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Many plant species have pollination and seed dispersal systems and evolutionary histories that have produced strong genetic structuring. These genetic patterns may be consistent with expectations following recent anthropogenic fragmentation, making it difficult to detect fragmentation effects if no prefragmentation genetic data are available. We used microsatellite markers to investigate whether severe habitat fragmentation may have affected the structure and diversity of populations of the endangered Australian bird-pollinated shrub Grevillea caleyi R.Br., by comparing current patterns of genetic structure and diversity with those of the closely related G. longifolia R.Br. that has a similar life history but has not experienced anthropogenic fragmentation. Grevillea caleyi and G. longifolia showed similar and substantial population subdivision at all spatial levels (global F'ST = 0.615 and 0.454; Sp = 0.039 and 0.066), marked isolation by distance and large heterozygous deficiencies. These characteristics suggest long-term effects of inbreeding in self-compatible species that have poor seed dispersal, limited connectivity via pollen flow and undergo population bottlenecks because of periodic fires. Highly structured allele size distributions, most notably in G. caleyi, imply historical processes of drift and mutation were important in isolated subpopulations. Genetic diversity did not vary with population size but was lower in more isolated populations for both species. Through this comparison, we reject the hypothesis that anthropogenic fragmentation has impacted substantially on the genetic composition or structure of G. caleyi populations. Our results suggest that highly self-compatible species with limited dispersal may be relatively resilient to the genetic changes predicted to follow habitat fragmentation.

Structurally complex forest provides important habitat for a diverse array of vertebrate fauna. Frequent fire can simplify forest structure, though topographic mitigation of fire effects could potentially preserve structurally more complex habitat within certain topographic locations of fire prone landscapes. Our study assessed whether the effects of fire frequency on forest structure (tree hollows, log volume, vegetation complexity) varied with topographic position. The effect of wildfire severity and intensive logging were also examined. Frequent fire reduced vegetation cover on ridges, but not in gullies. The risk of collapse (i.e. presence of fire scars) increased for large trees on frequently burnt ridges, but remained suppressed in gullies. Crown fire reduced hollow presence in dead trees (i.e. snags), but increased hollow presence in trees with a healthy crown. The volume of extensively decomposed logs was three times greater in gullies than ridges, but was unaffected by fire frequency. Intensive logging reduced the number of hollow bearing trees and increased the volume of extensively decomposed logs, though future declines in log volume are predicted due to bottlenecks in log input. Our results suggest that gullies may play a critical role in preserving structurally complex stands within frequently burnt temperate eucalypt forests. Protecting gullies from land clearing and intensive logging is likely to be an important step in maintaining key habitat features and associated fauna in these landscapes.

Log hollows provide important habitat for a range of vertebrate fauna. Despite this, little is known about the impact fire regimes have on this resource, or the role topography may play in preserving hollows through the mitigation of fire intensity. This study examined the effect different combinations of fire frequency and topography have on (i) the number of hollow bearing logs and (ii) the presence and size of hollows within logs. The influence of wildfire severity and logging were also examined. Hollow availability (i.e. density of hollow bearing logs and hollow presence within logs) was greatest at sites burnt at ‘low’ frequency. The density of hollow logs was greater in gullies, though the effect of fire frequency did not vary with topographic position. Hollows showing signs of internal fire charring typically had a greater entrance width than unburnt hollows, which suggests fire plays an important role in creating large hollows. The number of hollow bearing logs increased with logging intensity, due to unmerchantable timber being left in situ. Wildfire severity had little effect on log hollows. The results indicate that frequent burning may reduce hollow availability, though it is likely that gullies will still retain a high density of hollow bearing logs irrespective of burning, and may play an important role in preserving connectivity of this resource across landscapes.

The frequency of hybridization in plants is context dependent and can be influenced by the local mating environment. We used progeny arrays and admixture and pollen dispersal analyses to assess the relative importance of pre-mating reproductive barriers and the local demographic environment as explanations of variation in hybrid frequency in three mapped hybrid zones of Eucalyptus aggregata and E. rubida. A total of 731 open-pollinated progeny from 36 E. aggregata maternal parents were genotyped using six microsatellite markers. Admixture analysis identified substantial variation in hybrid frequency among progeny arrays (0–76.9%). In one hybrid zone, hybrid frequency was related to pre-mating barriers (degree of flowering synchrony) and demographic components of the local mating environment (decreasing population size, closer proximity to E. rubida and hybrid trees). At this site, average pollen dispersal distance was less and almost half (46%) of the hybrid progeny were sired by local E. rubida and hybrid trees. In contrast, at the other two sites, pre-mating and demographic factors were not related to hybrid frequency. Compared to the first hybrid zone where most of the E. rubida (76%) and all hybrids flowered, in the remaining sites fewer E. rubida (22–41%) and hybrid trees (0–50%) flowered and their reproductive success was lower (sired 0–23% of hybrids). As a result, most hybrids were sired by external E. rubida/hybrids located at least 2–3 km away. These results indicate that although pre-mating barriers and local demography can influence patterns of hybridization, their importance can depend upon the scale of pollen dispersal.

The Ground Parrot (Pezoporus wallicus) is a rare and iconic endemic of heathlands in southern Australia. It is threatened by frequent and widespread fire. The species has been an integral element in the development of our understanding of the impacts of fire regimes in heathlands and is an integral part of conservation management of these fire-prone ecosystems. This long-term study documents the densities of Ground Parrots in three areas of long-unburnt habitat in southern New South Wales. Using area searches and aural surveys, we estimated densities of Ground Parrots at Barren Grounds Nature Reserve–Budderoo National Park (1983–2009), Beecroft Weapons Range (1997–2008) and Nadgee Nature Reserve (1995–2009). At each location, the species occurred in long-unburnt habitat (≥20 years post-fire), sometimes at high densities (≥2 birds per 10 ha). We recommend that, in south-eastern Australia, fire should not be used to manipulate the ecological functioning of habitat for the persistence of Ground Parrot populations and conclude that there should be area-specific adaptive management plans that specify how the important elements of the biodiversity will be conserved and how this will be measured.

Recruitment in plant populations is often tightly coupled to major disturbances such as fires. For species with persistent seed banks, fire-related cues may allow or enhance germination. The litter layer influences germination and may modify the impact of seed predators on seeds and seedlings. The litter layer is obviously affected by fire, providing one mechanism by which disturbance can determine recruitment. We tested the role of litter in the disturbance–recruitment coupling of two species with contrasting seed release timing after fire—Banksia serrata (canopy seed bank) and Telopea speciosissima (transient seed bank) by planting their seeds both early and late in the post-fire recruitment period (PRP) and manipulating litter density in orthogonal treatments. Vertebrate seed predators were excluded. Both species established more seedlings late in the PRP, although results were strongly influenced by very poor establishment at one site. Invertebrate seed predators consumed more T. speciosissima seeds in sites early (69.5%) than late in the PRP (51.2%), while consumption of B. serrata seeds was lower overall and comparable across sites (average 47.3%). Surprisingly, litter had very little effect on establishment and none on invertebrate seed predation, suggesting that other factors are more important. Recruitment was only loosely coupled to disturbance for the canopy seed bank species; for the transient seed bank species, the coupling was tighter but separated in time from the disturbance. Understanding both the strength and temporal aspects of the disturbance–recruitment coupling is necessary for appropriate management of plant functional diversity in fire-prone habitats.

Summary 1 Increased fire frequency is seen as a key threat to plant populations in Mediterranean-type ecosystems across the globe. Short inter-fire periods may exhaust soil-stored and fire-stimulated seed banks of fire-sensitive species, reducing actual and effective population sizes and eroding genetic diversity. 2 Here we used microsatellite genotyping to investigate the genetic impacts of repeated wildfires and, in particular, the contribution of above-ground genetic processes (seed and pollen dispersal) to the genetic structuring and composition of post-fire recruits in an isolated population of the fire-sensitive shrub Persoonia mollis ssp. nectens. 3 We tested the hypothesis that limited pollen and seed dispersal, in combination with the potentially patchy effects of fire at a fine scale within populations, would generate a highly structured population, a decline in genetic diversity after each fire and genetic heterogeneity between successive cohorts. 4 Wildfires killed all 25 adult plants in 1997 and, in 2001, killed all of the 476 seedlings remaining from the 1997 seedling cohort. Although there was no possibility of replenishment of the seed bank in the interval between fires, a second cohort of 381 seedlings emerged after the 2001 fire. 5 We found no evidence that successive fires produced either a decline in genetic diversity, as measured by allelic richness or expected heterozygosity, or the genetic differentiation of adult and successive seedling cohorts (Pairwise FST = −0.0125 to 0.0009). The seedling cohorts displayed less genetic structuring than anticipated. Spatial genetic structure was low, ranging from Sp = 0.02 in the 1997 seedlings to Sp = 0.06 in the 2001 seedlings, and using parentage analysis, we found that seedlings clustered under dead adults rarely reflected simple seed shadows. 6 Synthesis. Overall, we found that a numerically large seed bank with a bet-hedging strategy of staged seed germination, in combination with genetic mixing achieved by both pollen and seed dispersal, provides a powerful buffer against the negative impacts of frequent fire in P. mollis ssp. nectens.

†Background and Aims In Australia, honey-bees have invaded systems that evolved without social insect pollinators, where many plants are adapted to vertebrate pollination. Behavioural differences between pollinators are likely to influence mating patterns, but few studies have examined this empirically in long-lived, woody, perennials. It was shown previously that outcrossing rates in Grevillea macleayana vary among populations. Here tests were conducted to determine whether the behaviour of birds and honey-bees differed between a population previously found to be highly outcrossed and two inbreeding populations. †Methods Visit frequencies and movement patterns of the visitors to inflorescences at three sites over two seasons were compared. A caging experiment was used to test the effects of excluding birds on pollen removal from newly opened flowers and on pollen deposition on stigmas that had been washed clean. †Key Results Honey-bees were the most frequent visitors overall, but honeyeaters were more frequent visitors in the population previously found to have a high outcrossing rate than they were in either of the other populations. More visits by honeyeaters were from distant plants. Pollen removal did not vary greatly among sites, and was not affected by bird exclusion; however, more pollen was deposited on the stigmas of cleaned pollen presenters in the population previously observed to be highly outcrossing than in the other two. This high level of pollen deposition was reduced by experimental bird exclusion. †Conclusions Honey-bees were the most frequent visitors, by an order of magnitude, and excluding vertebrates revealed that bees were removing most of the pollen but deposited fewer pollen grains on stigmas. Birds were more frequent visitors at the site previously found to be outcrossing than the other two sites, and they moved further between plants and visited fewer inflorescences on a plant during a foraging bout than bees did. These characteristics of bird visits to G. macleayana would be sufficient to produce significant variation in outcrossing rates among sites.

Spatial patterns of fruit set within inflorescences may be controlled by pollination, nutrient allocation, or inflorescence architecture. Generally, flowers that have spatial and/or temporal precedence are more likely to set fruits. We sought to separate these factors by comparing patterns of fruit set on inflorescences of two species of Telopea (Proteaceae); one that flowers from the tip to the base of the rachis, the other from base to tip. In both species, most fruits were set at the top of the inflorescence (the last flowers to open for T. speciosissima) and this was extreme for T. mongaensis, where the top flowers open first. Fruit set was not generally limited by inadequate pollination for either T. mongaensis or T. speciosissima, as hand pollinations did not increase fruit set and many abscised flowers contained pollen tubes. In T. speciosissima, we tested whether removal of developing topmost fruits would ‘release’ those that had initiated but not yet aborted lower down. There was no significant effect. Plant hormones can increase the degree to which a developing fruit is a sink for nutrients, so we applied cytokinin to the developing lower fruits on some inflorescences. There was no significant effect of the hormone treatment. We conclude that temporal precedence may contribute to the skewed pattern of fruit set in T. mongaensis, because there was an extreme concentration of fruit set on the distal part of the inflorescences, but it cannot explain this pattern of fruit set in T. speciosissima, where the distal flowers are the last to open. Some other process must therefore constrain fruit set to the topmost flowers in an inflorescence. While cytokinin application had no significant effect, the power of this experiment was low and we consider that the hypothesis of hormonal control is worth further exploration.

Litter accumulation after fire influences the magnitude of seed predation and seed germination. How litter accumulation and patchiness influence postfire seedling recruitment is poorly known. Species with persistent seed banks have seeds available for germination in the immediate postfire period. In contrast, plants with transient seed banks must flower after fire to place seeds in the postfire habitat. In southeastern Australian sclerophyll forests, most seedling recruitment occurs within 3 yr after fire. We found that less litter had accumulated in sites

Summary 1. Habitat fragmentation can alter the relative frequency of cross-compatible species within an area, which can affect the levels of interspecific hybrid production and reduce the viability of small populations through genetic and demographic swamping. For 18 populations of Eucalyptus aggregata, we examined the effects of absolute and relative population size (compared with its congeners E. rubida, E. viminalis and E. dalrympleand) on hybrid production, genetic diversity and subsequent seed production and seedling performance. 2. Relative population size was strongly negatively correlated with rates of hybrid seed production, suggesting increased hybridization when the potential sources of interspecific pollen outnumber the sources of intraspecific pollen for E. aggregata trees. 3. Genetic diversity was negatively correlated with relative population size which suggests that hybridization may maintain diversity lost through bottlenecks and drift following reductions in population size. However, the presence of fertile hybrid adults, and introgressed leaf traits within populations exhibiting high hybridization rates, suggests that small E. aggregata populations may be vulnerable to genetic swamping by common congeners. 4. Amongst an array of population parameters (population sizes, genetic diversity and inbreeding), seed production was only positively correlated with relative population size, whereby sites with low relative population sizes tended to produce fewer seed. This could be due to the action of pre-zygotic barriers which removes inviable hybrid genotypes as levels of interspecific pollen flow increase. 5. Germination and survivorship displayed a similar positive correlation with relative population size, suggesting post-zygotic hybrid breakdown may also contribute towards to demographic swamping of remnant populations. 6. Synthesis. Our results suggest that relative population size is an important parameter determining rates of hybrid production, seed production and seedling performance. Furthermore, relative population size has stronger effects on population fecundity than absolute population size, genetic diversity and levels of inbreeding. Relative population sizes > 0.5 (i.e. at least equal frequencies of parentals) may be required to avoid the deleterious effects of genetic and demographic swamping on the viability of rare species.

Remnant plants in urban fringes and native plants in gardens have the potential to contribute to the conservation of threatened plants by increasing genetic diversity, effective size of populations, and levels of genetic connectedness. But they also pose a threat through the disruption of locally adapted gene pools. At Hyams Beach, New South Wales, Australia, four bushland stands of the rare shrub, Grevillea macleayana McGillivray, surround an urban area containing remnant and cultivated specimens of this species. Numbers of inflorescences per plant, fruits per plant, and visits by pollinators were similar for plants in urban gardens and bushland. Urban plants represented a substantial but complex genetic resource, displaying more genetic diversity than bushland plants judged byH(e), numbers of alleles per locus, and number of private alleles. Of 27 private alleles in urban plants, 17 occurred in a set of 19 exotic plants. Excluding the exotic plants, all five stands displayed a moderate differentiation (F(ST)= 0.14 +/- 0.02), although the urban remnants clustered with two of the bushland stands. These patterns may be explained by high levels of selfing and inbreeding in this species and by long-distance dispersal (several seeds in the urban stand were fathered by plants in other stands). Genetic leakage (gene flow) from exotic plants to 321 seeds on surrounding remnant or bushland plants has not occurred. Our results demonstrate the conservation value of this group of urban plants, which are viable, productive, genetically diverse, and interconnected with bushland plants. Gene flow has apparently not yet led to genetic contamination of bushland populations, but high levels of inbreeding would make this a rare event and difficult to detect.

Native plants in gardens can potentially aid conservation by contributing to genetic diversity and buffering small and otherwise isolated populations from extinction. However, gene flow from such plantings may threaten the genetic integrity of natural populations. We assessed the morphological and genetic diversity of garden plants in an urban population of Grevillea macleayana in south-eastern Australia. There were two main groups of garden plants: some similar to plants in nearby natural populations; others with unusual morphology. Multivariate analysis of morphological characters separated these groupings, which were confirmed by genetic analysis. Both groups produced seeds and flowering phenologies overlapped, indicating a potential for gene flow. Hand pollination showed that plants in each group could fertilize flowers of the other. Thus, these garden plants contributed to genetic variation in an urban/bushland metapopulation but there was potential for gene flow from the unusual plants. Unless carefully managed, garden plants may therefore cause disruption of the genetic integrity of nearby natural populations.

Summary Royal National Park, Australia's oldest national park, is a significant reserve for conservation of the flora and fauna that are characteristic of the Hawkesbury Sandstone in New South Wales. Since at least 1974, Phytophthora Root Rot (caused by Phytophthora cinnamomi) has been known to occur in the Park, but there is no knowledge of the extent of infestation or the potential impacts of the disease within the Park. This study investigated the distribution of the pathogen within Royal National Park at two scales: a systematic survey by vegetation type, and a targeted survey of populations of Waratah and Spear Grass-tree. These two species are known to be susceptible to Phytophthora Root Rot and are therefore potential indicators of the impact of the pathogen on vegetation in Royal National Park. Phytophthora cinnamomi was recovered from all vegetation types sampled but most commonly in heathland/open scrub vegetation. The pathogen was easily recovered from sites containing Spear Grass-tree, but was not isolated from any sites containing Waratah. Because of the widespread distribution of P. cinnamomi, we conclude that hygiene measures will be of little use to prevent the spread of the pathogen within Royal National Park. Monitoring of the occurrence and spread of disease symptoms in plants and applying phosphite to protect susceptible rare or threatened flora may be the most appropriate management options.

Chrysanthemoides monilifera ssp. rotundata is an invasive plant in eastern Australia. It produces large quantities of fleshy fruits, which are dispersed by birds and mammals, and has the potential to alter ecological processes in native plant communities in several ways. Seed dispersal of native plants growing amongst C. monilifera could be decreased (if C. monilifera is effective in competing for limited seed dispersers), increased (if C. monilifera-infested vegetation supports more seed dispersers), or be unchanged (if there is sufficient separation in fruiting time or dispersal agents between the species, or if dispersers are not limiting). We compared the rates of removal of fruits of native plants (Monotoca elliptica and Elaeocarpus spp.) from experimental stations in C. monilifera stands, in uninfested coastal vegetation, and in vegetation from which C. monilifera had been eliminated with herbicide. The rate of removal of fruits differed between plant species and locations, but not between any of the habitat treatments. This may have resulted from temporal separation of peak fruit availability between M. elliptica and C. monilifera, and differences in fruit morphology and disperser assemblages between Elaeocarpus spp. and C. monilifera. We also measured removal of C. monilifera fruits from stations in C. monilifera stands and from where C. monilifera had been eliminated with herbicide. In the herbicide-treated habitat, removal of C. monilifera fruits was reduced. This may assist control efforts and suggests that, to reduce seed dispersal, dense (core) populations should be targeted in control programs.

In plants, understanding the interactions between breeding systems and pollination ecology may enable us to predict the impacts of rarity. We used a comparative approach to test whether rarity is associated with reproductive biology in two closely-related species pairs. This system has been recently altered by changes in fire regimes and the introduction of European honeybees. More than 35% of flowers matured fruits in the common species after natural-pollination compared to

The genetic effects of population fragmentation cannot be interpreted without understanding the underlying pattern of genetic variation resulting from historic population processes. We used AFLP markers to determine genetic structure and distribution of genetic diversity among populations of an endangered Australian shrub Grevillea caleyi (Proteaceae). Populations that occurred historically on four ridges have new been fragmented to varying degrees, producing some large, relatively pristine populations and very small populations consisting of fewer than 10 adult plants. We found marked population genetic structure (65.9% of genetic variation was among populations) and a significant relationship between genetic and geographic distance (rm=0.564, P=0.004). However, only 14% of overall genetic differentiation was attributable to variation among ridges, compared with 52% among populations within ridges. Moreover, genetic diversity within samples of plants did not vary with either population size or degree of isolation. Thus, the present genetic structure of populations is probably almost entirely the product of historical events. Fine-scale structuring within populations prior to fragmentation may have been caused by limited seed and pollen dispersal, despite a complex suite of (mostly avian) pollinators, and a mixed mating system that allows a large amount of selfing. The combined effects of adult longevity and a soil-stored seed bank may have buffered the recently fragmented populations against the effects of dramatic reductions in numbers of adult plants.

In many fire-prone habitats around the world, natural fire regimes have shaped the evolution of the associated flora. Critical life history stages are often linked to fire in species that occur in these fire-prone habitats but many species are unstudied. We investigated seedling emergence patterns over time, after several fires in south-eastern Australia, for three obligate seeders in the Genus Leucopogon (Family Epacridaceae): L. setiger, L. esquamatus and L. exolasius. Fixed quadrats were monitored for 12 to 30 months for newly emerged seedlings, both after fire and in unburnt L. exolasius and L. esquamatus habitats. There was a flush of seedling emergence in the first year after fire for all three Leucopogon species, with smaller pulses recorded in subsequent years. Time elapsed between fire and the onset of emergence differed between fires, but not between Leucopogon species. Whatever the timing of the fire, seedling emergence was restricted to the late autumn and winter periods, coinciding with emergence in unburnt habitat. This contrasts with patterns of emergence previously reported for other taxa, and also in this study, where emergence of the Leucopogon species after fire was delayed compared with co-occurring species in other genera. Our results suggest that seasonal factors are important to the germination ecology of these species and that combinations of fire-related and seasonal factors are necessary to maximise germination. Rainfall has a non-seasonal pattern in the study region and seasonal emergence post-fire has not previously been recorded. The magnitude of delay to emergence of species with seasonal emergence patterns will be determined by the season of fire but not by a seasonal pattern of rainfall in the post-fire year. A shift of the peak fire season could increase this delay, possibly affecting plant population recovery.

Seed germination is dependent on the interaction between the dormancy state of a seed and the presence of favourable environmental conditions. Thus, the spectacular pulse of seedling recruitment in many Australian vegetation communities following disturbances such as fire can be attributed to changes in microsite conditions and/ or the dormancy-breaking effect of the disturbance on accumulated seed banks. Grevillea rivularis is a threatened species endemic to the area immediately above Carrington Falls in the NSW Southern Highlands. Most of the population is confined to the riparian vegetation zone in woodland and heath, and is therefore subject to periodic disturbance from fire and flood. For this species, a pulse of seedling recruitment has been recorded after fire, flood and mechanical soil disturbance. The aims of this study were to examine the density and vertical distribution of the soil-stored seed bank and to investigate the role of heat and scarification as cues for germination of fresh and soil-stored seed. There was a large seed bank under the canopies of established individuals (194 ± 73 seeds m -2 ) and most seeds were found in the 0-2 cm and leaf-litter layers of the soil profile. The germination response of soil-stored and fresh seed was examined using a hierarchical series of laboratory experiments. Seeds of G. rivularis showed marked dormancy polymorphism. Thirty-six percent of soil-stored seed germinated without treatment, whereas no untreated fresh seeds germinated. Scarification or heating caused significant germination of dormant soil-stored seed, but only scarification resulted in germination of dormant fresh seeds. These results highlight important differences in the dormancy state of soil-stored and fresh seed. Thus, being a riparian species in a fire-prone environment, the dormancy mechanisms in seeds of G. rivularis suit this species to disturbance by both fire and flood.

Recent habitat loss and fragmentation superimposed upon ancient patterns of population subdivision are likely to have produced low levels of neutral genetic diversity and marked genetic structure in many plant species. The genetic effects of habitat fragmentation may be most pronounced in species that form small populations, are fully self-compatible and have limited seed dispersal. However, long-lived seed banks, mobile pollinators and long adult lifespans may prevent or delay the accumulation of genetic effects. We studied a rare Australian shrub species, Grevillea macleayana (Proteaceae), that occurs in many small populations, is self-compatible and has restricted seed dispersal. However, it has a relatively long adult lifespan (c. 30 years), a long-lived seed bank that germinates after fire and is pollinated by birds that are numerous and highly mobile. These latter characteristics raise the possibility that populations in the past may have been effectively large and genetically homogeneous. Using six microsatellites, we found that G. macleayana may have relatively low within-population diversity (3.2-4.2 alleles/locus; Hexp = 0.420-0.530), significant population differentiation and moderate genetic structure (FST = 0.218) showing isolation by distance, consistent with historically low gene flow. The frequency distribution of allele sizes suggest that this geographical differentiation is being driven by mutation. We found a lack mutation-drift equilibrium in some populations that is indicative of population bottlenecks. Combined with evidence for large spatiotemporal variation of selfing rates, this suggests that fluctuating population sizes characterize the demography in this species, promoting genetic drift. We argue that natural patterns of pollen and seed dispersal, coupled with the patchy, fire-shaped distribution, may have restricted long-distance gene flow in the past.

Introductions of European honeybees have occurred globally, potentially affecting the natural pollination ecology of many plants. Introduced honeybees are now the most frequent visitors to the inflorescences of the self-compatible, bird-pollinated Australian shrub Grevillea macleayana and may therefore be expected to have altered the mating system. To examine the degree to which birds continue to play a role in determining the mating system of G. macleayana in this disturbed system, we compared outcrossing rates in open-pollinated inflorescences with inflorescences from which birds had been selectively excluded. Outcrossing rates were estimated from the microsatellite genotypes of over 100 seeds per population in three populations. Outcrossing rates ( t) in open-pollinated seeds were surprisingly low (0.062–0.225) and did not vary significantly among the three populations. Nevertheless, outcrossing was significantly lower when birds were excluded (data pooled from all populations). Two lines of evidence suggest that there are temporal fluctuations in outcrossing rate and hence that birds usually have a major effect on the mating system of G. macleayana. First, at one site, t was substantially lower than estimates from an earlier study (0.06 in 1995 cf. 0.85 in 1990). Second, fixation indices based on seeds were high in all populations ( >0.68), whereas values for the established plants ( parental generation) were much lower in two of the three populations (0.06–0.32). Our findings suggest that honeybee activity is so high that the contribution of birds to pollination in G. macleayana is sometimes relatively trivial. Resumen: La introduccion de abejas europeas ha ocurrido globalmente, lo que potencialmente afecta la ecologia de polinizacion natural de muchas plantas. Las abejas introducidas son los visitantes mas frecuentes de las inflorescencias del arbusto australiano auto-compatible, polinizado por aves Grevillea macleayana y puede esperarse que su sistema de apareamiento ha sido alterado. Para examinar el grado al que las aves continuan jugando un papel en la determinacion del sistema de apareamiento de G. macleayana en este sistema perturbado, comparamos las tasas de exogamia en inflorescencias de polinizacion abierta con inflorescencias de que se excluyeron selectivamente las aves. Las tasas de exogamia fueron estimadas de los genotipos microsatelite de mas de 100 semillas por poblacion en tres poblaciones. Las tasas de exogamia ( t) en semillas de polinizacion abierta fueron sorprendentemente bajas (0.062–0.225) y no variaron significativamente entre las tres poblaciones. Sin embargo, la exogamia fue significativamente menor cuando las aves fueron excluidas (considerando los datos de todas las poblaciones). Dos lineas de evidencia sugieren que hay fluctuaciones en la tasa de exogamia y en consecuencia que las aves generalmente tienen un mayor efecto en el sistema de apareamiento de G. macleayana. Primero, en un sitio t fue sustancialmente menor que en estimaciones de un estudio anterior (0.06 en 1995 cf. 0.85 en 1990). Segundo, los indices de fijacion basados en semillas fueron altos en todas las poblaciones ( >0.68), mientras que los valores para las plantas establecidas (generacion parental) fueron mucho menores en dos de las tres poblaciones (0.06–0.32). Nuestros resultados sugieren que la actividad de las abejas es quizas tan alto que la contribucion de las aves a la polinizacion de G. macleayana a veces es relativamente trivial.

Summary 1 Although the season of fire occurrence is known to affect recruitment to plant populations, it has received little attention. This study investigated the dynamics of the canopy-stored seed banks of two Australian obligate seeder shrubs, Petrophile sessilis and Hakea sericea (Proteaceae), with the objective of determining the changes in viable seed supply over a year. 2 The total number of germinable seeds in the canopy, each month for 12 months during 1996–97, was estimated from separate measures of (i) pre-dispersal predation of fruits; (ii) seed predation of insect parasitoids; (iii) viability of intact seeds; and (iv) loss of seed viability following experimental heating. 3 The two species had very different seed bank dynamics throughout the year. The seed store of P. sessilis appeared to be being replaced annually, as seeds in the older fruits rapidly lost germinability and new fruits matured to replace them. For H. sericea, the seed store appeared to be accumulating each year, because older fruits retained a high level of germinability. 4 The study indicates that no one fire season will maximize the germinable seed release after fire for all species. Management strategies should therefore include varied seasons of prescribed burning to avoid compositional change and a decrease in diversity that may result from a single-season approach.

Long-term canopy storage of seeds in fruits (bradyspory) varies among species and is thought to be related to the fire regime experienced by the plant community. This study sought to quantify intraspecific variation in bradyspory among nine populations of Banksia serrata (Proteaceae) on the south coast of New South Wales. Marked differences were found between populations, ranging from more than 30% of follicles open at two coastal sites, to less than 5% of follicles open at two inland heath sites. Low levels of bradyspory occurred particularly in coastal sites which also had Banksia integrifolia, a non-bradysporous species, present. In addition to spontaneous follicle opening without fire, fall of infructes-cences to the ground after breaking of branches was observed to be a major contributor to seed release. At three sites where fire had not occurred for many years, the amount of seedling establishment since the last fire corresponded well with levels of bradyspory; there were no inter-fire recruits at the site with the strongest bradyspory, while at the site with the weakest bradyspory there were numerous inter-fire plants, some with lignotubers large enough to be able to tolerate the next fire. It is argued that populations of B. serrata exhibit variable patterns of recruitment, depending on the site characteristics, ranging from complete dependence on fire for population maintenance to bet-hedging (spreading potential recruitment between fire events and inter-fire periods). Variations in populations and reproductive characteristics among sites make the application of demographic models to management decisions habitat-specific.

Road verge remnant native vegetation often provides a last refuge for many endangered plant species. However, the value of road verge populations is often questioned because their relatively small size and isolation is expected to reduce both their reproductive potential and their genotypic diversity. We assessed the fitness, genetic variability and links with other populations of small, disjunct and highly disturbed road verge populations of the rare Australian shrub Grevillea barklyana. We found that a set of three road verge populations produced significantly more inflorescences and seed than three nearby nonverge populations. Using three random amplified polymorphic DNA (RAPD) primers, we detected similar levels of genetic variability within and among road verge and nonverge populations. We detected a total of 23 polymorphic marker bands, which allowed us to assign a unique phenotype to each of 60 surveyed plants. AMOVA revealed that only 3.3 per cent of the total variability detected was attributable to variation between the two groups of populations. The majority (80 per cent) of variation occurred among individuals within populations, and 16.7 per cent occurred among populations within each population type. Surprisingly, this pattern of variation is similar to results reported for obligatorily outcrossing species. We conclude that our three road verge populations of G. barklyana have relatively great conservation value, as all were apparently as fecund and as genetically diverse as conspecific nonverge populations.

Mammals are frequent visitors to flowers in some Australian plant communities Nectar ib usually considered to be the food sought, because pollen is thought to be of low digestibility This study compared the abilities of four non-flying mammal species to extract the protoplasts from Banksia pollen grains and quantified the amount of pollen in the diets of the species over 16 months All four species were capable of extracting the protoplast from a large proporuon of the pollen grains that they ingested the mean percentage of empty Banksia pollen grains in the faeces ranged from 37% to 66% Banksia pollen was a major component in the faecal samples from two species, Cercartetus nanus and Petaurus breviceps, between March and October It occasionally compnsed a large proportion of Amechmus stuartti faeces but was rare in the faeces of Rattusfuscipes Other major components of faeces included invertebrates and plant matenal other than pollen and fungal spores As the four mammal species tested were all from separate families and all capable of extracting the protoplast from a large proportion of the pollen grains, it is concluded that the extraction of pollen protoplasts by mammals may be widespread and may require no special adaptations

We developed eight primer pairs for Banksia microsatellite markers (five using DNA from Banksia oblongifolia and three from Banksia robur) in order to study the processes of speciation within hybridizing B. oblongifolia, B. robur and Banksia paludosa complex. We genotyped four populations of B. oblongifolia and B. robur, and three of B. paludosa. Numbers of alleles ranged from 1 to 13 across the three species and observed average heterozygosities ranged from 0.000 to 0.833. At least four loci completely discriminated B. robur from B. oblongifolia and three discriminated B. paludosa from B. oblongifolia. Seven of these primers amplified DNA from at least two of three other local species.

Seedbanks are expected to buffer populations against disturbances, such as fire, that could alter the genetic composition of smaller, ephemeral adult populations. However, seedling genotypes may be influenced by the spatially heterogeneous nature of both the seedbank and the disturbance (for example, germination may vary with local disturbance) and also by selection acting on germination and post-germination performance. We used microsatellite-DNA surveys of seedlings emerging from the soil-stored seedbanks of Grevillea macleayana after wildfire to compare diversity and spatial structure in seedlings and adults, and through resampling of the seedling data set, to determine whether the resultant adult population reflected the effects of selection or random seedling mortality. The large post-fire seedling cohorts captured the full allelic diversity of the pre-fire adult population. However, we found a mismatch in the genotypic structure of adults and seedlings. Seedlings displayed larger heterozygous deficits than adults; however, over the ensuing 11 years, seedling heterozygosity eventually matched values for the pre-fire adults. Increasing heterozygosity among adults has generally been attributed to heterosis and/or reduction in Wahlund effects via self-thinning. Resampling of early post-fire seedlings to generate samples of equivalent size to survivors at 11 years showed that increases in heterozygosity must be driven by selection favouring outcrossed seed. This finding is important in an evolutionary context but also has implications for the restoration of natural or managed populations where a seedbank is a viable source of recruits.

Fire-triggered release from seed dormancy is a characteristic of many Australian plant species. We investigated aspects of the seed-bank dynamics and dormancy characteristics in seeds of Grevillea barklyana, an understorey shrub of coastal sclerophyll vegetation in the Jervis Bay Region on the south coast of New South Wales. We used two soil core sizes to compare the number and distribution of stored seeds in soil cores taken from underneath and outside the limits of plant canopies at three study sites. Core size did not affect the estimate of seed density. No seeds were found outside the existing canopies. Even in under-canopy samples, seed numbers were small. Mean seed densities were estimated as 10.9, 14.1 and 4.3 seeds per ? ? ? for the three sites. A hierarchical series of laboratory experiments was used to test the germination response of both fresh and soil-stored seeds. Likewise, we attempted to simulate 'natural' disturbance conditions in a glasshouse experiment. Both laboratory and glasshouse experiments indicated polymorphism in germination behaviour. A constant proportion of seeds exhibited enforced dormancy, when moist at room temperature, while a smaller number of seeds showed either an induced dormancy or a non-seed-coat linked innate dormancy. The majority (75%) of seeds were innately dormant due to a hard seed-coat. This dormancy was broken when the seed-coat was damaged, for instance, by heat. The level of polymorphic germination behaviour will be dependent on the length of the inter-fire periods. We conclude that the expression of polymorphism within and between species across a range of environments and fire regimes is an important consideration for any further study attempting to assess the role of the seed-bank.

smoke, the sound of sirens, and constant news reports of evacuations, houses burned, houses saved, and national parks "destroyed." The news reports quickly spread across the globe, depicting the emergency as "a fire front stretching 60 km from the Blue Mountains to Wollongong and advancing towards Sydney." Although reports like these were exaggerated, the fires that ringed Sydney were as intense as any in memory, driven by hot, dry conditions and strong, changing winds. In 2 weeks in New South Wales, over 500,000 ha of native vegetation were burned, much of it in national parks and other conservation areas.

The description of a digital ecosystem as a “loosely coupled, demand-driven, domain clustered, agent-based, self organised, collaborative environment where agents form temporary coalitions for a specific purpose or goal, and each is proactive and responsive for its own benefit” has intriguing similarities with the definition of an ecosystem in ecology. Perhaps the similarities suggest that a deeper understanding of ecology may benefit the further development of ICT, and any differences may therefore represent cautionary tales. In this presentation, I describe characteristics of some ecological systems at several levels - from species to ecosystem - and speculate on the potential of these examples to catalyse innovation in ICT.

Dispersal in most plants is mediated by the movement of seeds and pollen, which move genes across the landscape differently. Grevillea macleayana is a rare, fire-dependent Australian shrub with large seeds lacking adaptations for dispersal; yet it produces inflorescences adapted to pollination by highly mobile vertebrates (eg birds). Interpreting fine-scale genetic structure in the light of these two processes is confounded by the recent imposition of anthropogenic disturbances with potentially contrasting genetic consequences: (1) the unusual foraging behaviour of exotic honeybees and 2. widespread disturbance of the soil-stored seedbank by road building and quarrying. To test for evidence of fine-scale genetic structure within G. macleayana populations and to test the prediction that such structure might be masked by disturbance of the seed bank, we sampled two sites in undisturbed habitat and compared their genetic structure with two sites that had been strongly affected by road building using a test for spatial autocorrelation of genotypes. High selfing levels inferred from genotypes at all four sites implies that pollen dispersal is limited. Consistent with this, we observed substantial spatial clustering of genes at 10 m or less in the two undisturbed populations and argue that this reflects the predicted effects of both high selfing levels and limited seed dispersal. In contrast, at the two sites disturbed by road building, spatial autocorrelation was weak. This suggests there has been mixing of the seed bank, counteracting the naturally low dispersal and elevated selfing due to honeybees. Pollination between near neighbours with reduced relatedness potentially has fitness consequences for G. macleayana in disturbed sites.

In southern New South Wales, a suite of widespread plant species exhibit short-statured ‘dwarf’ growth forms on coastal headlands. It is unclear whether such populations are genetically distinct or whether dwarfism is a plastic response to the environment. We used four microsatellite markers to assess genetic differentiation among populations from coastal and inland sites for Banksia spinulosa var. spinulosa. We sampled plants from six locations, including from three ‘dwarf’ and three ‘normal’ populations. Mean levels of genetic diversity were slightly higher in the forest (Na = 7.07 ± 0.25; He = 0.80 ± 0.09) than on the coast (Na = 5.92 ± 0.70; He = 0.72 ± 0.10). In general, populations displayed genotypic diversity expected for outcrossed sexual reproduction, with 161 of 172 individuals displaying unique genotypes and mean values of FIS close to zero. However, we found evidence of at least limited clonal replication in each of four populations and, within one coastal population, 11 of 27 individuals displayed one of three replicated genotypes, implying that the effective population size may be considerably smaller than would be inferred from the number of plants at this site. Relative to studies with other Proteaceae, this set of populations showed low, although significant, levels of differentiation (global FST = 0.061; P

In late December 2003, a wildfire in the Jervis Bay region of New South Wales burned through an area that previously supported a large population of the endangered eastern bristlebird (Dasyornis brachypterus). The eastern bristlebird has been described as fire-sensitive, and fire is implicated in the decline of the species. The frequency of occurrence of bristlebirds was investigated in the second week after the fire in a range of sites varying in fire intensity. Bristlebirds were found in burned habitats but were less common in the sites that were more intensely burnt. Bristlebirds had been surveyed along transects in this area two months before this fire and were surveyed again 1, 9 and 13 months after the fire. Compared with prefire numbers, bristlebird numbers decreased in burnt areas after the fire and increased in unburnt areas. This pattern was evident for up to nine months after the fire, after which bristlebird numbers returned towards prefire levels in both burnt and unburnt vegetation. This is in contrast to some previous research on bristlebirds and fire. We suggest that bristlebirds avoided the fire by moving to unburnt areas and returned later when conditions were more suitable. We consider that the apparently slight impact of this fire on bristlebirds was due to the close proximity of unburnt habitat and other refuges. The response of bristlebirds and presumably other birds to fire is likely to be strongly context-dependent, so fire management may be able to be designed so as to be compatible with the conservation of local bristlebird populations.

The ecological effects of roads on plant and animal populations are well recognized. However, very little is known about the magnitude of the effects created by powerline easements. Like roads, powerline easements are ubiquitous in many landscapes, including reserves such as National Parks, which have restricted human activities. Regular mowing of the easements to manage vegetation regrowth creates a stark discontinuity with adjacent natural vegetation. Abrupt transitions such as these contribute to habitat fragmentation and are associated with movement and dispersal inhibition of fauna. We used GIS to estimate the area of direct and indirect effects of powerline easements in a 5735 km2 area of coastal New South Wales, focusing on the potential reduction of habitat area both within and outside reserves. While the area directly replaced by these features is a small percentage of the total landscape (

Question: Is primary dormancy required for seed bank persistence of Leucopogon species? How does the distinction between dormancy and persistence affect our understanding of seed bank dynamics in fire-prone regions? Location: Sclerophyllous plant communities, Sydney region, southeastern Australia. Methods: Seed bank longevity of three morphophysiologically dormant species was ascertained using seed burial trials. Seeds of each species were buried in situ in replicate mesh bags and retrieved annually over three years. Laboratory germination trials and embryo growth measurements over time were used to establish in which order each component of dormancy was overcome, and whether seed banks persisted after the loss of primary dormancy. Results: All species had long-term persistent seed banks, with estimated half-lives between 3.5 and 5.5 years. Physiological dormancy was broken by stratification prior to embryo growth, during the first year of burial. Seeds were able to germinate after retrieval, in light and...

Understanding how a species persists under a particular fire regime requires knowledge of the response to fire of individual plants. However, categorising the fire response of a species solely based on known responses of individual plants can be misleading when predicting a population response. In the present study, we sought to determine the fire responses of several Leucopogon species at the population level, including the threatened L. exolasius. We found that, whilst all species studied were obligate seeders, the population responses of species to fire were dependent upon fire intensity and patchiness. Results showed first that low intensity fires were significantly patchier than higher intensity fires. Second, the proportion of plants killed within a population decreased with increased fire patchiness. We also assessed how populations were structured and found that stands were multi-aged at most sites, and did not have a single-aged structure, which is often assumed for obligate seeders. Both spatial complexity within the fire regime leading to adult plant persistence, and inter-fire recruitment, contributed to the multi-aged structure. It is possible that these Leucopogon species are gap recruiters, and may tolerate fire rather than be specifically adapted to it. Inter-fire recruitment may enable L. exolasius populations to persist for a much longer fire-free period than many other species in the region.

Powerline easements are typically a strip cleared of trees and tall vegetation to a width of approximately 50 m. They may affect avifauna by modification and fragmentation of forest habitat. We investigated the responses of the bird community to easements at three sites in southeastern Australia using 25 m radius point-counts spaced at 50 m intervals from the easement to 300 m inside the forest. The easements caused an absolute loss of habitat for forest avifauna, with abundance and species richness at the easement less than 20% of the forest values. Four species of easement opportunist and one easement specialist provided evidence that the easement represented a new type of habitat for avifauna. A barrier effect of fragmentation may occur for four species of easement avoiders. These were small to medium-sized terrestrial birds associated with dense ground and/or understorey cover. The edge effect of fragmentation was an adverse impact on forest avifauna. At the margin (25?125 m from the easement) of the forest, bird abundance, mean species richness and total species richness were significantly less than the corresponding values for the interior (225?325 m) of the forest. The mean abundance at the sites varied from 13.0?17.7 birds/ha and the species richness varied significantly among sites. The adverse impacts of powerline easements on native avifauna could be minimized by site-specific management which includes strategies to minimize the loss of forest habitat and to ameliorate the effects of fragmentation.

The distribution and abundance of small terrestrial mammals were assessed in forest adjacent to powerline easements at three different sites in New South Wales. At each site, four transects of 300 m length extended into the forest from the edge of the easement. The abundances of two native species (Antechinus stuartii, Rattus fuscipes) did not differ significantly with distance from the easement but abundances differed markedly among sites. Mammals were captured in only one easement where dense vegetation was present. Feral carnivores, which may mediate edge effects on small mammals, were surveyed by using hair-sampling tubes. Cats and dogs were detected only 50–200 m inside the forest. Foxes were not detected by hair-tubes but were observed on two easements. These results suggest that powerline easements may not create edge effects in eucalypt forest for some native mammal species, although further studies are needed to determine the generality of this conclusion. We recommend that easement management should be more benign to native mammals, given the ubiquity of this form of habitat fragmentation. Promotion of dense vegetative cover and habitat linkages within easements could achieve this.

Fire is a natural part of most Australian landscapes and has an important influence on the biological productivity and biotic composition of many ecosystems. Although fire is commonly used as a management tool, the precise nature of the way it may influence productivity and biotic composition is often poorly understood and, as a consequence, its use is controversial. This paper considers the use of fire for the management of ecosystems. Specifically, the influences of fire on environmental heterogeneity and the effects these have on shaping biological productivity and biotic patterns are discussed. Heterogeneity that affects biotic response includes variation in biophysical attributes of landscapes such as topography, fire regimes and the spatial attributes of fire. Examples are used to address the interplay between fires, environmental heterogeneity and biological patterns: (1) the effects of frees on plant resource availability; (2) crown scorch in eucalypt forests; and (3) the effects of spatial variation (patchiness) within a fire on species composition. Heterogeneity should be considered explicitly in management because prescriptions devised elsewhere may not be able to be imported with confidence to all sites and the responses of the biota to fires may differ from available information. Ecological monitoring and research into the ecological effects of heterogeneity are required to provide a predictive understanding of natural systems and provide information to aid decisions about the use of fire as a management tool.

The importance of non-flying mammals as pollinators has been a matter of debate in recent years. In the present study, non-flying mammals were regularly captured visiting several species of proteaceous plant at five sites in eastern Australia. Pollen was present in the faeces of these mammals, suggesting that visits to flowers of these plants were taking place. The two mammal species most frequently recorded as visitors (Antechinus stuartii and Petaurus breviceps) were studied to assess their potential as pollen vectors. The magnitude of the pollen loads they carried (several thousand pollen grains per head) is comparable to that of nectar feeding birds in other studies (...)

The influence of animals on patterns of seed dispersal has not been well explored, despite the importance of seed dispersal in plant population biology. Furthermore, the exploitation of animals as dispersal agents has been considered one reason for the replacement of gymnosperms by angiosperms in the Cretaceous. We studied seed dispersal in a cycad, Macrozamia riedlei, and showed that in the absence of animals, ripe seeds drop directly beneath the parent not more than 40 cm from the base. Several animals eat the fleshy outer integument of the seeds, and possums (Trichosurus vulpecula), transport seeds up to 24 m from the parent. The postdispersal positioning of seeds gave a log density-log distance relationship of y = 7.20 – 2.85x (r2= 0.96, N = 17). Effective local dispersal may have contributed to the persistence of cycads in the world flora for the last 200 million years.

This study investigates the impact of insect grazing on the establishment of plant populations from seed after bushfires in coastal plain woodland near Perth, Western Australia. Seedling germination was measured and individual seedlings were observed frequently to estimate survivorship and causes of mortality. Invasion rates of acridid grasshoppers into both small and large burnt areas were measured and palatabilities of seedlings to the most abundant grasshopper species were estimated. Escape of seedlings from insect grazing was influenced by both seedling palatability and area of burning. Grasshoppers were absent from large burnt areas for one to two years. In small burnt patches of vegetation, the patterns of grazing on seedlings were related to seedling palatabilities. These results are discussed in the light of current models of plant succession and the main conclusion is that fire is not a succession-initiating disturbance in this ecosystem because the long association with fire has allowed the evolution of specific survival and recruitment strategies.

The consequences of observed variations in pollinator activity for plant reproduction depend on the breeding system of the plant and also on whether pollination is a resource in short supply. These factors are frequently assumed rather than tested. In bagging experiments with Banksia paludosa in heath and B. spinulosa var. spinulosa in woodland, the present study demonstrated that seed-set does not occur by autogamy and that pollinators are indeed necessary. Experimental addition of outcrossed pollen to inflorescences failed to produce any increase in the mean number of seeds per inflorescence, measured for non-barren inflorescences, for either species. However, in B. paludosa, the addition of pollen increased the numbers of inflorescences that set seed from 20% (controls) to 45% (pollen-added treatment). This suggests either unusual patterns of pollen movement among and within plants or control of the pattern of seed-set within a plant. Pollen additions failed to alter seed-set in B. spinulosa. It is possible that a greater abundance of pollinators in the woodland ensures adequate pollination for these plants