Biological Conservation 193 (2016) 143–152

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Biological Conservation

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Discussion Cascading effects of cyclones on the biodiversity of Southwest Pacific islands

W. Goulding a,b,⁎, P.T. Moss a,C.A.McAlpinea a The University of , Landscape Ecology and Conservation Group, School of Geography, Planning and Environmental Management, 4072, Australia b Biodiversity and Geosciences Program, Queensland Museum, PO Box 3300, South Brisbane, Queensland 4101, Australia article info abstract

Article history: Human induced climate change is having a dramatic impact on global biodiversity and insular assemblages are Received 17 July 2015 particularly vulnerable. However, the cascading impacts of tropical cyclones on insular ecosystems are poorly un- Received in revised form 10 November 2015 derstood and expected to grow with the increasing intensity of these events associated with future anthropogen- Accepted 17 November 2015 ic climate change. This problem is particularly relevant to islands of the Southwest Pacific, which are cyclone- Available online 4 December 2015 prone and support high levels of endemic biodiversity. In this perspective, we present new information from a case study of the indirect effects of a (Ita) on forest extent and integrity from an endemic hotspot, Keywords: Island conservation the Louisiade Archipelago of . We highlight how a cyclone event can be a catalyst for human- Cyclones coping strategies that increase pressures on forest ecosystems and expose them to invasive plant species. These Climate change changes represent a major threat to forest-dependent bird species, many of which are endemic. Rather than Biodiversity being an isolated example, these observations provide an insight into human responses to climate change over Deforestation cyclone-prone tropical islands/regions where human populations are reliant upon subsistence agriculture and Birds the resources provided by forests. The cumulative anthropogenic impacts on forest ecosystems are potentially catastrophic to the future of island biodiversity and greater than the long-term shifts in mean climate. © 2015 Elsevier Ltd. All rights reserved.

1. Introduction density function (IPCC, 2013). Persistent severe weather events can be- come an extreme climate event and are often at the vanguard of climate Island biodiversity is under increasing pressure from multiple change. The study of the impact of climate change on island biodiversity interacting threats (Brook et al., 2008; Driscoll et al., 2012; has focused mainly on the effects of shifts in climate statistics, such as Nurse et al., 2014). History has demonstrated that island endemic taxa annual temperatures, precipitation or sea levels (Courchamp et al., are easily extirpated and disproportionately affected by the rapid eco- 2014; Harter et al., 2015; Laurance et al., 2011). However, the impacts system changes associated with humans (e.g. Fordham and Brook, of event-driven extremes (e.g. cyclones, floods, droughts; Easterling 2010; Steadman, 2006; Szabo et al., 2012). There have been numerous et al., 2000) have received less attention (Dale et al., 2001; Marler, studies proposing islands as arks for conservation (e.g. Abbott, 2000; 2014). Tropical cyclones are arguably the most globally important of Miskelly and Powlesland, 2013; Ottewell et al., 2014) and ridding these extremes to impact islands, exemplified by the recent and strong islands of the disproportionate impacts of invasive species (e.g. impacts of Cyclone Pam in Vanuatu (2015), Typhoon Haiyan in the Special Issue Vol. 185, Biol. Cons. 2015). Such approaches involve Philippines (2013) or Hurricanes Katrina and Wilma in the Caribbean redressing negative anthropogenic stressors. However, securing island (and continental U.S.; 2005). Critically, it is knowledge of the impacts biodiversity also requires understanding the added pressures of climate of cyclones on islands of the Pacific that is both the most globally rele- change on islands (Courchamp et al., 2014; Nurse et al., 2014). This is vant and least studied (Marler, 2014). particularly relevant to the tropics, where biodiverse insular regions The growing threat posed by cyclones in the Pacificregionis harbour the highest numbers of species vulnerable to climate change; concerning given the expected changes in the severity of these extreme for example, the Caribbean and Southwest Pacific regions (Pacifici weather events (IPCC, 2012a). There is a 66–100% likelihood (following et al., 2015). Mastrandrea et al., 2010) that tropical islands will experience increases Extreme weather events are those that can be considered rare in a in the intensity/severity of tropical cyclones (Emanuel, 2005; IPCC, time and place i.e. outside the 10th and 90th percentiles of a probability 2012b; Knutson et al., 2010), despite little change in frequency (Knutson et al., 2010; IPCC, 2012c). Strong winds and heavy rainfall are the two most destructive features of cyclones that, when combined ⁎ Corresponding author at: The University of Queensland, Landscape Ecology and with where and when they make landfall, determine the intensity and Conservation Group, School of Geography, Planning and Environmental Management, Brisbane 4072, Australia. severity of impacts (e.g. Emanuel, 2005; Peduzzi et al., 2012; E-mail address: [email protected] (W. Goulding). Seneviratne et al., 2012). Impacts are often measured through damage

http://dx.doi.org/10.1016/j.biocon.2015.11.022 0006-3207/© 2015 Elsevier Ltd. All rights reserved. 144 W. Goulding et al. / Biological Conservation 193 (2016) 143–152 to infrastructure and human livelihoods (e.g. Morton, 2007; Peduzzi New Guinea (Australian Government Bureau of Meteorology, 2015a). et al., 2012; Woodruff et al., 2013) but they also have profound effects This perspective is prompted by first-hand observations and discussions on ecosystems and species diversity (e.g. Lugo, 2008; Murphy et al., with local residents over a cumulative seven months spent on the 2014; Tanner et al., 2014). Louisiade Islands (2012–2015). Far from being an isolated case, the ob- The cyclone-prone Southwest Pacific contains a large proportion of servations from this extreme climatic event are highly relevant to island the world's islands and insular biodiversity (Kier et al., 2009; Neall conservation issues globally (see Marler, 2014). We highlight the rami- and Trewick, 2008; Steadman, 2006). Many of these islands have a fications of climate change for insular endemic species that are intrinsi- growing human population that relies on small-scale subsistence cally tied to extreme climate events and associated anthropogenic shifting agriculture (Barnett, 2011), particularly in Papua New Guinea factors. (PNG), where 87% of the population is rural (FAO, 2015). The traditional subsistence slash-and-burn agriculture involves the clearing and subsequent burning of native forests, and planting patches of native 2. Case study: Cyclone Ita, the sequence of events gardens up to several hectares in area, which are then left fallow for 4–15 years (Kinch, 1999). The general practise is to use and prepare Tropical Cyclone Ita formed as a tropical low-pressure weather sys- new gardens for staple food plants such as yam (Dioscorea spp.) and tem south of the (Inset, Fig. 1). It was categorised as a sweet potatoes (Ipomoea batatas), revisiting old gardens for green veg- Category 1 (low intensity) cyclone on the 5th of April 2014 and etables and fruit before they become too overgrown with woody suc- moved slowly in a west-southwest direction, stalling and intensifying cession (Kinch, 1999). The impact of this practise is strongly to the south of Sudest Island in the Louisiade Archipelago (PNG) be- associated with proximity to human populations and their density tween the 6th and 8th of April (12.1 S, 154.4 E). During this period the (Ferretti-Gallon and Busch, 2014; Macintyre and Foale, 2002). cyclone strengthened and developed into a Category three system, Here we provide a graphic case study of how a moderate-intensity battering Sudest and nearby islands with wind gusts above 160 kph cyclone can impact a subsistence agricultural community in the South- and heavy rain. The cyclone then continued strengthening and moving west Pacific and how the indirect or cascading effects of these affect westwards and southwards before making landfall on the north tropical forest ecosystems and endemic avifauna. We focus on the im- Queensland coast (Australia) on the 11th of April 2014 as a Category pact of cyclone Ita (April 2014) on the Louisiade Archipelago, Papua Four system (Australian Government Bureau of Meteorology, 2015a).

Fig. 1. Location of the case-study area affected by Cyclone Ita, the Louisiade Archipelago. The approximate path (red line) of Ita from a tropical low through its life as a cyclone and until it dissipated is indicated (inset). The solid hash zone represents the known distribution of siam weed (Chromolaena odorata)in2000(onlyMisima;Orapa et al., 2002) and the dashed hash represents the known range extension, post-Cyclone Ita in 2014. It is suspected to be from Utian/Brooker and intervening islands to Panawina but absent from Rossel. Download English Version: https://daneshyari.com/en/article/6298884

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