Elevational variation in density dependence in a subtropical forest
Article first published online: 30 MAY 2014
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Ecology and Evolution
Volume 4, Issue 14, pages 2823–2833, July 2014
How to Cite
Ecology and Evolution 2014; 4(14):2823–2833
- Issue published online: 21 JUL 2014
- Article first published online: 30 MAY 2014
- Manuscript Accepted: 30 APR 2014
- Manuscript Revised: 5 MAR 2014
- Manuscript Received: 8 AUG 2013
- National Natural Science Foundation of China. Grant Numbers: 31230013, 30730021
- Zhang-Hongda Science Foundation at Sun Yat-sen University
- Density dependence;
- Janzen–Connell hypothesis;
- mixed model;
- neighborhood effects;
- soilborne pathogens;
- subtropical forest
Density-dependent mortality has been recognized as an important mechanism that underpins tree species diversity, especially in tropical forests. However, few studies have attempted to explore how density dependence varies with spatial scale and even fewer have attempted to identify why there is scale-dependent differentiation. In this study, we explore the elevational variation in density dependence. Three 1-ha permanent plots were established at low and high elevations in the Heishiding subtropical forest, southern China. Using data from 1200 1 m2 seedling quadrats, comprising of 200 1 m2 quadrats located in each 1-ha plot, we examined the variation in density dependence between elevations using a generalized linear mixed model with crossed random effects. A greenhouse experiment also investigated the potential effects of the soil biota on density-dependent differentiation. Our results demonstrated that density-dependent seedling mortality can vary between elevations in subtropical forests. Species found at a lower elevation suffered stronger negative density dependence than those found at a higher elevation. The greenhouse experiment indicated that two species that commonly occur at both elevations suffered more from soilborne pathogens during seed germination and seedling growth when they grew at the lower elevation, which implied that soil pathogens may play a crucial role in density-dependent spatial variation.