Conserving large intact forest landscapes (IFLs) is one forest management strategy to mitigate industrial impacts on the environment. Measuring the IFL inventory at national scales has also been proposed as a means of assessing the conservation status at global scales. This paper explores the relationship between fire regimes and the size of intact forest landscapes required to meet specific conservation targets. In this paper, we demonstrate that variation in fire regimes results in changes in the minimum size of IFL required to meet habitat targets. In addition, minimum IFL size is also dependent on the nature of the habitat targets. Larger IFLs are required to improve likelihood of providing sufficient older habitat. There is significant risk of not meeting older forest age-class targets at higher annual area burned (AAB) rates, especially under climate change. In general, there is more risk of not meeting habitat targets associated with smaller IFLs, higher annual area burned (both due to spatial differences and between historical and projected burn rates under climate change), and for provision of older forests. We used habitat age-related targets as outlined in the recovery strategy for woodland caribou as an example to demonstrate the usefulness of this type of simulation experiment and risk curves to identify appropriate IFL size along a gradient of natural disturbance intensity.