The Impact of Cattle Introduction on Arid Sheeplands
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7^ ro -?'5 TI{E IMPACT OF CATTI.,E TNTRODUCT]ON CN ARIÐ SHEEPLANDS by Timothy James Fatchen, B. Sc. (tlons . ) , Department of Botany, Univer"sity of Adelaide Thesis submitted fon the degree of Doctor of PhiJ-osophy Uiriversity of Ade-laide Febr"uary, 1975, SUMMARY This thesis investigates the effect on vegetation of recent cattle introduction to the ar"id sheeplands of South Austnalia. While the effects of sheep on these nangelands are wel-l documented, those of cattl-e a:re not known. The study thus nepnesents the initial examination of the cattle impact. The main aim wä.s to dete:rmine the extent to which catt-le nodified the existing sheep-induced vegetation pattenn. For the sho::t tenm, thíswas achieved by a two-yealr companison of vege- tations, separatei-y grazed by cattl-e and sheep, on a rep::esentative station. The companison was begun soon after the first introduct- ion of cattle. Stocking effects were isolated fi:om background vegetation pattern by appJ-ication of the piospher"e concept. Detection of pattenn in density and estimated biomass of major" pastu:re species was emphasized, with negression and Pnincipal Components analyses being employed. The ::esults were compli- cated by the exceptionalJ-y heavy and extended rains which fel-l- duning much of the obse::vation period. The nesul-ts norretheless demonstrated that shor"t-tenm stocking effects diffened fon sheep and cattle, but became obscured in periods of pastune g::owth. No basis was found for the pnediction of the long-term trend fnom the shor.t-term obsenvations. Less intensive comparisons, with both sheep and vingin sites, wer"e used to infen long-term changes in vegetation nesulting fnom cattle stocking. Stocking effects were iso.l-ated by exam- ination of mapped nelative abundances of specíes, following a caneful matching of site landscapes. The nesufts indicated changes simil-a-n to those neponted to occun with sheep stocking. The causes of vegetation pattenn and change hlelle considened, but the t?eseanch needed to aflot^¡ definitive statement of these causes was beyond the scope of the study. Reponts on possible factons such as stock diet and behavioun are' therefone, re-' viewed in detail. on the basis of these reponts, it was con- cluded that the rnajonity of the stocking effects obsenved did not nesult fnom the pr:eferential selection of species by the grazing animal. This is contnany to common assumption. Mechanical- distr::rbance of soil and plants ín the cou::se of gnazing was pnoposed as the majon detenminant of stock-induced vegetation change. This hypothesis r.Ias pantially tested, but - with equivocal nesuft. The implications of the outcome of this study ar"e discussed, as negands both the future of the south Aust:ralían sheeplands and the requi:rements fo:r future study. DECLARATTON This thesis contains no matenial- which has been accepted for the award. of any other degnee on diploma in any Univensity. To the best of my knowledge and belief this thesis contains no matenial pneviously published on w::itten by anothen penson, except whene due nefe::ence is rnade in the text. T ,J Fatchen ACKNOtr'ILEDGEMENTS I wish to thank Dn R.T. Lange fon his suppont during this study. Mn Andrew Bnown and Mr D.H. Cna¡e also gave much assis- tance through both advice and introductions at the outset. 0f the many pastor"alists who tol-erated my pnesence and questions, I eepecially wish to thank Mn Hugh Macfachlan fon his co-oper- ation :reganding the observations on Mt Victon station, and his staff, Mn and Mns Fned Sleep, who kept a weather eye on mel M:r l'lalten Fnench and sons of Pennatty station, and Mn Tom All-Íson a¡d Mn Jack All-íson of Roxby Downs station fon th-eir help in other fiel-d studies; and Leste:: Lond, Ga:rnham Skipper"' and Dudley Ful-Ien. Al-1 the pastonalists I met showed a wel-come intenest and a great hospitality, and gave me no littl-e education in the intnicacies of management in the pastoral countny. My thanks must also go to Dr- Geor"ge Ganf and Dz' Susan Ba¡ken who cnitical-ly read pant of tb-e manuscript; to Daphne McEwen who typed the text; and to Debonah, Fatchen, who with patience and pensevenance not only withstood my plreoccupations but also dnafted the final diagnams. The research was supported by a Commonwealth Postgnaduate Student Awand and funds fnom the Sandlands Bequest to the Uni- vensity of AdelaiCe. NOTE ON PLANT IDENTIFTCATION AND NOMENCLATURE Voucher: specimens of all species named in this thesis have been ì-odged at the State Her^ba::ium of South Australia, Adelaide (AD) and at the Botany Depantment, Univensity of Adelaide. Most identifications vlene verified by Dn Hj. Eichl-en and staff at the Henbanium. The remainden, involving vegetative specimens on1y, were ver-ified by comparison with AD collections. All names are those given by Black (fg+e-t9S7), as amended by Eichler (1965). The appnopniate authon citations ane given in these wonks. CONTENTS SUMMARY DECLARATION ACIO{0T/¡LEDGEMENTS NOTE ON PLANT IDENTIFICATION AND NO}ÍENCLATURE Chapten Page t INTRODUCTION t t-T CAUSE AND PURPOSE OF RESEARCH t T_2 PLAN OF RXSEARCH I 1-3 HISTORY AND ANMINISTRÂTION OF RANGELANDS TN SOUTH AUSTR,ALIA 4 1- 31 Intz,oduction 4 7-32 Hístozg 4 1-33 AdmLnistration 6 1-34 Ihe r.ecent íntxoduction of eattLe on æíd z'øtgeLands I 1-4 DEMARCAT]ON AND CLIMATE OF SOUTH AUSTRALIAN RANGELANDS 10 1-41 Demarcation 10 7-42 CLimate 10 1-5 VEGETATION OF SOUTH AUSTRALIAN RANGELANDS t2 t-sr Main diuisíons t2 7-52 Trend ín grazed nøtgeLand uegetat'ion 13 1-53 Regeneration of chenopod shrubLøtds foLLouing 16 ouez'grazing 1-54 Contrasted AnerLcan øtd AustraLíæt sítuations 16 1_6 ASPECTS OF SHEEP AND CATTLE PERFORMANCE ON ARID RANGELANDS !7 1-61 fntroduetion t7 t-62 Aspects of physíology 18 1-63 Dietæy seleetion 20 1-64 Aspects of z,anging beharsíoz.tt 25 7-7 THE PIOSPHERX: STOCK-]NDUCED VEGETATION PATTERN 26 t-77 The concept of the piosphere 26 7-72 Tlte fsyn of pLont/distøtce reLationships in the piosphere 29 1-B THE CAUSAT'ION OF PATTERN AND TREND 31 Chapter Page 2 CATTLE ON SOUTH AUSTRALIAN SHEEPLANDS 34 2_T VEGETATIONS GRAZED BY CATTLE I^I]THIN THE DOG FENCE 34 2_2 MANAGEI'ENT SYSTEMS 35 2-21 Møtagement north qnd south of the dog føtce 35 2-22 Pz,obLems in ehartgíng to eattLe from sheep 39 2-23 CattLe husbandry on former sheepLm.d 4t 2_3 PASTORALISTSI OPINIONS ON THE EFFECT OF CATTLE +2 2_4 ECONOMICS OF CATTLE INTRODUCTION 43 3 COMPARISON OF SHEEP AND CATTLE PIOSPHERES OVER A SHORT TERM: METFIODS 46 3_1 TNTRODUCTTON 46 3-2 APPROACH TO TrrE MAJOR STUDY (SAUplrne BY QUADRATS) 50 3_3 PASTURE POPULATIONS STUDIED AND PARAMETERS ESTIMATED 52 3-31 Mqjor species 52 3-32 Minor speeies 59 3_4 SAMPLING SYSTEM 62 3-41 SatnpLing for catbLe/sheep cornparison 62 3-42 SønpLíng for background dynønics 64 3-+3 Quaárat size and shape 66 3-5 ANALYSTS I'ÍETHODS 67 3-51 Influence øtaLysís 67 3-52 CozveLation øtd regression 69 3-53 PrineípaL Conrponents AnaLysis 7t 3_6 M]NOR STUDY (SEUPITNE BY STEREOPHOTOPOINTS) 73 3-61 GeneraL approacLt 73 3-62 Photogtaphíc methods 73 3-63 PLant popuLatiorts studied øtd paxønetez's estimated 75 3-64 SarnpLing system 76 3-65 AnaLysis nethod 17 Chapten Page 3_7 RAINFALL MONITORTNG 78 3_8 STOCK MONITORING 78 3-81 Stoeking LeueLs 78 3-82 Mouements 79 4 COMPARISON OF SHEEP AND CATTLE P]OSPHERES OVER A SHORT TERM: RESULTS 80' 4-t RAINFALL OVER THE STUDY PER]OD 80 +_2 STOCK MONITORING 81 4-2t Stoekíng v,ates 81 +-22 Stock mouements 83 4-3 ABUNDANCE AND DYNAMICS OF MAJOR PASTURE SPEC]ES 83 4-31 In the ahsqnee of grazing 83 4-32 Grazed cornpæed uith wtgrazed 86 4-33 The effect of the 1973-1-974 rains 87 4-34 CorreLatíons üithin qnd betueen speeies B7 4_4 RËGRESSION ANALYSES: MAJOR SPECTES 89 4-41 Intz,oductíon 89 4-42 Lineæ and non-Linear negz.essions of totaL bíons,ss on distutce 91- 4-43 Regnessíon øtaLyses foz'Stipa nitida 94 4-44 Regresston øtlaLyses fon Enneapogon spp. 97 4-45 Regz,ession øtaLgses foz' Arístida contonta 103 4.46 Regression anaLgses foz'Kochia astnotnicha aduLts 108 +-47 Regressíoù artaLyses foz' Kochia asfi:otricha iuueniLes !12 4-tr'B Regression anaLyses foz' Kochia pyramidata 113 4-49 Ge-nexal discussion on vegression øtalyses 115 4-5 ABUNDANCE OF MINOR SPECIES 120 4_6 INFLUENCE ANALYSES !23 4-7 PRINCIPAL COMPONENTS ANALYSES 724 4-77 ResuLts t24 4-72 Discussion 126 Chapten Page 4-8 ANALYSES OF PHOTOPOINT DATA (UTNON STUDY) t3r 4-81 The effects of cattLe øtd sheep gtazing on pLøtt habits 131 4-82 Brousing by cattLe 131 4-83 Shruh øtd grass dynønícs 133 4-84 Píosphere patterms 13s 4-9 DISCUSSION AND CONCLUSIONS 135 4-91 The reLatiue intportance of stocking and oth,er influences 135 4-92 Linea.r. relationships uithtin the piosphez'e 737 4-93 PossibLe causes of stock-induced uegetatíon pattern 138 4-94 0n monítoring stock-induced chønges 139 4-95 The shot't term inrpaet of eattLe inttoduetion 741 5 LONG TERM CHANGE IN VEGETATION GRAZED BY CATTLE 144 5-1 INTRODUCTION 144 5-2 METHODS 145 5-2t SeLection of sarnPLe æed.s 145 5-22 Pavametev's used ín sønPLíng 146 5-23 SørcpLíng sgstem ]-47 5-24 Data presentation and øLaLysis 148 5-25 CriterLa for inferring Long tetrn ehange 148 5-3 RESULTS: VTRGIN/CATTLE COMPARISON 150 5-31 Stocking hóstory of sønpLe æeq,s 150 5-32 Descriptíon of matched Løndscapes 151 5-33 Abundøtce of pasture species 1s4 5-34 Assoeiation of pastu.re speeíes 1sB 5-4 DISCUSSION: VIRGIN/CATTLE COMPARISON 159 5-5 RESULTS: CATTLE/SHEEP COMPARISON 762 5-51 Stoeking hístory of sønpLe areas t62 5-52 Deseription of matched Løtdscapes 163 5-53 Abmdønce of Pasture sPecíes 165 5-54 Associatídn of pashtre specíes