RECONCILING SPATIAL, TEMPORAL, AND TAXONOMIC SCALE IN ECOLOGICAL AND PALEOECOLOGICAL STUDIES

Fossil data are potentially different from data collected from living communities in their spatial, temporal, and taxonomic scales and these differences must be understood so that accurate comparisons can be made between the past and present states of living communities and so that confident comparisons can be made between modern and ancient ecosystems. Fifty-four long-term ecological studies of a wide range of taxon groups (mammals, invertebrates, plants, corals) and habitat types (marine, terrestrial, freshwater) were surveyed from the published ecological literature to determine the range of spatial, temporal and taxonomic scales at which data are commonly collected on living communities. Long-term ecological studies encompass spatial scales from 50 m² to 100,000 km² and temporal scales from 5 to 100 years. Most studies resolve taxa to the species level and count individuals, although plant and coral studies sometimes quantify species by percent cover. Whether or not data from fossils can be collected and analyzed at scales comparable to data from living communities depends on the type of organism, as well as the taphonomic circumstances of preservation, accumulation and deposition. For fossil assemblages from the Quaternary, marine invertebrates can be sampled at comparable spatial and taxonomic scales to living invertebrates, but time averaging degrades the temporal resolution of the fossil deposits. Vertebrate fossils provide data at comparable taxonomic scales with some reduction in spatial and temporal resolution relative to live data. Plant fossils and pollen are capable of being sampled at temporal resolutions comparable to modern ecological studies, but pollen data are prone to spatial averaging and have much poorer taxonomic resolution than censuses of living communities. Currently we are surveying the paleoecological literature to assess to what degree paleoecological data diverges in scale from ecological data going back through the pre-Quaternary fossil record.