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Saintilan N.,NSW Office of Environment and Heritage | Rogers K.,University of Wollongong | Mazumder D.,Australian Nuclear Science and Technology Organization | Woodroffe C.,University of Wollongong
Estuarine, Coastal and Shelf Science | Year: 2013

Estimates of carbon store and carbon accumulation rate in mangrove and saltmarsh are beset by issues of scale and provenance. Estimates at a site do not allow scaling to regional estimates if the drivers of variability are not known. Also, carbon accumulation within soils provides a net offset only if carbon is derived in-situ, or would not otherwise be sequestered. We use a network of observation sites extending across 2000km of southeastern Australian coastline to determine the influence of geomorphic setting and coastal wetland vegetation type on rates of carbon accumulation, carbon store and probable sources. Carbon accumulation above feldspar marker horizons over a 10-year period was driven primarily by tidal range and position in the tidal frame, and was higher for mangrove and saltmarsh dominated by Juncus kraussii than for other saltmarsh communities. The rate of carbon loss with depth varied between geomorphic settings and was the primary determinant of carbon store. A down-core enrichment in δ13C was consistent with an increased relative contribution of mangrove root material to soil carbon, as mangrove roots were found to be consistently enriched compared to leaves. We conclude that while surface carbon accumulation is driven primarily by tidal transport of allocthonous sediment, in-situ carbon sequestration is the dominant source of recalcitrant carbon, and that mangrove and saltmarsh carbon accumulation and store is high in temperate settings, particularly in mesotidal and fluvial geomorphic settings. © 2013 Elsevier Ltd. Source

Luo Q.,University of Technology, Sydney | Wen L.,NSW Office of Environment and Heritage | McGregor J.L.,CSIRO | Timbal B.,Center for Australian Weather and Climate Research
Climatic Change | Year: 2013

This study aims to evaluate the performance of two mainstream downscaling techniques: statistical and dynamical downscaling and to compare the differences in their projection of future climate change and the resultant impact on wheat crop yields for three locations across New South Wales, Australia. Bureau of Meteorology statistically- and CSIRO dynamically-downscaled climate, derived or driven by the CSIRO Mk 3.5 coupled general circulation model, were firstly evaluated against observed climate data for the period 1980-1999. Future climate projections derived from the two downscaling approaches for the period centred on 2055 were then compared. A stochastic weather generator, LARS-WG, was used in this study to derive monthly climate changes and to construct climate change scenarios. The Agricultural Production System sIMulator-Wheat model was then combined with the constructed climate change scenarios to quantify the impact of climate change on wheat grain yield. Statistical results show that (1) in terms of reproducing the past climate, statistical downscaling performed better over dynamical downscaling in most of the cases including climate variables, their mean, variance and distribution, and study locations, (2) there is significant difference between the two downscaling techniques in projected future climate change except the mean value of rainfall across the three locations for most of the months; and (3) there is significant difference in projected wheat grain yields between the two downscaling techniques at two of the three locations. © 2013 Springer Science+Business Media Dordrecht. Source

Fordham D.A.,University of Adelaide | Akcakaya H.R.,State University of New York at Stony Brook | Araujo M.B.,CSIC - National Museum of Natural Sciences | Araujo M.B.,University of Evora | And 4 more authors.
Ecography | Year: 2013

Ecological niche models (ENMs) are the primary tool used to describe and forecast the potential influence of climate change on biodiversity. However, ENMs do not directly account for important biological and landscape processes likely to affect range dynamics at a variety of spatial scales. Recent advances to link ENMs with population models have focused on the fundamental step of integrating dispersal and metapopulation dynamics into forecasts of species geographic ranges. Here we use a combination of novel analyses and a synthesis of findings from published plant and animal case studies to highlight three seldom recognised, yet important, advantages of linking ENMs with demographic modelling approaches: 1) they provide direct measures of extinction risk in addition to measures of vulnerability based on change in the potential range area or total habitat suitability. 2) They capture life-history traits that permit population density to vary in different ways in response to key spatial drivers, conditioned by the processes of global change. 3) They can be used to explore and rank the cost effectiveness of regional conservation alternatives and demographically oriented management interventions. Given these advantages, we argue that coupled methods should be used preferentially where data permits and when conservation management decisions require intervention, prioritization, or direct estimates of extinction risk. © 2013 The Author. Ecography © 2013 Nordic Society Oikos. Source

Auld T.D.,NSW Office of Environment and Heritage | Auld T.D.,University of New South Wales | Leishman M.R.,Macquarie University
Austral Ecology | Year: 2015

Gnarled Mossy Cloud Forest is a globally unique ecosystem, combining floristic elements from Australia, New Zealand and New Caledonia. It is restricted to a very small area (28ha) at elevations above 750m on the summits of two mountains on Lord Howe Island in the Pacific Ocean, approximately 570km off the east coast of Australia. Moisture derived from clouds is a key feature of the ecosystem. We assessed the conservation status of this ecosystem using the International Union for the Conservation of Nature Red List criteria for ecosystems. There has been no historical clearing of the ecosystem, but declines (with large uncertainty bounds) were estimated for two abiotic variables that are important in maintaining the component species (cloud cover and rainfall). Overall, we found the ecosystem to be Critically Endangered based on a restricted geographic distribution combined with continuing decline (criterion B1aii, iii, B1b, B1c and B2aii, iii, B2b, B2c). Decline was inferred from: a loss of moisture from declining rainfall and cloud cover due to climate change (affecting disturbance regimes, gap formation and species survival and recruitment); ongoing exotic rat predation on seeds and seedlings of several sensitive species that are structural components of the ecosystem (affecting survival and recruitment); and the fact that the ecosystem is considered to exist at only one location. This mirrors similar threats from exotic species and climate change to other Pacific island cloud forests. Eradication of rats from Lord Howe Island will reduce the immediate risk to this ecosystem; however, only global mitigation of greenhouse gases could alleviate risk from declining cloud cover and moisture availability. © 2014 Ecological Society of Australia. Source

Tozer M.G.,NSW Office of Environment and Heritage | Leishman M.R.,Macquarie University | Auld T.D.,NSW Office of Environment and Heritage
Austral Ecology | Year: 2015

The International Union for the Conservation of Nature (IUCN) has proposed a standard global assessment protocol for the evaluation of conservation risks to ecosystems. The assessment criteria mirror the IUCN protocol for the assessment of species, however there are relatively few case studies available to demonstrate their utility across a broad range of ecosystems. We applied the IUCN protocol to assess the conservation status of the Cumberland Plain Woodland (CPW) located in the western suburbs of Sydney, Australia. The ecosystem has been the focus of extensive survey and research and has been determined to be critically endangered under NSW and Australian Government legislation, primarily as a consequence of its history of extensive clearing. The outcome of the risk assessment for CPW using the IUCN protocol was identical to those under the NSW and Australian legislation. Data for risk assessment fell into two categories, each with different limitations. Phytosocialogical data and distribution models provided a strong basis for quantifying past and future changes in the distribution of CPW, but offered only indirect measures of functional symptoms of decline. Conversely, local case studies documenting declines in ecosystem function due to weed invasion, soil disturbance and alteration of fire regimes could not easily be extrapolated in order to evaluate the assessment criteria. The critically endangered rating was based solely on the historic reduction in geographic distribution (92-94%), however clearing poses an ongoing threat to the ecosystem. The contemporary clearing rate of CPW is approximately half the historical average but there is evidence that the rate will double in the next decade as a consequence of ongoing urbanisation and Government policy of biodiversity offsets. A systematic approach to documenting the extent of environmental degradation and disruption to biotic processes would assist the assessment of CPW and other ecosystems against the IUCN criteria. © 2014 Ecological Society of Australia. Source

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