Peter G. Spooner

Spatial analysis of roadside Acacia populations on a road network using the network K-function

Spatial patterning of plant distributions has long been recognised as being important in understanding underlying ecological processes. Ripley’s K-function is a frequently used method for studying the spatial pattern of mapped point data in ecology. However, application of this method to point patterns on road networks is inappropriate, as the K-function assumes an infinite homogenous environment in calculating Euclidean distances. A new technique for analysing the distribution of points on a network has been developed, called the network K-function (for univariate analysis) and network cross K-function (for bivariate analysis). To investigate its applicability for ecological data-sets, this method was applied to point location data for roadside populations of three Acacia species in a fragmented agricultural landscape of south-eastern Australia. Kernel estimations of the observed density of spatial point patterns for each species showed strong spatial heterogeneity. Combined univariate and bivariate network K-function analyses confirmed significant clustering of populations at various scales, and spatial patterns of Acacia decora suggests that roadworks activities may have a stronger controlling influence than environmental determinants on population dynamics. The network K-function method will become a useful statistical tool for the analyses of ecological data along roads, field margins, streams and other networks.

Land‐use change: incorporating the frequency, sequence, time span, and magnitude of changes into ecological research

The frequency and extent of human-induced land-cover changes is escalating worldwide. Recurrent turnover of land-cover types will affect ecosystems over and above major, one-time changes (eg deforestation). Here, we show how a deeper appreciation of the temporal dynamics of land-cover change is needed to understand its effects on ecosystems. We distinguish between four key components of land-change regimes: (1) frequency of land-cover changes over a period of time, (2) the sequence of land-cover types, (3) the time span over which each land-cover type extends, and (4) the magnitude of difference between land-cover types. We synthesize the impacts of these four components on ecological communities, showing that frequent land-cover changes are likely to favor species that are habitat and dietary generalists. Greater attention to the complex dynamics of land-cover changes is critical for a better understanding of the future impacts that human-generated land-use changes will have on global biodiversity.

The influence of land-use history on roadside conservation values in an Australian agricultural landscape

We investigated the influence of land-use history on roadside conservation values in a typical agricultural landscape of southern New South Wales (NSW), Australia. Historical information on the development of rural road reserves was collated from recently digitised 19th and 20th century pastoral and parish maps, such as road-reserve age and original survey width, as well as data relating to locations of old fence lines, county or parish boundaries, previous reserves, stock routes and road re-alignments. Ordinal regression statistics showed that road-reserve age and road width were significant predictors of roadside conservation values. Importantly, analyses showed that the first roads surveyed during the pastoral era (1840–1860s) were often of lower conservation value than roads surveyed in the 1870s, when major clearing of these landscapes commenced. Most roads were surveyed at one-chain width (20.12 m); however, pre-1870s historic roads, traveling stock routes (TSRs) and county or parish boundaries were significantly wider, decisions that have indirectly led to higher present-day conservation values. In separate analyses, historical data also formed a useful model to predict the absence of short-lived shrub species. These results highlight the influence and prevailing imprint of historical land-use on current roadside conservation values.

On Squatters, Settlers and Early Surveyors: historical development of country road reserves in southern New South Wales

Country roads are an important social, economic and ecological component of agricultural landscapes in many parts of New South Wales. Using the Lockhart Shire Council area as a case study, this paper describes how present-day rural road networks are a historical vestige of past land-use decisions; a collection of Travelling Stock Routes, pastoral boundaries of early squatters, rail reserves, county and parish boundaries, and an ad hoc collection of mostly 1 chain (20.12 m) roads surveyed during the late 1800s. Road reserves were allocated across the landscape at the discretion of early surveyors, so new land titles could access vital water resources. Nineteenth-century surveyors faced many difficulties in surveying the extent of NSW, sometimes resulting in misalignments which today give ‘character’ to many country roads. Road reserves were often surveyed 2 or 3 chains wide to allow for predicted usage and provide materials for road construction. In the 1870s, Travelling Stock Routes of varying widths from 1 to 80 chains wide (one mile) were gazetted, which often form an integral part of many country road networks. In this way, present-day conservation values of many road reserves is a direct legacy of land policies, administrators and surveyors on the landscape today.

The importance of managing the costs and benefits of bird activity for agricultural sustainability

The behaviour of wild animal species in agricultural landscapes may confer benefits to growers through the provision of ecosystem services (e.g. control of agricultural pests) or inflict costs through direct or indirect damage to crops or livestock. The literature on the costs that species inflict or the benefits they provide has evolved largely independently with few attempts to synthesize information across studies. However, managing cost–benefit trade-offs to maximize agricultural productivity while ensuring native species conservation is vital to the future of ecologically sustainable agriculture. Using birds as a case study, we review the two bodies of literature on the costs and benefits attributed to bird activity in agricultural landscapes. In each case, we examine the major types of costs (e.g. consumption of crops) and benefits (e.g. pollination of crops) and assess approaches to quantifying these in terms of changes in crop yield or monetary value. We then synthesize this information to examine options for balancing cost–benefit trade-offs through coordinated and integrated management strategies that consider all aspects of species activity in agricultural landscapes. Employing strategies that successfully balance costs and benefits is fundamental to future food security and agricultural sustainability.

Changes in forest structure over 60 years: tree densities continue to increase in the Pilliga forests, New South Wales, Australia

Studies of long-term vegetation changes are critical for enhancing our understanding of successional dynamics in natural ecosystems. By comparing forest inventory data from the 1940s against field data from 2005, we document changes in stand structure over 60 years in forests co-dominated by Callitris glaucophylla J.Thompson & L.Johnson, Allocasuarina luehmannii (R.Baker) L.Johnson and Eucalyptus crebra F.Muell., in central Pilliga, New South Wales (NSW), Australia. Sampling was stratified across two forest types and across a 1951 wildfire boundary, to assess the effects of initial stand structure and early disturbance on stand dynamics. Stems in the size range tallied in the 1940s (>8.9 cm DBH for Callitris and >11.4 cm for Allocasuarina and Eucalyptus) of each genus increased about three-fold in density and about four-fold in basal area over 60 years, with similar trends in both forest types and fire zones. On average, there were 3638 stems ha–1 in 2010, of which 86% were small Allocasuarina and Callitris (<11.4-cm and <8.9-cm diameter at breast height, DBH, respectively). These results illustrate a continuation of forest encroachment that was initially documented in the late 1800s. However, increases in Allocasuarina have received little attention compared with Callitris recruitment. In the absence of disturbance, ongoing increases in stand stocking may be expected.

Origins of Travelling Stock Routes. 2. Early development, management, and the growing embrace of the law (1830-70s).

Travelling Stock Routes (TSRs) are a network of grazing routes and reserves which are thought to have originated from the informal tracks of early European explorers, pastoralists and settlers. However, their origins are much more complex, and entwined in legislative and administrative attempts from the 1830s to 1870s to manage and control diseases in sheep and cattle. We describe (1) the development of management controls for the emerging TSR network, through the series of enactments in legislatures designed to eradicate scab in sheep, and ovine catarrh from the pastoral industry, and (2) identify the people who made the decisions which influenced the management and design of the TSR network. Requirements for droving permits, access to squatting runs, and historic methods for sheep disease control are described, and development of major quarantine points on stock routes are highlighted. As we indicate, this narrative sets the stage for the formal survey of the first TSRs in the early 1870s, and highlights the rich social and economic drivers that contributed to their development upon the landscape, their design and location, and influence on present-day management approaches.

Bird use of almond plantations: implications for conservation and production

Abstract Context. Farmland crops may suffer damage from native animals, but also provide a critical resource during times of food scarcity. We know little about bird use of almond crops. Aims. To examine factors influencing temporal and spatial variation in the use of almond crops in north-western Victoria by bird species, including the threatened regent parrot (Polytelis anthopeplus), and to record levels of crop damage. Methods. We measured bird occurrence in 15 transects during the almond-growing season of 2009/10, and 32 transects during 2010/11. Crop-damage assessments were conducted in 2010/11. Spatio-temporal variation in bird occurrence was related to seasonal factors, landscape variables and bird-control activities. Key results. Significantly more regent parrots and small parrots (e.g. Platycercus elegans and Psephotus haematonotus) were recorded in almond plantations in 2009/10 than in 2010/11. Rainfall and wheat production was much higher in 2010/11, and we hypothesise that the availability of alternative foods reduced parrot dependence on almonds. Regent parrot occurrence did not differ across months within a season, but more small parrots were recorded during almond nut maturity. Regent parrots appeared to prefer locations where almond crops abutted native vegetation, but only during 2009/10, a dry year with likely limited food availability. Small parrots occurred more often in crops close to riverine vegetation and distant from farm offices. Nut damage was generally low, with only 7 of 32 transects sustaining >4% total damage, but damage assessments were conducted during a season of high rainfall, with likely greater availability of alternative food. Percentage damage was significantly correlated with the number of regent and small parrots. Shooting activity did not deter birds from using almond crops. Conclusions. Parrots appear to rely more on almond crops for food when environmental conditions limit other food resources. A key strategy for managing bird impacts on almonds while supporting species conservation is to provide decoy crops of preferred native plants. Implications. Rapid loss of almond plantations may lead to population declines in the threatened regent parrot if the availability of alternative food is not simultaneously increased. The role of production land uses in supporting native birds needs to be recognised by conservation management agencies.

Historical forest survey data from Eucalyptus–Callitris forests: a valuable resource for long-term vegetation studies

Quantitative information about historical changes in natural ecosystems is important for guiding management interventions. However, few accurate data sources are available for documenting long-term vegetation changes. In this paper, we describe a neglected source of quantitative information on historical forest structure: forest inventory strip surveys, which were widely used in eastern Australia from 1915 to the 1940s. Strip surveys provide quantitative information on the species composition, stem density, basal area, stem form and size class distributions of dominant tree species. Such information is not available from other widespread data sources. Strip surveys usually surveyed 10% of the total forest area. In this paper, we describe the original survey methods, demonstrate how to decode data-book entries, and analyse a sample dataset from the Pilliga State Forests in northern New South Wales to illustrate the information that can be obtained from this material. Strip survey data-books are poorly archived. Many books exist for Eucalyptus–Callitris forests in northern and central NSW, and additional books may exist for many other forest types in eastern Australia. Strip surveys provide a valuable data source for studying long-term vegetation changes in forest ecosystems. We urge forest managers to search for and preserve this precious archival material.

The influence of urban encroachment on squirrel gliders (Petaurus norfolcensis): effects of road density, light and noise pollution

Abstract Context. Loss and degradation of habitat from urban development is a key threat to the squirrel glider (Petaurus norfolcensis), because its distribution coincides where most people live in Australia. Squirrel gliders are known to occur in or around urban fringes where native vegetation is retained; however, little is known about specific anthropogenic factors that may affect their persistence. Aims. We investigated the relative influence of biophysical and urban factors on the use of large hollow-bearing Eucalyptus trees, which are a key resource for squirrel gliders. The study was located in a typical urban growth area located in southern New South Wales. Methods. A stratified random sampling approach was used to survey squirrel gliders in urban and rural areas. Infrared, motion-sensor cameras were placed in 34 selected trees for 17 nights to record squirrel glider occupancy and activity. Data on urban (e.g. light and noise pollution levels, road and housing density) and biophysical (e.g. tree height, hollow-bearing tree density, vegetation cover) variables were recorded at each survey tree. Data were statistically analysed using general linear modelling approaches. Key results. Squirrel gliders were detected more frequently in the rural matrix (23.4% of camera trap-nights) than in urban areas (9.5%). Model results showed that tree height, and the distance to neighbouring trees, had a significant influence on the occurrence and activity of squirrel gliders. Road density and light pollution were included in ‘best’ models to explain glider activity (a negative influence), and noise pollution negatively influenced glider occurrence. Although gliders used large trees in both urban and rural areas, activity generally decreased as levels of urbanisation increased. Conclusions and implications. Access to and availability of key resources such as tall, hollow-bearing trees is critical for gliders to persist in urban environments. Squirrel gliders will tolerate human stressors such as roads, noise and light pollution to a certain extent, but impacts on population viability remain largely unknown. Novel solutions need to be developed to lessen the effects of anthropogenic factors (such as light and noise) on patches of native vegetation retained in urban areas for conservation purposes.