Remnant Patches Of Native Vegetation Research Articles

Large-Area, High-Resolution Tree Cover Mapping with Multi-Temporal SPOT5 Imagery, New South Wales, Australia

Tree cover maps are used for many purposes, such as vegetation mapping, habitat connectivity and fragmentation studies. Small remnant patches of native vegetation are recognised as ecologically important, yet they are underestimated in remote sensing products derived from Landsat. High spatial resolution sensors are capable of mapping small patches of trees, but their use in large-area mapping has been limited. In this study, multi-temporal Satellite pour l’Observation de la Terre 5 (SPOT5) High Resolution Geometrical data was pan-sharpened to 5 m resolution and used to map tree cover for the Australian state of New South Wales (NSW), an area of over 800,000 km2. Complete coverages of SPOT5 panchromatic and multispectral data over NSW were acquired during four consecutive summers (2008–2011) for a total of 1256 images. After pre-processing, the imagery was used to model foliage projective cover (FPC), a measure of tree canopy density commonly used in Australia. The multi-temporal imagery, FPC models and 26,579 training pixels were used in a binomial logistic regression model to estimate the probability of each pixel containing trees. The probability images were classified into a binary map of tree cover using local thresholds, and then visually edited to reduce errors. The final tree map was then attributed with the mean FPC value from the multi-temporal imagery. Validation of the binary map based on visually assessed high resolution reference imagery revealed an overall accuracy of 88% (±0.51% standard error), while comparison against airborne lidar derived data also resulted in an overall accuracy of 88%. A preliminary assessment of the FPC map by comparing against 76 field measurements showed a very good agreement (r2 = 0.90) with a root mean square error of 8.57%, although this may not be representative due to the opportunistic sampling design. The map represents a regionally consistent and locally relevant record of tree cover for NSW, and is already widely used for natural resource management in the state.

Identifying essential ecological factors underpinning the development of a conservation plan for the Endangered Australian tree Alectryon ramiflorus

AbstractReintroduction of rare and threatened species often fails to yield quantifiable conservation benefits because insufficient attention is focused on the species’ habitat requirements and biology. We demonstrate the value of such data in informing a recovery plan for Alectryon ramiflorus S.Reyn. (Sapindaceae), a tree species endemic to a region on the southern coast of Queensland, Australia. When the species was categorized as Endangered on the IUCN Red List in 1997 the total known population consisted of only 26 adult plants, in five disjunct populations in remnant patches of native vegetation. Analysis of vegetation type, soil chemistry and composition data comparing remnant patches with and without A. ramiflorus revealed that the species is not restricted to a specific soil type but prefers sites with relatively fertile soil and a more complex vegetation structure. The species is cryptically dioecious, displays asynchronous flowering between individuals, and requires insect-vectored pollination. The low rate of seedling production recorded within individual patches was attributed to the scarcity of trees of both genders, asynchronous flowering of individual trees and, in smaller patches, a sparse population of pollinating insect species. Successful reintroduction of A. ramiflorus will require consideration of these aspects of demographic success. The findings highlight the importance to species recovery plans of the knowledge of habitat requirements, interspecific relationships and critical dependencies, as well as species reproductive biology.

Epigaeic beetle communities of the Green Triangle plantation landscape, southern Australia: effect of remnant size, vegetation quality and structural complexity

SummaryAcross the Green Triangle plantation landscape of south-eastern South Australia and south-western Victoria there remain remnant patches of native vegetation which vary considerably in both size and vegetation quality. This study focused on how the vegetation quality and or size of remnants embedded within the bluegum (Eucalyptus globulus) plantation landscape influence the local ground-dwelling Coleoptera (beetle) assemblages found within them. The aim was to particularise those remnant characteristics (in terms of size and vegetation quality) that are likely to result in the most effective protective management of local remnant beetle biodiversity. Pitfall sampling was carried out over a 13-month period. All beetles sampled via pitfall traps were identified to family level, and the three most abundant beetle families (Carabidae, Staphylinidae and Tenebrionidae) identified to genus. Remnant vegetation was assigned to one of the four quality categories (as defined by the Land for Wildlife (LFW) method), and structural attributes of the vegetation surrounding each trap were also measured.Different beetle taxa responded independently to remnant vegetation quality and size, and to the measured vegetation structural variables. Mean beetle family abundance and estimated richness increased with decreasing remnant vegetation quality. However, when Carabidae, Staphylinidae and Tenebrionidae beetle families were analysed separately at genus level, taxa responded independently to vegetation quality and size. Furthermore, different vegetation structural variables such as the percentage cover of litter and shrubs as well as the number of overstorey stems were correlated with estimated richness of different beetle taxa. Beetle abundance was significantly influenced by mean litter depth and shrub and litter cover. This study also showed that remnants of different vegetation quality supported beetle assemblages composed of significantly different communities. However, these differences were not consistent between all sites of different vegetation quality, suggesting that there may be additional ecological characteristics within the landscape responsible for shaping remnant beetle communities. No single, specific quality of remnant vegetation was optimal for supporting the most diverse assemblage of beetles, as different taxa responded independently. A range of remnants of differing qualities maintained across the landscape may provide the resources needed for the widest range of beetle taxa, by accommodating their varying habitat requirements.

Recruitment of Eucalyptus strzeleckii (Myrtaceae) in remnant patches of native vegetation in the Latrobe Valley and South Gippsland, Victoria

Eucalyptus strzeleckii K.Rule (Strzelecki gum) is a medium to tall, forest swamp gum endemic to the foothills and flats of southern Victoria. It is listed as Vulnerable at State (Victoria) and Federal levels. Many of the existing populations are dominated by mature, senescing trees in highly degraded habitats and recruitment of the species is rarely observed. The present study assessed the natural recruitment of Strzelecki gum at locations where mature Strzelecki gums are present and habitat degradation is not a significant limiting factor. The number of mature and recruiting Strzelecki gum individuals was assessed within gradient-oriented belt transects (gradsects) and a range of variables considered to be likely to affect recruitment were measured and correlated with the results of the recruitment study. Strzelecki gum recruits (<5 m tall) were found in 68.8% of gradsects and recruits accounted for 8–14% of the total stems counted for this species. Areas that had been recently burnt (within the past 5 years) had 15 times the number of Strzelecki gum recruits. Disturbance by flooding may also be positively associated with recruitment. Litter cover, habitat quality and density of intermediate-sized Strzelecki gums were all strong positive predictors for the density of Strzelecki gum recruits. Results from the present survey have provided a basis for land managers to estimate quantities of mature and recruiting Strzelecki gums in large populations.

The importance of viticultural landscape features and ecosystem service enhancement for native butterflies in New Zealand vineyards

The fragmentation of habitats in intensively managed farming landscapes is often considered to be partly responsible for butterfly population decline in Europe and the USA. Although relatively little is known about New Zealand butterfly ecology, agricultural landscapes in lowland New Zealand are managed similarly to those in Europe and ecosystem services (ES) in these landscapes are generally at a low level. In the northern hemisphere, attempts are being made to address the problem through agri-environment schemes, but such farmer compensation is not available in New Zealand. Instead, landowner- and research-led initiatives are currently the only potential approaches. One such project in the Canterbury province, New Zealand, is the Greening Waipara project. This aims to return native plants to viticultural landscapes and enhance ES, and while research has sought to quantify economic benefits of the project, there has been no work to establish if the plantings are improving or are likely to improve non-target invertebrate biodiversity, for example arthropods that are not biocontrol agents. In the first study of its kind in New Zealand, butterfly surveys were conducted in vineyards and linear mixed modelling techniques were used to identify the most important vegetation and structural features which may influence butterfly distribution. While the native planting areas were not important for butterflies, remnant patches of native vegetation in unproductive areas were vital for sedentary species. These results are discussed in relation to the conservation of native species in New Zealand vineyards and in the context of conservation in and around farmland in general.

Determinants of native avian richness in suburban remnant vegetation: Implications for conservation planning

While urban areas are increasingly recognized as having potential value for biodiversity conservation, the relationship between biodiversity and the structure and configuration of the urban landscape is poorly understood. In this study we surveyed birds in 39 remnant patches of native vegetation of various sizes (range 1–107 ha) embedded in the suburban matrix in Melbourne, Australia. The total richness of species within remnants was strongly associated with the size of remnants. Remnant-reliant species displayed a much stronger response to remnant area than matrix-tolerant species indicating the importance of large remnants in maintaining representative bird assemblages. Large remnants are important for other ecological groups of species including migratory species, ground foraging birds and canopy foraging birds. Other landscape (e.g. amount of riparian vegetation) and structural components (e.g. shrub cover) of remnants have a lesser role in determining the richness of individual remnants. This research provides conservation managers and planners with a hierarchical process to reserve design and management in order to conserve the highest richness of native species within urban areas. First of all, conservation efforts should preferentially focus on the retention of larger remnants of native vegetation. Second, where possible, riparian vegetation should be included within reserves or, where it is already present, should be carefully managed to ensure its integrity. Third, efforts should be focused at maintaining appropriate habitat and vegetation structure and complexity.

Efficacy of Control Measures for European Buckthorn (Rhamnus cathartica L.) in Saskatchewan

Introduced to Saskatchewan in the 1930s as a potential shelterbelt species, European buckthorn is now a prominent understory shrub in riparian woodland and shrub communities around Saskatoon. Locally, the Meewasin Valley Authority (MVA) is actively controlling buckthorn as part of its mandate to conserve natural heritage resources of the South Saskatchewan River Valley, with the goal of restoring the natural biodiversity of remnant patches of native vegetation. European buckthorn is normally dioecious, and MVA has chosen to treat only fruiting stems in an attempt to limit seed production. Two control techniques have been used. In one treatment, glyphosate was applied to stems after cutting; alternatively Garlon 4 Dow AgroSciences herbicide (active ingredient triclopyr) was applied as a chemical girdle directly to the stems using a streamline basal bark spray method. To date, more than 347,000 fruiting stems of buckthorn have been treated. Results indicate good initial progress in limiting seed production in dense buckthorn sites, but at a high cost. Although seed eradication is not a practical short-term goal for the Saskatoon buckthorn population, chemical girdling can substantially and strategically reduce seed and effectively limit spread. Field-tested strategies to reduce costs and improve efficiencies are discussed.

A Conceptual Model of Land Conversion Processes: Predictions and Evidence from a Microlandscape Experiment with Grassland Insects

Land conversion due to human activities produces distinctive spatial patterns across the landscape. It remains unclear, however, how particular spatial arrangements of remnant habitat patches influence species persistence. We present a conceptual model of landscape change that focuses explicitly on habitat spatial arrangement. Four sequences, characterized as shrinkage, bisection, fragmentation, and perforation, differ qualitatively in the spatial arrangement of intact habitat and differ quantitatively in boundary length, amount of interior area, and connectivity. We tested the predictions of this conversion sequence model in a microlandscape field experiment with insects in a native grassland habitat. The four conversion sequences significantly influenced the species composition of the above-ground insect community, and insect species groups varied in their responses. Four patterns were evident from the field experiment: (1) as habitat decreased, insect density rose sharply on small dispersed patches of the bisection and fragmentation sequences, an effect less evident in the large remnant patch of the shrinkage sequence; (2) species richness declined only in the case of shrinkage, whereas richness increased in the fragmentation sequence; (3) most individual species examined responded similarly to the community as a whole: and (4) large rare species were concentrated in remaining habitat of the shrinkage and fragmentation sequences. Overall, the shrinkage and perforation sequences, which had high connectivity, were similar to one another in species composition, while the bisection and fragmentation sequences, which had low connectivity, were similar to one another. Based on these results, we conclude that a spatial pattern of land conversion that maintains one or more large, closely spaced remnant patches of native vegetation is essential for species persistence.

13. Endemism in freshwater algae

Across the world there is a prevailing view that freshwater algae are cosmopolitan. The notion has seldom been tested and is unlikely to be true in genetic terms. Nonetheless, some morphospecies of several groups of algae do have a worldwide distribution. Others have restricted distributions and may be regarded as endemic to a region. However there is always the possibility that they will be discovered in far away places. Australia has a rather large element of endemicity in its algal flora. From the early days of Australian phycology many new genera and species of freshwater algae have been described. Some are of such distinctive appearance or novelty as to be regarded as 'flagship' taxa. There is little doubt about their endemicity and their existence increases the probability of less-distinguished species also being endemic. The degree of endemicity is probably masked by the 'force-fitting' of European names to Australian species. Some Australian endemics are robust and are widely distributed in a variety of types of water body. Others, the frail endemics, the ones of greatest novelty and phylogenetic significance, have a very restricted range with their strongholds in dystrophic coastal lagoons where tracts or remnant patches of native vegetation survive. Their survival and the conservation of their biodiversity depends on recognition of the significance of coastal lagoons and swamps.

The relative conservation value of remnant patches of native vegetation in the wheatbelt of Western Australia: I. Plant diversity

Accurate assessment of the relative conservation value of remaining areas of native vegetation is of primary importance to both land planners and land managers wishing to conserve the biodiversity of an area. Selection procedures aimed at identifying sets of patches for nature reserve networks stress the importance of retaining beta diversity (or diversity of habitats). This paper describes a new procedure that incorporates a measure of relative alpha diversity (or within habitat diversity) of plant species, as well as beta diversity, using the Kellerberrin area of the Western Australian wheatbelt as an example. The inclusion of such an algorithm in selection procedures is justified since beta and alpha diversity, together with genetic diversity, determine the overall biotic heterogeneity of an area. A five-step ranking method is used to prioritize remnant patches of native vegetation with respect to plant diversity, both at regional and local scales. Ranking at a regional scale is important for state authorities able to deal with only a limited number of widely dispersed sites such as nature reserves; whereas ranking at the local scale provides a guideline for the conservation of biodiversity at a level where many land use and management decisions are made by local government and private citizens.