THE INVASIVENESS OF CRATAEGUS MONOGYNA AND MAHALEB, AT ARMIDALE, NEW SOUTH WALES, AUSTRALIA

By

DAVID ANDREW BASS

A Thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy at the University of New England, Armidale.

Department of Geography and Planning University of New England, Armidale New South Wales, Australia

30 March 1994 TABLE OF CONTENTS Page

TITLE PAGE

CONTENTS ii

LIST OF TABLES vii

LIST OF FIGURES xii

LIST OF PLATES xv

CERTIFICATE xvi

ACKNOWLEDGEMENTS xvii

ABSTRACT xx

CHAPTER 1: INTRODUCTION 1

1.1 Biological invasions: introduction and literature 1 review.

1.1.1 Terminology of biological invasions 4

1.1.2 Characteristics of biological invasions with 9 reference to Australia

1.1.3 Ornamental invasions in Australia 18

1.1.4 Impacts of invasive 21 1.1.5 Focus of biological invasion research 23

1.1.6 Attributes of biological invaders 25 1.1.7 Attributes of invaded environments 27 1.1.8 Safe sites and biological invasions 29 1.2 The project 31 1.3 Study region 33

1.4 Study sites 35

1.4.1 Armidale State Forest (ASF) 35

1.4.2 Saleyards site 37

1.4.3 University of New England site (UNE) 38

ii CHAPTER 2: , MORPHOLOGY, PHENOLOGY 40 AND REPRODUCTIVE ECOLOGY OF CRATAEGUS MONOGYNA AND PR UNUS MAHALEB

2.1 Crataegus monogyna 40

2.1.1 Uses of Crataegus monogyna 41

2.1.2 Taxonomy 42

2.1.3 Morphology 45 2.1.4 Phenology 46 2.1.5 Reproductive ecology 48

2.1.6 Distribution 48

2.2 Prunus mahaleb 51 2.2.1 Taxonomy 51

2.2.2 Morphology 52 2.2.3 Phenology 53 2.2.4 Reproductive ecology 54

2.2.5 Distribution 54

CHAPTER 3: HISTORY OF INTRODUCTION AND RATES 56 OF SPREAD OF CRATAEGUS MONOGYNA AND PRUNUS MAHALEB IN AUSTRALIA 3.1. The process of range expansion 56

3.1.1 Rates of spread 58 3.1.2 Determination of rates of spread 61 3.2 Crataegus monogyna in Australia 62

3.2.1 Tenterfield case study 66 3.3 Prunus mahaleb in Australia 78 3.4 Comparison of the rates of spread of Crataegus 82 monogyna and Prunus mahaleb in Australia.

CHAPTER 4: DEMOGRAPHY OF CRATAEGUS MONOGYNA AND 85 PR UNUS MAHALEB

4.1 Introduction and literature review. 85

4.1.1 Population models 85

iii 4.1.2 Development of matrix models of population 88 growth

4.1.3 Modelling of long-lived perennials 91

4.1.4 Modelling of populations 92 4.1.5 Construction of matrix models 94

4.1.6 Population dynamics of biological invaders 98 4.1.7 Determination of life-table data 101 4.1.8 Calculation of survival rates 101

4.1.9 Calculation of fecundity rates 102

4.1.10 Growth and transition rates 105

4.1.11 Determination of the latent root of 106 transition matrices 4.1.12 Census plots for Crataegus monogyna and 106 Prunus mahaleb

4.2 Crataegus monogyna demography 108 4.2.1 Flowering success of Crataegus monogyna 108

4.2.2 crop size of Crataegus monogyna 109 4.2.3 Estimates of density, standing crop and age 112 of seedlings 4.2.4 Fecundity of Crataegus monogyna 113 4.2.5 Survival and growth of established seedlings 113

4.2.6 Survival and growth of reproductive plants 114

4.2.7 Age structure of Crataegus monogyna 115 4.2.8 Causes of morbidity and mortality of Crataegus 116 monogyna 4.2.9 Life-tables and transition matrices for 119 Crataegus monogyna

4.3 Prunus mahaleb demography 123

4.3.1 Flowering success in Prunus mahaleb 123

4.3.2 Fruit crop size in Prunus mahaleb 124

4.3.3 Estimation of density, standing crop and age 126 of seedlings

iv 4.3.4 Fecundity of Prunus mahaleb 128 4.3.5 Survival and growth of established seedlings 129 4.3.6 Survival and growth of reproductive plants 130

4.3.7 Age structure of Prunus mahaleb 130

4.3.8 Causes of mortality in Prunus mahaleb 132

4.3.9 Life-tables and transition matrices for Prunus 135 mahaleb

4.4 Discussion of the demographies of Crataegus monogyna 138 and Prunus mahaleb

CHAPTER 5: DISPERSAL ECOLOGIES OF CRATAEGUS 143 MONOGYNA AND PR UNUS MAHALEB

5.1 Specialist and generalist dispersal systems 144 5.2 Biological invasions and seed dispersal 145

5.2.1 Interactions between introduced plants and 148 birds

5.3 Assessment of the dispersal ecologies of 149 Crataegus monogyna and Prunus mahaleb 5.3.1 The characteristics of Crataegus monogyna 150 and Prunus mahaleb fruit 5.4 Crataegus monogyna 153 5.4.1 Bird facilitated seed dispersal 153

5.4.2 Pied Currawong behaviour and seed dispersal 157 5.4.3 Pied Currawong autumn-winter diets in Armidale 163 5.4.4 Autumn-winter fruiting ornamental plants in 167 Armidale 5.4.5 Mammals 173 5.5 Prunus mahaleb 177 5.5.1 Bird facilitated seed dispersal 177

5.5.2 Mammal facilitated seed dispersal 189

5.6 Comparison of Crataegus monogyna and Prunus 191 mahaleb dispersal ecologies CHAPTER 6: DISCUSSION AND CONCLUSIONS 196 6.1 Overview of biological invasions 196 6.2 The specific outcomes of the project 197 6.3 Reasons for the differences in relative invasiveness 198 of Crataegus monogyna and Prunus mahaleb

6.3.1 Rate of spread of Crataegus monogyna and 199 Prunus mahaleb

6.3.2 Population growth of Crataegus monogyna and 200 Prunus mahaleb

6.3.3 Dispersal ecologies of Crataegus monogyna and 201 Prunus mahaleb 6.4 The relative importance of humans, plant 204 demography and seed dispersal in determining invasiveness of Crataegus monogyna and Prunus mahaleb

6.5 Management of invasions by fleshy fruiting 207 woody plants

6.5.1 Impact of fleshy fruiting woody plants 207

6.5.2 Weak points in the life histories of 208 Crataegus monogyna and Prunus mahaleb 6.5.3 Integrated approach to management of invasion 216 by ornamental plants

6.6 Recommendations for further research 218

6.7 Conclusion 219

REFERENCES 221 APPENDIX 1 254 APPENDIX 2 270 APPENDIX 3 272

vi LIST OF TABLES Page Table 1.1 Scale of biological invasions as regards the place of origin in a given invasion (from di Castri 1989). 11 Table 1.2. Scale of time of biological invasions with respect to the initial driving forces for a biological invasion (from di Castri 1989). 12 Table 1.3 The origins of the naturalized flora of South Australia at three different periods (from Kloot 1991). 16 Table 1.4. The manner of introduction of the naturalized species of South Australia. From Kloot (1991). 20 Table 1.5. Characteristics of the ideal invader (from Roy 1990). 26 Table 1.6 Yearly rainfall totals in millimetres between 1980 and 1991 for Armidale, New South Wales (from Burr 1988-1992). 34 Table 1.7 Mean daily minimum and maximum temperature (degrees Celsius) for Armidale (from Burr 1988-1992). 35

Table 2.1. morphology of C.monogyna in Australia and south-eastern England (after Byatt 1975). Sample sizes are shown in brackets. 45 Table 2.2. Prunus species naturalized or becoming naturalized in New South Wales (from Smith 1988). 52 Table 3.1 Estimated rates of spread of in the British Isles and mainland Europe (from Table 1 in Birks (1989)). 60 Table 3.2 Number, height, girth and ages of C.monogyna trees felled in 1990 at Tenterfield and calculated rates of spread away from the Poplar Gardens hedge with an establishment date between 1863 and 1890 (A in Fig. 3.3). See text for details. 78 Table 3.3 Ages of P.mahaleb trees felled from ASF in 1990. Rates of spread are calculated from the centre of the main infestation (point x in Fig. 3.4). 80 Table 4.1 Hypothetical life-table data grouped into age classes. 95

vii Table 4.2 Hypothetical transition matrix constructed from fecundity and survival values from table 4.1 95 Table 4.3. Population matrix divided into n classes 96 Table 4.4 The form of a size classified transition matrix for a population divided into five size classes (adapted from Caswell 1989). 96 Table 4.5 Proposed demographic differences between species with differing degrees of invasiveness. 100

Table 4.6. Fruit set rates for C.monogyna in ASF, Saleyards and Newholme sites for Spring 1988. Numbers in brackets refer to the number of branches in each size class surveyed. 109

Table 4.7 Regression equations for fruit crop estimates of C.monogyna at ASF in 1988 and 1989. Circumference = basal circumference (cm), height = height of tallest stem (cm), and basal area = basal cross--sectional area (cm 2 ), d.f. = degrees of freedom, and p = probability that S does not equal 0. 110

Table 4.8 Average fruit crops (1988 and 1989 combined) for C.monogyna at ASF based on height and basal circumference size classes. N = number of individual plants in each size class. Numbers are rounded to the nearest whole number. 111

Table 4.9 Average growth rates and proportion of individuals in each size class moving up a size class for C.monogyna at Armidale. s.d. = standard deviation rounded to nearest whole number for height classes and one decimal place for basal circumference classes. 114 Table 4.10 Initial size class distribution, growth rates, survival rates, transition probabilities and fecundity for C.monogyna near Armidale. Size classes based on height of tallest stem. 120 Table 4.11 Initial size class distribution, growth rates, survival rates, transition probabilities and fecundity for Crataegus monogyna at Armidale. Size classes based on height of plants 0-100 cm, and basal circumference for plants > 100 cm tall. 121

Table 4.12 Transition matrix for Crataegus monogyna at Armidale. Size classes are based on height of tallest stem.

viii Data from table 4.10. See explanation in text (section 4.1.5) for calculation of matrix elements. X=1.13804. 122

Table 4.13 Transition matrix for Crataegus monogyna at Armidale. Size classes are based on height for plants 0-100 cm tall and basal circumferences for plants > 100 cm tall. Data from table 4.11. See explanation in text (section 4.1.5) for calculation of matrix elements. X=1.10293. 122 Table 4.14 Fruit set rates for P.mahaleb in isolated and non- isolated plants, Spring 1988. Numbers in brackets refer to the number of branches in each size class surveyed. 124

Table 4.15 Regression equations for fruit crop estimates of P.mahaleb at ASF in 1988 and 1989. Circumference = basal circumference (cm), height = height of tallest stem (cm), and basal area = basal cross-sectional area (cm2). 125

Table 4.16 Average fruit crops (1988-1989) for P.mahaleb at ASF based on height and basal circumference size classes. 126

Table 4.17 Average growth rates and proportion of individuals in each size class moving up a size class for P.mahaleb at Armidale. s.d. = standard deviation rounded to the nearest whole number for height and one decimal place for basal circumference classes. 129 Table 4.18 Initial size class distribution, growth rate, survival rates, transition rates and fecundity for Prunus mahaleb at Armidale. Size classes are based on height of tallest stem. Numbers in brackets relate to fecundity rates incorporating 13626 seedlings dispersed away from nursery trees. 136 Table 4.19 Initial size class distribution, growth rates, survival rates, transition rates and fecundity for Prunus mahaleb at Armidale. Size classes are based on height for plants 0-100 cm tall and basal circumference for plants > 100 cm tall. Numbers in brackets relate to fecundity rates incorporating 13626 seedlings dispersed away from nursery trees. 137

Table 4.20 Transition matrix for Prunus mahaleb at Armidale. Size classes are based on height of tallest stem. Numbers in brackets refer to fecundity rates based on seedlings dispersed away from nursery trees. X = 1.71346. (For seedlings dispersed away from nursery trees X = 1.22431). 137

ix Table 4.21 Transition matrix for Prunus mahaleb at Armidale. Size classes are based on height of tallest stem for plants < 100 cm tall and basal circumference in cm for plants > 100 cm tall. Numbers in brackets refer to fecundity rates based on seedlings dispersed away from nursery trees. X, = 1.49409 (For seedlings dispersed away from nursery trees A, = 1.18559). 138

Table 5.1 The physical and biochemical characteristics of C.monogyna and P.mahaleb fruit (from Herrera 1987). Numbers in brackets are data for Armidale material collected in 1989. 152 Table 5.2 Birds ingesting C.monogyna fruit and dispersing seeds. Names follow Blakers et al. (1984). 156 Table 5.3 Analysis of mammal faeces collected in the Armidale region from 1988 to 1991 174

Table 5.4 List of all birds seen in the ASF study area both in and out of the formal observation period. Birds seen feeding on P.mahaleb are indicated by SP for seed predator, PP for pulp predator and D for disperser based on field observations. Names follow the nomenclature of Blakers et a/. (1984). 178

Table 5.5 Visitation index for birds visiting a single Prunus mahaleb , Armidale State Forest, January 1990. (Birds listed in order of body size, see Table 5.6). 180

Table 5.6. Body mass and foraging statistics of the avian fruit eaters of P.mahaleb at ASF. Sample sizes are shown in parentheses. 181

Table 5.7. Successful feeding attempts of the birds at ASF. N = number of observations. 184 Table 5.8. The number of fruit ingested and dropped while feeding by each species calculated by multiplying the number of birds seen in the 560 observations by the average number of ingested per visit and the feeding success rate form table 5.7. 185 Table 5.9 The number of P.mahaleb seeds collected from rabbit, fox and possum faeces at ASF. 190

Table 6.1 Simulated effects of changing survival rates at various stages of C.monogyna at ASF. Size classes are based on height. 211

x Table 6.2 Simulated effects of changing survival rates at various stages of C.monogyna at ASF. Size classes are based on height for plants 0-100 cm tall and basal circumferences for plants > 100 cm tall. 212

Table 6.3 Simulated effects of changing survival rates at various stages of P.mahaleb at ASF. Size classes are based on height. Numbers in brackets refer to seedling survival rates away from nursery trees. 213

Table 6.4 Simulated effects of changing survival rates at various stages of P.mahaleb at ASF. Size classes are based on height for plants 0-100 cm tall and basal circumferences for plants > 100 cm tall. Numbers in brackets refer to seedling survival rates under nursery trees. 214

xi LIST OF FIGURES Page Figure 1.1 The symbolic overlapping and intercrossing of four approaches to cover the definition and characteristics of a biological invader. From di Castri (1990, 5). 5 Figure 1.2 The modification of Australian ecosystems has taken place at a much faster rate than ecosystems in Europe and the Mediterranean. This figure shows symbolically the compression of human technology developed over thousands of years into 200 years in Australia (Hobbs and Hopkins 1990). 15

Figure 1.3 The location of study sites near Armidale, New South Wales. ASF = Armidale State Forest, SY = Saleyards site, UNE = University of New England, PO = Post Office. Shaded boxes represent the location of study plots at each site. Inset shows location of Armidale (A), Sydney (S) and Canberra (C) in New South Wales. 39

Figure 2.1 The morphology of a C.monogyna leaf and the measurements used to generate leaf and sinus depth ratios. From Byatt (1975). 44

Figure 2.2 Phenological timetable of C.monogyna and P.mahaleb at Armidale, New South Wales. 47

Figure 2.3 Distribution of C.monogyna in New South Wales identified from herbaria records, correspondence with New South Wales Department of Agriculture and Fisheries Weeds Officers, and from personal observations as of 1993. T = Tenterfield, A = Armidale, S = Sydney, C = Canberra. The 500 m and 1000 m contours are shown. 50 Figure 2.4 Distribution of P.mahaleb around the Armidale State Forest, 1994. Stippled areas represent dense thickets. 55 Figure 3.1 The addition of foci increases the rate of new range occupation in the form of a quadratic function even if the total area initially remains constant. In this example plotted from Mack (1985, 133) the area occupied by n = 1,2,3,4 and 10 foci at any one time t (1,2,...20). At t=0 (not shown) each group of foci beside its curve has the same total area. 59

Figure 3.2 Distribution of C.monogyna along roadsides on the Northern Tablelands of New South Wales. Te = Tenterfield, GI = Glen Innes, I = Inverell, Ti = Tingha, G = Guyra, D = Dorrigo, E = Ebor, A = Armidale, K = Kingston, U = Uralla, B = Bendemeer, W = Walcha. Modified from Smith (1982). 68

xii Figure 3.3 Distribution of hawthorn hedges (A-H) and trees felled for age determination indicated by numbers at Tenterfield in 1990. ML = Millers Lane, LG = Leeches Gulley, SV = Spring Valley, TS = Tenterfield Station. Qld = Queensland, NSW = New South Wales, (---) state border. Inset shows location of study area in northern New South Wales; S = Sydney, C = Canberra. 70

Figure 3.4 Distribution of P.mahaleb in and around the Armidale State Forest in 1994. Stippled areas represent dense thickets. Numbers refer to felled trees (see Table 3.3). Distance in Table 3.3 taken from X. 81

Figure 4.1 Age structure of (a) C.monogyna and (b) P.mahaleb in ASF1 estimated from trees > 1 m tall felled in 1991. 131

Figure 5.1 Relative abundance of Pied Currawongs in Armidale between 1988 and 1990. Data derived from daily observations along a 6.8 km transect (see text for details). 159

Figure 5.2 Armidale study area showing the location of the Armidale State Forest (ASF), Saleyard site (SY), University of New England (UNE), Water tower site (1) and the bird bath site (2) used for the collection of Pied Currawong ejecta. Dashed lines represent Pied Currawong flight paths out of Armidale. Inset showing New South Wales and locations of A = Armidale, S = Sydney and C = Canberra. 161

Figure 5.3 Breakdown of flight direction and numbers of Pied Currawongs observed over ASF in 1988. A shows sector numbers. B and C represent morning flights out of ASF on 31 July and 4 August respectively. D, E and F represent afternoon flights into ASF on 28, 29 July and 3 August respectively. The centre of each circle represents the observation point adjacent to ASF1. Numbers along side circles refer to the total numbers of Pied Currawongs observed in each time period and the length of the lines are proportional to the numbers of birds for each sector. (Modified from Bass 1990). 162 Figure 5.4 Seeds contained in Pied Currawong ejecta collected from a water tower located in the northern part of Armidale in 1989. 165 Figure 5.5 Seeds contained in Pied Currawong ejecta collected from a bird bath located under a E.viminalis tree near the Rockvale Road, Armidale in 1989. 166 Figure 5.6 Proportion by volume of canopies of fruiting species of Cotoneaster (COT), Pyracantha (PYR), C.monogyna (CM), Ligustrum (LIG) Pistacia (PIST), and others from two parallel 6 km transects in the Armidale area in 1989. 168 Figure 5.7 Proportion of fleshy fruiting taxa naturalised (or in the process of naturalization) in five sites around Armidale (from Smith unpublished data). The genera and species are the same as shown in Fig. 5.6. Cotoneaster (COT), Pyracantha (PYR), C.monogyna (CM), Ligustrum (LIG) Pistacia (PIST), and others. 169

Figure 5.8 Relationships of mean body mass in grams to (a) length of visit of birds in seconds, (b) the number of fruits ingested per minute, and (c) average number of fruit ingested per visit. Data from a single P.mahaleb shrub during 5-18 January, 1990, Armidale State Forest. Vertical bars are standard deviations. Where there are no bars the same size or deviations are too small to represent on the scale. Half bars are used where deviations extend beyond the scale of graphs. 182

Figure 5.9 Frequency of post-feeding flight distances of birds ingesting P.mahaleb fruit 5-18 January, 1990. N is the number of observations. 187

Figure 5.10 Seed dispersal shadow for P.mahaleb in ASF, derived from Table 5.6, Fig. 5.9. See explanation in text. 188

Figure 6.1 Sensitivity analysis of changes to the survival of individuals in each size class (stage). (a) and (b) sensitivity plots for C.monogyna height and basal circumference classified models respectively. (c) and (d) sensitivity plots for P.mahaleb height and basal circumference classified models respectively. Solid dots survival of individuals moving into the next size class (G i ). Open diamonds represent survival of individuals remaining in the same size class (Pi). 215

xiv LIST OF PLATES Page

Plate 3.1 Orchard and hawthorn hedge at Poplar Gardens (Circa 1890). P = pine trees, E = eucalyptus, 0 = orchard, H = hawthorn hedge, ML = Millars Lane. The photograph looks west towards the pine tree hedge. Photograph by kind permission of L. Woolnough. 71

Plate 3.2 Orchard and hedge at Poplar Gardens (Circa 1929). P = pine trees, 0 = orchard, H = hawthorn hedge. The photograph looks west towards Tenterfield. Photograph by kind permission of L. Woolnough. 72

Plate 3.3 Orchard at Poplar Gardens (Circa 1929). P = pine trees, 0 = orchard, H = hawthorn hedge, Pop = poplar trees. Photograph by kind permission of L. Woolnough. 73

Plate 3.4 Poplar Gardens (Circa 1981) looking towards the south east. H = hawthorn hedge, 0 = site of orchard, P = old pine tree, part of previous hedge, W = wild hawthorn plant. Photograph with kind permission of L. Woolnough. 76

xv ACKNOWLEDGEMENTS

I owe a lot of thanks to many people for their assistance with

my research, fieldwork and preparation of this thesis. Like

most PhD projects this project witnessed a number of personal milestones. Through the highs and lows I owe a debt of gratitude to many people.

Above all, I thank dearly my wife Alice who, despite the death

of her mother, kept up her strength. It is to her love and

tenacity I owe so much.

I thank especially my parents who supported me financially and

morally through the arduous task of attempting a PhD.

I especially thank my supervisor Associate Professor J.M.B. Smith for his academic guidance and moral support over the

entire duration of this project. Apart from the ubiquitous

HHH, xxxx and unpredictable zones of confusion, he also introduced me to the world of alien fleshy fruiting woody plants. His enthusiasm and endurance kept me going and saw me through to this final stage of the project. The members of the

Geography and Planning Department, UNE also need to be thanked

for their support. In particular John Humphreys and family

fuelled my fetish for Pied Currawong ejecta. Robert

Crittendens resounding eminations provided continued inspiration for my scat analyses. Barbara Waterhouse, Mark

xvii Tippett, Michael Hall, Russell Drysdale, Roger Epps, Jim Walmsley and Megan Wheeler all provided their own brand of

sanitity and support, which made each day in Armidale memorable. I thank the army of paid and unpaid workers, including Keren Halliday, Peter Kay, Russell Drysdale, Russell

Harlen, John Greenway, John Jenkins, Caroline Smith, Inne

Bosche, Kim Dawson, Simon Pocock, Roslyn Blanche and Bob

Haworth who all helped with my fieldwork especially during the 18 months I was on crutches.

I thank the keen and enthusiastic locals of the Northern

Tablelands. Their recollections of hawthorn were invaluable. In particular Lloyd Woolnough (especially for the use of photographs of Poplar Gardens at Tenterfield), Robet Miller, Ms J. Rickard, Ms Alice Norton, Ms Ruth Chant.

I wish also to thank colleagues and friends in the Department of Geography at the University of Adeliade who encouraged me through the final stages of the production of this thesis, especially Ruth Lawrence, Maureen Longmore and Graeme Hugo. The draughting and advice on figures by Sue Murray is much appreciated.

Richard Vyner allowed me to undertake field work on Newby

Park. The Forestry Commission of New South Wales provided permission to work in the Armidale State Forest.

A PhD is also a costly exercise and without financial support would not be completed. The project was partly funded by the

xviii Australian Research Council, University of New England Internal research grants scheme, Australian Postgraduate Research Award, Newholme Research grants scheme and the

Department of Geography and Planning, UNE-Armidale.

xix ABSTRACT

Crataegus monogyna and Prunus mahaleb are two related fleshy fruiting that were introduced to Australia as ornamental and commercial plants in the nineteenth and twentieth centuries. C.monogyna is very invasive in the region, having spread rapidly and conspicuously throughout northern New South Wales and elsewhere in south eastern

Australia. P.mahaleb is far less invasive, being restricted to a small and slowly expanding population near Armidale in northern New South Wales. Calculation of rates of spread of both species by analysis of annual growth rings indicated that C.monogyna is spreading at 80 m yr -1 , four times faster than

P.mahaleb which is spreading at 20 m yr-1.

Demographic analysis of both species using modified Leslie matrices showed that potential population growth rates of

P.mahaleb are however more rapid than those of C.monogyna.

P.mahaleb had projected population growth rates of 1.71346 and 1.49041 and C.monogyna 1.13804 and 1.10293 for height and basal circumference classified models respectively.

Assessment of the seed dispersal ecologies of both species showed that C.monogyna, an autumn-winter fruiting species, has seeds capable of dispersal by Pied Currawongs (Strepera graculina) over many kilometres. P.mahaleb, a summer fruiting species, has seeds dispersed predominantly by Noisy Friarbirds

xx (Philemon corniculatus) over distances generally less than 100 m. Both species had seeds dispersed in smaller numbers by other birds and a range of native and introduced mammals

including Brush-tailed possums, macropods, foxes and rabbits.

The main factors determining the difference in invasiveness between the two species were that (1) C.monogyna was widely and extensively planted in hedges and gardens which provided many foci for further and accelerated spread facilitated by seed dispersal by vertebrates. (2) P.mahaleb was not planted widely and as a result spread relatively slowly from a single focus. (3) despite a more rapid population growth rate

P.mahaleb only had seeds dispersed relatively short distances compared to C.monogyna which has seeds dispersed over many kilometres.

The results indicate that the pattern of invasion by fleshy fruited alien woody plants in the Armidale region is changing.

This has implications for ongoing and future invasions by a range of species and suggests that further taxa such as

Ligustrum, Pyracantha and Pistacia will become more invasive.

xxi