In tropical rainforests, trees and associated plants form vertical layers, providing habitats for insects and other animals. Seasonal changes affect plant growth and life cycles, which in turn influence when and where insects are most active. While insect diversity in tropical forests has been studied extensively, research often overlooks the importance of vertical layers and seasons.

In a study published in Integrative Conservation, researchers investigate the vertical stratification and spatiotemporal dynamics of insect diversity using a spatially explicit sampling protocol in two tropical rainforests at lower and higher latitudes in Thailand. They focused on three taxonomic groups (viz., Coleoptera, Hymenoptera, and two families of Lepidoptera.

They used a spatially explicit sampling design to sample insects in the canopy and understory layers of two tropical rainforests during the dry and wet seasons. They conducted a detailed record and analysis of the diversity of three major insect taxa (Coleoptera, Hymenoptera, and Lepidoptera), by using standard insect collection methods such as trapping and hand-collecting.

They tested the differences in species richness (alpha diversity), horizontal heterogeneity (beta diversity), and abundance between the vertical strata (canopy vs. understory) and seasons (dry vs. wet) within each of the two forests.

They found that the spatio-temporal dynamics of insect diversity was highly context-dependent, both in terms of the specific environment and the temporal frame of reference. The insect diversity was slightly higher in the canopy than in the understory, although this pattern changed depending on the season, forest, and type of insect. Over half of the insect species were unique to specific vertical layers but were found in certain seasons.

Their study suggested that insect diversity depended strongly on the vertical position and the time of year, suggesting that insect studies and monitoring should consider these factors in tropical rainforests.

“Our study has implications for suggesting a more nuanced approach to monitoring and conserving insect biodiversity in tropical rainforests, one that takes into account the influence of vertical strata and seasonal variation,” said Akihiro Nakamura of XTBG.

Contact

Akihiro Nakamura Ph.D Principal Investigator

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China

E-mail: a.nakamura@xtbg.ac.cn