Post-fire spatial heterogeneity alters ground-dwelling arthropod and small mammal community patterns in a desert landscape experiencing a novel disturbance regime

- Novel disturbance regimes create complex spatial mosaics.
- Remnant vegetation alters community structure in landscapes faced with a novel disturbance.
- Remnant perennials can mitigate the impact of novel disturbances, such as wildfire, on wildlife.
- Burned/unburned landscape descriptions are inadequate for understanding community structure.

Anthropogenic activities have resulted in novel disturbance regimes which have unknown impacts on biodiversity. A notable example is the establishment of fire regimes in ecosystems that have not historically burned. These new disturbance regimes leave behind a complex spatial matrix with varying patterns of landscape heterogeneity. Research on novel disturbance regimes often ignores remnant vegetation within disturbed habitats, even though landscape variation in a disturbed area can influence population and community dynamics. Our objective was to understand the influence of spatial heterogeneity, characterized by varying levels of isolation and remnant vegetation, within a landscape disturbed by a novel fire regime in the Mojave Desert where wildfire was exceedingly rare to non-existent in this landscape prior to recent times. We found that community patterns of both ground-dwelling arthropods and small mammals varied based on the amount of remnant vegetation and isolation levels within burned habitats. Ground-dwelling arthropod abundance and richness measurements were highest in burned habitats that had remnant long-lived vegetation present, whereas small mammal abundance and richness measurements were highest in continuous expanses of unburned habitat. We also found that the negative impacts of fire on arthropods and small mammal communities in isolated, burned habitats were masked by the presence of long-lived perennial vegetation. Our study highlights the importance of incorporating habitat heterogeneity into future studies of novel disturbance regimes and provides evidence for the utility of restoration plantings in desert ecosystems.