How flammable is your farm? Measuring the flammability of crops and pastures, and other plant species commonly found on farms in Canterbury, New Zealand : A thesis submitted in partial fulfilment of the requirements for the Degree of Master at Lincoln University

Abstract

Due to human-induced climate change, global temperatures are expected to rise, leading to increased extreme fire weather being predicted for New Zealand (NZ). Destructive fires are becoming more prevalent every year, threatening our biodiversity, and causing damage to human infrastructure, crops, and pastures. Hence, NZ's landscapes must be made more resilient to wildfires. One potential tool to help reduce fire spread is green firebreaks, strips of low flammability vegetation that are strategically placed across the landscape. However, to establish green firebreaks, we first need to know the flammability of different species. While there has been some research examining the flammability of introduced and native trees, shrubs, and grasses in NZ, there is a lack of information regarding the flammability of common crops and pasture grasses used not only in NZ, but around the world. This thesis intends to address this knowledge gap by testing the shoot flammability of common pastures, crops and other plant species that occur on Canterbury farms. This thesis also compares the flammability of these crop and pasture species to that of other plant species already tested in NZ to produce a list of low flammability species which can be used to develop potential green firebreaks on farms in NZ and other temperate regions of the world where similar crops are grown. The shoot-level flammability of 47 common NZ crop and pasture species found on rural Canterbury farms was tested and most of these species were found to be of Low or Very Low flammability. Only three of the species, Common pear (Pyrus communis) and two Apple varities (Malus domestica var. Braeburn, M. domestica var. Royal Gala) were of Very High flammability, indicating that many crop and pasture species grown in Canterbury are suitable to use as green firebreaks. These 47 crop and pasture species were then compared to 269 other plant species already tested in NZ and found to be comparatively very low in flammability, further suggesting that crop and pasture species are excellent candidates for green firebreaks on agricultural and rural land. This supports recent suggestions that diversified agricultural systems can lower the likelihood of large, intense fires and will assist farmers and landowners in redesigning their farms so they can plant low-flammability species in areas they deem to be high fire dangers. Overall, this knowledge will improve our understanding of how fire regimes change over time and space in agricultural landscapes and help mitigate wildfires in an era of rapid climate change and increasingly destructive wildfires in NZ and around the world.