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Weed management remains a central problem for landscape-scale conservation projects in Australia and globally. However, little is known about the invasive species that will be favoured by new land use regimes intended to protect and enhance native biodiversity, and whether these species have the greatest impact on broad-scale conservation goals. In this paper we use survey data collected from landholders and regional land managers to provide an initial identification and prioritisation of the weed species that have the greatest potential to degrade conservation management areas in the Kosciusko to Coast (K2C) Partnership corridor area of south-eastern New South Wales. We show that the control of invasive weeds remains a significant problem for virtually all landholders and managers in the region, and that consistent with expectation, Hypericum perforatum L. (St. John's wort), Rubus fruticosus L. (blackberry) and a range of annual and biennial herbs tend to increase under management regimes designed to benefit native biodiversity. However, the most serious invaders were invasive grasses species like Eragrostis curvula (Schrad.) Nees, (African lovegrass), Nassella neesiana (Trin. & Rupr.) Barkworth (Chilean needle grass) and Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock), which degrade both agricultural and conservation land use types and drive reorganisation of recipient socio-ecological systems. Infestations of E. curvula in particular appear to be expanding in most areas, and this largely intractable species must now be considered the primary weed threat to biodiversity conservation and agricultural production across the K2C region. There is a strong need for further research into the impacts of invasive weeds on functional landscape connectivity and the development of integrated weed management strategies for the most damaging species, especially E. curvula. [ABSTRACT FROM AUTHOR]

Abstract: Regional-scale native vegetation mapping in Australia has traditionally focussed on the detection of woody vegetation. However there is an increasing recognition that transformation of the native herbaceous ground layer to exotic species is an equally important element of vegetation loss. In grass-dominated vegetation, the ground layer contains most of the plant diversity and hence its condition is critical for maintaining the ecological function of grasslands and woodlands. However, decades of fertiliser use have transformed native pastures to exotic dominance and there is a need for regional-scale ground layer condition assessment. We used time-series Landsat 5 imagery, combined with rainfall and soil moisture data, and coupled with site-based soil phosphorus data to develop assessments of ground layer nutrient status from spectral indices. We found significant relationships between soil available phosphorus and NDVI seasonal change. A constraint in the exploration of this relationship is the need for active plant growth, and therefore sufficient rainfall for a signal to be detected. Similarly performing models were derived from two time periods and while they differed in their direction of response, both were able to predict sites with low P. Differences were due to the functional attributes of the dominant vegetation that were active at the time of image collection. Further refinement of the models should be achievable by designing plot sampling strategies more aligned to synoptic remote sensing needs, and incorporating plant composition data into the analysis. [Copyright &y& Elsevier]