Lippia (Phyla canescens) and its response to fire

Lippia (Phyla canescens), a significant invasive weed, is a recognized threat to floodplain woodlands in Australia, particularly in the Murray-Darling Basin. Current control methods include the use of herbicides, which can be costly and environmentally harmful, particularly in riparian areas. 'Environmentally friendly' control mechanisms are yet to be found, with the potential for biological control still being researched. This research explores the use of fire as a potential control method to help slow the expansion and growth of lippia. Lippia response to fire and the effect of fire in lippia-invaded landscapes has not previously been investigated. Half of the St. Ruth Reserve south of Dalby in Southern Queensland was subject to a control burn in November 2013 by the Western Downs Regional Council in an attempt to reduce lippia abundance in this remnant riparian woodland. This research investigates the response of lippia to the burn. The study will compare the cover abundance of lippia and major functional plant groups between burnt and unburnt (control) sites within the reserve; it will also investigate the impact of fire on lippia germination rates in soil samples from burnt and unburnt sites. Additional studies testing lippia seed viability, using tetrazolium staining, will also be conducted after a range of fire mimicking treatments have been applied to seeds and compared to controls from an unburnt area. This research will contribute to evidence-based decision-making for improved management of lippia-invaded remnant ecosystems

Riparian woodlands in crisis? Disturbance ecology on the Condamine floodplain

The Condamine River, at the headwaters of the Murray-Darling basin, drains one of the most intensively-farmed landscapes in eastern Australia. Riparian woodland remnants on the floodplain sections of the upper Condamine are widely recognised as being in generally poor condition, with evidence of significant dieback and limited recruitment of canopy species, as well as widespread invasion by the introduced perennial herb Phyla canescens (lippia). These communities, in keeping with most remnant ecosystems of agricultural landscapes, are poorly understood in terms of their diversity, function and dynamics (resilience) under altered disturbance regimes. This research investigates the condition (health and function) of Eucalyptus tereticornis/camaldulensis riparian woodland communities of the Condamine floodplain in relation to selected natural and anthropogenic disturbance factors (e.g. climate variability, changes in land- and wateruse, weed invasion) operating at a range of spatial and temporal scales. The study takes a multi-dimensional approach aimed at developing an integrated understanding of key drivers and mechanisms of ecosystem change in these environments. It also investigates the potential of simple conceptual tools (e.g. State-and-Transition and Bayesian Belief Network approaches) to model system dynamics and predict outcomes of future climate and land and water management scenarios, including environmental flow restoration

Chronic groundwater decline: a multi-decadal analysis of groundwater trends under extreme climate cycles

Chronic groundwater decline is a concern in many of the world’s major agricultural areas. However, a general lack of accurate long-term in situ measurement of groundwater depth and analysis of trends prevents understanding of the dynamics of these systems at landscape scales. This is particularly worrying in the context of future climate uncertainties. This study examines long‐term groundwater responses to climate variability in a major agricultural production landscape in southern Queensland, Australia. Based on records for 381 groundwater bores, we used a modified Mann-Kendall non-parametric test and Sen’s slope estimator to determine groundwater trends across a 26-year period (1989–2015) and in distinct wet and dry climatic phases. Comparison of trends between climatic phases showed groundwater level recovery during wet phases was insufficient to offset the decline in groundwater level from the previous dry phase. Across the entire 26-year sampling period, groundwater bore levels (all bores) showed an overall significant declining trend (p0.05). Spatially, both declining and rising bores were highly clustered. We conclude that over 1989–2015 there is a significant net decline in groundwater levels driven by a smaller subset of highly responsive bores in high irrigation areas within the catchment. Despite a number of targeted policy interventions, chronic groundwater decline remains evident in the catchment. We argue that this is likely to continue and to occur more widely under potential climate change and that policy makers, groundwater users and managers need to engage in planning to ensure the sustainability of this vital resource

Groundwater thresholds for drought resilience in floodplain woodlands: a case study from the northern Murray-Darling Basin

In ephemeral river systems, canopy condition in dominant riparian and floodplain tree species may depend on access to shallow groundwater resources, particularly during drought. However, unsustainable groundwater extraction and chronic groundwater decline, evident in many agricultural landscapes worldwide, effectively decouples tree roots from deep soil moisture resources, increasing the susceptibility of trees to changes in precipitation. In such regions, drought may trigger loss of canopy condition and have long term consequences for the function and survival of trees and the composition, structure and function of ecosystems they dominate. However, critical groundwater depth thresholds have been difficult to identify. This study used a novel approach including boosted regression trees, quantile regression and threshold analysis to explore the relationship between groundwater depth and tree condition for two dominant tree species, Eucalyptus camaldulensis (river red gum) and E. populnea (poplar box); both species occur on the Upper Condamine floodplain, a region experiencing groundwater depth declines of 25+m in the northern Murray-­‐Darling Basin, southern Queensland. Distinct non-­‐linear responses were apparent, with minimum groundwater depth thresholds identified at 12.1m for E. camaldulensis and 12.6m for E.populnea, beyond which canopy condition declined significantly. This approach represents a repeatable method of quantifying ecological response thresholds along groundwater depth gradients. Its application may enable safe operating limits for groundwater resource management to be identified, supporting improved decision making to support resilient floodplain ecosystems. This will be particularly important in regions where groundwater decline driven by increasing water demand and drying climates is predicted

Groundwater depth thresholds for tree condition

A range of ecological processes supported by groundwater are at risk where socio-economic and climate drivers increase net groundwater demand. Previous research has indicated close links between groundwater and riparian/floodplain tree condition. However, little is known about the nature of the relationship or whether critical groundwater-tree condition thresholds exist. Threshold responses may indicate the existence of groundwater depths associated with rapid ecological change. This study provides evidence of threshold responses between groundwater depth and tree condition in the Condamine catchment in eastern Australia, where groundwater decline due to over-extraction is well documented. It collates tree condition data (118 sites) from recent studies of two dominant Australian floodplain species, Eucalyptus camaldulensis Denh. (river red gum) and E. populnea F. Muell. (poplar box). Boosted regression trees and quantile regression were used to investigate the nature of the relationship and threshold values. A distinct non-linear response of tree condition to groundwater depth was identified, with thresholds identified at 12.5–17.2 m for E. camaldulensis and 15.6–22.0 m for E. populnea. Threshold responses may be explained in terms of physiological limitations to rooting depth in these and similar floodplain/riparian species, with groundwater decline effectively decoupling tree roots from accessible moisture resources leaving trees more vulnerable to hydraulic stress and/or failure particularly under drought conditions. The existence of thresholds suggest that groundwater decline may trigger rapid ecological changes in riparian and floodplain tree species, which may have important implications not only for their future persistence but also the various ecological functions they support

Trade patterns facilitating highly pathogenic avian influenza virus dissemination in the free-grazing layer duck system in Vietnam

Highly pathogenic avian influenza (HPAI) viruses continue to threaten smallholder poultry producers in several South‐east Asian countries, including Vietnam. In particular, the free‐grazing duck system has been repeatedly highlighted as a major risk factor for HPAI outbreaks. Free‐grazing ducks, which scavenge on rice paddies after the harvest, account for a large proportion of the duck population in Vietnam and the wider South‐east Asian region. However, the structure and dynamics of the free‐grazing duck production from farm to consumption has not been described for Vietnam. In this study, we used a value chain approach to provide a complete picture of the actors involved in the production and marketing of free‐grazing duck eggs and spent layer ducks, as well as to investigate the governance structure of this food system. Group interviews and key informant interviews were conducted in two provinces located in the Mekong River Delta (MRD) and the Red River Delta (RRD). The results presented here highlight similarities and differences in farming and trade practices between the two provinces. The trade of spent layer ducks involved large volumes of live ducks being sent to China and Cambodia for consumption, generating a substantial risk of transboundary spread of pathogens, including HPAI viruses. We describe the major role of “duck yards”, which act as hubs in the northbound trade of spent layer ducks. These yards should be considered as essential links in the value chain of spent layer ducks when considering HPAI surveillance and control. The veterinary authorities are only marginally involved in the value chain activities, and their influence could be strengthened by increasing surveillance activities for instance in duck yards. Last, we discuss the dynamics of the duck value chain and further implications for future HPAI management policies

Identifying groundwater thresholds for drought resilience in floodplain tree species in the northern Murray-Darling Basin

Previous research identifies links between groundwater depth and canopy condition in dominant riparian and floodplain tree species associated with ephemeral river systems, particularly during drought. Chronic groundwater decline, evident in many agricultural landscapes worldwide, effectively decouples tree roots from deep soil moisture resources, increasing the susceptibility of trees to changes in precipitation. Drought may trigger loss of canopy condition and, where severe or prolonged, have long term consequences for the function and survival of trees and the composition, structure and function of ecosystems they dominate. However, critical groundwater depth thresholds, which may reflect ecological 'tipping points' in such systems, have been difficult to identify. This study used boosted regression trees, quantile regression and Threshold Indicator Taxa Analysis to investigate the relationship between groundwater depth and tree condition for two dominant tree species, Eucalyptus camaldulensis (river red gum) and E. populnea (poplar box). Both occur on the Upper Condamine floodplain, a region experiencing significant groundwater decline due to unsustainable groundwater extraction in the northern Murray-Darling Basin, southern Queensland. Distinct non-linear responses were found, with groundwater depth thresholds identified at 12.1–22.6m for E. camaldulensis and 12.6–22.6m for E. populnea, beyond which canopy condition declined abruptly. This approach represents a repeatable method of quantifying ecological response thresholds along groundwater depth gradients, application of which may assist in identifying safe operating limits for groundwater resource management to support resilient floodplain ecosystems. It will be particularly important in regions where increasing water demand and drying climates may drive further groundwater decline

Managing pest species under climate change: risks and opportunities

Human activity is driving significant changes in global and regional climate systems through the enhanced greenhouse effect (IPCC 2007). Global climate models predict that this anthropogenic forcing will alter both mean climate parameters and the frequency and magnitude of extreme meteorological events (e.g. heat waves, severe storm events and droughts). Such changes may have significant destabilizing effects, decoupling existing relationships between species, altering species distributions and challenging current management regimes. However, they may also provide significant management opportunities. Many pest species are expected to expand their geographical range in a warmer, more extreme, climate. Despite this, there is likely to be great variation both in pest species responses to changing climatic conditions and impacts on ecological and production systems, and in the effectiveness of current pest management strategies. This implies a need for ongoing monitoring and assessment of pest species responses to environmental change and management at local and regional scales. It also indicates a need for research aimed at identifying potential tipping points (or critical thresholds) in relation to significant meteorological events. This presentation will focus on the role of risk assessment in decision-making for pest species management under uncertainty. Probabilistic modelling approaches, such as Bayesian Belief networks, provide a valuable adjunct to monitoring and evaluation programs. They facilitate the synthesis of current knowledge (including expert opinion), highlight critical knowledge gaps, and provide a basis for both targeted research and adaptive management. Integrated modelling to predict invasive species response to management under variable climatic conditions can be used to identify key opportunities for management which will contribute disproportionately to effective pest species control. Pest species management programs under future climatic regimes are likely to require the capacity for more adaptive and strategic response, and will need to be supported by flexible investment strategies which enable timely (adaptive) responses at critical periods

The conserved C-terminus of the PcrA/UvrD helicase interacts directly with RNA polymerase

Copyright: © 2013 Gwynn et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by a Wellcome Trust project grant to MD (Reference: 077368), an ERC starting grant to MD (Acronym: SM-DNA-REPAIR) and a BBSRC project grant to PM, NS and MD (Reference: BB/I003142/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

The Lore of Low Methane Livestock:Co-Producing Technology and Animals for Reduced Climate Change Impact

Methane emissions from sheep and cattle production have gained increasing profile in the context of climate change. Policy and scientific research communities have suggested a number of technological approaches to mitigate these emissions. This paper uses the concept of co-production as an analytical framework to understand farmers’ evaluation of a 'good animal’. It examines how technology and sheep and beef cattle are co-produced in the context of concerns about the climate change impact of methane. Drawing on 42 semi-structured interviews, this paper demonstrates that methane emissions are viewed as a natural and integral part of sheep and beef cattle by farmers, rather than as a pollutant. Sheep and beef cattle farmers in the UK are found to be an extremely heterogeneous group that need to be understood in their specific social, environmental and consumer contexts. Some are more amenable to appropriating methane reducing measures than others, but largely because animals are already co-constructed from the natural and the technical for reasons of increased production efficiency