The idea that the response of an organism to components of its physical environment, as distinct from the availability of resources, is an important component of its niche. Differences between species in their environmental niches may promote their coexistence. The coexistence mechanism involved is the storage effect, augmented in the case of spatial variation by fitness density covariance. Environmental niches are temporal niches if they refer to temporally varying aspects of the physical environment, or spatial niches if they refer to spatially varying aspects of the physical environment, or spatio-temporal niches, if they refer simultaneously to variation in both space and time.
Chesson, P.L. 1985. Coexistence of competitors in spatially and temporally varying environments: a look at the combined effects of different sorts of variability. Theor. Pop. Biol. 28, 263-287.
Chesson, P., Pacala, S., Neuhauser, C. 2001. Environmental niches and ecosystem functioning. Pages 213-245 in "The Functional Consequences of Biodiversity", Ann Kinzig, Stephen Pacala, and David Tilman, eds, Princeton University Press.
Snyder, R.E. and Chesson, P. 2003. Local dispersal can facilitate coexistence in the presence of permanent spatial heterogeneity. Ecology Letters 6,301–309.
Chesson, P., Donahue, M., Melbourne, B., Sears, A. 2004. Scale transition theory for understanding mechanisms in metacommunities. In Holyoak, M, Leibold, M.A., Holt, R.D., eds, Metacommunities: spatial dynamics and ecological communities.