The influence of changing fire regimes on specialized plant-animal interactions

Abstract

Ecological effects of changing fire regimes are well documented for plant and animal populations, but less is known about how fire influences, and is influenced by, specialized plant-animal interactions. In this review, we identified mutualistic (pollination, seed dispersal and food provision), commensal (habitat provision) and antagonistic (seed predation, herbivory and parasitism) plant-animal interactions from fire-prone ecosystems. We focused on specialized interactions where a single genus depended on one to two genera in a single family of plant or animal. We categorized the plant partner's post-fire reproductive mode to assess the likely outcome of changing fire regimes on ecological functions provided by these interactions. Traits underlying specialization in fire-prone ecosystems for plants were: post-fire reproductive mode, time to maturity, morphology and phenology; and, for animals: dispersal, specialized organs, nesting and egg deposition substrates, plant consumption behaviours and pollinator behaviours. Finally, we identified a number of cases where stabilizing feedbacks maintained plant-animal interactions under natural fire regimes. Potential reinforcing feedbacks were also identified, but were more likely to happen abruptly and result in collapse of the plant-animal partnership, or partner switching. Our synthesis reveals how fire regime changes impact fire-dependent specialist plant-animal interactions and potentially drive eco-evolutionary dynamics in fire-prone ecosystems globally.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

Keywords: ecological specialization; evolutionary ecology; feedback; fire ecology; global change; niche breadth.

Figure 1.

Plant and animal morphological, behavioural and reproductive traits involved in specialized plant–animal interactions in fire-prone ecosystems. Points indicate traits identified from the literature as being involved in different types of interactions. The relative potential for selection to act on traits and feed back into ecological dynamics is signified by the size of the points: small points indicate traits likely under weak selection and large points indicate traits potentially under strong selection. Environmental variation influences these interactions and the fire regime by controlling habitat structure, connectivity and aridity. The fire regime controls the environment by consuming vegetation and influencing recruitment and mortality processes in plants and animals. Plant and animal traits, particularly plant post-fire reproductive mode and morphology, and plant consumption behaviours in animals, are likely to feed back into the environment and fire regime. For example, herbivory affects habitat connectedness, which in turn affects the size, patchiness and intensity of fires, feeding back into population dynamics of herbivores. Pollinators affect habitat structure by influencing flowering season, rate of seed set and, therefore, the potential for plant recruitment. This feeds back into the fire regime by influencing biomass and post-fire succession, with subsequent influences on fire frequency.