Nonrandom Processes Maintain Diversity in Tropical Forests

• DOI: 10.1126/science.1117715
• Publication Date: 2006-01-26T21:33:35Z
• Authors: Christopher Wills; Kyle E. Harms; Richard Condit; David King; Jill Thompson; Fangliang He; Helene C. Muller-...; Peter Ashton; Elizabeth Losos; Liza Comita; Stephen Hubbell; James LaFrankie; Sarayudh Bunyavej...; H. S. Dattaraja; Stuart Davies; Shameema Esufali; Robin Foster; Nimal Gunatilleke; Savitri Gunatilleke; Pamela Hall; Akira Itoh; Robert John; Somboon Kiratipra...; Suzanne Loo de Lao; Marie Massa; Cheryl Nath; Md. Nur Supardi Noor; Abdul Rahman Kassim; Raman Sukumar; Hebbalalu Satyana...; I-Fang Sun; Sylvester Tan; Takuo Yamakura; Jess Zimmerman
• Keywords: Population Density; 0106 biological sciences; Tropical Climate; Population Dynamics; bats; bat; Biodiversity; 15. Life on land; 01 natural sciences; Trees; Chiroptera; Mammalia; Animalia; Chordata; Ecosystem

An ecological community's species diversity tends to erode through time as a result of stochastic extinction, competitive exclusion, and unstable host-enemy dynamics. This erosion of diversity can be prevented over the short term if recruits are highly diverse as a result of preferential recruitment of rare species or, alternatively, if rare species survive preferentially, which increases diversity as the ages of the individuals increase. Here, we present census data from seven New and Old World tropical forest dynamics plots that all show the latter pattern. Within local areas, the trees that survived were as a group more diverse than those that were recruited or those that died. The larger (and therefore on average older) survivors were more diverse within local areas than the smaller survivors. When species were rare in a local area, they had a higher survival rate than when they were common, resulting in enrichment for rare species and increasing diversity with age and size class in these complex ecosystems.