Fire and fragmentation interactions: effects on reptiles and small mammals in modified semi-arid landscapes
Creators: name: Lazzari, Juliana
Publisher: name: The Australian National University
Year: 2019

description: Interactions between fire and fragmented landscapes could be a primary factor influencing the distribution and persistence of species. However, historical and recent land use change and land management practices have altered the spread, frequency and intensity of fires globally. This presents a major challenge to biodiversity management because ecosystems are being modified by fire in already fragmented systems. Within fragmented fire-affected landscapes, the use or suppression of fire can provide successional habitats for a range of biota. However, records of fire history that are essential for managing fire-sensitive species, are often limited for many reserves and for remnant patches on private land. In addition, little is known about how reptiles and mammals use fragmented fire-affected landscapes, nor the role of reserves and remnants in mediating the interacting effects of these two major disturbances on co-occurring species. Due to this gap in understanding biodiversity responses to fire in fragmented landscapes, inappropriate fire regimes in such landscapes could lead to species losses. My aim was to understand species responses to interactions between experimental fire and habitat fragmentation in an agricultural matrix. To achieve this, I conducted studies that specifically addressed: 1) the current status of research, 2) how to build on current knowledge to predict fire age, 3) reptile trait responses, and 4) how small mammals are affected. For study 1) I undertook a systematic review of the literature that discusses the fire-fragmentation interaction effects on biodiversity. For study 2) I developed a model to predict fire age using environmental covariates and stem diameters. For studies 3) and 4), I undertook a natural and manipulative experiment using fire in remnants and trapped reptiles and small mammals. The key findings are: 1) there is limited peer reviewed research that investigates the effects of fire interactions with habitat fragmentation on biodiversity; 2) that local environmental covariates influence stem diameter growth, showing strong modelling potential to predict fire age; 3) that reptile trait responses to fire by fragmentation interactions were not detected, but prescribed fire in remnants close to the reserve, with initially low abundance, may provide colonisation opportunities for insectivorous, nocturnal or burrowing species; and 4) that the occurrence of native mammals was affected more by fragmentation than by fire, including a lower occurrence in remnants than the reserve and in remnants further from the reserve, and conversely for the exotic mammal. To improve our knowledge of reptiles and mammals in fragmented fire-affected, semi-arid mallee cropping landscapes, I recommend that: i) further testing and refining of the fire age prediction models to improve the reliability of mapping fire ages in remnants and reserves; ii) further research into species specific responses be undertaken, including by using reptile mark-recapture data collected in this study; and iii) future studies be undertaken over a longer period than my three year study. Also, to inform and improve conservation management of these species already persisting in small, long unburnt and isolated patches, I recommend that: iv) the use of prescribed fire in reserves and remnants be minimised while; v) more study is conducted to fill the research gaps into the effects of fire interactions with habitat fragmentation on species responses. In making these recommendations, I emphasise that management strategies targeting the conservation of reptile and mammal persistence in fragmented and fire affected mallee landscapes, need to i) take a precautionary approach to using prescribed fire, particularly while many of the cause and effect relationships of multiple environmental threats have not been established scientifically, and ii) urgently be informed by empirical research of reptile and mammal species in these landscapes.