Invasive Plants in the Floodplains of Australia’s Kakadu National Park

Setterfield, Samantha A.; Douglas, Michael M.; Petty, Aaron M.; Bayliss, Peter; Ferdinands, Keith B.; Winderlich, S.

doi:10.1007/978-94-007-7750-7_9

Cited by 15 publications

(23 citation statements)

References 19 publications

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“…, Setterfield et al . ), in this case, by increasing heterotrophy. However, because we know so little about the function of most tropical floodplain wetlands, caution needs to be used if extrapolating these results to other regions or times of the year.…”

Section: Discussionmentioning

confidence: 86%

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The contribution of epiphyton to the primary production of tropical floodplain wetlands

et al. 2017

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Tropical floodplains are one of the most productive ecosystems on earth. Studies on floodplain productivity have primarily focused on trees and macrophytes, rather than algae, due to their greater biomass. However, epiphyton—algae and bacteria attached to the submerged portion of aquatic macrophytes—is a major source of energy in many tropical floodplains. Epiphyton productivity rates are unknown for most tropical floodplain wetlands, and spatial variability is not well understood. In this study, we measured primary productivity of epiphyton in Kakadu National Park in northern Australia. We estimated the relative contribution of epiphyton to aquatic production (epiphyton, + phytoplankton + macrophytes). We sampled sites dominated by different macrophyte structural types: vertical emerging grasses, horizontal emerging grasses, submerged macrophytes, and macrophytes with floating leaves. Epiphyton productivity was highly influenced by the structural type of the macrophyte. Highest potential productivity per weight was measured from epiphyton growing on macrophytes with floating leaves and horizontal grasses (1.52 ± 0.53 and 1.82 ± 0.61 mgC/dw g epiphyton/h, respectively) and lowest in submerged macrophytes and vertical grasses (0.57 ± 0.26 and 0.66 ± 0.47 mgC/dw g epiphyton/h, respectively). When considering the areal biomass of the macrophyte and the amount of epiphyton attached, epiphyton on horizontal grasses and submerged macrophytes had productivity values approximately ten times higher (45–219 mgC/m2/d) compared to those on vertical grasses and macrophytes with floating leaves (2–18 mgC/m2/d). Epiphyton contributed between 2 to 13 percent to the aquatic production of these tropical floodplain wetlands.

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Section: Discussionmentioning

confidence: 86%

“…However, in recent years, invasive macrophyte species such as Urochloa mutica (‘para grass’) and Hymenachne amplexicaulis (‘olive hymenachne’), have become widely distributed (Setterfield et al . ).…”

Section: Methodsmentioning

confidence: 97%

The contribution of epiphyton to the primary production of tropical floodplain wetlands

et al. 2017

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“…To compile the initial distribution, we therefore included substantial areas of para grass mapped in 1996 by Knerr (), upstream paddocks identified through expert interviews and herbarium records, and one northern infestation identified through expert interviews (Setterfield et al . ).…”

Section: Model Application To Two Invasive Grasses In Northern Australiamentioning

confidence: 97%

“…Para grass has been assessed as a high‐risk invasive species in northern Australia by the Northern Territory and Queensland Governments (Setterfield et al . ), and infestations are now present in many wetlands in northern Australia (including a core infestation of para grass in KNP). Para grass can form dense monocultures over large areas displacing native plant species and substantially altering the structure and function of the floodplain (Douglas & O'Connor ; Ferdinands, Beggs & Whitehead ).…”

Section: Model Application To Two Invasive Grasses In Northern Australiamentioning

confidence: 99%

Distribution, demography and dispersal model of spatial spread of invasive plant populations with limited data

et al. 2015

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Summary1. Invasive weeds are a major cause of biodiversity loss and economic damage world-wide. There is often a limited understanding of the biology of emerging invasive species, but delay in action may result in escalating costs of control, reduced economic returns from management actions and decreased feasibility of management. Therefore, spread models that inform and facilitate on-ground control of invasions are needed. 2. We developed a spatially explicit, individual-based spread model that can be applied to both data-poor and data-rich situations to model future spread and inform effective management of the invasion. The model is developed using a minimum of two mapped distributions for the target species at different times, together with habitat suitability variables and basic population data. We present a novel method for internally calibrating the reproduction and dispersal distance parameters. We use a sensitivity analysis to identify variables that should be prioritized in future research to increase robustness of model predictions. 3. We apply the model to two case studies, gamba grass and para grass, to provide management advice on emerging weed priorities in northern Australia. For both species, we find that the current extent of invasion in our study regions is expected to double in the next 10 years in the absence of management actions. The predicted future distribution identifies priority areas for eradication, control and containment to reduce the predicted increase in infestation. 4. The model was built for managers and policymakers in northern Australia working on species where expert knowledge and environmental data are often lacking, but is flexible and can be easily adapted for other situations, for example where good data are available. The model provides predicted probability of occurrence over a user-specified, typically short-term, time horizon. This output can be used to direct surveillance and management actions to areas that have the highest likelihood of rapid invasion and spread. Directing efforts to these areas provides the greatest likelihood of management success and maximizes the return on investment in management response.

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“…For each threat, we considered a remediating management action: aerial shooting of water buffalo and feral pigs, building cattle‐proof fences along riparian zones to reduce cattle trampling and other damages to freshwater ecosystems and chemical spraying of para grass (Bayliss & Yeomans, ; Carwardine et al., ; Setterfield et al., ). The management costs of implementing different levels of effort of each action (AU$ ha‐1 year‐1) were sourced from peer‐reviewed studies in other river–floodplain ecosystems of northern Australia (see Supporting Information, Section ).…”

Section: Methodsmentioning

confidence: 99%

Information uncertainty influences conservation outcomes when prioritizing multi‐action management efforts

Cattarino

Hermoso

Carwardine

et al. 2018

Journal of Applied Ecology

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In managing various threats to biodiversity, it is important to prioritize multiple management actions and the levels of effort to apply. However, a spatial conservation prioritization framework that integrates these key aspects, and can be generalized, is still missing. Moreover, assessing the robustness of prioritization frameworks to uncertainty in species responses to management is critical to avoid misallocation of limited resources. Yet, the impact of information uncertainty on prioritization of management effort remains unknown. We present an approach for prioritizing alternative levels of conservation management effort to multiple actions, based on the ecological responses of species to management. We estimated species responses through a structured email‐based expert elicitation process, where we also captured the uncertainty in individual experts' assessments. We identified priority locations and associated level of management of effort of four actions to abate threats to freshwater‐dependent fauna, using a northern Australia case study, and quantified sensitivity of the proposed solution to uncertainty in the answers of each individual expert. Achievement of conservation targets for freshwater‐dependent fauna in the Daly River catchment would require 9.4 million AU$ per year, for a total of approximately 189 million AU$ investment over 20 years. We suggest that this could be best achieved through a mix of aerial shooting of buffalos and pigs, riparian fencing and chemical spraying of weeds, applied at varying levels of management effort in key areas of the catchment. Uncertainty in experts' estimation of species responses to threats causes 60% of the species to achieve 80% of their conservation targets, which was consistent across target levels. Synthesis and applications. Our prioritization approach facilitates the planning of conservation management at fine spatial scales and is applicable to terrestrial, freshwater and marine realms. Plan implementation may require policy instruments ranging from landowner stewardship agreements, market‐based mechanisms and low‐intensity land use management schemes, to regulation of commercial activities within portions of marine protected areas. However, assessing plan sensitivity to uncertainty in species response to management and finding ways of dealing with it in the prioritization rather than ignoring it, as often done, remains vital for effective achievement of conservation objectives.

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Invasive Plants in the Floodplains of Australia’s Kakadu National Park

Cited by 15 publications

References 19 publications

The contribution of epiphyton to the primary production of tropical floodplain wetlands

The contribution of epiphyton to the primary production of tropical floodplain wetlands

Distribution, demography and dispersal model of spatial spread of invasive plant populations with limited data

Information uncertainty influences conservation outcomes when prioritizing multi‐action management efforts

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