The Importance of Demographic Niches to Tree Diversity
Richard Condit,1,2*
Peter Ashton,3
Sarayudh Bunyavejchewin,4
H. S. Dattaraja,5
Stuart Davies,3
Shameema Esufali,6
Corneille Ewango,7
Robin Foster,8
I. A. U. N. Gunatilleke,6
C. V. S. Gunatilleke,6
Pamela Hall,9
Kyle E. Harms,10
Terese Hart,11
Consuelo Hernandez,12
Stephen Hubbell,13
Akira Itoh,14
Somboon Kiratiprayoon,15
James LaFrankie,16
Suzanne Loo de Lao,2
Jean-Remy Makana,11
Md. Nur Supardi Noor,17
Abdul Rahman Kassim,17
Sabrina Russo,3
Raman Sukumar,5
Cristián Samper,18
Hebbalalu S. Suresh,5
Sylvester Tan,19
Sean Thomas,20
Renato Valencia,12
Martha Vallejo,21
Gorky Villa,12
Tommaso Zillio1,2
Most ecological hypotheses about species coexistence hinge on species differences, but quantifying trait differences across species in diverse communities is often unfeasible. We examined the variation of demographic traits using a global tropical forest data set covering 4500 species in 10 large-scale tree inventories. With a hierarchical Bayesian approach, we quantified the distribution of mortality and growth rates of all tree species at each site. This allowed us to test the prediction that demographic differences facilitate species richness, as suggested by the theory that a tradeoff between high growth and high survival allows species to coexist. Contrary to the prediction, the most diverse forests had the least demographic variation. Although demographic differences may foster coexistence, they do not explain any of the 16-fold variation in tree species richness observed across the tropics.
1 National Center for Ecological Analysis and Synthesis, 735 State Street, Santa Barbara, CA 93101, USA.
2 Center for Tropical Forest Science, Smithsonian Tropical Research Institute, Unit 0948, APO AA 34002–0948, USA.
3 Center for Tropical Forest Science, Asia Program, Arnold Arboretum Asia Program, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA 02138, USA.
4 Thai National Park Wildlife and Plant Conservation Department, Research Office, 61 Phaholyothin Road, Chatuchak, Bangkok 10900, Thailand.
5 Center for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India.
6 Department of Botany, Faculty of Science, University of Peradeniya, Peradeniya 20400, Sri Lanka.
7 University of Missouri, 8001 Natural Bridge Road, St. Louis, MO 63121–4499, USA.
8 Botany Department, The Field Museum, Roosevelt Road at Lake Short Drive, Chicago, IL 60605–2496, USA.
9 Department of Biology, Florida State University, 5051 Quail Valley Road, Tallahassee, FL 32309, USA.
10 Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
11 Wildlife Conservation Society, 1725 Avenue Monjiba, Chanic Building, 2nd floor, Ngalinema, Boîte Postale 240, Kinshasa I, Democratic Republic of Congo.
12 Pontifícia Universidad Católica de Ecuador, Post Office Box 17012184, Quito, Ecuador.
13 Department of Plant Sciences, University of Georgia, 2502 Miller Plant Sciences Building, Athens, GA 30602, USA.
14 Plant Ecology Lab, Faculty of Science, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558, Japan.
15 Faculty of Science and Technology, Thammasat University (Rangsit), Klongluang, Patumtani 12121, Thailand.
16 Center for Tropical Forest Science, Asia Program, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, 637616 Singapore.
17 Forest Environment Division, Forest Research Institute Malaysia, Kepong, Kuala Lumpur 52109, Malaysia.
18 National Museum of Natural History, Smithsonian Institution, 10th Street and Constitution Avenue, NW, Washington, DC 20560, USA.
19 Forest Research Center, Sarawak Forest Department, Km10 Jalun Datak Amar Kalong Ningkan, 93250 Kuching, Sarawak, Malaysia.
20 University of Toronto, 33 Willcock Street, Toronto, Ontario M5S 3B3, Canada.
21 Instituto Alexander von Humboldt, Carrera 13 #28-01, Piso 7, Edifico Palma Real, Bogotá, Colombia.
* To whom correspondence should be addressed: condit{at}ctfs.si.edu
