Variation in fern species richness, assemblages and morphology along a tropical riparian humidity gradient: an example from Borneo

ABSTRACT

Riparian vegetation experiences a little spatial distance humidity gradient, especially in the hyper-humid tropics. In Borneo, with almost no seasons and rather constant local climatic conditions, the riparian plant species show a wide range of morphological and physiological adaptations. This study assesses the adaptation strategies of ferns along a riparian humidity gradient in the submontane forest of Sarawak, Malaysia (Borneo). The species richness and cover, morphological traits, leaf area, leaf perimeter, leaf dissection, leaf elongation ratio, and stomatal density of 63 fern species were surveyed in six study areas along six stream transects. Significant trends in species richness and species cover were identified along the six transects, and changes in morphological traits such as leaf area, leaf perimeter, and leaf dissection were also discovered. With increasing distance from the streams (i.e. decreasing humidity), ferns tended to show longer leaves and a lower stomatal density. We conclude that the morphological traits of fronds change significantly within a short tropical riparian humidity gradient. This reveals variations in the energy investment and adaptation efficiency of ferns within a tropical forest microsite.

KEYWORDS:

• Environmental gradient
• stomatal density
• leaf shape
• leaf traits
• leaf dissection

View correction statement:

Correction

Acknowledgment

We would like to acknowledge the Hearth of Borneo Initiative and the Department of Forestry of Malaysia, Sarawak, for the invitation to DC to the HoB Tama Abu expedition. We would also like to thank the lab technicians and the UBD Herbarium the Faculty of Science, Environmental and Life Sciences Department, for their logistical support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/23818107.2024.2346480.

Author contributions

DC designed and conducted the research program; DC, FBHY, JSY, NBS, NBW, NAHZA have contributed to the morphological traits assessment; DC elaborated the data and conducted the statistical analysis; DC, JSY, and JRJ wrote and contributed to the manuscript; all authors have revised the final version of the manuscript.

Correction Statement

This article was originally published with errors, which have now been corrected in the online version. Please see Correction (http://dx.doi.org/10.1080/23818107.2024.2362004)

Additional information

Funding

This work was supported by the Universiti Brunei Darussalam, under Grant UBD/RSCH/1.4/FICBF(b)/2020/028; The first author was honored to be invited to join the Heart of Borneo Expedition (HoB) Sarawak (13-27 August 2017) by the HoB and Sarawak Forestry Department.

Notes on contributors

Daniele Cicuzza

Daniele Cicuzza is a senior assistant professor at the University of Brunei Darussalam, Faculty of Science. He focuses on taxonomy, ecology and ecophysiology of Southeast Asia ferns. He conceived and designed the project, collected the field data, and elaborated the data. He drafted the manuscript.

Fauziah Binti Haji Yahya

Fauziah Binti Haji Yahya is a research assistant at the University of Brunei Darussalam, Faculty of Science. She has measured the morphological traits of the fern species. She contributed in the preliminary data elaboration. She drafted the manuscript.

Jiun Sim Yi

Jiun Sim Yi is a B.S. student from the University of Brunei Darussalam. She measured the morphological traits of selected fern species, elaborated on the results, and produced the final thesis. She drafted the manuscript.

Nurhazwani Binti Sirun

Nurhazwani Binti Sirun is a research assistant at the University of Brunei Darussalam, Faculty of Science. She has measured the morphological traits of the fern species. She contributed in the preliminary data elaboration. She drafted the manuscript.

Norhaslinda Binti Wasli

Norhaslinda Binti Wasli is a research assistant at the University of Brunei Darussalam, Faculty of Science. She has measured the morphological traits of the fern species. She contributed in the preliminary data elaboration. She drafted the manuscript.

Nur Aqilah Haji Zainal Ariffin

Nur Aqilah Haji Zainal Ariffin is a research assistant at the University of Brunei Darussalam, Faculty of Science. She has measured the morphological traits of the fern species. She contributed in the preliminary data elaboration. She drafted the manuscript.

James Robert Jennings

James Robert Jennings is a senior assistant professor at the University of Brunei Darussalam, Faculty of Science. He contributed to the analysis and drafted the manuscript.