Fire Ecology Volume 13, Issue 3, 2017 Krix et al.: Ecological Impacts of Fire Trails doi: 10.4996/fireecology.130395119 Page 95 RESEARCH ARTICLE ECOLOGICAL IMPACTS OF FIRE TRAILS ON PLANT ASSEMBLAGES IN EDGE HABITAT ADJACENT TO TRAILS Daniel W. Krix, Matthew C. Hingee, Leigh J. Martin, Megan L. Phillips, and Brad R. Murray* School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, New South Wales 2007, Australia * Corresponding author: Tel.: +61-2-9514-4075; e-mail: [email protected] ABSTRACT RESUMEN Fire trails provide access into vegeta- Las sendas o “huellas” de fuego proveen de tion for controlled burns in fire-prone acceso a áreas vegetadas en distintos ecosiste- regions of the world. We examined the mas del mundo propensos al fuego. En este ecological impacts of fire trails on trabajo examinamos los impactos ecológicos plant assemblages in edge habitat adja- de las huellas de fuego en el ensamble de plan- cent to trails in eucalypt woodlands of tas en bordes adyacentes a estas huellas, en World Heritage Blue Mountains Na- bosques de eucaliptus del “Parque Nacional de tional Park, southeastern Australia. We las Montañas Azules” del sudeste de Australia, found that understory plant species declarado como Patrimonio Histórico de la richness, total plant density, and leaf Humanidad. Encontramos que en el sotobos- mass per area (LMA) were significant- que de estos bordes, la riqueza de especies, la ly higher in fire-trail edge habitat than densidad total de plantas, y la masa de hojas in the understory of interior woodland por unidad de área (LMA), fueron significati- habitat without fire trails. Understory vamente mayores que en áreas del sotobosque plant species composition also differed interior sin presencia de estas huellas. La significantly between fire-trail edge composición de especies también difirió entre and interior habitats. Higher total plant ambos sotobosques (bordes de huellas e inte- density, higher LMA, and composi- rior). La mayor densidad, masa de hojas por tional differences in understory assem- unidad de área (LMA) y diferencias en la com- blages of fire-trail edge habitat were posición de especies en los bordes de las hue- significantly related to increases in the llas estuvieron significativamente relacionadas availability of photosynthetically ac- con incrementos en la disponibilidad de radia- tive radiation. In addition, higher soil ción fotosintéticamente activa. Adicionalmen- clay content in fire-trail edges, which is te, el mayor contenido de arcillas en los bordes linked to increased soil water availabil- de las huellas, el cual ha sido vinculado a in- ity for plant growth, was significantly crementos en la disponibilidad de humedad related to higher species richness and para el crecimiento de las plantas, fue signifi- compositional differences in the under- cativamente relacionado con una mayor rique- story, as well as to compositional dif- za y diferencias en la composición de especies ferences in overstory assemblages. del sotobosque, como así también en el ensam- From a conservation and management ble de plantas del dosel superior. Desde la perspective, we suggest that, although perspectiva de la conservación y el manejo, Fire Ecology Volume 13, Issue 3, 2017 Krix et al.: Ecological Impacts of Fire Trails doi: 10.4996/fireecology.130395119 Page 96 significant ecological effects of fire sugerimos que aunque los efectos ecológicos trails on plant assemblages in edge de las huellas de fuego sobre los ensambles de habitats were detected, our work pro- plantas de sus bordes fueron significativos, vides evidence that fire trails are un- nuestro trabajo provee evidencias de que es likely to lead to serious conservation improbable que estas huellas de fuego conduz- issues such as local extirpations of na- can a serios problemas de conservación, como tive species or the facilitation of exotic la extinción local de plantas nativas o la facili- plant invasion. Nevertheless, our study tación de invasión de plantas exóticas. No has identified those plant species that obstante, nuestro estudio ha identificado aque- are unique to, or particularly sparse or llas plantas que son únicas, particularmente common in, fire-trail habitat, which dispersas, o comunes en hábitats de huellas de should be prioritized for demographic fuego, que deberían ser priorizadas para su and distributional monitoring should monitoreo demográfico y distribucional, si the need arise to increase the extent of fuese necesario incrementar la extensión de es- fire trails in the future. tas huellas de fuego en el futuro. Keywords: controlled burn, plant functional traits, plant density, richness, species composition, trait-based ecology, woodlands Citation: Krix, D.W., M.C. Hingee, L.J. Martin, M.L. Phillips, B.R. and Murray. 2017. Ecologi- cal impacts of fire trails on plant assemblages in edge habitat adjacent to trails. Fire Ecology 3(13): 95−119. doi: 10.4996/fireecology.130395119 INTRODUCTION tive that any ecological impacts of fire trails in wilderness areas are identified to ensure in- Globally, controlled burns are strategically formed conservation of biodiversity and fire- used to manage threats posed by wildfires to risk management. life, property, and biodiversity (Gill 2001, El- Apart from the directly observable effects lis et al. 2004, Penman et al. 2007, Bradstock of clearing to remove vegetation for the cre- et al. 2012, Spies et al. 2012, Price et al. ation of fire trails, there is currently a paucity 2015). Hazard reduction burns during cooler of information about the ecological impacts of months of the year seek to reduce fuel loads established fire trails on plant assemblages in before the commencement of the fire season, edge habitats adjacent to trails. Previous work while back-burning operations create fire- has shown that features like trails, such as breaks that help slow the progress of wildfires. sealed roads and walking paths that abut vege- In fire-prone regions, fire trails (Figure 1a) are tation, bring about ecological changes to plant constructed to provide access into and assemblages in edge habitats (Forman and Al- throughout broad areas, such as national exander 1998, Smit and Asner 2012, Neher et parks, for these fire management activities. al. 2013, Ballantyne and Pickering 2015). With growing concern that wildfires will in- Such changes include predominantly increases crease in frequency and intensity under future (but also decreases) in plant species richness climate-change scenarios (Williams et al. and diversity (Angold 1997, Gelhausen et al. 2001, Moriondo et al. 2006, Clarke 2013, 2000, Watkins et al. 2003, Avon et al. 2010), Hughes and Steffen 2013), there is a need to changes in plant species composition com- maintain and possibly create more fire trails pared to vegetation well away from the edge for management of fire risk. It is thus impera- habitat (Karim and Mallik 2008), and increas- Fire Ecology Volume 13, Issue 3, 2017 Krix et al.: Ecological Impacts of Fire Trails doi: 10.4996/fireecology.130395119 Page 97 For instance, removal of canopy cover can cre- ate brighter conditions at the interface between roads and forests compared with assemblages within forest interior (Delgado et al. 2007). The effects of an increased light environment have been well documented in these circum- stances and include changes to both species richness and species composition of assem- blages (Kupfer 1996, Gehlhausen et al. 2000, Avon et al. 2010, Vallet et al. 2010, Hofmeis- ter et al. 2013, Suárez-Esteban et al. 2016). Additionally, erosion of road surfaces and deposition at road edges, as well as increased runoff, can increase available soil water in edge habitats, leading to increases in densities of species with a preference for moister envi- ronments (Avon et al. 2010; Wei et al. 2015, 2016). In our study, we determined the ecological effects of established fire trails on plant assem- blages in edge habitats adjacent to fire trails in woodlands in Blue Mountains National Park (BMNP). This region in southeastern Austra- lia is one of the most fire-prone regions in the world (Hammill and Tasker 2010). With its large number of endemic species and high bio- Figure 1. Examples of fire-trail (a) and interior (b) diversity value, it has been named a United habitats in fire-prone woodland. Faulconbridge, Nations Educational, Scientific and Cultural NSW, Australia, 2014. Organization World Heritage Area (Hammill es in weed infiltration (Vakhlamova et al. and Tasker 2010). As a fire-prone area of 2016). A range of human activities have been World Heritage significance, the BMNP pro- linked to such alterations to plant assemblages, vides insights into the ecological impacts of including motorized vehicles as a vector for fire management activities that are potentially the spread of weeds (Mortensen et al. 2009), valuable in the management of fire-prone sys- pollution from vehicle emissions (Bignal et al. tems across the world. A key difference be- 2007), and the effects of high-traffic roads tween our study and previous research on (Richard et al. 2000). Importantly, responses roads and other transport corridors is the low of plant assemblages in edge habitats are often amount of vehicle traffic that fire trails receive, underpinned by shifts in abiotic conditions in with fire trails often permanently closed to the the edge habitat (Fox et al. 1997, Trombulak public and used only during active fire fighting and Frissell 2000, Watkins et al. 2003, Pellisi- or hazard-reduction activities.