Environment-diversity relationships of bryophyte communities in Northeastern Taiwan forest

Master thesis at the School of Forestry and Resource Conservation, National Taiwan University (November 2023)

https://doi.org/10.6342/NTU202304498

Author: Tsung-Chen Lee (李宗宸)

Advisor: David Zelený, Co-advisor: Biing T. Guan

Abstract:

This study investigated the relationships between bryophytes and environmental factors in Taiwan, specifically focusing on species turnover and richness patterns. By conducting bryophyte surveys and combining them with data on vascular plant composition from the same plots, this study provided insights into the relationship between environmental factors and bryophyte communities. On a 20 m × 20 m plot scale, the canonical correspondence analysis (CCA) revealed the environment-species turnover relationship of some bryophyte species and specific environmental preferences. Additionally, combined with detrended correspondence analysis (DCA), the results showed varying responses to environmental factors between liverworts, mosses, and vascular plants, possibly due to their anatomical differences, sampling completeness, and sensitivities. Notably, liverworts and mosses exhibited different orders of importance of environmental factors in explaining species turnover, with fog frequency being more critical for liverworts and canopy openness for mosses. Analyzing all life-form groups' species richness-environmental factor patterns, a positive linear relationship was found for mosses with canopy openness. Furthermore, fog frequency was identified as a driver of liverwort species richness, suggesting its influence on both species turnover and richness in liverworts. In contrast, no significant relationship was found between environmental factors and the species richness of vascular plants, indicating that the response of species richness of bryophytes may be more sensitive to environmental changes than that of vascular plants. This study highlights the different responses in species turnover and richness between liverworts, mosses, and vascular plant communities to environmental factors in Taiwan. In addition, this study provides possible explanations for the results and cautions to interpret them.

Keywords: bryophytes, canopy openness, cloud forest, elevation, environmental factors, fog frequency, liverworts,mosses, species richness, species turnover

中文摘要

本研究在臺灣東北部森林進行了苔蘚植物物種組成調查,以瞭解苔蘚植物與環境因子之關係,並結合樣區內維管束植物物種組成資料進行分析。研究旨在闡明環境因子對苔蘚植物之物種豐富度和物種組成所造成的影響,並且透過與維管束植物群集進行比較,以提供苔蘚植物群集與環境因子關係之見解。 在20 m × 20 m樣區尺度上,本研究先以典型對應分析(Canonical correspondence analysis)量化苔蘚植物之物種更迭(Species turnover)與環境因子之間的關係,結果發現數個苔蘚物種對特定環境具有偏好,且可與過去文獻之定性及觀察性描述相應對照。其次以典型對應分析之結果搭配降趨對應分析(Detrended correspondence analysis)探討苔蘚植物群集與維管束植物群對於環境因子之反應之差異。結果發現苔類植物與蘚類植物對不同環境因子在解釋其物種更迭的重要性排序不同:對於蘚類植物而言,雲霧頻率對物種更迭的解釋比樹冠開闊度更為重要;然而,對於苔類植物上則呈現相反的排序。這些結果可能是由於苔類植物和蘚類植物在構造上的差異所致,反映了這些苔蘚植物對不同環境因子的敏感性。而與維管束植物相比,苔蘚植物在海拔梯度上的物種更迭最低,這可能是由於苔蘚植物高度的散佈能力及較高的取樣完整度所致。 本研究亦使用多元線性迴歸分析苔蘚植物和維管束植物的物種豐富度沿海拔梯度變化的模式。研究結果顯示苔類植物的物種豐富度與海拔呈現正相關,進一步分析顯示環境因子中僅樹冠開闊度對其具有顯著影響,這或許代表即使與海拔不相關的環境因子,也可能會對觀察到的苔類植物物種豐富度的變化有所影響。此外,本研究的結果顯示雲霧頻度對蘚類植物的物種豐富度有顯著影響,這表明雲霧頻度不僅影響蘚類植物的物種更迭,還影響其物種豐富度,再次驗證各環境因子在苔類植物和蘚類植物上的重要性排序不同。對於維。管束植物群集而言,沒有環境因子與其物種豐富度呈顯著相關,顯示苔蘚植物之物種豐富度對環境因子之改變可能較為敏感。 總結而言,本研究突顯了臺灣的蘚類植物、苔類植物及各維管束植物群集在不同的環境因子下,其物種組成與物種豐富度會表現出不同的反應。此外,本研究亦提供了可能的解釋並指出研究結果在推論上的限制。

關鍵字:苔蘚植物、樹冠開闊度、雲霧森林、海拔、環境因子、雲霧頻度、蘚類植物、苔類植物、物種豐富度、物種更迭