translating our science into practical outcomes for the benefit of society |
| Country/Territory | Australia |
| City | Sydney |
| Period | 05/02/18 → 09/02/18 |
| Internet address |