Philip Ladd

Floristically rich and ecologically complex, Mediterranean-type ecosystems are rapidly being cleared for urban, horticultural and industrial development. A prime example is Banksia woodland, an ecosystem restricted to the Swan Coastal Plain in Western Australia. In order to compensate for the clearing of Banksia woodland due to urbanization, land developers are required to attempt biodiversity offsets whereby topsoil from newly cleared landscapes can be moved to degraded land with the aim of restoring Banksia woodland. Yet the science and practice of restoration ecology is not sufficiently advanced to know for certain that this aim can be achieved. Assessing the efficacy of a spectrum of restoration techniques will provide new insights for the restoration of endangered plant communities, and critically, a test of the feasibility of biodiversity off setting. The topsoil was subjected to three site-scale treatments: altering topsoil depth, ripping & herbivore exclosures. Additionally, six plot-scale treatments were applied to explore germination effect (three smoke water-related, topsoil heating) and competition effect (herbicide & artificial shade installation) on native seedlings’ emergence and survival. Significantly fewer seedlings emerged from ripped (17.01 ±1.03 SE) than unripped plots (37.99 ±2.05 SE). Species richness was similar across all treatments with a total number of native plant species emerging from the transferred topsoil of 129 in the first year and 115 in the second year. Mean survival rates of native perennial seedlings were very low (year I = 11.1% & year II = 1.2%). The maximum average survival was recorded under artificial shade (41% ±12.2 SE).

Delayed seed release (serotiny) is a syndrome of adaptive significance in a randomly fluctuating environments such as fire-prone and arid ecosystems. Selective forces involving fire, rainfall and seed predators have been suggested as factors influencing serotiny. Callitris preissii is a conifer in the Cupressaceae found only in Australia and New Caledonia and it is regarded as “fire sensitive”. It has excellent potential for erosion control of sandy, alkaline coastal sites and has been used in revegetation in many region in Western Australia. We compared the degree of serotiny among different populations and related this to fire history, climate and seedling predators.The relative ages of cohorts of closed cones were determined on trees in populations ranging from arid interior sites to islands with much higher annual rainfall. The individuals with the greatest serotiny grow at inland sites (Kalgoorlie and Lake Grace), while the plants with the lowest serotiny were recorded at island sites. Seedling recruitment after fire at Boorabin National Park burnt in 2007 was dense and at Cape Le Grand National Park near the south coast of Western Australia a patchy fire produced many seedlings in burnt areas. However in both areas seedlings were absent from unburnt sections. The strong serotiny at these sites ensures an abundant seed rain after fire kills adult plants. The weaker serotiny at the island sites might be thought to relate to the possibility that there is interfire recruitment of the plants.

Background/questions/methods: The main urban areas of Western Australia (WA) are located on the Swan Coastal Plain - the 400 km long sandy landform between the Indian Ocean and Darling Scarp that encompasses the main habitat for endangered Banksia woodland. This floristically rich but poorly understood Mediterranean-type ecosystem is being rapidly destroyed by urban, horticultural and industrial development. In order to partially ameliorate the damage being inflicted on Banksia woodland vegetation WA land developers have been required to purchase offsets of, often degraded, land to where topsoil from construction sites can be moved to help rehabilitate the damaged areas. The aim of this project is to restore Banksia woodlands by optimising germination and survival of native species from the soil seed bank contained within transferred topsoil. The project is a part of an offset program associated with the development of the Jandakot Airport 25 km south of Perth city. In the first year, key research questions are focused on enhancing germination by varying depth of returned topsoil, ripping, fencing, weed control and experimental additions of smoke. Subsequent work will examine the survival and persistence of germinants including treatments such as provision of artificial shade. Assessing the efficacy of a spectrum of novel restoration technologies will provide new insights for environmental management of endangered plant communities. Results/conclusions: Preliminary results will be presented at the conference.

South-western Australia is a global biodiversity hotspot that boasts the continent’s highest orchid diversity, yet is under increasing pressure from rapid urbanisation. Bushland remnants in the Perth metropolitan area host approximately 74 orchid species and the viability of many of these populations is threatened by ongoing urbanisation. Despite this, little is known about the influence that habitat condition and reserve characteristics have on pollination success, the ultimate measure of population viability. To address this, we investigated orchid pollination success along a habitat condition cline within urban reserves. The study utilised pollination success as a measure of population viability among orchid genera that represented the full spectrum of pollination syndromes, from sexual through to food deception. We found no significant correlation between overall habitat condition and pollination success (rs= 1.99, P= 0.313). Significant correlations with individual components comprising habitat condition such as litter (rs= 0.502, P= 0.005), shape index (rs= -0.487, P=0.009), and bareground (rs= -0.413, P= 0.026) were found, lending power to the use of predictive models. Our results show that pollination syndromes have variable responses to urbanisation which can be linked to their ecology. This study has conservation and management implications, providing insights into the influence of habitat condition components on population viability within urban reserves.

Prior to this research, the size class structure, levels of canopy deaths and an absence of juveniles indicated all known populations of Acacia chapmanii subsp australis R.S.Cowan & Maslin, a Declared Rare Flora, were in decline. Utilising an adaptive management approach when required to make conservation decisions on rare species substantially reduces risk whilst increasing our understanding of managed ecosystems (Wilhere 2002). A.chapmanii is killed by fire and therefore relies on seed for survival, with the hard seededness requiring fire related germination cues to break dormancy. After a 2004 experimental burn when both burnt and control plots were fenced, seedling establishment from soil seed bank and planted seed only occurred in burnt plots. Monthly monitoring over the first 12 months showed 43% of planted seed and 50% of soilbank seed that initially germinated, survived to seedling stage. Following this success, to monitor herbivore effect a normal DEC fuel reduction burn was conducted, with seedling emergence in the same order as after the 2004 fire. Seedling survival in open burnt plots was much lower than in fenced plots with skat counts indicating kangaroos as the culprits. Only an occasional seedling in unfenced burnt plots survived into its second year. However, when these unfenced and well grazed plots were enclosed in 2007 which eliminated herbivory impacts, there was a significant increase in A. chapmanii seedlings establishing 2 and 3 years following the fire. This increase was not seen in the initial fenced plots, possibly due to the dense ground cover of a range of species that had germinated or resprouted following the fire. A number of other species also established within the burnt area, with indications that some species may become more dominant than they were prior to the fire. Of most concern is the extensive establishment of Eucalyptus wandoo seedlings. The established populations of A. chapmanii were mostly in open kwongan or low shrubland areas. Further research needs to be undertaken to understand how A. chapmanii will cope in future years under the canopy of an over-storey of E. wandoo, particularly as the fenced plot adjacent to the canopy of established E. wandoo had significantly fewer A. chapmanii seedlings establishing than in the other fenced burnt plots.

Whiteman Park is a 4,200 ha conservation and recreation reserve situated approximately 16 km NE of the Perth CBD. Within the Park there exists a 930 ha area of relatively undisturbed bushland that has been set aside as a conservation reserve. The vegetation of the Park is a mixture of Banksia, Eucalyptus and Melaleuca woodlands, which have been classified by Mattiske and Associates (1989) into seven broad vegetation types based on Havel (1976). As part of a proposed conservation initiative attempting to enhance mammal biodiversity, Whiteman Park management wishes to construct a feral animal-proof fence around the conservation reserve and to re-introduce a selection of locally extinct mammal species (Bancroft 2005). Concern over the possible negative impact of mammal reintroduction on vegetation mass has prompted the need to document the above-ground vegetation biomass of the conservation reserve.

This study has examined the effect of the Department of Environment and Conservation's (DEC) prescribed burning on the leaf litter invertebrates of the Northern Jarrah Forrest in southwestern Australia. These burns are an important management practice to reduce fuel loads in forests, minimizing damaging wildfires. The fires are lit in either spring or autumn, and are intended to be cool and to leave a mosaic of burnt and unburnt patches. Although the invertebrate biota of Western Australia has evolved in a fire-prone environment the response of the leaf litter invertebrates to such regular burning is not well understood. The leaf litter of eucalypt forests supports a diverse invertebrate fauna which is essential for nutrient recycling, and a critical component of Western Australia's biodiversity. This study examines the effect of autumn and spring burns on the invertebrate fauna generally, but with particular reference to Apocrita (Insecta: Hymenoptera). The Apocrita are a keystone group that controls the other invertebrate populations through predation and parasitism and, although often present in low numbers, is considered to be possibly the most speciose invertebrate group (Saaksjarvi et al. 2004 ). Due to their low numbers Apocrita are considered to be vulnerable to events like burning, but little research has been conducted to confirm this hypothesis (Lasalle and Gauld 1993). Due to their host specificity, an analysis of apocrita can be used to determine other invertebrate populations and assess changes (Stephens 2005).

The search for structure in biological communities, which would suggest that rules exist, that arbitrate which species can co-exist locally, is of central importance to community ecologists (Wilson and Whittaker 1995). Questions such as "what are the constraints on membership in a community" (Temperton and Hobbs 2004) are critical to our understanding of the way species coexist. The search for structure within communities is characterised by the search for assembly rules, whereby species presence or abundance is based on the presence or abundance of several other species, or types of species, and not simply on the response of individual species to the environment (Wilson 1999). However, the evidence for assembly rules is widely regarded as being indirect and is based on the demonstration of non-random patterns, which are interpreted as representing assembly rules (Wilson and Whittaker 1995). In this study the existence of assembly rules is not assumed. However the presence of some sort of community structure can be tested against a null model in which there are no constraints on the local association of species (Wilson and Whittaker 1995). The community structure of a salt marsh and sand heath in Jurien Bay, Western Australia, were examined to see if there was evidence of assembly rules in terms of species richness, favoured states and fine-scale species-pairs associations.

Introduction: Of the estimated 8,000 species in the Southwest Botanical Province of Western Australia, about 25% are either under threat or have poorly known conservation status, with a third of the 564 Acacia taxa in the region considered in this category (Yates and Broadhurst 2002), Acacia chapmanii subsp. Australis RS,Cowan and Maslin is typical of many of these species, It has an aging population with little recruitment. is confined to narrow linear remnants on road and rail reserves, and has patches of limited extent in one managed reserve. As little was specifically known about the biology of A chapmanii, strategies for assisting population recovery were based on general characteristics of Acacia population biology and likely landscape processes in the area it occupies, The strategy developed was a stepped process using an adaptive management approach based on a scientific model with replicated trial plots and controls (Blumstein 2007), An adaptive management approach enables decisions to be made on management strategies as soon as conclusive results are evident. After elimination of factors such as Phytophthora cinnamomi and rising saline water tables, the most likely factor contributing to decline appears to be lack of disturbance, such as fire, with no recorded fire in over 20 years. As many Acacia taxa in the transitional rainfall zone of southwest Western Australia are stimulated to germinate by the heat of a fire, the initial experiment utilized a control burn of small plots designed to have minimal impact on the majority of the community in which the species occurs. No herbivore impact was measured as all plots were fenced. Initial results following monitoring of the germination response for A chapmanii, both from the soil seed bank as well as from planted seed showed no seedlings surviving in unburnt plots. The success of seedling survival from the soil seed bank in burnt plots led to the decision in 2005 to measure ecosystem scale behaviour on this community following a normal autumn Department of Environment and Conservation (DEC) fuel reduction burn, which more closely resembles a wildfire. This research was designed to measure whether regeneration of A. chapmanii, and other species, was similar to the first burn and the influence of herbivory on seedling survival.