Rossiter-Rachor Natalie A, Adams Vanessa M, Canham Caroline A, Dixon Dan J, Cameron Thorsteinn N, Setterfield Samantha A
National Environmental Science Programme (NESP) Northern Australia Environmental Resources Hub, Charles Darwin University, Darwin, Northern Territory, Australia; Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia.
National Environmental Science Programme (NESP) Northern Australia Environmental Resources Hub, Charles Darwin University, Darwin, Northern Territory, Australia; School of Geography, Planning, and Spatial Sciences, University of Tasmania, Hobart, Tasmania, Australia.
J Environ Manage. 2023 May 1;333:116785. doi: 10.1016/j.jenvman.2022.116785. Epub 2023 Feb 7.
Globally, invasive grasses are a major threat to protected areas (PAs) due to their ability to alter community structure and function, reduce biodiversity, and alter fire regimes. However, there is often a mismatch between the threat posed by invasive grasses and the management response. We document a case study of the spread and management of the ecosystem-transforming invasive grass, Andropogon gayanus Kunth. (gamba grass), in Litchfield National Park; an iconic PA in northern Australia that contains significant natural, cultural and social values. We undertook helicopter-based surveys of A. gayanus across 143,931 ha of Litchfield National Park in 2014 and 2021-2022. We used these data to parametrise a spatially-explicit spread model, interfaced with a management simulation model to predict 10-year patterns of spread, and associated management costs, under three scenarios. Our survey showed that between 2014 and 2021-22 A. gayanus spread by 9463 ha, and 47%. The gross A. gayanus infestation covered 29,713 ha of the total survey area, making it the largest national park infestation in Australia. A. gayanus had not been locally eradicated within the Park's small existing 'gamba grass eradication zone', and instead increased by 206 ha over the 7-year timeframe. Our modelled scenarios predict that without active management A. gayanus will continue spreading, covering 42,388 ha of Litchfield within a decade. Alternative scenarios predict that: (i) eradicating A. gayanus in the small existing eradication zone would likely protect 18% of visitor sites, and cost ∼AU$825,000 over 5 years - more than double the original predicted cost in 2014; or (ii) eradicating A. gayanus in a much larger eradication zone would likely protect 86% of visitor sites and several species of conservation significance, and cost ∼AU$6.6 million over 5 years. Totally eradicating A. gayanus from the Park is no longer viable due to substantial spread since 2014. Our study demonstrates the value of systematic landscape-scale surveys and costed management scenarios to enable assessment and prioritisation of weed management. It also demonstrates the increased environmental and financial costs of delaying invasive grass management, and the serious threat A. gayanus poses to PAs across northern Australia.
在全球范围内，入侵性草类对保护区构成了重大威胁，因为它们能够改变群落结构和功能、降低生物多样性并改变火灾模式。然而，入侵性草类所构成的威胁与管理应对措施之间往往存在不匹配的情况。我们记录了生态系统改造型入侵性草类——冈巴草（Andropogon gayanus Kunth）在利奇菲尔德国家公园的扩散及管理情况的案例研究。利奇菲尔德国家公园是澳大利亚北部一个具有标志性的保护区，拥有重要的自然、文化和社会价值。2014年以及2021年至2022年期间，我们对利奇菲尔德国家公园143,931公顷的区域进行了基于直升机的冈巴草调查。我们利用这些数据对一个空间明确的扩散模型进行参数化，并与一个管理模拟模型相结合，以预测在三种情景下10年的扩散模式及相关管理成本。我们的调查显示，在2014年至2021 - 22年期间，冈巴草扩散了9463公顷，增幅为47%。冈巴草的总侵染面积覆盖了调查总面积的29,713公顷，使其成为澳大利亚国家公园中侵染面积最大的。在公园现有的小型“冈巴草根除区”内，冈巴草并未被本地根除，反而在7年时间里增加了206公顷。我们模拟的情景预测，如果不进行积极管理，冈巴草将继续扩散，十年内将覆盖利奇菲尔德42,388公顷的区域。其他情景预测：（i）在现有的小型根除区内根除冈巴草可能会保护18%的游客景点，5年成本约为82.5万澳元——比2014年最初预测的成本高出一倍多；或者（ii）在一个大得多的根除区内根除冈巴草可能会保护86%的游客景点以及几种具有保护意义的物种，5年成本约为660万澳元。由于自2014年以来冈巴草已大量扩散，从公园完全根除它已不再可行。我们的研究证明了系统的景观尺度调查和成本核算管理情景对于评估和确定杂草管理优先级的价值。它还表明了延迟入侵性草类管理所增加的环境和财务成本，以及冈巴草对澳大利亚北部保护区构成的严重威胁。
