Remotely sensed agricultural grassland productivity responses to land use and hydro-climatic drivers under extreme drought and rainfall

Kath, Jarrod and Le Brocque, Andrew and Reardon-Smith, Kathryn and Apan, Armando (2019) Remotely sensed agricultural grassland productivity responses to land use and hydro-climatic drivers under extreme drought and rainfall. Agricultural and Forest Meteorology, 268. pp. 11-22. ISSN 0168-1923

Abstract

Climate change is expected to increase the frequency and intensity of drought globally with potentially significant consequences for grasslands. We examined grassland responses to a long-term drought on the Darling Downs, eastern Australia, using the Enhanced Vegetation Index (EVI), a remotely sensed measure of primary productivity. This extreme drought period had rainfall deficits comparable to the hottest and driest projected climate change scenarios for 2030 and was followed by extreme rainfall. This juxtaposition allowed investigation of grassland dynamics (decline and recovery) under extreme climatic variability. Our aim was to determine whether factors associated with grassland decline during extreme drought are the same as those that drive recovery post drought. There is limited knowledge about whether the determinants of grassland decline and recovery are consistent, but this information is important for understanding how best to reduce grassland decline, without inhibiting recovery. We calculated EVI (Enhanced Vegetation Index) trends at 2549 grassland sites situated in an agricultural landscape and used boosted regression trees to model these against multiple hydroclimatic and land use factors. As anticipated, hydro-climatic variables were key drivers of EVI trends in both the drought and wet phases, with higher soil moisture corresponding to less decline in the drought phase and enhanced recovery in the wet phase; however, land use and plant trait variables were also important predictors of EVI trends. Higher proportions of dryland agriculture in the local landscape, high C3:C4 ratios and lower proportions of woody vegetation in the local landscape were associated with negative EVI trends (i.e. greater decline) during drought, but had inverse or negligible effects during the post drought recovery phase. Our results suggest that mitigating decline and fostering grassland recovery following drought requires considering multiple hydro-climatic, land use and plant trait drivers and how their importance changes under drought and wet
phases.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version, in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 30 Jan 2019 04:08
Last Modified: 30 Jan 2019 04:13
Uncontrolled Keywords: extreme weather; millennium drought; resilience; pasture; remote sensing
Fields of Research : 05 Environmental Sciences > 0501 Ecological Applications > 050101 Ecological Impacts of Climate Change
07 Agricultural and Veterinary Sciences > 0703 Crop and Pasture Production > 070301 Agro-ecosystem Functionand Prediction
Socio-Economic Objective: D Environment > 96 Environment > 9605 Ecosystem Assessment and Management > 960510 Ecosystem Assessment and Management of Sparseland, Permanent Grassland and Arid Zone Environments
Identification Number or DOI: 10.1016/j.agrformet.2019.01.007
URI: http://eprints.usq.edu.au/id/eprint/35374

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