Conspecific negative density dependence (CNDD) is the process that decreases population growth rates at high densities and considered as an important mechanism for maintaining plant diversity. However, the strength of CNDD varies greatly in space and time as well as among species, and the factors related to this variation have not been fully quantified.
In a study published in Ecology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) explored the interspecific and temporal variation of CNDD and its potential associated factors. The researchers used a long-term study of seedling survival in tropical forests to quantify variation in the strength of CNDD among species related to enemy defense and resource acquisition, as well as interannual and intraannual variation.
The researchers quantified the interspecific and temporal variation of CNDD intensity, and studied the potential associated factors including species functional traits (such as drought resistance, defense-related traits, and resource acquisition traits).
They found that the density of conspecific seedlings was negatively correlated with seedling survival when water resources are scarce (i.e., during the dry season). However, when resources are abundant (i.e., the rainy season), the density of conspecific adult individuals was negatively correlated with seedling survival. Furthermore,they found that interspecific variation in CNDD was related to drought-tolerance traits in the dry season but not in the wet season.
Moreover, they found that species with weaker drought resistance were less affected by CNDD in the dry season when precipitation was higher, whereas species with stronger drought resistance were less affected by CNDD in the dry season when precipitation was lower. Rare species were also found to be more strongly affected by CNDD than common species in the dry season.
“Our study highlights the high variability of CNDD among different species and over time, thus requiring a deeper understanding of the environmental and functional context of CNDD and their interactions. It also provides new perspectives and ideas for further exploring mechanisms underlying species diversity maintenance under a changing climate,” said YANG Jie of XTBG.
The study was financially supported the National Natural Science Foundation of China, Youth Innovation Promotion Association of the Chinese Academy of Sciences, and others.
The 20-ha forest plot in Xishuangbanna. (Image by XTBG)
Contact
YANG Jie Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
E-mail: yangjie@xtbg.org.cn
Published: 26 July 2024
