Houston, I. W.

Orr, David M.

Phelps, David G.

Rolfe, L.

Silcock, J.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Decline in Land Condition in Astrebla Grassland during Prolonged Drought in Australia David G. Phelps Department of Primary Industries and Fisheries, Australia David M. Orr Department of Primary Industries and Fisheries, Australia I. W. Houston Department of Primary Industries and Fisheries, Australia L. Rolfe Department of Primary Industries and Fisheries, Australia J. Silcock Department of Primary Industries and Fisheries, Australia Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/4-1/30 The 21st International Grassland Congress / 8th International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 瞯 ]588　 瞯 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　Grasslands/Rangelands Resources and Ecology ——— Indicators for Sustainable Use and Conservation of Grasslands/Rangelands ResourcesDecline in land condition in Astrebla grassland during prolonged drought in AustraliaD . G . Phelps , D . M . Orr , I . W . Houston , L . Rol f e and J . Silcock . Dep t . Primary Industries and Fisheries , PO Box519 , Longreach , Queensland 4730 , A ustralia . E‐mail :dav id .phelps＠ dp i .qld .gov .auKey words : A strebla grassland , pasture condition , sustainable use , monitoringIntroduction Mitchell grasses ( A strebla spp .) are arid tropical tussock grasses endemic to Australia which become dormantduring drought to escape desiccation and death . Drought is a regular feature of these grasslands . The Mitchell grasslands ofQueensland , Australia , cover ３３ ,８００ ,０００ ha , support １５％ of the cattle herd , more than ４０％ of the Merino sheep flock andprovide employment to ２５００‐３０００ people . The short‐term productivity of these grasslands declined as pasture yield was reducedin association with prolonged drought from ２００１ to the present . Many Mitchell grass tussocks failed to respond to reasonablerains during the ２００３‐０４ summer and this created concerns about extensive tussock death and hence reductions in long‐termproductivity and land condition . This paper presents preliminary results from surveys undertaken to quantify the extent oftussock death and resultant reduction in land condition .Materials and methods A rapid appraisal technique ( Hassett et al . ２０００ ) was modified to assess pasture condition in westernQueensland during winter ２００５ and again in the same area in ２００６ . Nearly ６０００ observations of live and dead A strebla tussockdensity ( number /m２ ) and response ( grow th relative to the average) together with pasture species abundance were used toclassify １ ha sized roadside areas into A ( good) , B ( moderate) , C ( poor) or D ( degraded) condition classes .Results and discussion Less than １０％ of observations of condition were assessed as being in A ( good) condition in ２００５ and２００６ ( Figure １ ) . In ２００５ , ６０％ of observations were in B condition but this declined to ４１％ in ２００６ in association withcontinued drought and in conjunction with the frequency of C condition observations increasing from ３２％ to ５３％ . D conditionwas less than ５％ in each year . This decline in overall condition was associated with a reduction in live A strebla spp density andan increase in undesirable forbs and annual grass species . Orr and Phelps ( this volume) provided evidence that plant speciesdiversity analyses would strengthen the assessment of land condition in A strebla grassland . Historically , land condition in thesegrasslands has improved through seedling recruitment associated with improving summer rainfall . However , predictions ofgreater rainfall variability and increased incidence of drought associated with climate change may restrict future recovery .Figure 1 The f requency ( ％ o f total observations) o f A ( good) , B (moderate) , C ( poor) and D (degraded) condition classesin Queensland摧s M itchell grasslands in 2005 and 2006 .Conclusions A strebla spp . are generally drought tolerant , but the severe drought conditions of ２００１‐２００６ resulted in tussockdeath and hence reduced land condition . Recovery may be limited under climate change scenarios of increasing droughts .ReferencesHassett , R .C . , Wood , H .L . , Carter , J .O . and Danaher , T .J . ( ２０００ ) . A field method for statewide ground‐truthing of aspatial pasture grow th model . A ustralian Journal o f Ex perimental A griculture ４０ : １０６９‐７９ .Orr , D . M . and Phelps , D . G . ( ２００８ ) . Plant species diversity as an indicator of sustainable use of A strebla grasslands inAustralia .~ 70 -U) 60 s::: 0 +3 50 ra C: Cl) 40 U) .c 0 30 -0 ~ 20 s::: Cl) 10 ::::s C" Cl) 0 ... LL 60 A B C Condition class D ■ 2005 D2006 

Decline in Land Condition in \u3cem\u3eAstrebla\u3c/em\u3e Grassland during Prolonged Drought in Australia

https://uknowledge.uky.edu/cgi/viewcontent.cgi?article=2690&amp;context=igc

Decline in Land Condition in \u3cem\u3eAstrebla\u3c/em\u3e Grassland during Prolonged Drought in Australia

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