Ecological networks have been widely used to describe the complex biological interactions in ecosystems, and the topological structure indicators of the network provide a systematic framework for characterizing and comparing the pattern features of interactions. Under the influence of mutualistic networks and antagonistic networks, most of the studies on epiphyte–host networks are based at the species level. However, species-based networks overlook the intraspecific variation by pooling all the individuals in a single group.
In a study published in Ecological Indicators, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) tried to explore how to identify the critical transition indicator by simulating the dynamics of network assembly and use this indicator to compare the stability structure of different ecological networks. They utilized dynamic simulations to identify how three key structural indicators (connectance, nestedness and modularity) changed with increasing sampling size, by integrating data on epiphytic mosses and epiphytic vascular plants collected from investigations in tropical rainforest and subtropical forest of Yunnan.
The researchers assessed and compared the critical points at which different epiphytic relationship networks reached a stable state and their structural characteristics under stable conditions. Additionally, they analyzed the dynamics of host size and epiphyte richness to reveal potential mechanisms shaping the stable structure of the epiphytic relationship network.
They found that when the number of host samples reached 30 and 100 respectively, the structural indicators of epiphytic mosses and epiphytic vascular plant-host networks gradually stabilized. In a stable state, the connectivity and nestedness of the epiphytic relationship network in subtropical forests were significantly higher than those in tropical rainforests, while the modularity of the epiphytic relationship network in tropical rainforests was higher. The coefficients of variation for host size and epiphyte richness tended to stabilize at the same critical point, indicating that these two variables may be fundamental elements in constructing a stable epiphytic relationship network.
“This study suggests that host size and epiphyte richness distribution may be underlying factors in forming stable epiphyte-host networks. It also provides a new method that combines indicator dynamics with critical transitions to determine whether the network structure has reached a stable state under different sampling intensities,” said SONG Liang of XTBG.
Epiphytic mosses and epiphytic vascular plants in subtropical forest of Yunnan. (Image by SING Liang)
Contact
SONG Liang Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
E-mail: songliang@xtbg.ac.cn
Published: 17 August 2024
