Geographical, anthropogenic and climatic determinants of bryophyte species composition and richness in the Shengsi archipelago, East China Sea

ABSTRACT

Introduction. Few attempts have been made to assess the comparative contributions of different environmental factors on species composition (SC) and richness (SR) of bryophytes on continental islands.

Methods. The bryophyte flora and the impact of seven environmental variables (island area, elevation, isolation, human disturbance, rainfall, vegetation cover, and exposed rock area) on 18 continental islands of the Shengsi archipelago in the East China Sea were investigated. Redundancy Analysis and Canonical Correspondence Analysis were used to determine to what extent the environmental variables could explain variation in species richness and species composition on these islands.

Key results & Conclusions. Island elevation, isolation, area and human disturbance intensity all significantly influenced bryophyte SC at island level, accounting for 12.7%, 9.9%, 8.8% and 7.8% of the total SC variation, respectively. Island area was the most important determinant of bryophyte SR (P = 0.002), accounting for 58.3% of the total variation (9.7% by area per se and 48.6% confounded with other variables); elevation and human disturbance intensity also significantly influenced species richness, accounting for 10.5% and 6.9% of the total SR variation (conditional effects), respectively. Elevation and area had a positive interaction effect on SR while isolation exerted no significant effects (P > 0.05). The relationships of bryophyte species number (S) with area (A) follow log₁₀ (S) = c + z × log₁₀ (A), with z values from 0.28 to 0.38. The effects of human disturbance on bryophyte SR followed the Gaussian model, supporting the ‘intermediate disturbance hypothesis’ to some extent.

KEYWORDS:

• Area
• continental island
• elevation
• disturbance intensity
• island biogeography
• isolation
• human disturbance
• species richness

Acknowledgement

We are grateful to the financial support from the National Nature Science Foundation of China (Bryophyte diversity and biogeography of the coastal island along Zhejiang and Fujie Provinces, China, No. 31570208) and Shanghai Engineering Research Centre of Plant Germplasm Resources (No. 17DZ2252700). We also thank Prof. Tong Cao, Shanghai Normal University, for their collection and identification of the specimens. Thanks are also due to Prof. Rod Seppelt, Bundall, Queensland, for his valuable suggestions and for improving the English text.

Notes on contributors

Jing Yu works as a bryologist at Shanghai Normal University, focusing on bryophyte ecology, taxonomy and palynology.

Lin Shen, Cheng Zang and Jinrong Cai are Master degree candidates, majoring in bryophyte ecology.

Shuiliang Guo is a bryologist at Herbarium (SHTU), Shanghai Normal University. His research mainly focuses on bryophyte ecology and taxonomy, more specifically on Ptychomitriaceae and Orthotrichaceae.

ORCID

Shuiliang Guo http://orcid.org/0000-0001-5666-6045

Additional information

Funding

We are grateful to the financial support from the National Nature Science Foundation of China (Bryophyte diversity and biogeography of the coastal island along Zhejiang and Fujie Provinces, China, grant number 31570208) and Shanghai Engineering Research Centre of Plant Germplasm Resources [grant number 17DZ2252700)].