City slickers: poor performance does not deter \u3cem\u3eAnolis\u3c/em\u3e lizards from using artificial substrates in human‐modified habitats

1. As animals move through their environments, they encounter a variety of substrates, which have important effects on their locomotor performance. Habitat modification can alter the types of substrates available for locomotion. In particular, many types of artificial substrates have been added to urban areas, but effects of these novel surfaces on animal locomotion are little known. In this study, we assessed locomotor performance of two Anolis lizard species (A. cristatellus and A. stratulus) on substrates that varied in inclination and surface roughness. Rough substrates represented the tree trunks and branches typically used in natural forest habitats, whereas smooth, vertical substrates captured the qualities of artificial surfaces, such as posts and walls, available in human‐modified habitats. We then observed habitat use to test the habitat constraint hypothesis – that lizards should more frequently occupy portions of the habitat in which they perform better. Increased inclination and decreased surface roughness caused lizards to run slower. Both A. cristatellus and A. stratulus ran slowest on the smooth, vertical surface, and A. cristatellus often slipped and fell on this surface. In contrast to predictions, both species frequently used smooth, vertical substrates in the wild. Anolis cristatellus occupied artificial substrates 73% of the time in human‐modified habitats despite performing worse than A. stratulus on the smooth, vertical track. We therefore rejected the habitat constraint hypothesis for anoles in these human‐modified habitats. Despite overall poor performance on the smooth, vertical track, A. cristatellus had a significant morphology–performance relationship that supports the prediction that selection should favour smaller lizards with relatively longer limbs in human‐modified habitats. The smaller bodied A. stratulus performed better than A. cristatellus on smooth, vertical substrates and therefore may not be exposed to the same selective pressures. We contend that habitat modification by humans may alter morphology‐performance–habitat use relationships found in natural habitats. This may lead to changes in selective pressures for some species, which may influence their ability to occupy human‐modified habitats such as cities

Can forest management based on natural disturbances maintain ecological resilience?

Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance