The Effects of Fire-Related Germination Cues, Time-Since-Fire and Habitats on the Germinable Soil-Borne Seed Banks at the Torrington State Conservation Area (NSW)

The effects of fire-related germination cues, time-since-fire and habitats on the germinable soil-borne seed banks at the Torrington State Conservation Area (NSW).

Kinzang Dorji

November 2004

A thesis submitted for the degree of Master of Scientific Studies at the University of New England, Armidale, Australia.

ABSTRACT

To determine the effects of fire-related germination cues, time-since-fire and habitats, soil-borne seed bank samples of rocky outcrops and forest habitats of Torrington State Conservation Area were examined under glasshouse conditions. A total of 1766 seedlings were recorded from the 128 sample trays over the trial duration of 9 weeks. After 9 weeks, no more seedlings emerged.

The seedlings were identified as belonging to 44 species from 38 genera and 23 plant families; comprising 21 woody species, 17 forb species, 3 graminoid species and 3 grass species. The most prominent plant families were Fabaceae (8 woody species) followed by Myrtaceae (4 woody species), Apiaceae (4 forb species) and Epacridaceae, Poaceae and Asteraceae with 3 species each.

Both seedling emergence and species richness was greater for heat and combinatorial effect of heat and smoke induced treatments than for control and smoke treatments. However, only the species richness was significant for treatments.

Time-since-fire significantly affected the community composition. There were a total of 1351 seedlings germinated from the sites with long time-since-fire (>10 yrs.) and 415 seedlings were emerged from the sites with short time-since-fire (18 months). Germinants were mostly shown from the long-burnt rocky outcrops.

There was a habitats effect with rocky outcrop samples having significantly more germinable seeds (1522 seedlings) than soil samples collected from forest habitats (144 seedlings).

Examination of the soil seed bank samples and the ground standing vegetation of the study sites showed that the species composition was similar. However, there was a large difference in species richness, with richness showing higher in the ground standing vegetation than the soil samples.

DECLARATION

I certify that the substance of this thesis has not been submitted for any other degree or award and is not currently being submitted for any other qualification. In addition, I declare that to the best of my knowledge, all assistance and sources of information in the preparation of this thesis have been acknowledged.

…………………………

Kinzang Dorji

Acknowledgements

My profound and heartfelt thanks to my academic supervisor Associate Professor Dr. Peter Clarke for his close supervision, proper guidance, advice, invaluable support and encouragement throughout the duration of this research. Thanks for many other fruitful discussions and constant positive reinforcements.

I am grateful to Mr. Ian Simpson for his contribution in the field soil sampling collections and continually providing technical assistance related to the glasshouse germination trials throughout the experiment. I thank Mr. Lachlan Copeland (PhD student) for all the assistance in identifying the seedlings to species level.

I am grateful to the members of the Botany Department for their assistance and encouragement during my studies at the University.

I wish to express my appreciations to Associate Professor Warren Halloway for his editorial suggestions.

My Bhutanese postgraduate friends Ms. Namgay Lhamu and Ms. Karma Tshering are gratefully acknowledged for their time in obtaining the correct census records of the initial vigorous seed germinations in the glasshouse.

Many people supported me both directly and indirectly and I would like to thank them. These include Ms. Monica Campbell whose advice and guidance was an immense help in keeping initial records of individual seedlings, and Mr. Doug Clark for providing office materials.

Finally, I am indebted to the Bhutanese Government for providing me with the scholarship to undertake these studies at the UNE.

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Table of Contents

CHAPTER -1 INTRODUCTION ...... 1 1.1 Thesis outline ...... 1 1.2 Effects of fire regime on composition of sclerophyll vegetation ...... 2 1.3 Aims and objectives of the research ...... 3 1.4 Hypotheses ...... 4 CHAPTER - 2 LITERATURE REVIEW ...... 6 2.1 Introduction ...... 6 2.2 Types of seed banks and their distributions ...... 8 2.3 Heat as soil seed bank germination cues...... 9 2.4 Smoke as soil seed bank germination cues ...... 11 2.5 Effects of fire regimes (fire frequency, fire intensity and season of fire) on soil- borne seed banks ...... 13 2.6 Effects of habitats (rocky outcrops and forests) on plant population dynamics .... 15 2.7 Soil seed bank germinating methods ...... 16 2.8 Seed separation methods ...... 16 2.8.1 Extraction of seeds by flotation ...... 16 2.8.2 Extraction of seeds by washing and sieving ...... 16 2.9 Sample treatment prior to germination under controlled conditions ...... 17 CHAPTER - 3 METHODS AND MATERIALS ...... 18 3.1 Study region ...... 18 3.2 Climate ...... 19 3.3 General vegetation of Torrington ...... 21 3.4 Sites description ...... 23 3.4.1 Rocky outcrop vegetation ...... 23 3.4.2 Dry sclerophyll forest vegetation ...... 24 3.5 Fire history ...... 24 3.6 Soil seed bank field-sampling methods ...... 25 3.7 Vegetation sampling ...... 27 3.8 Glasshouse experimental design ...... 27 3.9 Numerical and statistical analyses ...... 33 CHAPTER – 4 UNIVARIATE ANALYSES OF SOIL SEED BANKS ...... 34 4.1 Analyses of seedling numbers ...... 34 4.1.1 Descriptive analysis ...... 34 4.1.2 Statistical analyses of seedling germination responses to treatments, time-since- fire and habitats ...... 35 4.1.3 Grass seedlings response to treatments, time-since-fire and habitats ...... 36 4.1.4 Graminoid seedlings response to treatments, time-since-fire and habitats ...... 37 4.1.5 Number of forb individuals response to treatments, time-since-fire and habitats 37 4.1.6 Total number of obligate seeder shrubs response to treatments, time-since-fire and habitats ...... 37

4.1.7 Total number of resprouting shrubs response to treatments, time-since-fire and habitats ...... 38 4.1.8 Total number of woody individuals response to treatments, time-since-fire and habitats ...... 38 4.2 Analyses of species richness ...... 41 4.2.1 Effects of treatments, time-since-fire and habitats on the composition of all species ...... 42 4.2.2 Number of grass species response to treatments, time-since-fire and habitats . 43 4.2.3 Total number of graminoid species response to treatments, time-since-fire and habitats ...... 44 4.2.4 Total number of forb species response to treatments, time-since-fire and habitats ...... 44 4.2.5 Total number of herbaceous species response to treatments, time-since-fire and habitats ...... 45 4.2.6 Total number of woody species response to treatments, time-since-fire and habitats ...... 45 4.2.7 Total number of resprouting shrubs response to treatments, time-since-fire and habitats ...... 46 4.2.8 Total number of obligate seeder shrubs response to treatments, time-since-fire and habitats ...... 46 4.3 Discussion ...... 49 4.3.1 Species richness and abundance ...... 49 CHAPTER-5 UNIVARIATE ANALYSES OF STANDING VEGETATION ...... 52 5.1 Dominant species in ground standing vegetations ...... 52 5.2 Species richness of ground vegetation at the study sites ...... 52 5.3 Effects of habitats and time-since-fire ...... 53 5.4 Discussion ...... 57 CHAPTER -6 MULTIVARIATE ANALYSIS ...... 58 6.1 Introduction ...... 58 6.2 Methods...... 58 6.3 Results ...... 59 6.4 Discussion ...... 63 CHAPTER – 7 GENERAL DISCUSSION AND CONCLUSION ...... 64 7.1 Discussion ...... 64 7.1.1 Treatments effect on seedling emergence and species richness ...... 64 7.1.2 Effects of time-since-fire on seedling emergence and species richness ...... 66 7.1.3 Habitat effects on seedling emergence and species richness ...... 68 7.1.4 Species richness comparison between standing vegetation and soil seed bank samples ...... 70 7.2 Conclusion ...... 71 REFERENCES: ...... 72 APPENDICES ...... 82

Chapter 1- Introduction ______CHAPTER -1 INTRODUCTION

1.1 Thesis outline

This thesis is presented in seven chapters dealing with the ecological impacts of the fire- related germination cues, time-since-fire and habitats on the distribution of soil-borne seed banks. Chapter 1 describes a brief outline of the thesis, the effects of fire regimes on the composition of sclerophyll vegetation, the specific scientific aims, objectives and hypotheses of the research undertaken. Chapter 2 presents the literature review on the related aspects of fire ecology, effects of plant-derived combustion products as germination cues on soil-stored seed banks in the fire-prone ecosystems, effects of habitats and time-since-fire on the accumulation of soil seed banks and the experimental materials and methods of seed banks germination. Chapter 3 gives a brief introduction to the physical location of study sites and application of specific methods with required materials in the field survey and glasshouse experiment. Chapter 4 presents the univariate analyses of the glasshouse soil seed bank germination. Chapter 5 provides the univariate analyses on the comparison of species richness between soil seed bank samples and the ground standing vegetation in the study sites. Chapter 6 discusses the multivariate data analysis on the floristic composition of individual species in relation to the effects of habitats and time-since-fire. Chapter 7 contains a general discussion of the main findings of the research undertaken and a brief conclusion.

A schematic diagram for the thesis is outlined in figure 1.2.1.

Chapter 1- Introduction ______

Introduction (Chapter 1)

Literature Review Materials & Methods (Chapter 2) (Chapter 3)

Results (Chapter 4 & 5)

Univariate Analysis of Univariate Analysis of the Multivariate Analysis Seed banks Standing Vegetation (Chapter 6) (Chapter 4) (Chapter 5)

General Discussion & Conclusion (Chapter 7)

Fig. 1.2.1. Thesis outline and chapter sequence.

1.2 Effects of fire regime on composition of sclerophyll vegetation

Fire is one of the most important ecological factors that influence dry forests by opening up the canopy for regeneration, controlling tree pests and diseases, releasing nutrients to encourage plant growth, and hence playing a crucial role for fire dependent species in germinating seeds. For example, the burning of grasslands and grassy woodlands is generally followed by a flush of a wide range of germination and resprouting by fire- tolerant species (Marsden-Smedley et al. 1997). In fire-prone vegetation communities, a fire regime plays a major influence on the floristic compositions of vegetation through

Chapter 1- Introduction ______demographic processes such as mortality, reproduction, germination and survival of plant populations (Bradstock et al. 1997). However, its effects on the floristic composition of communities vary according to sequences of fire events. Sometimes, seedlings may be killed by a single fire event but mature plants of the same species may resist the intensity of fire and persist to survive in disturbed areas. Some woody species have “fire sensitive” individuals also called „obligate seeders‟ which can be readily killed by a single fire but many of these species still are able to survive in the fire-prone ecosystems because regeneration takes place from the canopy and soil-stored seed banks (Gill 1994).

Specht (1981) and Fox and Fox (1986) describe how species richness and fire-prone plant communities tend to increase immediately after a fire event and gradually declines in the course of time. This is because the initial re-establishment of the plant community soon after the fire is usually represented by those species whose adult plants can survive fire (fire-tolerant species) while, those species whose adult plants do not normally tolerate fire (fire-sensitive species) tend to revive and contribute to the ground level of plant community after several years of disturbance (Morrison et al. 1995; Morrison 2002).

Mediterranean-climate ecosystems are commonly regarded as good examples of convergent evolution in vegetation function and structure where dominant evergreen sclerophyll vegetations produce a predictable and extended wildfire season. There is evidence that plant species in these communities have adapted to become „fire- dependent‟ for the completion of their life cycle (Keeley and Bond 1997). Thus, the role of seed banks in relation to fire is a critical ecological issue and reviewed in detail in chapter 2.

1.3 Aims and objectives of the research

Many sclerophyll forest species regenerate after fire by seedlings and /or by re-sprouts. Therefore, it is presumed that the larger seedling production by non-sprouting species is due to their ability for greater seed production and accumulation of a large number of seeds in the soil (Keeley 1977). However, there is evidence that even under favourable moisture conditions, seeds of many plant species do not germinate because germination is

Chapter 1- Introduction ______being controlled by a seed physiological dormancy that needs to be broken by environmental cues (Thornton et al. 1999; Gilmour et al. 2000). In recent years, there has been a growing interest in the role of fire and fire by-products such as heat, smoke, ash and charred wood to promote germination in seeds that remain innately dormant (Keeley 1977; Gilmour et al. 2000).

This study was undertaken to examine the response of germinable seed banks in two contrasting habitats (i.e. rocky outcrops and dry sclerophyll forests) at the Torrington State Conservation Area, New South Wales. This study also investigated what fire related cues are required to break such dormancy and stimulate germination by using treatments of heat, combinatorial effect of heat and smoke; smoked water and rainwater. Finally, the research also investigated the effects of time-since fire (TSF) and habitats that structure the floristic composition of the natural vegetation.

The study aimed to answer the following questions.

(1) Does fire or fire-related germination cues such as heat, smoke and combined effect of heat and smoke stimulate the seed banks to germinate? (2) Does TSF affect the types of soil seed banks that accumulate after a fire event? (3) Does habitat affect the type of seed banks irrespective of time-since fire?

1.4 Hypotheses

Hypothesis 1: Rocky outcrops have a more diverse floristic composition than forest habitats because they are more heterogeneous habitats and more heterogeneous fire histories.

Hypothesis 2: Habitats with long time-since-fire have a greater accumulation of soil seed banks than habitats with short time-since-fire because fire dependent species require fire components for breaking the innate seed dormancy.

Chapter 1- Introduction ______Hypothesis 3: Fire-related germination cues will differ among habitats because more obligate seeders occur on rocky outcrops.

Chapter 2- Literature review ______CHAPTER - 2 LITERATURE REVIEW

2.1 Introduction

In every habitat where higher plants grow, there is a reserve of dormant seeds in the soil, usually referred as a soil seed bank (Kigel & Galili 1995). These seed banks can persist in a viable state for many decades and are an important source for regeneration of plant communities and re-establishment of plant species into disturbed sites after destructive biotic and abiotic events (Meney et al. 1994; Kigel & Galili 1995; Hill & French 2003). The existence of seed banks in the soil has been known for centuries. Darwin in 1859 illustrated the existence of soil-borne seed banks. He sampled a cup full of mud from the edge of a pond and recorded the seedling emergence from dormant seeds in the sample. A total of 537 seedlings were found to be germinated over a period of six months (Kigel & Galili 1995). More recently, interest has been aroused in different fields of study by the recognition of the key role that seed banks play in the population dynamics of individual species and the maintenance of communities (Kigel & Galili 1995; Giessow & Zedler 1996).

It is generally assumed that seeds and fruits of plants fall into cracks in the soil or are buried in the soil by external forces. Surface organic matter helps trap these seeds to build the seed bank (Zabinski et al. 2000). For obligate seeders, re-establishment of a population after physical disturbance (e.g. fire) entirely depends on successful germination of canopy and soil-borne seed banks. This is because long distance seed dispersals are generally very poor in many fire-prone ecosystems (Pickup et al. 2003). The greater seedling productions by these non-sprouting species after fire are due to their enhanced reproduction allocation by the parent plants and subsequent accumulation of a larger number of seeds in the soil (Keeley 1977; Zabinski et al. 2000). The spatial magnitudes of soil-borne seed banks have a marked effect on the distribution and abundance of obligate seeders in fire-prone ecosystems (Meney et al. 1994).

Plant species have developed a range of seed dormancy „strategies‟ that allow seed germination in the soil and prevent germination when the environmental conditions are

Chapter 2- Literature review ______unfavourable for establishment. To overcome seed dormancy, an appropriate environmental condition is required (Bakin & Bakin 1998; William et al 2003). Fire is usually a common trigger for breaking this dormancy for most of the genera of South African fynbos, Mediterranean garrigue, the California chaparral and the Australian kwongan (Keeley 1977; Meney, et al. 1994; Read et al. 2000). In the Californian chaparral, seed requiring a fire-related stimulus is termed „refractory‟ (Meney et al. 1994). Many chaparral shrub species have the ability to regenerate rapidly after a fire event and for this reason, it is stated that fire has played an important role in their evolution (Meney et al. 1994; Keeley 1977). Therefore, an understanding of soil-stored seed bank dynamics is of considerable importance for successful management of natural vegetations.

As early as 1935, Levyns reported on the germination of seeds of a wide variety of heath species after a fire event. Wicklow (1977) first reported a combustion product aiding in the seed germination in both laboratory and field experiments where charred wood was found to be the stimulating agent in the fire-related germination of the chaparral shrub Emmenanthe penduliflora. In 1985, Keeley et al. reported a similar effect in the Californian chaparral (Olde 2001). It has been long known that heat produced by fire is a crucial cue for germination of soil-borne seeds and in the regeneration of bushlands in which a hard seed coat enforces dormancy. Heat also facilitates the release of seeds stored in the canopy of serotinous species. However, most recently, many studies have revealed that heat is not the only responsible cue for seed germination but other products derived from fire such as smoke, ash, charred wood, and release of chemicals such as ethylene and ammonia during combustion are also important (Marsden-Smedley et al. 1997; Olde 2001; Gashaw & Michelsen 2002). This has indeed broadened the new field of research for fire ecologists seeking to determine which aspects of a fire are the most crucial for seed germination.

This chapter critically reviews the soil seed banks literature in terms of:

(i) types of seed banks and their distributions, (ii) heat as soil seed bank germination cues, (iii) smoke as soil seed bank germination cues,

Chapter 2- Literature review ______(iv) effects of fire regimes on soil-borne seed banks, (v) effects of habitats on plant population dynamics and (vi) soil seed bank germinating methods.

2.2 Types of seed banks and their distributions

The seed bank of any plant community usually consists of a mixture of transient and persistent species (Thompson & Grime 1979). Thompson (1993) distinguished three fundamental types of seed banks: (i) „transient‟ seeds, which persist in the soil for 1 year at most, (ii) „short-term persistent‟ seeds, which persist for 1-5 years and (iii) „long-term persist‟ seeds, which persist for a least 5 years (Lunt 1995; Thompson et al. 1997; Baskin & Baskin 1998). Species with transient seed banks are of two types. Type 1 consists mostly of large-seeded grasses, which germinate in the autumn following shedding. In Britain, Type 1 seed banks are mostly shown by perennials such as Arrhenatherum elatus, Lolium perenne and Festuca rubra while in regions with a Mediterranean climate having a more severe summer drought; annual species such as Bromus molllis, Lolium multiflorum and Festuca megalura are common. Type 2 transient seed banks are commonly represented by large-seeded forbs such as Hyacinthoides non-scripta, Haracleum sphondylium and Galium aparine (Fenner 1992). In contrast, species with persistent seed banks occur in the soil in a viable condition for more than one year (Kigel & Galili 1995; Thompson et al. 1997). However, Thompson and Grime (1979) classified relatively short-lived annuals such as Deschampsia caespitosa, Poa spp. and Holcus lanatus under persistent seed banks. Long-term persistent seed banks are mostly contributed by Juncus spp., Sagina procumbens, Filaginella uliginosa, Rumex acetosa and Cerastium fontanum (Thompson & Grime 1979; Fenner 1992).

Fenner (1992) stated that the dominant species of both tropical and temperate woodlands, permanent grassland and undisturbed wetlands do not accumulate much seeds in the soil. In contrast, arable weeds and other dominants of heathland, chaparral and disturbed wetlands store large, persistent seed banks in the soil.

Chapter 2- Literature review ______The size of seed banks greatly varies from one habitat to another. In general, the largest seed banks in terms of number of seeds per m2 are associated with arable sites (20,000- 40,000 m-2), with progressively smaller seed banks in grasslands, moorlands (5,000- 20,000 m-2) and mature forests (1,000-10,000 m-2). Mature conifer forests and salt marshes (100-1,000 m-2) seem to have rather fewer seed banks in the soil, while alpines and sub-artic vegetations (100-1,000 m-2) may have relatively fewer buried seeds (Kigel & Galili 1995). Vlahos and Bell (1986) found that total germinable seed reserve for the jarrah forest (Eucalyptus marginata) ranged from 377-876 seeds m-2. Koch et al. (1996) sampled the seed reserve on the areas of jarrah forest before they were cleared for bauxite mining and their result indicated that total germinable seed reserve was 212 - 424 seeds m-2.

Studies on the distribution of seeds in the soil profile indicated that most of the soil seed banks are found in the soil surface at about 5 or 10 cm depth (Vlahos & Bell 1986; Koch et al. 1996; Grant & Koch 1997). However, in some cases, seeds can also be found at about 2 cm surface depth. For instance, Tacey and Glossop (1980) discovered that 77% of the seeds in the top 10 cm in the jarrah forest occurred in the top 2 cm of the soil (Ward et al. 1997).

2.3 Heat as soil seed bank germination cues

Fire-related cues such as heat shock, combustion products including smoke, ash, and charcoal, altered soil temperature regimes, aqueous solution from leached and removal of allelopathic substances have been found to enhance seed germination when applied singly or in combination (Keeley & Bond 1997; Thornton et al. 1999, Thomas et al. 2003). The direct effect of heat from fire is the well-recognized factor that stimulates germination for fire-dependent species in fire-prone ecosystems (Izhaki et al. 2000).

According to Tozer (1998) many plant species rely on heat generated in the soil during a forest fire to break dormancy and such phenomena are commonly noticed in species of the plant families such as Fabaceae, Lamiaceae and Rhamnaceae. The optimal range of temperature between 40 o C - 80 o C is sufficient to break seed dormancy in many plant

Chapter 2- Literature review ______species (Read et al. 2000). However, maximum germinations of the seed were achieved after heating in temperature range between 80 o C - 100 o C (Tozer 1998). Temperatures exceeding 120 o C are generally found to be lethal to soil-borne seed banks (Tozer 1998). Heat weakens hard seed coats particularly the cuticle and other localized cell regions such as the helium and strophiole. Once the coat is permeable to water, seed germination can take place (Bissett & Parkinson 1979).

Ward et al. (1997) measured germinable seed stores in jarrah forest soils and their study indicated that germination of most common species such as Acacia drummondii, A. pilchella, Bossiaea auqifolium, Kennedia coccnea, Lasiopetalum floribundum and Trymalium ledifolium were significantly enhanced by heating the soil. Wills and Read (2002) found that heat was clearly the most successful treatment followed by smoke for promoting seed germination of the soil seed bank in the mature sand heathland within the Gippsland Lakes Coastal Region, in south-eastern Australia. They also discovered that mean species richness of the germinable soil-borne seed bank was significantly higher in heat-treated soil than in smoke and other control treatments. A study undertaken by Pickup et al. (2003) on the role of heat as cues for germination of Grevillea rivularis in the Carrington Falls in the NSW Southern Highlands showed that heating caused significant germination of dormant soil-borne seeds.

Seed tolerance to extremely high temperatures is one factor that has a strong influence on community structure through seed survival and post-burn recruitment of seedlings. Some Australian native species particularly in legume species showed more tolerance to thermal-shock than species reported from other parts of the world (Gilmour et al. 2000). Bell and Williams (1998) reported that the soil-borne seed banks of legume species in both Eastern and Western Australia have highly developed tolerance to heat-shock. Species such as Acacia myrtifolia, Sphaerolobium viminium and several species of Pultenaea survived more than two hours at 100 o C temperatures. Heat tolerant species from other regions include the Mediterranean genus Cistus, the South African fynbos genera Podalyria and Agathosma and the California chaparral genus Ceanothus (Bell & Williams 1998). In contrast, Bell and Williams (1998) showed that seeds of serotinous species in Western Australia were vulnerable to even short durations of thermal-shock.

Chapter 2- Literature review ______Their findings indicated that seeds of serotinous species and small-seeded species did not show any sign of survival when exposed to a temperature of 100 o C for duration of even 30 seconds. Thus, the interaction of seed type, depth of seed burial and intensity of heat will influence the flux of seed that germinates from the seed bank.

2.4 Smoke as soil seed bank germination cues

It was initially assumed that heat alone from forest fires cracked seed coats that allowed soil-borne seed banks to germinate in the fire-prone ecosystems (Keeley 1977). However, most recently, a number of reasons have been given for the enhancement of seed germination by fire. Among these are reduction of inhibitory substances in soil and litter, chemical stimulation from charred wood, release of ethylene and ammonia in the plant- derived smoke and soil nutrients have been found to be influential and contribute much to soil-stored seed germination in fire-prone ecosystems (Enright & Kintrup 2001; Gashaw & Michelsen 2002). More recently, smoke-induced germination has been reported for a large number of species from a wide range of plant families from South Africa (e.g. Keeley 1977; Brown et al. 1994) and Western Australia (e.g. Dixon et al. 1995; Roche et al. 1997; 1998). Similar findings were reported by several other studies where smoke has been shown as one of the most important contributing factors that promote seed germination for a wide range of species (Baldwin et al. 1994; Gilmour et al. 2000; Kenny 2000).

The effect of smoke or smoke-derive extracts on breaking dormancy and increasing seed germination of many species was first reported in South Africa by de Lange, a Ph. D student and Boucher in 1990 (Read & Bellairs 1999; Olde 2001). They examined the effects of ethylene and smoke on seed germination and found that smoke had a maximum influence on seed germination (Ward et al. 1997). According to Keeley and Bond (1997), in the Californian chaparral and South African fynbos, there are a substantial number of species with germination stimulated chemically by charred wood and smoke.

In Australia, Roche et al. (1998) reported on their success using smoke to germinate seeds of some native Australian plants (Lloyd et al. 2000; Enright & Kintrup 2001). In

Chapter 2- Literature review ______1997, Roche et al. discovered that the application of smoke to undisturbed jarrah (Eucalyptus marginata) forest induced a 48-fold increase in the total number of germinations and a 4-fold increase in species richness which indicated smoke had a considerable practical relevance in regeneration of plant communities. Roche et al. did not cease their quest and in 1998, their publication on smoke-induced seed germination and seedling recruitment of Banksia woodland in Western Australia further confirmed that the application of smoke promoted a prolific germination of soil-borne seed banks (Roche et al. 1997; 1998; Lloyd et al. 2000). Dixon et al. (1995) reported similar effects on 45 out of 94 native species in Western Australia. They identified smoke as a germinating trigger for a broad range of plant species in fire-prone ecosystems including a number of previously recalcitrant species (eg Verticordia densiflora) in floriculture and horticulture (Enright et al. 1997; Olde 2001).

In 1997, Enright et al. reported on the separate effects of heat, smoke and ash on seedling emergence from the soil-borne seed banks of heathy Eucalyptus woodland in the Grampians National Park, Western Victoria. Their findings indicate greater emergence of seedlings from smoke and heat-treated soil (Read et al. 2000). Tang et al. (2003) compared the effects of smoke and heat on soil bank samples collected from two different ecosystems (i.e. the edge between subtropical rainforest and an adjacent eucalypt- dominated wet sclerophyll forest) at Lamington National Park, southeastern Queensland. Their search was mainly focused on the distribution of species between these two contrasting ecosystems. Upon treatment of soil samples with smoke, they discovered that there was a significantly higher density and wide diversity of species richness within the eucalypt forest than at any sites within the rainforest, thereby suggesting that smoke is an important trigger for species regenerating at this interface i.e. ecotone (Tang et al. 2003). Compared to heat, smoke can make a deeper penetration into the soil because it is soluble in water. It is likely that bush fires followed by rain may promote deeper penetration of active smoke components thereby stimulating germination of soil-stored seed banks remaining at depth (Marsden-Smedley et al. 1997).

Chapter 2- Literature review ______2.5 Effects of fire regimes (fire frequency, fire intensity and season of fire) on soil-borne seed banks

Fire regimes are usually considered to have three closely associated components that can affect composition of plant communities in fire-prone ecosystems. These components are fire frequency (how often the fires occur), fire intensity (heat energy output of the fire) and season of fire (times of the year they occur) (Enright et al. 1996).

The density and species composition of the seed bank is dynamic and changes from year to year as a result of fluxes into and out of the soil of seeds and seedlings (Jimenez & Armesto 1992). A study undertaken by Morrison et al. (1995) on plant species composition of sandstone communities in the Sydney Region indicated that fire frequency accounts for 60 % of the floristic variation and confirmed that the recent fire frequency (< 30 years) produces effects on floristic composition of dry sclerophyll forests in fire-prone plant communities. Giessow and Zedler (1996) reported fire frequency as a main factor controlling the abundance and species richness of non-native forbs in coastal sage scrub in California. Their greenhouse study results indicated that there was a significantly greater number of seedling emergence for higher fire frequency sites, on the other hand, seedling emergence were shown to be less abundant when time-since-fire was long and more seedlings were observed when the fire-interval was short. Therefore, time- since-fire and length of inter-fire interval are likely to be key factors that promote soil- borne seed banks in the fire-prone ecosystems. For instance, softening of the seed coat in hard-seeded species in the absence of fire may allow some germination. As a result of this, the soil-stored seed banks are likely to respond to fire in a complex way reflecting the range of dormancy mechanisms represented such as the depth distribution of dormant seeds in the soil and the intensity of the fire (Enright et al. 1997; Watson & Johnson 2004).

Many fire-dependent species only germinate after fire, in other words, they show low numbers of emergence during the inter-fire period (Wills & Read 2002). If the inter-fire interval exceeds 7-10 years, the diversity of native species may not be re-instated after the incidence of eventual burning because many native species may not form long-term seed banks (e.g. grasslands, Lunt 1995; Harrington & Driver 1995). Therefore, the

Chapter 2- Literature review ______germination of seeds from soil and canopy-stored seed banks affect the composition of the post-fire plant communities (Izhaki et al. 2000). Under the condition of low fire frequency, those plant species that require longer time for reproduction will have a higher likelihood of survival (Bradstock et al. 1995).

Nieuwenhuis (1987) reported on the effects of time-since-fire on plant communities in Victoria's Dandenong Range and at Myall Lakes in NSW and particularly in the Sydney Region. Her findings indicated that obligate seeders such as Banksia ericifolia and Hakea teretifolia were reduced in abundance or eliminated on frequently burnt sites. This is because the obligate seeders entirely rely on seed regeneration to maintain their survival in the community after fire. A second fire at a short interval within the juvenile stage will eliminate these species unless propagules reach the sites from outside (Watson & Johnson 2004).

Cary and Morrison (1995) also showed that the abundance of resprouters were likely to be higher in sites experiencing multiple short intervals of burning. Increasing time-since- fire is associated with a decline in the evenness of fire-tolerant species resulting in fewer of these species coming to dominate a plant community in the prolonged absence of fire. In other words, herbs and small shrubs will decrease in abundance while larger shrubs will increase in abundance. On the other hand, decreasing length of inter-fire interval is associated with a decrease in the evenness of fire-sensitive species (Morrison et al. 1995). At the community level, short inter-fire intervals are associated with lower evenness in species composition than is found in longer inter-fire intervals (Bradstock et al. 1997). These effects should be reflected in the seed bank but to my knowledge, have not been examined in Australia.

Fire intensity influences seed release through breakage of seed dormancy and setting suitability of the seedbed for germination. A study undertaken by Morrison (2002) showed that fire intensity has a clear effect on the relative abundance of the vascular plant species. Greater intensity of fire produces increasingly different forms of vegetation from the unburnt vegetation. According to Enright et al. (1996); Morrison et al. (1995) and Lamont et al. (1991), the effects of fire season on plant community

Chapter 2- Literature review ______composition were poorly understood but certainly appear to be one of the very important factors for the re-establishment of seedlings and the survival of resprouting individuals. However, the effects on seed banks are poorly known

Hill and French (2003) reported on the response of the soil seed-banks to heating at the Cumberland Plain Woodland, in the southeastern regions of Sydney. They found that species responded differently to heating. The seeds of some species germinated when heated to a temperature of 80 o C (particularly species of the family Fabaceae) while the emergence of other species were more common in unheated or lightly heated samples (i.e. to 40o C). This indicates that fire intensity is likely to alter the floristic composition of plant communities in forest fire-prone ecosystems. Fire sensitive species killed during a forest fire or a prescribed burning rely immensely on seed banks to recruit individuals following the passage of fire (Hill & French 2004).

2.6 Effects of habitats (rocky outcrops and forests) on plant population dynamics

Habitat is one of the important ecological factors that influence the distribution and abundance of plant populations of shrub species in fire-prone landscapes. Woody shrubs occur throughout the landscapes but less abundant and low species richness in the grassy woodlands (Benson & Ashby 2000; Clarke & Knox 2002), while rocky outcrops usually support higher species richness of woody shrubs (Clarke & Knox 2002). For example, a study by Clarke and Knox (2002) indicated a higher proportion of woody obligate seeders and seedling recruitment occurs on rocky outcrops and to a lesser extent in shrubby forests on well drained nutrient-poor soils in the tablelands of eastern Australia. However, forest habitats support a higher proportion of resprouting shrubs than the outcrops (Clarke 2002).

Studies by Keeley (1977) and Myerscough et al. (1995) claimed that more open habitats such as rocky outcrops, may promote woody obligate seeders through the availability of nutrient and space where competition from resprouting shrubs is less. In more open habitats, these fast-growing species (obligate seeders) are provided with increased opportunities to complete their life cycles as long as fire intervals are shorter than the

Chapter 2- Literature review ______primary juvenile periods (Clarke & Knox 2002). Differences in the seed banks between potential fire refugia and the surrounding matrix have, however, not been examined.

2.7 Soil seed bank germinating methods

Various methods of separation, extraction or emergence are adapted for the analysis of soil seed banks. They are: (i) soil samples can be taken from the natural vegetation and the sample volume can be reduced followed by extraction of seeds by flotation or by washing, (ii) soil samples can be taken from the natural vegetation and the seeds can be germinated inside a glass house or outside without extraction or sample reduction and (iii) the soil samples can be thoroughly dug to an appropriate depth in the natural vegetation and seeds can be germinated in the field (Thompson et al. 1997).

2.8 Seed separation methods

2.8.1 Extraction of seeds by flotation

In this method, soil samples are washed thoroughly with a variety of different salt solutions of a specific density. Seeds may then be separated from other organic and mineral parts of the sample through their own species-specific density (Thompson et al. 1997). Malone (1967) successfully applied the flotation method for arable weeds and reported that the method was mainly appropriate for the size of the seed bank of a single species (Thompson et al. 1997).

2.8.2 Extraction of seeds by washing and sieving

In this method, seeds are collected by washing soil samples through sieves of different mesh sizes. The finest mesh size of 0.212 mm has been effective enough to hold the seeds of Juncus species. The main advantage of using this method is that the volume of soil samples is substantially reduced, which makes it easier to see seeds under a dissecting

Chapter 2- Literature review ______microscope. According to Fay and Olsen (1978), Benz et al. (1984) and Malone (1997), both flotation and washing methods of seed separation were found to be very effective in terms of large-seeded species (Thompson et al. 1997). Ter Heerdt et al. (1996) reported on a comparison between concentrated and unconcentrated soil samples. They claimed that sieving with a 0.2 mm mesh width reduced the bulk of soil by 85% for clay, 70% for peaty soil and 55% for sandy soil, which required less space in the glasshouse. Both species richness and abundance were higher in the concentrated than in the unconcentrated soil samples. Rubbing the seeds over the sieve apparently scarified the seed coat that allowed all viable seeds to germinate in the glasshouse (Thompson et al. 1997).

2.9 Sample treatment prior to germination under controlled conditions

In this method, the soil samples are finely spread over the surface of sterile sand in the trays and kept under controls. Samples are then watered daily for their initial germination. Seedlings attaining their true leaves are then removed from the experimental trays and transplanted into separate pots where they are grown to flowering stage so that they can be identified. Seedlings are then counted, identified and removed to prevent competition for light and nutrients (Thompson et al. 1997).

In my current study, I have followed the sample treatment prior to germination under controlled conditions method for my project in order to minimize the time requirement in the field survey and to provide adequate time to make a daily close observation in the glasshouse on the individual seedling emergence. Moreover, this method of sampling collection has the advantage of being able to include a wide range of species in a short period of time. The details of this method are given in Chapter 3.

Chapter 3- Methods and materials ______CHAPTER - 3 METHODS AND MATERIALS

3.1 Study region

The study was undertaken in the Torrington State Conservation Area (SCA), which is located between Glen Innes, approximately 60 km to the south, and Tenterfield, 30km to the northeast on the western fall of the New England Tablelands in New South Wales (Fig. 3.1).

Torrington SCA is situated almost entirely upon a granite pluton of late Permian age known as the Mole granite batholith. The reserve comprised approximately 30,000 hectares with rugged granite outcrops and a central sedimentary pendant and forms part of the greater geological landmass, referred to as the Mole Tableland, which rises to 450m above the surrounding country (James et al. 1976; Clarke et al. 1997; NSW National Parks & Wildlife Service 2003).

The Reserve has the largest area of native vegetation remaining on the Northern Tablelands. It is also recognized as being of State significance for nature conservation, mining, honey production, recreation and cultural heritage. There are more than 750 different plant species with over 36 considered rare or threatened, many of which are only found in this area. Several endemic plant species also await formal description. Twenty different species of mammals and more than 30 species of reptiles and frogs are found in the Region (NSW National Parks & Wildlife Service 2003).

Chapter 3- Methods and materials ______

Figure 3.1. Map showing the location of study areas (NSW National Part & Wildlife Service 2003)

3.2 Climate

Climatic information about the Torrington Region, defined by James et al. (1976), is based on the three weather stations at Monkstadt (elevation 347m) located east of Torrington, Tenterfield (elevation 862m) north-east of Torrington and Deepwater (elevation 976m), located south-east of Torrington. Winter months are cool to cold and summers are warm to hot (Clarke et al. 1997). The region experiences variable temperatures mainly due to high elevations, undulating landscapes and the influence of global warming. According to information recorded by the Australian Bureau of

Chapter 3- Methods and materials ______Meteorology weather station at Wood Street, Tenterfield (elevation 870m), the area's maximum daily average temperature was 27 °C and its lowest recorded average daily temperature was 1.0 °C (Fig. 3.2) (NSW National Part & Wildlife Service, 2004).

The region receives moderate annual rainfall of between 674mm to 863mm but this varies considerably from one locality to another owing to different elevations and topographic aspects (Clarke et al. 1997). On average, the reserve gets 856.3mm of rain each year while the highest rainfall recorded was 228.6mm in one day (NSW National Park & Wildlife Service, 2004). The region experiences highest rainfall in the month of January and lowest rainfall in August (Fig. 3.3) (NSW National Part & Wildlife Service 2004).

Figure 3.2. Average daily temperature ranges at Torrington State Recreation Area (NSW National Part & Wildlife Service 2004).

Chapter 3- Methods and materials ______

Figure. 3.3. Average monthly rainfall at Torrington State Recreation Area (NSW National Part & Wildlife Service, 2004)

3.3 General vegetation of Torrington

Clarke et al. (1997) classified the types of vegetation into six major groups within the vicinity of Torrington State Conservation Area. They are (i) Wet heath (ii) Grassy forest (iii) Shrubby woodland and forest (iv) Dry woodlands (vi) Riparian and (vii) Rock outcrop. The groups correspond with correlations of physical environment including lithology, physiography and climate patterns. Within each group, there is a high degree of uniformity in their floristic composition and consistency with vegetation structure and environmental variations. Further, the major groups are subdivided into twelve-minor groupings such as Sedge-heath complex, Pendent grassy forest, Shrubby forest, Shrubby low forest, Shrubby woodlands, Shrubby creeklines, Grassy creeklines, Iron bark (Callitris) woodlands, Red gum-apple woodlands, Outcrop woodlands, Outcrop heaths and Outcrop grassy heaths respectively (Clarke et al. 1997).

Chapter 3- Methods and materials ______This steeply dissected rugged terrain of the Mole Tableland is distinguished by a series of parallel, massive Permian granite ridges with exposed rocky outcrops. The nature of landscape and the forested ridges provide sequences of plant communities across varied geologic and physiographic position (Fig. 3.4). The less steep terrain corresponds with the Paleozoic sedimentary and meta-sediment.

(a)

(b)

Figure 3.4 Landscape profiles from the Mole Tableland through: (a) west to east on the eastern fall and, (b) east to the west on the western fall showing sequences of plant communities across geologic and physiographic position. Source: (Clarke et al. 1997).

Chapter 3- Methods and materials ______3.4 Sites description

Field sampling was done in two of the six major groups of vegetation. The sites comprise two contrasting habitats of rocky granite outcrops and surrounding dry sclerophyll forests. The outcrops were dissimilar in species composition from the surrounding sclerophyll forests. However, the outcrops share some genera and families with the forest matrix (Clarke 2002). Their vegetation types are discussed in detail below.

3.4.1 Rocky outcrop vegetation

Structure: The structures of the vegetations on rocky outcrops are distinguished by low open woodland to heathland with a sparse ground stratum (Clarke et al. 1997).

Composition: Species compositions on the outcrops are distinguished by frequent trees, shrubs, forbs, grasses and graminoids. The most common tree species are Callitris endlicheri, Eucalyptus andrewsii, Eucalyptus prava and Eucalyptus subtilior. Shrub species are commonly shown by Acacia viscidala, Brachyloma saxicola, Hibbertia sp. Kuenzea bracteolate, Leucopogon neo-anglicus, Leptospermum novae-angliae, Leucopogon melaleucoides, Leucopogon muticus and Prostanthera ataurophylla. Frequent forbs such as Brachycome stuartii, Cheilanthes sieberi, Crassula sieberiana, Dianella revolute, Gonocarpus teucrioides and Isotoma anethifolia are some of the common species that grow well on the outcrops. The ground stratums are represented by grasses and graminoids such as Aristida jerichoensis, Entolasia stricta, Digitaria breviglumis, Lepidosperma laterale, Laxmania compacta and Tripogon loliiformis (Clarke et al. 1997).

Chapter 3- Methods and materials ______3.4.2 Dry sclerophyll forest vegetation

Structure Forest habitats are mainly distinguished by open-forest to low open-forest to woodland with a mid-dense to sparse shrub layer and a sparse graminoids ground stratum (Clarke et al. 1997).

Composition Compositions of species on forest habitats are characterized by frequent tree species such as Eucalyptus andrewsii, Eucalyptus brunnea, Eucalyptus subtilior, Eucalyptus williansiona and Eucalyptus caliginosa while mid dense shrubs such as Acacia buxifolia, Aotus subglaca, Bossiaea obcordata, Brachyloma daphnoides, Correa reflexa, Hibbertia obtusifolia, Leptospermum trinervium, Leucopogon lanceolatus, Lomatia silaifolia and Petrophile canescens prevail in the surrounding forest habitats. Mid-dense ground stratums are commonly distinguished by the forbs, ferns, grasses and graminoids species such as Dampiera stricta, Goodenia hederacea, Opercularia aspera, Gonacarpus tetragunus, Aristida jerichoensis, Chionochloa pallida, Entolasia stricta, Imperata cylindrical, Lepidosperma laterale, Lomandra longifolia, Xanthorrhoea johnsonni and Themeda australis.

3.5 Fire history

The history of fire for the regions is poorly known, however, it is thought that major wildfires occurred in 1965, 1975, 1985, 1990 and the most recent occurred in Oct. 2002. This gives a preliminary indication that large wildfires approximately occur every 10 years owing to stochastic factors such as lightning strikes, arson and hazard reduction burns and burns escaping from adjacent private property. However, it is likely that the overall fire frequency is much higher owing to the occurrence of many small fires which remain unreported and therefore not on the public record. The most recent wildfire in October 2002 burnt about 8,000 ha of the reserve to the north and east of Torrington (NSW National Park & Wildlife Service 2004).

Chapter 3- Methods and materials ______3.6 Soil seed bank field-sampling methods

Four sites (forest habitat 1 & 2 and outcrop 1 & 2) were selected for soil sample collection. Four 20m long transects were randomly established at each site representing long-burnt (> 10 years) dry sclerophyll forest patches 1 & 2 and recent-burnt (18 months) dry sclerophyll forest patches 1 & 2. Ten soil samples were pooled at every 2m of each transect. Each soil core was approximately 10 cm in diameter by 5 cm depth including ash, duff and litter layers. Similar transects were established for the rocky habitats of the study sites (long-burnt rocky outcrops 1 & 2 and recent-burnt rocky outcrops 1 & 2). Samplings were carried out in the same way as the forest habitats. Soil samples were immediately put into plastic containers labeled with its site location. As there were four study patches at each of the rocky outcrops and forest habitats, a total of 32 soil samples were collected. All the soil samples were collected in mid March 2004. Figure 3.5 represents the schematic diagrams of field sampling methods. In the laboratory, the soil samples were dried under room temperature for a period of one week to inhibit seed germination and to ensure seeds did not rot in the soil.

Chapter 3- Methods and materials

______

TSF

(>10years)

atch II atch

TSF

Forest p Forest

(18 months) (18

TSF

(>10years)

Forest patch I patch Forest

TSF

(18 months) (18

Habitats

TSF

(>10years)

Replicate 4. Replicate

TSF

Rocky outcrop II outcrop Rocky

(18 months) (18

Replicate 3, R4

TSF

(>10years)

Replicate 2, R3

Schematic diagram indicating the field the indicating diagram sampling methods Schematic

Rocky outcrop I outcrop Rocky R4

since fire

TSF

(18 months) (18

Time

Replicate 1, R2

Figure 3.5. 3.5. Figure TSF R1 R1

Chapter 3- Methods and materials ______3.7 Vegetation sampling

Vegetation sampling was undertaken to determine the coverage and density of each species under study in both long burnt and recent burnt sites of both rocky outcrops and surrounding forest habitats following two weeks of soil sampling. Transects were established at the previous soil sampling of each site that measured 20m x 2m. Different plant species growing within one meter wide on either side of each transect at each site were identified to species level.

3.8 Glasshouse experimental design

To determine the promotive effects of fire-related germination cues on soil-stored seed banks, the soil samples were exposed to individual and combinatorial treatments effect in the glasshouse. Each soil sample collected from both rocky outcrops and forest patches were spit into four parts in the splitter, consequently a total of 128 samples were obtained. Sixty four samples of the total of 128 were treated with the heat shock in the electric oven at 80 o C for 5 minutes and then gently crumbled over the sterile sand in the trays for heat, and the combined effect of heat and smoke treatments respectively. The other 64 samples were not subjected to the heat shock treatment and were finely spread over the sterile sand surface of each tray for water and smoked water treatments (see Fig. 3.6).

The glasshouse experiment was set up on March 26, 2004 (Fig. 3.6). A total of 128 trays were established in the Mesacozom greenhouse, Department of Botany, UNE with descriptive labeling of each tray according to sites. Each tray was 270 by 330 mm in size. Sand was sterilized at 110o C for 24 hours in the electric oven. Sterile sand was then finely spread 1 cm depth in each tray (Fig. 3.7).

Chapter 3- Methods and materials ______

Soil-borne seed bank samples

Rocky outcrops I & II Forest habitats I & II

Treatments Treatments

Heat Smoke Heat + smoke Water Heat Smoke Heat+ smoke Water

Figure 3.6. Schematic diagram showing the glasshouse experimental design.

Concentrated smoked water was prepared in the water smoking apparatus by burning some Eucalyptus litter (Fig. 3.8). 1000 ml of concentrated smoked water was diluted with rainwater in the ratio of 1: 6. 200 ml of smoked water was then sprinkled over every soil sample for heat smoke and smoke treatments. 200 ml of rainwater was similarly sprinkled over the rest of the samples, which were set up for heat and water treatments. An hour of settling time was allowed for all the samples established in the glasshouse before finally added rainwater.

The temperature in the greenhouse was maintained at a minimum of 12.5 - 15 o C and maximum of 28 – 34 o C. The trays were watered daily with rainwater and randomized every two weeks of time to obtain an equal distribution of light for all emerging seedlings.

Levels of new seedling emergence were monitored after two weeks of setting up the greenhouse experiment. Seedling emergence was not observed for the first 3 weeks. However, a massive flush of germination occurred at 3-6 weeks, with germination peaking after 6 weeks. The first census was conducted on April 13, 2004 (Fig. 3.9). Subsequent censuses were repeated every week for the first six weeks of vigorous

Chapter 3- Methods and materials ______seedling emergence. After 6 weeks, a census was conducted for every two weeks as seedling emergence declined. Different seedlings were recorded in the spreadsheet based on given names and they were individually pinned to avoid miscounting in the following census records. Different coloured pins were used in every census conducted. New emergence of seedlings was specifically recorded in the spreadsheet.

When the seedlings attained their true leaves, they were individually transplanted into a separate pot where they were placed under the mister in another greenhouse allowing them to establish their roots in the new pots for at least two weeks. A very small number (< 0.5 %) of seedlings died shortly after transplantation, presumably from damage incurred during the process of transplantation and they were replaced by the new ones. After their roots were well established in the pots, the seedlings were again brought back to the original greenhouse and were watered every alternate day. The seedlings were identified to species level where possible.

The pins were removed from the trays after eight weeks of censuses were conducted as there was no further sign of seedling emergence and remnant soil samples in the trays were allowed to dry considerably in the glasshouse for two weeks. Once the soil had considerably dried, the upper hard soils in the trays were thoroughly scarified and crumbled without disturbing the sand beneath and the trays were watered daily to see if any new seedlings emerged. A small number of seedling emergences mostly occurred from the unburnt sites of rocky outcrops after 3 weeks of soil scarification. Seedlings were identified to species level and recorded in the spreadsheet.

Chapter 3- Methods and materials ______

Figure 3.7 Arrangement of sampling trays in the greenhouse.

Chapter 3- Methods and materials ______

Figure 3.8 Method for the production of smoke. Smoke was sucked through a flask filled with distilled water for 20 minutes.

Chapter 3- Methods and materials ______

Figure 3.9 Example of emergence of seedlings after the 3rd week in the greenhouse trials. The seedling in lower photograph with the long cotyledons is Dodonaea hirstuta, a rock outcrop shrub species.

Chapter 3- Methods and materials ______3.9 Numerical and statistical analyses

Census records on the abundance of individuals and species were compiled in a single spreadsheet. Counts on the seedling emergence of individual germinants recorded during the trial duration of nine weeks in the glasshouse were identified to species level. Individual species were grouped according to their growth forms to aid the interpretation on the effects of different treatments, time-since fire and habitats, and their abundance scores were summed to provide the abundance of each growth form. Five growth form groups were derived by separating herbaceous species into three groups: (i) grasses, (ii) graminoids, and (iii) forbs; and woody species into two groups: (iv) shrubs and (v) trees. In addition to the five growth form groups, woody plant species were further classified as „resprouters‟ and „obligate seeders‟ in order to assess whether resprouters were advantaged over obligate seeders by particular fire regime and habitats.

The computer package Stat View was used for univariate data analyses. Significant differences among treatments, variable time-since fire (long burnt and recent burnt) and habitats (rocky outcrops and forest habitats) were assessed through univariate analyses. The effects of the individual and combinatorial treatments, time-since fire and habitats on the seedling emergence and species richness were analyzed both descriptively and statistically by three factor ANOVA test. Details of the univariate analyses are discussed in chapter 4.

Furthermore, species richness of different growth forms of the ground standing vegetation at the study sites were assessed through univariate analyses and their results are discussed in detail in chapter 5.

The computer package Canoco for Windows 4.5 was used for multivariate analyses in order to determine whether there were pattern differences in the floristic composition of each growth form of plant species on the influence of variables, time-since fire and habitats. Details of multivariate analyses are discussed in chapter 6.

Chapter 4 – Univariate analyses of soil seed banks ______CHAPTER – 4 UNIVARIATE ANALYSES OF SOIL SEED BANKS

4.1 Analyses of seedling numbers

4.1.1 Descriptive analysis

A total of 1766 seedlings were recorded from the 128 sample trays over the trial duration of 9 weeks in the glasshouse (Table 4.1). Of the total, 1522 seedlings were recorded from the rocky outcrop samples and the other 244 seedlings from the forest samples.

There were a total of 1351 individuals recorded from the long-burnt soil samples and 415 individuals from the recent-burnt soil samples. However, germinants were mostly recorded from the samples of long-burnt outcrops than long-burnt forest habitats. In total, 1157 germinants were recorded from the long-burnt outcrop samples and only 194 germinants were shown to be germinated from the long-burnt forest samples (Table 4.1). Seedlings of herbaceous species were more abundant than seedlings of woody species especially on rocky outcrop habitats (Table 4.1).

Table 4.1 Total number of germinants in the soil samples collected from the outcrops and forest habitats with different fire history. TSF= time-since fire.

Habitats/TSF Herbaceous Woody species Total germinants Rocky long burnt (>10 yrs.) 958 119 1157 Forest long burnt (>10 yrs.) 94 100 194 Rocky recent burnt (18 months) 262 103 365 Forest recent burnt (18 months 33 17 50 Total individuals 1347 419 1766

Chapter 4 – Univariate analyses of soil seed banks ______4.1.2 Statistical analyses of seedling germination responses to treatments, time-since- fire and habitats

Statistical test (three-way ANOVA) performed for the individual treatment effect of heat, smoke and the combinatorial treatment effect of heat and smoke on germinable seed banks was generally not significantly different from the control treatment (Table 4.2; Appendix 4.1a). However, the effects of time-since-fire and habitats have highly significant effect on the emergence of total number of seedlings (Table 4.2; Fig. 4.1; Appendix 4.1a). Overall, the interaction between habitats and time-since-fire was also significant for some growth forms (Table 4.2; Fig. 4.1; Appendix 4.1a).

60 heat

50 heat+smoke smoked water 40 water

No. of seedlings of No. 10

DSF, recent burnt (18m) burnt recent DSF,

DSF, long burnt (>10 yrs.) (>10 burnt long DSF, (18m) burnt recent Rocky, Rocky, long burnt (>10 yrs.) (>10 burnt long Rocky,

Figure 4.1 Mean (+ Se) number of all seedlings emergence after trial duration of 9 weeks in the glasshouse for each treatment of habitat and time-since-fire. DSF= dry sclerophyll forest.

Chapter 4 – Univariate analyses of soil seed banks ______Table 4.2 Summary results of three-ways ANOVA test performed for the responses of the total number of individuals of different growth forms to treatments, time-since-fire (TSF) and habitats. Significance levels: (**** = p<0.0001; *** = p<0.001; ** = p< 0.01; * = p<0.05; ns= not significant).

Factors

All seedlings All Grasses Graminoids Forbs herbaceous All Resprouters seeders Obligate woody All Habitats **** ** *** **** **** *** *** **** Time-since fire (TSF) *** ** ** * **** ** **** **** Treatments ns ns Ns ns ns * ns * Habitats x TSF *** ns ** * *** ns *** ns Habitats x treatments ns ns Ns ns ns ns ns ns TSF x treatments ns ns Ns ns ns ns ns ns Habitats x TSF x treatments ns ns Ns ns ns ns ns ns

4.1.3 Grass seedlings response to treatments, time-since-fire and habitats

A total of 257 grass seedlings were recorded from the glasshouse experiment, which comprised 14.5% of total individuals. Treatments as a factor did not indicate any significant effect on the emergence of seedlings in the soil samples (Table 4.2; Appendix 4.1b). However, time-since-fire and habitats have a marked effect. Long-burnt samples had significantly more seedlings than recent-burnt samples (Fig. 4.2a; Table 4.2; Appendix 4.1b). In addition, seedling emergence was significantly more abundant in the rocky outcrop samples than forest ones and this was consistent in both recent-burnt and long-since-burnt sites (Fig. 4.2a; Table 4.2; Appendix 4.1b).

Chapter 4 – Univariate analyses of soil seed banks ______4.1.4 Graminoid seedlings response to treatments, time-since-fire and habitats

A total of 411 graminoid seedlings were recorded from the soil seed bank experiment. Graminoids represented 23.2% of the total number of seedlings germinated from the samples. The effect of treatments on the abundance of seedling emergence was not significant (Fig. 4.3; Table 4.2; Appendix 4.1c). The two environmental variables such as habitats and time-since fire were significantly related to the total number of seedling emergence. Long time-since-fire and rocky habitats showed a significantly enhanced abundance of individuals in the samples (Table 4.2; Appendix 4.1c; Fig. 4.2b).

4.1.5 Number of forb individuals response to treatments, time-since-fire and habitats

Forbs dominated the overall composition of the soil seed banks in terms of the total number of germinable seeds in the samples. A total of 679 individuals were recorded, which represented 38.4 % of total germinants. There was no significant difference detected on the emergence of seedlings among treatments. Comparisons of germinants that responded to different habitats and time-since-fire showed that outcrops and long- burnt sites have significantly stimulated the germinable seed banks in the samples showing a similar pattern to grasses and graminoids (Appendix 4.1.d; Table 4.2; Fig. 4.2c).

4.1.6 Total number of obligate seeder shrubs response to treatments, time-since-fire and habitats

There were 102 individuals of obligate seeder shrubs recorded from the experiment, which comprised 24.3 % of total individual woody germinants and 4.5 % of total emergence. Treatments and their interactions did not show any significant effect. On the other hand, long time-since-fire and the rocky habitats have significantly shown a marked effect on the greater accumulation of soil seed banks (Table 4.2; Appendix 4.1e; Fig.

Chapter 4 – Univariate analyses of soil seed banks ______4.3a). Nevertheless, the number of shrub seedlings was far less than the herbaceous species.

4.1.7 Total number of resprouting shrubs response to treatments, time-since-fire and habitats

In total, 317 individuals of resprouter woody species (mostly shrubs) were recorded from the samples, which represented the majority (75.6 %) of total woody individuals and 17.95 % of total germinants. Germination was significantly influenced by all the three factors; of them, the habitats effect was the most powerful vector (Table 4.2). However, none of the interactions was significant (Table 4.2; Appendix 4.1.f; Fig. 4.3b). Heat stimulated germination of species and rocky outcrop habitats had more germinants than the forest sites particularly in the recently burnt samples.

4.1.8 Total number of woody individuals response to treatments, time-since-fire and habitats

Woody plants as a group represented 23.7 % of total number of seeds that germinated. Germination rate was significantly affected by all the three variables, i.e. habitats, time- since-fire and fire-related treatments. Treatments effect was marginally significant with a stimulation of germination of heat. However, the effects of habitats and time-since fire were highly significant. Seedling emergences were vigorously influenced by the rocky outcrop habitats and long-time-since-fire. Greater numbers of woody individuals were recorded from the long-burnt sites of rocky outcrop habitats than the forest habitats (Appendix 4.1g; Table 4.2; Fig. 4.2f).

Chapter 4 – Univariate analyses of soil seed banks ______(a) Grasses (b) Graminoids

10 long burnt (>10 yrs.) long burnt (>10 yrs.) 16 recent burnt (18m) recent burnt (18m) 14 8 12

6 10

8 4

6 Grass seedlings Grass 2 4

Graminoid seedlings Graminoid 2 0 0 DSF rocky DSF Rocky Habitats Habitats

long burnt (>10 yrs.) 3 16 recent burnt (18m) long burnt (>10 yrs.) 14 recent burnt (18m)

12 2 10

6 1 Obligate seeders Obligate

Forb seedlings Forb 4

0 0 DSF Rocky DSF rocky Habitats Habitats

Figure 4.2 Mean (+ s.e.) number of germinants for different growth forms of each treatment, habitats and time-since-fire: (a) grasses, (b) graminoids, (c) forbs, (d) obligate seeders woody plants.

Chapter 4 – Univariate analyses of soil seed banks ______(a) Resprouters (b) Woody individuals

8 heat 12 heat 7 heat+smoke heat+smoke 10 6 smoked water smoked water water 5 water 8

4 6 3 4

2 Woody individuals Woody Resprouters 2 1

0 0

DSF, recent burnt (18m) burnt recent DSF,

rocky, recent burnt (18m) burnt recent rocky,

DSF, long burnt (>10 yrs.) (>10 burnt long DSF,

DSF, long burnt (>10 yrs.) (>10 burnt long DSF, rocky, long burnt (>10 yrs.) (>10 burnt long rocky, yrs.) (>10 burnt long rocky,

Figure 4.3 Mean (+ s.e.) number of germinants for different growth forms of each treatment, habitats and time-since-fire: (a) resprouters woody species (b) woody individuals.

Chapter 4 – Univariate analyses of soil seed banks ______4.2 Analyses of species richness

One thousand seven hundred and sixty six germinants recorded in the glasshouse experiment were identified as belonging to 44 species from 38 genera and 23 families; comprising 21 woody species, 17 forb species, 3 graminoid species and 3 grass species (Appendix 4.3). The most prominent families were Fabaceae (8 woody species), Myrtaceae (4 woody species), Apiaceae (4 forb species), followed by Epacridaceae (3 woody species), Poaceae (3 species) and Asteraceae (3 forb species) (Appendix 4.3).

The soil seed bank samples contained fewer species than the ground standing vegetation at the study sites although this pattern probably reflects the smaller sampling area for the soil-borne seed bank survey. There was a substantial difference in the abundance of species when species recorded from the samples were compared to those present at the ground standing vegetation. A total of 44 species were recorded from the soil samples and contrastingly, 134 species were obtained in records from the ground standing vegetation along all the transects (Table 4.3).

Table 4.3 Total number of species obtained in record from the sites and the soil samples with their percentage proportion.

No. species in No. species in standing Life forms samples (%) vegetation (%) Grasses 3 6.82 14 10.45 Graminoids 3 6.82 16 11.94 Forbs 17 38.64 28 20.89 Resprouters 12 27.27 45 33.59 Obligate seeders 9 20.45 31 23.13

Total 44 100 134 100

Chapter 4 – Univariate analyses of soil seed banks ______Table 4.4 Summary results of three-ways ANOVA test performed for the responses of the total number of species to treatments, time-since-fire (TSF) and habitats. Significance levels: (**** = p<0.0001; *** = p<0.001; ** = p< 0.01; * = p<0.05; ns=

not significant).

cies

Grass species Grass species Graminoid species Forbs species Herbaceous Resprouters seeders Obligate spe woody All

Factors species All

Habitats **** *** **** **** **** * **** *** Time-since fire (TSF) **** *** **** ** **** ** **** **** Treatments ** Ns ** * ** * ns * Habitats x TSF ns Ns **** ns * * ** ns Habitats x treatments ns * ns * ns ns ns ns TSF x treatments ns Ns ** ns ns ns ns ns Habitats x TSF x treatments ns Ns * ns ns ns ns ns

4.2.1 Effects of treatments, time-since-fire and habitats on the composition of all species

Overall, there were significant trends in species richness as a function of treatments, time-since-fire and habitats (Table 4.4). Long time-since-fire and rocky outcrops had the greatest effect in the composition of species by increasing richness. Treatments also had a significant effect for overall species diversity with enhanced emergence in the heat treatments especially on the rocky outcrops (Table 4.4; Appendix 4.2a; Fig. 4.3).

Chapter 4 – Univariate analyses of soil seed banks ______

14 heat 12 heat+smoke smoked water 10 water 8 6

No. of species of No. 4 2

DSF, recent burnt (18m) burnt recent DSF,

rocky, recent burnt (18m) burnt recent rocky, DSF, long burnt (>10 yrs.) (>10 burnt long DSF, rocky, long burnt (>10 yrs.) (>10 burnt long rocky,

Figure 4.3 Mean (+ s.e.) species richness of the germinable soil seed banks in each treatment, habitats and time-since fire.

4.2.2 Number of grass species response to treatments, time-since-fire and habitats

A total of 257 grass seedlings that germinated in the samples were identified to 3 species level, which comprised 6.8% of total species. Three ways analysis of variance (ANOVA) test performed for the species richness of grass indicated no significant differences among the fire-related treatments. However, the abundance of grass species was significantly enhanced by the time-since-fire and habitats. Greater numbers of seedlings were shown from the sites with a long-burnt history and rocky outcrop habitats with enhanced emergence in the heat treatment especially on the rocky outcrop habitats but

Chapter 4 – Univariate analyses of soil seed banks ______not in the forest sites, hence the significant interaction of habitats and treatments (Table 4.4; Appendix 4.2b; Fig. 4.4a).

4.2.3 Total number of graminoid species response to treatments, time-since-fire and habitats

Graminoids comprised 6.8% of total species in the experiment. Significant differences were detected among treatments, time-since-fire and habitats. A statistical test (three- way ANOVA) was performed for the number of species among treatments, which indicated a significantly greater number of graminoid species was germinated from the fire-related treatments than the control treatment (Appendix 4.2c; Fig. 4.9). In addition, the test further confirmed that long time-since-fire and rocky habitats possess a greater number of species than short time-since-fire and forest habitats. Two-way interactions between habitats and time-since fire; time-since-fire and treatments, and three way interactions among habitats, time-since-fire and treatments were also significant. These interactions resulted from smoke induced emergence of Juncus planifolius, Lomandra filliformis and Laxmannia gracilis (Table 4.4; Appendix 4.2c; Fig. 4.4b).

4.2.4 Total number of forb species response to treatments, time-since-fire and habitats

Forbs represented 38.6% of total species in the samples. All individual fire-related treatments (i.e. heat, smoke and combinatorial effect of heat and smoke) have significantly increased seed germination of forb species when compared to the control treatment. In addition, effects of long time-since-fire and outcrops were also found to exert significant influence on the emergence of forb species in the samples (Appendix 4.2d; Fig. 4.4c; Table 4.4). Enhanced emergence of forbs on rocky outcrops was mostly stimulated by heat but not in the forest samples resulting in a significant interaction of habitats versus treatments. These interactions between sites and treatments were induced by species such as Gnaphalium sphaericum, Gonocarpus tetragynus, Pomax umbellata,

Chapter 4 – Univariate analyses of soil seed banks ______Hydrocotyle pendicularis, Gonocarpus teucrioides, Bracryscome stuartii, Drosera auriculata, Trachymene incisa, Actinolus gibbonsii, Gonocarpus micranthus and Polymeria calycina (Appendix 4.2d).

4.2.5 Total number of herbaceous species response to treatments, time-since-fire and habitats

Overall, herbaceous species comprised 38.6% of total species that germinated. Three- ways analysis of variance (ANOVA) test performed for three variables such as time- since-fire, habitats and fire-related treatments effect indicate significant association with the species richness in the soil samples investigated, of which the effects of habitats and time-since-fire were the most powerful factors. One of the three variables (i.e. interaction between habitats and time-since-fire) was also significantly associated with the richness of the species and this was mostly enhanced by species such as Lomandra filliformis (266), Gnaphalium sphaericum (193), Entolasia stricta (136), Gonocarpus tetragynus (132), Eragrostis leptostachya (112) and Pomax umbellata (89) (Table 4.4; Appendix 4.2e; Fig. 4.4d).

4.2.6 Total number of woody species response to treatments, time-since-fire and habitats

Woody plants represented 47.7% of the total species that germinated in the samples. Analysis of variance (ANOVA) test performed for the species richness indicated significant differences between habitats, time-since-fire and fire-related treatments effect. There were greater numbers of woody species shown from the rocky outcrops than forest habitats. Species diversity was even more significant in long-burnt samples than recent- burnt samples (Appendix 4.2f; Fig. 4.5a; Table 4.4). Woody species that occurred at the highest density in the soil seed bank samples were Leptosperum arachnoides, Pultanaea foliolosa, Baeckea densifolia, Callitris endlicheri, Calytrix tetragona, Aotus subglauca var. subglauca, Leucopogon microphyllus, and Bossiaea obcordata (Appendix 4.3).

Chapter 4 – Univariate analyses of soil seed banks ______

4.2.7 Total number of resprouting shrubs response to treatments, time-since-fire and habitats

Resprouting shrubs comprised 57% of total woody species and 27% of all species in the samples. Treatments effect on the emergence of reprouters was marginally significant (Table 4.4). Species richness also declined by short time-since-fire. There were significantly more species in the outcrops than forest matrix. Interaction between habitats and time-since-fire was also significant and resulted from the enhanced germination of the resprouting shrubs such as Leptospermum arcachnoides, Pultanaea foliosa, Baeckea densifolia, Aotus subglauca and Bossiaea obcordata (Appendix 4.2g; Fig. 4.5b; Table 4.4).

4.2.8 Total number of obligate seeder shrubs response to treatments, time-since-fire and habitats

Woody obligate seeders represented 43% of total woody species and 20% of total species that germinated in the samples. Statistical test (ANOVA) indicated that they did not differ in abundance among treatments. However, high significant differences were detected in time-since-fire and habitats. Long time-since-fire had shown a highly significant difference than short time-since-fire. In addition, rocky outcrops comprised a substantially higher proportion of obligate seeders than forest habitats suggesting a highly significant difference (Fig. 4.5c; Table 4.4). Furthermore, there was a significant interaction of habitats and time-since-fire and this pattern in the samples was mostly enhanced by two species such as Callitris endlicheri and Calytrix tetragona (Fig. 4.5c; Appendix 4.2h; Table 4.4).

Chapter 4 – Univariate analyses of soil seed banks ______(a) Grass species (b) Graminoid species

heat heat heat+smoke heat+smoke smoked water 2 smoked water water water 1

Grass species Grass Graminoid species Graminoid

0 0

DSF, recent burnt (18m) burnt recent DSF,

DSF, recent burnt (18m) burnt DSF,recent

rocky, recent burnt (18m) burnt recent rocky,

DSF, long burnt (>10 yrs.) (>10 burnt long DSF,

DSF, long burnt (>10 yrs.) (>10 burnt DSF,long rocky, long burnt (>10 yrs.) (>10 burnt long rocky, rocky, long burnt (>10 yrs.) (>10 burnt long rocky,

6 heat 9 heat heat+smoke 5 8 heat+smoke smoked water 7 smoked water 4 water 6 water 3 5 4 2 3 Forb speciesForb 1 2

Herbaceous species Herbaceous 1

0 0

DSF, recent burnt (18m) burnt DSF,recent

rocky, recent burnt (18m) burnt recent rocky,

DSF, long burnt (>10 yrs.) (>10 burnt DSF,long

DSF, long burnt (>10 yrs.) (>10 burnt DSF,long rocky, long burnt (>10 yrs.) (>10 burnt long rocky, rocky, long burnt (>10 yrs.) (>10 burnt long rocky,

Figure 4.4 Mean (+s.e.) number of species richness of the germinable soil seed banks in each treatment, habitats and time-since-fire: (a) grass species, (b) graminoid species, (c) forb species, (d) herb species.

Chapter 4 – Univariate analyses of soil seed banks ______(a) Woody species

heat 4 heat+smoke smoked water 3 water 2

Woody species Woody 1

DSF, recent burnt (18m) burnt DSF,recent

rocky, recent burnt (18m) burnt recent rocky, DSF, long burnt (>10 yrs.) (>10 burnt DSF,long rocky, long burnt (>10 yrs.) (>10 burnt long rocky,

(b) Resprouter (c) Obligate seeders

heat 3 heat+smoke 2 heat 2.5 smoked water heat+smoke water 2 smoked water water 1.5 1

1 Resprouters

.5 Obligate seeders Obligate 0

DSF, recent burnt (18m) burnt recent DSF,

DSF, recent burnt (18m) burnt DSF,recent

rocky, recent burnt (18m) burnt recent rocky,

DSF, long burnt (>10 yrs.) (>10 burnt long DSF,

DSF, long burnt (>10 yrs.) (>10 burnt DSF,long rocky, long burnt (>10 yrs.) (>10 burnt long rocky, yrs.) (>10 burnt long rocky,

Figure 4.5 Mean (+s.e.) number of species richness of the germinable soil seed banks in each treatment, habitats and time-since-fire: (a) woody species (b) resprouters, (c) obligate seeders.

Chapter 4 – Univariate analyses of soil seed banks ______4.3 Discussion

4.3.1 Species richness and abundance

Rocky outcrops and forest habitats had different degrees of soil seed banks accumulation for different life forms of plant species prior to fire regimes. The present study supports the idea that the effects of time-since-fire and habitats have a marked effect in sculpting the attributes of both rocky and forest plant communities. Both time-since-fire and habitats had significant impacts on the germinable seed banks investigated, affecting both community floristic and the abundance of individual species. Outcrop seed banks contained significantly more species and individuals than forest seed banks. This may be because rocky habitats experience longer fire-free intervals and their rocky surroundings further lower the intensity of fire. Some of the hard-seeded species especially legumes require high intensity of fire to enhance their germination (Watson & Johnson 2004). Forest seed banks differed in composition from virtually all rocky outcrop seed banks indicating that the dominant and regional patterns in the vegetation were manifested in the seed banks.

In general, fire-related treatments had very little impact on germinable seed banks and species compositions but, there was enhanced germination of hard-seeded legumes (e.g. Acacia pruniosa, Aotus subglauca, Pultanaea foliosa, Bossiaea obcordata) especially on the rocky outcrop samples when heat treatment was used. Herbaceous species as a group showed no significant differences in the abundance of both seedling emergence and species richness among heat and/or smoke treatments, which contrasts with several other findings of de Lange and Boucher (1990); Dixon et al. (1995); Read et al. (1999). Species that did not germinate in the seed bank trial experiment cannot be presumed totally absent from the samples as sampling and germination procedures sometimes may not have been appropriate for all species. Studies by Lunt (1995; 1996) and Morgan (1995) indicated that several common grass species, particularly those with large seed have little ability to develop long-term persistent soil seed banks as seeds readily germinate or they lose their viability. Moreover, some of the grassy understorey forest species do not possess dormancy.

Chapter 4 – Univariate analyses of soil seed banks ______However, this study supports the findings of Williams et al. (2003), who did not detect clear fire effects on grasses and forbs during a five-year experiment in eucalypt savanna at the Kapalga research station in the Northern Territory. Their findings indicate neither the abundance of herbs nor species richness responded to fire regimes. Many forbs and grasses at the study sites showed their germination at the start of each wet season irrespective of fire (Williams et al. 2003).

The effectiveness of fire-related treatments will entirely depend on the species composition of the topsoil seed banks. In communities where the topsoil seed reserve is dominated by hard seeded shrub species, the potential of a fire regime is likely to be lower (Read et al. 2000).

The dominance of the rocky outcrops soil seed bank reserves by resprouters in the current study contrasts with Clarke (2002) who reported that forest matrix was dominated by more resprouting shrubs than on the outcrops. Nevertheless, there were more species and numbers of obligate seeders on the rocky outcrops than the forest samples especially in long-burnt sites. The visual interpretation of this study is supported by the result of Clarke (2002), who found significantly greater number of obligate seeder species supported by rocky habitats than in the forest matrix. Differences in response may be the result of high intensity of fire where forests are likely to have higher fuel debris than granites or outcrops. This may explain the greater accumulation of soil seed reserve on the granite or rocky islands than forest habitats.

Overall germination of herbaceous individuals (i.e. grasses, graminoids/sedges, and forbs) in this current study indicates that there was a substantial number of germinants shown on rocky outcrops than forest habitats especially after fire. Such species, being annual plants, produce a greater amount of seeds during their life cycle (Lunt 1997; Tozer 1998), thus stores larger amount of seeds in the soil-borne seed banks, which usually dominates the plant community at the sites after fire (Williams 1984; Wang 1997; Williams et al. 2003). Such a pattern was not indicated in the forest habitats because short-term fire intervals had already influenced their germination and they are more closed habitats.

Chapter 4 – Univariate analyses of soil seed banks ______In conclusion, this study has confirmed that a soil-borne seed bank accumulation on outcrops and forest habitats was significantly influenced by the time-since-fire and habitats. The effect of rocky outcrops and long time-since-fire were evident in promoting both individual-level germination and species richness of grasses, graminoids, forbs and woody species. Although, overall, the effect of fire-related treatments at the individual level germination was less distinct yet it played a very crucial role in promoting species richness at community level.

Chapter 5- Univariate analyses of standing vegetation ______CHAPTER-5 UNIVARIATE ANALYSES OF STANDING VEGETATION

5.1 Dominant species in ground standing vegetations

On the outcrop study sites the two most common trees recorded were Callitris endlicheri and Eucalyptus prava and the dominant shrub species were Acacia torringtonensis, Baeckea densifolia, Brachyloma daphnoides, Dillwynia phylicoides, Dodonaea hirsuta, Hovea graniticola, Leptospermum trinervium, Leucopogon melalucoides, Leucopogon neo-anglica, Prosthanthera staurophylla, and Pultanaea foliosa.

By contrast, the adjacent forest habitats were mostly dominated by mixed shrubby stringy bark Eucalyptus caliginosa, Eucalyptus youmanii and Eucalyptus cameronii with low open-forest to woodland with a dense to sparse shrub layers of Acacia buxifolia, Aotus subglauca, Boronia microphylla, Bossiaea scortechenii, Davesia latifolia, Dillwynia phylicoides, Hibbertia riparia, Hibbertia vestida, Leptospermum trinervium, Leucopogon melalucoides, Monotoca scoparia, Personnia tenuifolia, Perophile canecens, Phyllanthus hirtelus and Pultanaea foliosa.

Ground covers are mainly dominated by the species of the families such as Poaceae, Cyperaceae, Goodeniaceae, Rubiaceae, Lomandraceae and Haloragaceae.

5.2 Species richness of ground vegetation at the study sites

A total of 134 different species were recorded from the ground standing vegetations of both rocky and forest study sites, comprising 14 grass species; 16 sedges/graminoids; 25 forbs; 45 resprouters and 31 obligate seeder woody plants. On average, the number of species did not differ significantly between habitats and time-since-fire. However, the significant effects of habitats on species richness were shown in woody resprouting shrubs and obligate seeders (Table 5.1; Appendix 5.1 f & g).

Chapter 5- Univariate analyses of standing vegetation ______Similarly, the effect of time-since-fire was indicated as affecting the species richness of forbs and woody obligate seeders at ground standing vegetations (Table 5.1; Appendix 5.1g).

Table 5.1 Summary results of analysis of variance (ANOVA) test performed for the ground standing vegetation for species richness in response to time-since fire (TSF) and habitats. Significance levels: (**** = p<0.0001; *** = p<0.001; ** = p< 0.01; * =

p<0.05; ns= not significant).

minoids

Factors

All species All Grasses Gra Forbs Herbaceous Resprouters Obligateseeders woody All species

Habitats ns ns ns ns ns **** **** ns

Time-since fire (TSF) ns ns ns * ns ns ** ns

Habitats x Time-since fire ns ns ns ns ns * ns ns

5.3 Effects of habitats and time-since-fire

At ground standing vegetation, the effect of habitats on plant community composition and species abundance did not differ significantly for grasses, graminoids and forbs (Table 5.1; Fig. 5.1a,b&c; Appendix 5.1b,c&d). However, highly significant differences were detected in both woody resprouting shrubs and obligate seeders. The study result indicated that forest habitats support greater abundance of woody resprouters than rocky outcrops. Similarly, the most woody dominant species on the rocky outcrops were obligate seeders (Table 5.1; Fig. 5.2 a & b; Appendix 5.1f).

Chapter 5- Univariate analyses of standing vegetation ______In resprouting shrubs, a significant difference was mainly enhanced by Acacia buxifolia, Bossiaea obcordata, Davesia latifolia, Dillwynia phylicoides, Leptospermum trinervium, Leptospermum melalucoides, Monotoca scoparia, Personnia tenuifolia, Petrophile canescens, Phyllanthus hirtellus, Pultanaea foliosa and Eucalyptus andrewsii in the forest habitats (Table 5.1; Fig. 5.2 a; Appendix 5.1f).

Similarly, in woody obligate seeders, a significant trend was enhanced by the dominant species such as Dillwynia sericea, Dodonaea hirsuta, Hovea graniticola, Leucopogon microphylla, Leucopogon neo-anglica, Mirbelia speciosa, Micromyrtus sessilis, Prosthanthera staurophylla, Persoonia cornifolia and Callitris endlicheri in the rocky outcrops (Table 5.1; Fig. 5.2 b; Appendix 5.1g).

The effect of time-since-fire showed significant differences in forbs and woody obligate seeders in the ground standing vegetation (Table 5.1; Fig. 5.1c; Fig. 5.2b; Appendix 5.1d&g). In forbs, a significant difference was enhanced by the ground dominant forb species such as Goodenia bellidifolia, Goodenia hederacea, Poranthera corymbosa, Wahlenbergia communis, Trachymene incise and Lagenifera stipitata being more abundant in the forest habitats. In woody obligate seeders, a similar pattern was induced by Dillwynia sericea, Dodonaea hirsuta, Hovea graniticola, Leucopogon microphylla, Leucopogon neo-anglica, Mirbelia speciosa, Micromyrtus sessilis, Prosthanthera staurophylla, Persoonia cornifolia and Callitris endlicheri being more abundant in the rocky outcrops (Table 5.1; Fig. 5.1c; Appendix 5.1d).

Furthermore, there was a significant interaction brought about between habitats and time- since-fire on the resprouting shrubs and such a pattern was enhanced by Acacia buxifolia, Bossiaea obcordata, Davesia latifolia, Dillwynia phylicoides, Leptospermum trinervium, Leptospermum melalucoides, Monotoca scoparia, Personnia tenuifolia, Petrophile canescens, Phyllanthus hirtellus and Pultanaea foliosa being more abundant in the forest habitats (Table 5.1; Appendix 5.1f).

Chapter 5- Univariate analyses of standing vegetation ______

(a) Grass species (b) Graminoids

Long burnt >10 yrs.) Long burnt >10 yrs.) 5 Recent burnt (18m) 4 Recent burnt (18m)

4 3

2 2

1 1

Speciesrichness Speciesrichness

0 0 Forest Rocky Forest Rocky Habitats Habitats

Long burnt >10 yrs.) 6 Long burnt >10 yrs.) Recent burnt (18m) 14 Recent burnt (18m) 5 12

4 10

3 8

6 2

4 Speciesrichness 1 Speciesrichness 2

0 0 Forest Rocky Forest Rocky Habitats Habitats

Figure 5.1 Mean (+s.e.) number of species richness of ground standing vegetations in each habitat and time-since fire: (a) grass species, (b) graminoid species, (c) forb species, (d) herbaceous species

Chapter 5- Univariate analyses of standing vegetation ______

(a) Resprouters (b) Obligate seeders

14 Long burnt >10 yrs.) Recent burnt (18m) Long burnt >10 yrs.) 12 9 Recent burnt (18m) 8 10 7 8 6 5 6 4

4 3 Speciesrichness

Speciesrichness 2 2 1 0 0 Forest Rocky Forest Rocky Habitats Habitats

Long burnt >10 yrs.) Long burnt >10 yrs.) Recent burnt (18m) 16 Recent burnt (18m) 24 14 22 20 12 18 16 10 14 8 12 10 6 8

4 6 Speciesrichness Speciesrichness 4 2 2 0 0 Forest Rocky Forest Rocky Habitats Habitats

Figure 5.2 Mean (+s.e.) number of species richness of ground standing vegetations in each habitat and time-since fire: (a) resprouters (obligate seeders (c) all woody species (d) all species.

Chapter 5- Univariate analyses of standing vegetation ______5.4 Discussion

As expected, forest habitats support greater species richness of resprouting woody plants than rocky outcrops. Significant habitats x time-since-fire interaction were found for resprouting shrubs and such a pattern at community-level was mainly enhanced by the dominant species of Acacia buxifolia, Bossiaea obcordata, Davesia latifolia, Dillwynia phylicoides, Leptospermum trinervium, Leptospermum melalucoides, Monotoca scoparia, Personnia tenuifolia, Petrophile canescens, Phyllanthus hirtellus, Pultanaea foliosa, Eucalyptus andrewsii and Eucalyptus prava. This result supports the findings of Clarke and Knox (2002) on the post-fire response of shrubs on the tablelands of eastern Australia. Their study indicated more than 70% of species resprout after fire and the most dominant species in the shrubby forests, heath-lands and grassy forests were all resprouters while the dominant species on rocky outcrops were mostly obligate seeders.

Similarly, woody obligate seeders were found to be the most dominant species on the rocky outcrops. The study confirmed that the richness of woody obligate seeders was significantly affected by time-since-fire. Greater richness of woody obligate seeders was detected in the habitats with long time-since-fire than habitats with short time-since-fire. The results of this study are similar to that found in kwongon in southwestern Australia (Meney et al. 1994) and Clarke and Knox (2002) where obligate seeders rely entirely on seed produced by the parent plants in the years between disturbances for their survival hence suggesting that these species do not have the ability to set seed and accumulate seed banks in the habitats with short time-since-fire.

Furthermore, richness of forbs was also significantly affected by time-since-fire in the ground standing vegetation. There was higher richness of forbs species in the short-burnt sites than long-burnt sites. Such a pattern in this study indicates that short time-since-fire may be very influential in shaping post fire communities of these annual species especially on the rocky outcrops.

Chapter 6- Multivariate analyses ______CHAPTER -6 MULTIVARIATE ANALYSIS

6.1 Introduction

Canonical Correspondence Analysis (CCA) is a widely used tool in multivariate analyses for ecological research. The contents of an ordination diagram can be used to determine the correlations or dissimilarities between individual species and sites. Ordination analysis, using available environmental variables can also be used to determine the relationship between the species and the environmental variables, the correlations among environmental variables and approximate the contents of the environmental data table (Makarenkov & Legendre 2002; Leps & Smilauer 2003).

In my present study, floristic patterns of vegetation distribution data obtained from the soil seed bank samples were explored by multivariate analysis in Canonical Correspondence Analysis (CCA) with regard to variables such as habitats and time-since- fire using log transformed data. The Canonical Correspondence Analysis (CCA) generates ordination axes that are linear combinations of environmental variables and determines the floristic composition in ordinal space.

6.2 Methods

Canoco was used to aid the ecological interpretation of community patterns, vegetation distribution and species richness in relation to environmental variables such as habitats (rocky and forest) and time-since-fire (recent and long burnt sites). The relationship of the fire regime and environmental variables to the ordination patterns was explored through multivariate analysis of similarity, using Correspondence Analysis (CA). In addition, species-environmental covariables (habitats and time-since-fire) correlations were assessed with CCA. Furthermore, CCA with passive variables were explored to assess species richness for plant growth forms.

Chapter 6- Multivariate analyses ______6.3 Results

Species-sites biplot from Correspondence Analysis (CA) ordination based on total germinant density for 44 species recorded from the soil samples showed strong clustering in relation to habitats and time-since-fire (Fig. 6.1). However, woody resprouting shrub species such as Acacia buxifolia, Boronia algida, Bossiaea obcordate, Davesia latifolia, Hakea laevipes, and a single woody obligate seeder Leucopogon microphyllus were widely separated, demonstrating dissimilarity in habitats. In addition, only one forb species, Poranthera corymbosa was widely separated from the rest of the species (Fig. 6.1). Overall, samples from environmental variables; habitats (long & recent burnt sites) and time-since-fire (long & short) were tightly clustered, suggesting a high similarity among replicates.

Species-environmental covariables (habitats and time-since-fire) biplot ordination diagram indicated that first ordination axis (horizontal) negatively correlated with the second ordination axis (vertical) to a lesser extent (Fig. 6.2). Axis 1 represents habitats and axis 2 represents time-since-fire.

The Detrended Correspondence Analysis (DCA) with passive variables plot for species richness of plant growth forms indicated correlations among habitats and time-since-fire. Both forest long-burnt and recent-burnt sites were negatively correlated to species richness of plant growth forms (Fig. 6.3). However, rocky long-burnt sites indicated positive correlations with species richness of plant growth forms except in woody species in general and resprouting shrubs (Fig. 6.3).

Chapter 6- Multivariate analyses ______

6 Boronia

Acacia b

Callitri Gamochae Leucopog Eragrost Acacia t Juncus p Leucopog Laxmania Lomandra Bracysco 13 Gniphali Hydrocot Actinolu7 26 2324 22 3027 Gonocarp6 18 8 2911 324 Entolasi 21 171031 Gonacarp 5 14 12 Leptospe Davesia 1 161928 20 3 Pomax um Baeckea Calytric9 Aristida2 Acacia p Trachyme Hakea la Lobelia 15 Aotus su Dodonaea Eucalypt Polymeri Gonocarp Crassuli Drosera Pultanae Hovea gr ProsthanZieria l Actinolu Bossiaea

Leucopog

Poranthe -4 -4 5

Figure 6.1 Species-environment biplot from Correspondence Analysis (CA) summarizing the species composition of 44 plant species. Axis 1 is horizontal and axis 2 is vertical. Species are labelled by their generic names. The composition of species defined the position of sampling point (∆) in relation to the sites/habitats and time-since- fire. Rocky recent burnt (■); forest recent burnt (●); rocky long-burnt (■); forest long- burnt (●).

Chapter 6- Multivariate analyses

______2.5

Short TS 13 7 26 24 23

22 30 27 18 8 Rcoky 6 29 11 4 3217 31 21 10 12 5 14 19 1 28 20 16 Forest 3

9 2 Long TSF

15 -0.5 -1.0 2.0

Figure 6.2 The species-environmental variables biplot from Canonical Analysis Correspondence (CCA) with 44 plant species summarizing differences in floristic composition in relation to habitats and time-since-fire. Axis 1 represents habitats and axis 2 represents time-since-fire.

Chapter 6- Multivariate analyses

______2.5

7 26 24 23 graminoi 30 22 27 obligate 18 8 6 29 11 4 3217 grass ri 31 21 10 herbs ri 12 5 14 19 1 28 16 20 forbs ri 3 all wood

9 2 resprout

15 -0.5 -1.0 2.0

Figure 6.3 Detrended Correspondence Analysis (DCA) ordination diagram with passive variables for species richness of grasses, graminoids, forbs, herbs, resprouters, obligate seeders and all woody species. Axis 1 is horizontal and axis 2 is vertical. Longer arrows indicate a greater correlation between the ordination axes and the habitats. Rocky recent burnt (■); forest recent burnt (●); rocky long-burnt (■); forest long-burnt (●).

Chapter 6- Multivariate analyses ______6.4 Discussion

The Canonical Correspondence Analysis (CCA) ordination performed on 44 different species recorded in the soil samples confirmed that rocky outcrop seed bank samples have comparable floristic composition to forest seed bank samples.

The most common growth forms recorded on the basis of total germinants in the seed banks samples were forbs (679 individuals), followed by woody species (419 individuals) graminoids (411 individuals) and grasses (257 individuals) in terms of abundance. However, the most species-rich growth forms were woody species (21 species) followed by forbs (17 species), grasses and graminoids (three species each). Floristic composition, species richness and numbers of species correlate with the environmental variables between rocky outcrops and the forest habitats. Rocky outcrop seed banks had a similar species composition to forest seed banks. This reflects that outcrops share some common genera and families with the forest habitats.

In addition, rocky habitats showed a diverse range of plant species (higher species richness) than forest habitats. Short time-since-fire negatively correlated both in terms of species richness and abundance.

Chapter 7- General discussion and conclusion ______CHAPTER – 7 GENERAL DISCUSSION AND CONCLUSION

7.1 Discussion

As early as 1935, (e.g. Levyns 1935) and in subsequent research to date (e.g. Hill & French 2004; Thomas et al. 2003; Tang et al. 2003) plant-derived combustion products have been indicated to have a marked effect on the germinable soil seed banks in the fire- prone ecosystems. In addition, plant community composition and its relations to habitats and time-since-fire have been reported in several other studies (e.g. Morrison et al. 1995; Clarke & Knox 2002; Clarke 2002; 2003; Watson & Johnson 2004).

This study was designed to determine whether fire-related germination cues (i.e. heat, smoke and combinatorial effect of heat and smoke), habitats (rocky outcrops and forest habitats) and time-since-fire (long/short time-since-fire) have discernible effects on the germinable soil-borne seed banks of the fire-prone vegetations at the Torrington Conservation Reserve Areas.

7.1.1 Treatments effect on seedling emergence and species richness

In this study, the results indicate that the treatments effect were not distinct for numbers of germinations for some of the plant groups. The effect of individual fire-related treatments such as heat, smoke and combinatorial effect of heat and smoke was not found to influence the numbers of seedling emergence as compared to the control treatment. This result is consistent with the results of several other studies, which have indicated that heat treatment was not often successful for some woody plant species. For example, Edward and Whelan (1995) observed heat treatment of Gravillea barklyana was only successful when it resulted in obvious cracking of seed coats. A similar result was observed by Auld and Tozer (1995), whose study on pattern in emergence of Acacia and Grevillea seedlings did not significantly respond to a fire event. Williams et al. (2003) also observed a similar pattern during their five years experiment in eucalypt savanna at the Kapalgo research station in the Northern Territory.

Chapter 7- General discussion and conclusion ______There are at least two possible reasons why the fire-related treatments effect was not significant at individual-level germination. Either there was an initial flush of individual species, which do not require any more special treatment for triggering their germination and/or that for many species the treatments were not intense enough. The variability shown in this study suggests that level of fire-related germination cues within the soil profile would also be spatially heterogeneous, and hence the treatments effect and reaction of individual seeds would be quite variable across the entire seed banks. Kenny (2000) stated that some plant species failure to respond to heat treatment may be a result of either insufficient heat to give scarification, or too high temperature damaging the embryo.

Nevertheless, significant differences were detected in some of the woody plant groups e.g. resprouting legume species such as Pultanaea foliosa, Aotus subglauca and Bossiaea obcordata with enhanced germinations. This suggests that treatments provide some influential triggers on the germinable seed banks of shrub species. It was also found that significant differences on individual seedling emergence were mainly stimulated by the heat and combinatorial effect of heat and smoke induced treatments. This finding is supported by the results of several other studies examining the effects of different fire- related germination cues in Western Australia (e.g. Meney, et al. 1994; Dixon et al. 1995; Roche et al. 1997; 1998) and from wide range of plant families from South Africa (e.g. Keeley 1977; Brown et al. 1994; Keeley & Bond 1997).

Although, in general, the overall treatments effect was unconvincing at individual level germination it was shown to be significantly related to species richness and community composition. This study indicated a more diverse range of species richness (particularly forbs and woody shrubs) emerged from heat and combinatorial effect of heat and smoke induced germinations. This interpretation is supported by the results of Read et al. (2000), who found heat stimulated seed germination has a wide range of plant species from a native forest community in New South Wales. For example, Read et al. (2000) demonstrated heat promoted the greatest germination from the shrub component of the soil seed bank, with 18% of shrub species significantly stimulated. Similar findings were also reported by several other researchers (e.g. Hill & French 2004; Wills & Read 2002;

Chapter 7- General discussion and conclusion ______Pickup et al. 2003), who observed both richness and abundance of woody shrubs and trees was greater in the burnt rather than unburnt plots.

7.1.2 Effects of time-since-fire on seedling emergence and species richness

At individual-level germination, the results of this study indicated that fire variable i.e. time-since-fire, had a clearly discernible effect on the germinable soil-borne seed banks distribution, affecting both floristic community and the abundance of individual species. Long-burnt sites have a substantially greater number of germinable seed banks than the recent-burnt sites. The most pronounced effects were indicated in the plant groups such as forbs, graminoids and woody species (both obligate seeder shrubs and resprouters) thereby, suggesting sites experiencing long time-since-fire support for the greater accumulation and/or distribution of soil seed banks. This result is consistent with the finding of Nieuwenhuis (1987), who reported that obligate seeders such as Banksia ericifolia and Hakea teretifolia were reduced in abundance or eliminated on frequently burnt sites in Victoria‟s Dandenong and at Myall Lakes in NSW. This is because the obligate seeders entirely depend on seed regeneration to maintain survival in the community after fire. A similar effect of time-since-fire on distribution and plant community composition was reported by several other studies (e.g. Morrison et al. 1995; Bradstock et al. 1995, 1997). Watson and Johnson (2004) also observed similar result suggesting that time-since-fire was significantly related to community composition and the clearest evidence came from their findings on open-forest and woodland flora of Girraween National Park in south-east Queensland.

Grasses as a group, were the least affected among the plant growth forms in this study. This result is supported by the findings of Lunt (1995), which suggested that if the fire- interval exceeds 7-10 years, the diversity of native species does not seem to be re-instated after the eventual burning because native grass species do not form long-term persistent seed banks in grasslands. An alternative reason could be that grasses being short-lived species might have already stimulated the germination of the seeds under favourable environmental conditions such as high rainfall.

Chapter 7- General discussion and conclusion ______The present study indicates that the life forms of plant species particularly woody species (i.e. both resprouters and obligate seeders) could be at risk of local extinction under frequent forest fire. Significant differences were shown between long-burnt sites and recent-burnt sites. The most proximal reason for recent-burnt sites (short time-since-fire) having fewer soil seed banks than long-burnt sites (long time-since-fire), could be because of the recent fire event that took place in October 2002, might have either already triggered the germination of soil-borne germinable seeds or interrupted the reproduction of adult parent plants, hence, the reduction in size of the viable seed banks in the soil samples.

The result indicated that among the woody species, resprouting shrubs were the most affected plant group in this study. For example, substantially fewer numbers of resprouting seedlings were recorded from the recent-burnt forest seed bank samples than the recent-burnt rocky outcrop seed bank samples under the same fire history. This suggests that young plants might be vulnerable to high intensity of fire where forest habitats are likely to show higher fire intensity owing to higher fuel debris than rocky outcrops, thus minimizing the ability of these species to replace adult plants that were killed during the fire event. This interpretation is supported by Watson and Johnson (2004), who suggested juvenile seedlings of resprouting shrubs are not immediately fire tolerant species and it takes many years to attain the stage of lignotuber development. They also claimed that resprouting seedlings show considerably slower growth rates than obligate seeder seedlings and might not survive if sites experience short time-since-fire or high fire frequency. This result is also similar to several other studies (e.g. Enright & Goldblum 1999; Bell 2001; Clarke 2002; Bowen & Pate 2004), which have indicated that resprouting shrubs typically produce fewer seedlings after the fire event. Morrison et al. (1995) also found a similar distinction in dry sclerophyll vegetation in the Sydney region.

The present study thus indicates that short fire-intervals or short time-since-fire are likely to disadvantage some shrub and tree species which require a longer period to flower and set seed. Other factor such as predation effects, which were not addressed here, may have further contributed to seed losses in the soils. Therefore, one would expect a

Chapter 7- General discussion and conclusion ______persistent soil seed bank of these species to accumulate progressively over several years between successive fire events.

Overall, the above variable (long time-since-fire) had highly significant impacts and was the most powerful factor that influenced the germinable soil-borne seeds in this study.

7.1.3 Habitat effects on seedling emergence and species richness

The study results indicate rocky outcrops have a greater number of seedling emergences than the forest habitats. The present study thus adds support to the notion that rocky habitats possess a substantially greater number of soil-borne seeds that may lie dormant and require unusual stimuli to break their innate dormancy for germination. This result is similar to the finding of Fenner (1992), who claimed that in habitats such as both tropical and temperate woodlands, permanent grassland and undisturbed wetlands do not accumulate much seeds in the soil. In this study, woody species that occurred at the highest density in the rocky samples were Leptosperum arachnoides, Pultanaea foliolosa, Baeckea densifolia, Callitris endlicheri, Calytrix tetragona, Aotus subglauca var. subglauca, and Leucopogon microphyllus, (Appendix 4.3). These species show most likelihood of survival on the rocky outcrops than the forest habitats in the fire-prone ecosystems as they are mainly obligate seeders.

In addition, there was a significant association between habitats (rocky outcrops and forest habitats) and time-since-fire (long time-since-fire and short time-since-fire). The close association of these two variables on the germinable seed banks obviously indicates the crucial role played by rocky outcrops at individual-level germinations. The rocky outcrops may be burnt less intensely resulting in patchiness of fire-stimulated germination. Large numbers of forbs also may be resulted from the rocky habitats being open and less competitive on the post-fire environment because there are fewer trees and resprouting shrubs resulting more light space, hence the “fire ephemeral” forbs do well.

A statistical test (three-way ANOVA) performed on the species composition between habitats indicated that rocky outcrops contain a diverse range of species compositions

Chapter 7- General discussion and conclusion ______making it a valuable seed source for re-establishment of a plant community in the fire- prone ecosystems. There was less species diversity in forest habitats, which indicates the forest habitats are likely to promote higher fire intensity than rocky outcrops owing to higher fuel debris. This might have either already influenced the germination of seeds or interrupted their reproductions. This result is similar of findings by Clarke (2002), who suggested that outcrops are distinct in species composition compared to the surrounding forest matrix.

Destruction of seeds by high intensity of fire is a likely factor in accounting for low production of seedlings of herbaceous species in the forest habitats. Although, seed germination is greatly stimulated by the fire-related components, high temperature exceeding 120 o C is lethal to germinable soil-borne seed banks (Tozer 1998). Temperature can exceed 600 o C in the duff beneath during fire (Keeley 1977), thus ensuring the destruction of many seeds. It has been said that there are more shrub seedlings after “low fire intensity” than “high fire intensity” (Keeley 1977).

The study also indicated that forest habitats do not store much seeds of woody obligate seeders, while most of these species were recorded from the rocky outcrop samples. This supports the results of a study by Clarke (2001), who found that the dominant species on the rocky outcrops were mainly obligate seeders. Pickup et al. (2003) reported that the re-establishment of obligate seeders after disturbance (e.g. fire) entirely depends on successful germination of both canopy and soil-borne seed banks. This result has important implications for the dynamics of plant communities at landscape scales.

The analysis of data further confirmed that some of the woody species (i.e. both obligate seeders and resprouters) such as Acacia buxifolia, Boronia algida, Dodonaea hirsuta, Hovea granticola, Leptospermum neo-anglica, and Zieria laevigata were found to germinate in very limited numbers in the soil samples. This result suggests that these woody species are probably not able to produce sufficient seeds for regeneration in the younger forest stands owing to both biotic and abiotic disturbances. Therefore, both woody resprouting and obligate seeder shrubs have recently gained more attention than other groups of plant.

Chapter 7- General discussion and conclusion ______7.1.4 Species richness comparison between standing vegetation and soil seed bank samples

A total of 134 species were recorded from the ground standing vegetation along the 32 transects established in both rocky outcrops and forest habitats. In contrast, only 44 species were germinated from the entire soil seed bank samples that were examined during the experiment. This suggests that the soil seed bank samples contained fewer species than the ground standing vegetation at the study sites. The above pattern in the composition of soil-borne seed bank probably indicates the relatively small sampling area for the seed bank survey. A low correspondence and dissimilarity between the soil seed bank compositions and standing vegetation is widely reported in several other studies (e.g. William 1984; Hopkins et al. 1990; Wisheu & Keddy 1991; Lunt 1997). Almost all the species represented in the soil seed banks were represented in the standing vegetation except two taxa of Eragrostis leptostachya (Poaceae) and Bossiaea obcordata (Fabaceae) were not known to occur at the study sites. This indicates the importance of the soil seed reserve for the regeneration of the plant community in frequently disturbed areas.

Species richness differed dramatically between habitats (outcrops and forests). In seed bank samples, 17 species (38.7% of total species germinated) were recorded exclusively from rocky habitats and only 5 species (11.3% of total species germinated) occurred exclusively from the forest habitats. Twenty-two species (50% of total species germinated) were found to occur in both the habitats. Similarly, in the ground standing vegetation, 60 species (45% of total species recorded) were found to occur in the rocky habitats and only 32 species (24% of total species recorded) occurred in the forest habitats. Forty species (31% of total species recorded) were recorded from both the habitats.

The study indicates that rocky habitats support a more diverse range of species compositions than the forest habitats. The forest habitats do not store an appreciable quantity of seed banks probably because they are dominated by reprouters, which allocate resources to root stocks rather than reproduction (Clarke 2000).

Chapter 7- General discussion and conclusion ______7.2 Conclusion

Seeds of the various plant growth forms such as grasses, sedges/graminoids, forbs and woody species were better represented in the rocky outcrops than the forest habitats. This research has demonstrated that testing of soil-borne seed banks of rocky outcrops and adjacent dry sclerophyll forest habitats is a viable method for developing a conservation perspective of plant species, particularly for woody shrubs at the risk of local extinction. Both the abundance and richness of plant species were highly influenced by the effects of habitats and time-since-fire and fire-related treatments to a lesser extent. Throughout this study, variables such as habitats and time-since-fire were the most highly influential factors. The habitats prone to most frequent fire with short intervals is producing dramatic changes that are leading to local species decline with the potential for local extinctions for some of the woody species. Fire-related treatments did indicate an important role in structuring the plant communities on both the rocky outcrops and forest habitats through affecting the abundance and species richness, particularly the woody resprouting and obligate seeder shrubs.

The results ascertained in this research have indicated scope for further research. From a conservation perspective, I would suggest that the above factors would be the fundamental management tools to promote species regeneration and vegetation re- establishment in the Torrington State Conservation Area. These findings have important implications for the restoration and management of natural vegetation in the fire-prone ecosystems. Future study of this Reserve would become an important implication in assessing the long-term impacts of these variables (i.e. habitats, fire and time-since-fire) on the Reserve, which provides a dwelling shelter for more than 750 different plant species with over 36 rare or threatened species and 20 different species of mammals and more than 30 species of reptiles and frogs. Currently, not much information on the effects of habitats and time-since-fire on soil-borne seed banks is available, so further research in this area would be of great value.

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Williams, P. R., Congdon, R. A., Grice, A. C. and Clarke, J. P. (2003) Fire-related cues break seed dormancy of six legumes of tropical eucalypt savannas in north- eastern Australia. Austral Ecology 28, 507-514.

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References ______Wisheu, I. C. and Keddy, P. A. (1991) Seed banks pf a rare wetland plant community: distribution patterns and effects of human-induced disturbance. Journal of Vegetation Science 2, 181-188.

Zabinski, C., Wojtowicz, T. and Cole, D. (2000) The effects of recreation disturbance on sub-alpine seed banks in the Rocky Mountain of Montana. Canadian Journal of Botany 78, 577-582.

Appendices

APPENDICES

Appendix 1. Three-ways ANOVA tables for the total number of seedling emergence in the samples on the influential of to treatments, TSF and habitats: (a) grasses (b) graminoids (c) forbs (d) resprouters (e) obligate seeders (f) trees and shrubs

(a) Germination in all seedlings

DF Mean square F-Value P-Value Habitats 1 373.885 1.579 <0.0001 Time-since-fire 1 6844.500 28.908 <0.0001 Treatments 3 12760.031 53.892 0.1984 Habitats x Time-since-fire 1 3280.500 13.855 0.0003 Habitats x Treatments 3 164.635 0.695 0.5568 Time-since-fire x Treatments 3 71.604 0.302 0.8236 Habitats x Time-since-fire x Treatments 3 58.271 0.246 0.8640 Residual 112 236.772

(b) Germination in grasses

DF Mean square F-Value P-Value Habitats 1 134.070 7.332 0.0078 Time-since-fire 1 202.508 11.074 0.0012 Treatments 3 10.362 0.567 0.6381 Habitats x Time-since-fire 1 43.945 2.403 0.1239 Habitats x Treatments 3 10.633 0.581 0.6284 Time-since-fire x Treatments 3 7.904 0.432 0.7303 Habitats x Time-since-fire x Treatments 3 5.883 0.322 0.8097 Residual 112 18.287

Appendices

DF Mean square F-Value P-Value Habitats 1 1158.008 12.629 0.0006 Time-since-fire 1 1040.820 11.351 0.0010 Treatments 3 29.586 0.318 0.8120 Habitats x Time-since-fire 1 984.570 10.738 0.0014 Habitats x Treatments 3 22.341 0.244 0.8657 Time-since-fire x Treatments 3 28.987 0.316 0.8137 Habitats x Time-since-fire x Treatments 3 25.570 0.279 0.8405 Residual 112 91.693

(d) Germination in forbs

DF Mean square F-Value P-Value Habitats 1 2601.008 34.567 <0.0001 Time-since-fire 1 416.883 5.540 0.0203 Treatments 3 125.154 1.663 0.1790 Habitats x Time-since-fire 1 328.320 4.363 0.0390 Habitats x Treatments 3 116.070 1.543 0.2075 Time-since-fire x Treatments 3 16.820 0.224 0.8799 Habitats x Time-since-fire x Treatments 3 25.799 0.343 0.7944 Residual 112 75.244

(e) Germination in obligate seeders

DF Mean square F-Value P-Value Habitats 1 32.000 15.465 0.0001 Time-since-fire 1 52.531 25.387 <0.0001 Treatments 3 1.115 0.539 0.6568 Habitats x Time-since-fire 1 24.500 11.840 0.0008 Habitats x Treatments 3 1.750 0.846 0.4717 Time-since-fire x Treatments 3 0.531 0.257 0.8564 Habitats x Time-since-fire x Treatments 3 1.917 0.926 0.4306 Residual 112 2.069

Appendices

(f) Germination in resprouters

DF Mean square F-Value P-Value Habitats 1 114.383 13.634 0.0003 Time-since-fire 1 73.508 8.762 0.0038 Treatments 3 27.112 3.232 0.0251 Habitats x Time-since-fire 1 14.445 1.722 0.1921 Habitats x Treatments 3 7.008 0.835 0.4772 Time-since-fire x Treatments 3 7.049 0.840 0.4756 Habitats x Time-since-fire x Treatments 3 4.154 0.495 0.6864 Residual 112 8.390

(g) Germination in woody individuals

DF Mean square F-Value P-Value Habitats 1 267.383 27.364 <0.0001 Time-since-fire 1 250.320 25.618 <0.0001 Treatments 3 25.904 2.651 0.0522 Habitats x Time-since-fire 1 1.320 0.135 0.7139 Habitats x Treatments 3 6.966 0.713 0.5463 Time-since-fire x Treatments 3 4.570 0.468 0.7054 Habitats x Time-since-fire x Treatments 3 7.904 0.809 0.4945 Residual 112 9.771

Appendices

Appendix 2. Three-ways ANOVA tables for the germination of the total number of species in the soil samples on the influential of treatments, TSF and habitats: (a) grass species (b) graminoid species (c) forb species (d) resprouter species (e) obligate seeders (f) woody species.

(a) Germination in all species

DF Mean square F-Value P-Value Habitats 1 496.125 62.751 <0.0001 Time-since-fire 1 306.281 38.739 <0.0001 Treatments 3 37.281 4.725 0.0038 Habitats x Time-since-fire 1 19.531 2.470 0.1188 Habitats x Treatments 3 10.229 1.294 0.2801 Time-since-fire x Treatments 3 9.802 1.240 0.2987 Habitats x Time-since-fire x Treatments 3 14.760 1.867 0.1393 Residual 112 7.906

(b) Germination in grass species

DF Mean square F-Value P-Value Habitats 1 3.781 9.625 0.0024 Time-since-fire 1 5.281 13.443 0.0004 Treatments 3 0.865 2.201 0.0919 Habitats x Time-since-fire 1 0.281 0.716 0.3993 Habitats x Treatments 3 1.115 2.837 0.0413 Time-since-fire x Treatments 3 0.198 0.504 0.6804 Habitats x Time-since-fire x Treatments 3 0.115 0.292 0.8313 Residual 112 44.000

Appendices

DF Mean square F-Value P-Value Habitats 1 18.758 59.811 <0.0001 Time-since-fire 1 14.445 46.060 <0.0001 Treatments 3 1.404 4.476 0.0052 Habitats x Time-since-fire 1 8.508 27.128 <0.0001 Habitats x Treatments 3 0.362 1.154 0.3306 Time-since-fire x Treatments 3 1.424 4.542 0.0048 Habitats x Time-since-fire x Treatments 3 1.070 3.413 0.0200 Residual 112 0.314

(d) Germination in forbs

DF Mean square F-Value P-Value Habitats 1 116.281 53.266 <0.0001 Time-since-fire 1 19.531 8.947 0.0034 Treatments 3 6.771 3.102 0.0296 Habitats x Time-since-fire 1 6.125 2.806 0.0967 Habitats x Treatments 3 6.177 2.830 0.0417 Time-since-fire x Treatments 3 1.760 0.806 0.4929 Habitats x Time-since-fire x Treatments 3 3.646 1.670 0.1775 Residual 112 2.183

(e) Germination in herbaceous species

DF Mean square F-Value P-Value Habitats 1 219.008 66.669 <0.0001 Time-since-fire 1 110.633 25.346 <0.0001 Treatments 3 16.362 3.748 0.0131 Habitats x Time-since-fire 1 23.633 5.414 0.0218 Habitats x Treatments 3 7.633 1.749 0.1612 Time-since-fire x Treatments 3 4.549 1.042 0.3768 Habitats x Time-since-fire x Treatments 3 8.258 1.892 0.1350 Residual 112 4.365

Appendices

(f) Germination in woody species

DF Mean square F-Value P-Value Habitats 1 27.195 15.999 0.0001 Time-since-fire 1 48.758 28.685 <0.0001 Treatments 3 4.904 2.885 0.0389 Habitats x Time-since-fire 1 0.195 0.115 0.7353 Habitats x Treatments 3 1.091 0.642 0.5896 Time-since-fire x Treatments 3 2.112 1.243 0.2978 Habitats x Time-since-fire x Treatments 3 1.591 0.936 0.4258 Residual 112 1.700

(g) Germination in resprouters

DF Mean square F-Value P-Value Habitats 1 6.125 5.359 0.0224 Time-since-fire 1 10.125 8.859 0.0036 Treatments 3 3.219 2.816 0.0424 Habitats x Time-since-fire 1 5.281 4.621 0.0337 Habitats x Treatments 3 0.438 0.383 0.7656 Time-since-fire x Treatments 3 1.771 1.549 0.2057 Habitats x Time-since-fire x Treatments 3 1.135 0.993 0.3987 Residual 112 1.143

(h) Germination in obligate seeders

DF Mean square F-Value P-Value Habitats 1 7.508 17.656 <0.0001 Time-since-fire 1 14.445 33.971 <0.0001 Treatments 3 0.487 1.145 0.3341 Habitats x Time-since-fire 1 3.445 8.102 0.0053 Habitats x Treatments 3 0.258 0.606 0.123 Time-since-fire x Treatments 3 0.029 0.067 0.9771 Habitats x Time-since-fire x Treatments 3 0.195 0.459 0.7113 Residual 112 0.425

Appendices

Appendix 3. Total number of germinants in the experiment identified to 44 species level and 23 families.

Species Family Total no. of germinants

Grasses Entolasia stricta Poaceae 136 Eragrostic leptostachya Poaceae 112 Aristida jerichoensis var. subspinulifera Poaceae 9 Graminoids Juncus planifolius Juncaceae 63 Lomandra filliformis Lomandraceae 266 Laxmannia gracilis Anthericaceae 81 Forbs Actinolus gibbonsii Apiaceae 18 Actinolus helianthi ” 1 Hydrocotyle pendicularis ” 56 Trachymene incise ” 19 Bracryscome stuartii Asteraceae 49 Gamochaeta spicata ” 1 Gnaphalium sphaericum ” 193 Crassula sieberiana Crassulaceae 4 Drosera auriculata Droseraceae 24 Poranthera corymbosa Euphorbiaceae 1 Polymeria calycina ” 15 Gonocarpus teucrioides Haloragaceae 53 Gonocarpus micranthus ” 16 Gonocarpus tetragynus ” 132 Lobelia gibbosa Lobeliaceae 5 Pomax umbellata Rubiaceae 89 Stockhousa viminea Stackhousiaceae 1

Woody species Callitris endlicheri Cuppressaceae 29 Leucopogon melalucoides Epacridaceae 3 Leucopogon microphyllus ” 16 Leucopogon neo-anglicus ” 1 Acacia buxifolia Fabaceae 1 Acacia pruinosa ” 6 Acacia torringtonensis ” 2 Aotus subglauca var. subglauca ” 22 Bossiaea obcordata ” 10 Davesia latifolia ” 3 Hovea lanceolata ” 1 Pultanaea foliolosa ” 55 Prosthanthera staurophylla Lamiaceae 4 Baeckea densifolia Myrtaceae 45 Calytric tetragona ” 26 Eucalyptus prava ” 3 Leptospermum arachnoids ” 188 Hakea laevipes Proteaceae 4 Boronia algida Rutaceae 1 Zieria laevigata ” 1 Dodonaea hirsute Sapindaceae 1

Appendices

Appendix 4. ANOVA tables for the species richness at ground standing vegetations along the transects in response to TSF and habitats: (a) all species (b) grass species (c) graminoid species (d) forb species (e) herbaceous species (f) resprouter species (g) obligate seeders (h) woody species.

(a) All species

DF Mean Square F-Value P-Value Habitats 1 0.712 0.017 0.8957 Time-since-fire 1 2.367 0.058 0.8112 Habitats x time-since fire 1 1.539 0.038 0.8472 Residuals 28 40.680

(b) Grass species

DF Mean Square F-Value P-Value Habitats 1 1.531 0.519 0.4773 Time-since-fire 1 0.291 0.095 0.7598 Habitats x time-since fire 1 0.031 0.011 0.9188 Residuals 28 2.951

DF Mean Square F-Value P-Value Habitats 1 0.000 0.000 0.000 Time-since-fire 1 0.500 0.448 0.5088 Habitats x time-since fire 1 0.125 0.112 0.7404 Residuals 28 1.116

Appendices

(d) Forb species

DF Mean Square F-Value P-Value Habitats 1 0.500 0.092 0.7643 Time-since-fire 1 24.500 4.491 0.0431 Habitats x time-since fire 1 1.125 0.206 0.6532 Residuals 28 5.455

(e) Herbaceous species

DF Mean Square F-Value P-Value Habitats 1 0.281 0.019 0.8901 Time-since-fire 1 22.781 1.574 0.2201 Habitats x time-since fire 1 1.531 0.175 0.6790 Residuals 28 14.478

(f) Resprouters

DF Mean Square F-Value P-Value Habitats 1 276.125 31.850 <0.0001 Time-since-fire 1 0.500 0.058 0.8120 Habitats x time-since fire 1 36.125 0.4167 0.0507 Residuals 28 8.670

Appendices

(g) Obligate seeders

DF Mean Square F-Value P-Value Habitats 1 242.000 76.349 <0.0001 Time-since-fire 1 21.125 6.665 0.0154 Habitats x time-since fire 1 6.125 1.932 0.1754 Residuals 28 3.170

(h) All woody species

DF Mean Square F-Value P-Value Habitats 1 1.125 0.071 0.7912 Time-since-fire 1 15.125 0.961 0.3354 Habitats x time-since fire 1 12.500 0.794 0.3805 Residuals 28 15.741