GCB Bioenergy (2014) 6, 587–598, doi: 10.1111/gcbb.12068 Balancing bioenergy and biosecurity policies: estimating current and future climate suitability patterns for a bioenergy crop D. J. KRITICOS*,† ,H.T.MURPHY‡ , T. JOVANOVIC*, J. TAYLOR§ ,A.HERR*,J.RAISON* and D. O’CONNELL* *CSIRO Ecosystem Sciences, GPO Box 1700, Canberra, ACT, 2601, Australia, †EH Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW, Australia, ‡CSIRO Ecosystem Sciences, PO Box 780, Atherton, QLD, Australia, §CSIRO Ecosystem Sciences, Box 312, Clayton South, VIC, 3169, Australia Abstract In an apparent paradox, bioenergy crops offer potential benefits to a world adjusting to the challenges of climate change and declining fossil fuel stocks, as well as potential ecological and economic threats resulting from bio- logical invasions. In considering this paradox it is important to understand that benefits and threats may not always be apparent in equal measure throughout the potential range of each candidate biofuel species. In some environments, a species could potentially produce valuable biological materials without posing a significant invasion threat. In this study, we develop a bioclimatic niche model for a candidate biofuel crop, Millettia pinnat- a, and apply the model to different climatic and irrigation scenarios to estimate the current and future patterns of climate suitability for its growth and naturalization. We use Australia as a case study for interpreting the niche model in terms that may be informative for both biofuels proponents and biosecurity regulators to plan management programmes that reflect the invasive potential in different areas. The model suggests that suitable growing conditions for M. pinnata in Australia are naturally restricted to the moist and semimoist tropics. Irriga- tion can extend the suitable growing conditions more widely throughout the tropics, and into more arid regions. Under future climate scenarios, suitable growing conditions for M. pinnata under natural rainfall contract towards the east coast, and extend southward into the subtropics. With irrigation, M. pinnata appears to have the potential in the future to naturalize across much of Australia. The bioclimatic modelling method demon- strated here is comparatively quick and easy, and can produce a rich array of data products to inform the inter- ests of both bioenergy proponents and biosecurity regulators. We show how this modelling can support the development of spatially explicit biosecurity policies designed to manage invasion risks in a manner that balances bioenergy and biosecurity concerns. Keywords: biosecurity, CLIMEX, invasive alien species, Millettia pinnata, niche model, oilseed tree, Pongamia pinnata Received 16 January 2013 and accepted 14 February 2013 distillation plants. Such efforts are intended to replace Introduction supplies of liquid fossil fuels and reduce the net emis- Presently, there is a great deal of interest worldwide in sions of GHGs. the development of biofuels industries as a replace- Much of the early interest in biofuels was focused ini- ment for fossil fuels. Demand for liquid fuels continues tially on using traditional food crops such as soybean, to rise at the same time as global production of liquid maize, palm oil and sugar cane to generate nonfood fossil fuels is set to decline (so-called peak oil), and products such as oil and ethanol. In the face of concern efforts to stem global emissions of greenhouse gases over food security issues posed by competition for land (GHGs) increase (Barney & Ditomaso, 2008; Penuelas~ & (Boddiger, 2007; Johansson & Azar, 2007; Dale et al., Carnicer, 2010; Verbruggen & Al Marchohi, 2010; 2010) and phosphorous fertilizers (Cordell et al., 2009), Farine et al., 2011). Biofuel proponents are interested in more recent fuel stock attention has been focused on establishing crop plantations to generate raw biological plant species that are not traditional crops. Traditional materials as inputs to new energy or liquid fuel crop systems are characterized generally by significant bodies of knowledge regarding the plant’s growing Correspondence: D. J. Kriticos, tel. +61 2 6246 4252, requirements, production capacity under various fax +61 2 6246 4094, e-mail: [email protected] environmental conditions, weed potential, postharvest © 2013 Blackwell Publishing Ltd 587 588 D. J. KRITICOS et al. processing systems and product qualities. For such The paradox here is that the knowledge of the spatial cropping systems it is relatively easy to develop suffi- patterns of production parameters and invasion risks ciently accurate estimates of the variables needed to needed to locate plantings and associated processing plan and implement a broad scale extension of the infrastructure accurately would be best gauged follow- geographical area under cultivation. Conversely, there ing the establishment of the industry, and from wide- is very little known about most of the noncrop plant spread trial sites. The problem of estimating a priori the species being proposed for biofuel feedstocks, except production potential, mirrors that of pest risk assess- that many of them are notorious weeds (Raghu et al., ment: the impacts of an unwanted invasive alien species 2006; Barney & Ditomaso, 2008; Di Tomaso et al., 2010). (IAS) can most reliably be gauged after it has invaded a The lack of knowledge surrounding the prospective new risk area, but this may then have little informative biofuels crops adds weight to concerns regarding both value for deciding how much effort should be expended their financial viability and the environmental impacts on preventing its further spread into that new risk area. of attempts to utilize marginal lands that are subse- Because biological invasions are generally irreversible, quently abandoned (Gutierrez & Ponti, 2009). Such con- modelling tools have been developed to estimate the cerns obviously parallel those regarding the financial potential for pests to spread and grow as a function of risks associated with the substantial investments climate. These tools can inform biosecurity authorities required to create the germplasm, planting, growing, of the risks posed by IAS either prior to their establish- harvesting, transportation and processing infrastructure ment in a jurisdiction, or soon thereafter (Eyre et al., required to support such embryonic industries. In estab- 2012). lishing a nascent biofuels industry in Europe based CLIMEX [Hearne Scientific Software, Melbourne, upon Miscanthus 9 giganteus, the main production limi- Australia, (Sutherst & Maywald, 1985; Sutherst et al., tations concerned poor overwintering and insufficient 2007)] is a popular computer package for pest risk water supply at some sites (Lewandowski et al., 2000). modelling of arthropods, diseases and weeds, with Prior knowledge of such climatic growth responses and more than 200 published applications. It has also been stresses in different areas could assist in planning field used successfully to project the potential distribution trials, and will allow the need for special agronomic of invasive plants including tropical woody weeds techniques and new genotypes with improved charac- (Kriticos et al., 2003a,b) and herbs (McConnachie et al., teristics to be factored into regional development plans 2011), subtropical trees (Watt et al., 2009), temperate (Barney & Di Tomaso, 2011). shrubs (Potter et al., 2009; Kriticos et al., 2011; Taylor The plant attributes that make for ideal biofuel crops et al., 2012) and grasses (Chejara et al., 2010; Watt et al., are frequently the same attributes that make for a suc- 2011; Bourdot^ et al., 2012). More recently, CLIMEX has cessful invasive plant (Raghu et al., 2006), including been used to assess the climatic niche for many climatic similarity to the introduced range (Barney & Di leading bioenergy crops (Barney & Di Tomaso, 2010, Tomaso, 2011). Such is the concern that biofuels crops 2011). could impact significantly on biodiversity and other The Compare Locations module in CLIMEX models conservation values that the International Union for climatic suitability for a species, rather than habitat Conservation of Nature (IUCN) is drafting guidelines similarity (Kriticos et al., 2007; Sutherst et al., 2007). for sustainable biofuels production that address the use CLIMEX uses biologically relevant functions to relate of invasive alien species; specifically, under Criterion species climate suitability to raw climate data. The spe- 7.e ‘Biofuel production shall not use crops considered as cies response functions in CLIMEX are founded in fun- alien invasive species under local conditions’ (Anony- damental ecological concepts. Because it characterizes mous, 2009b). Under this criterion, if a biofuels propo- the species response functions in a biologically mean- nent intends to use a species recorded in the Global ingful manner (Austin, 2007), it can project species Invasive Species Database (GISD), the operator needs to potential distributions into novel climates with more complete a risk assessment of the invasiveness of the confidence than empirical regression-based species dis- species in the local context. If there is clear evidence that tribution models (Kriticos & Randall, 2001; Webber the proposed species is likely to be invasive in the local et al., 2011), which are inherently risky when faced with context, the operator should not use the species. this extrapolation problem (Peterson et al., 2007; Duncan Although these draft guidelines do not yet