# Morphological variation in liverwort traits influences community assemblage along an elevational gradient in northern Madagascar

Lovanomenjanahary Marline, Claudine Ah-Peng, Olivier Flores, Terry Hedderson

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## ► To cite this version:

Lovanomenjanahary Marline, Claudine Ah-Peng, Olivier Flores, Terry Hedderson. Morphological variation in liverwort traits influences community assemblage along an elevational gradient in northern Madagascar. Plant Ecology and Evolution, 2025, 158, pp.181 - 194. 10.5091/plecevo.139573. hal-05074527

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Submitted on 20 May 2025

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# Morphological variation in liverwort traits influences community assemblage along an elevational gradient in northern Madagascar

Lovanomenjanahary Marline¹,², Claudine Ah-Peng³,⁴, Olivier Flores³, Terry Hedderson⁵

1. Association Vahatra, Antananarivo, Madagascar

2. Kew Madagascar, Antananarivo, Madagascar

3. UMR PVBMT, Université de La Réunion, Saint-Pierre, La Réunion, France

4. Observatoire des Sciences de l'Université de la Réunion (OSU-Réunion), UAR 3365, Université de la Réunion, CNRS, Météo France, IRD, Saint-Denis, France

5. Bolus Herbarium, Department of Biological Sciences, University of Cape Town, Cape Town, South Africa

Corresponding author: Lovanomenjanahary Marline (marlinelova@gmail.com)

**Academic editor:** Jérôme Degreef

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Received 5 December 2024

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Accepted 10 March 2025

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Published 19 May 2025

## Abstract

**Background and aims** – Epiphytic bryophytes play a crucial role in forest ecosystems by contributing to water retention, nutrient cycling, and microhabitat creation. However, despite their ecological importance, epiphytic bryophytes in Madagascar remain poorly studied, especially in terms of their functional traits and responses to environmental change. This study addresses this gap by investigating epiphytic liverwort communities along an elevational gradient in northern Madagascar. We aim to assess the relationship between functional diversity among liverwort species and community assembly using a trait-based approach, focusing on how habitat filtering and niche differentiation shape community structure.

**Material and methods** – Epiphytic bryophytes were collected at 10 elevations along an elevational transect from 250 to 2050 m. We measured 12 morphological traits related to resource use, life history, defense, desiccation resistance, and photosynthetic activity. Functional evenness (FEve) and functional dispersion (FDis) were calculated for each community. To investigate functional responses underlying community assembly, we measured community-weighted means (CWM) and variances (CWV) for each trait along the transect. We analyzed trait-environment relationships using multiple general linear models and evaluated community assembly processes (convergence or divergence) across the gradient.

**Key results** – Community assembly is influenced by environmental conditions and vegetation structure. At lower elevations, higher temperatures and taller vegetation lead to trait convergence, particularly in size-related traits. In contrast, at higher elevations, increased species richness is associated with trait divergence. Habitat filtering drives trait convergence at lower elevations, while niche differentiation becomes more important at species-rich higher elevations.

**Conclusion** – Morphological traits reveal how habitat filtering and niche differentiation jointly influence species distribution. Including physiological traits like water-holding capacity and carbon fixation in future studies will provide deeper insights into ecosystem processes. Together, these findings will contribute to a better understanding of the mechanisms that shape biodiversity in tropical forest ecosystems.

## Keywords

community assembly, elevational gradient, epiphyte liverworts, habitat filtering, morphological traits, niche differentiation, Madagascar, tropical ecosystems
# INTRODUCTION

Understanding ecosystem function requires quantification of species responses to environmental change and evaluation of the role of biotic interactions in shaping community composition (Gross et al. 2013). Community ecologists increasingly recognize that specific functional traits of assemblages may significantly influence ecosystem function, often more than species richness or composition (Hinz et al. 2021; Liu et al. 2021). Consequently, interest in the relationship between biodiversity and functional diversity has surged in recent years (Díaz et al. 2007). Morphological traits, in particular, serve as valuable proxies for functional traits, as they often correlate with an organism's performance and ecological strategies. These traits can provide insights into how species interact with their environments and contribute to ecosystem processes (Cadotte et al. 2011; Wang et al. 2024). Functional diversity encompasses measures of ecological importance and impacts on ecosystem functions, while also challenging traditional species assembly rules (Violle et al. 2007). By linking morphological characteristics to functional traits, we can better understand community assemblage and species contributions to ecosystem functioning (Davies et al. 2007).

Bryophytes, comprising mosses, liverworts, and hornworts, are the second most successful group of land plants after angiosperms in terms of species richness and their geographical distribution. Bryophytes are poikilohydric (Pardow et al. 2012; Pardow and Lakatos 2013), i.e. their hydration status depends to a great extent on the water content of their surrounding environment. Many species have the ability to desiccate completely as the surrounding environment dries out but to then rapidly resume photosynthesis and growth upon rewetting (Proctor et al. 2007; Pardow and Lakatos 2013). They lack a root system, absorbing water and nutrients across their surface, which explains their high sensitivity to air and water pollution (Govindapyari et al. 2010). Bryophytes also exhibit functional diversity (e.g. variation in drought tolerance, water retention, etc.) allowing them to survive in a wide range of climates and habitats, making them suitable indicators for detecting climate change impacts (Gignac 2001; Bergamini et al. 2009). In tropical montane systems, they contribute significantly to forest biomass (Pócs 1982; Holz and Gradstein 2005; Gehrig-Downie et al. 2011) and play a crucial role in mist forests due to their high surface area and water retention capacity (Muchura et al. 2014; Ah-Peng et al. 2017). They often colonize tree trunks and branches without drawing water or nutrients from living tissues of their support plants. The overwhelming abundance of epiphytic liverworts in cloud forests is considered an important factor in mitigating the negative effects of heavy rains, by increasing slope stability and prevention of soil erosion. Epiphytic liverworts are ubiquitous components of bryophyte communities in tropical rainforests and provide a classic example of a

taxonomically rich group with varied ecology and life-history (Gradstein and Pócs 1989).

This study focuses on epiphytic liverworts in montane rain forests of northern Madagascar, a region known for its unique biodiversity and complex ecosystems. Despite the ecological importance of liverworts in forest environments, research on these epiphytes remains limited, particularly in the context of Madagascar's montane ecosystems. To our knowledge, this study is the first to investigate the functional traits of epiphytic liverwort communities in this region, addressing a critical gap in the literature. We investigate the epiphytic liverwort communities distributed along an elevational gradient by assessing variation in informative functional traits among species and across elevation ranges on a tropical mountain in the north of Madagascar. We hypothesize that, if epiphytic bryophyte functional diversity is closely associated with species diversity in rich tropical plant communities, two possibilities may arise: functionally similar species can coexist in a confined functional space, or there may be a greater range of functions involved (Swenson 2011). Moreover, as environmental adversity increases toward the upper limits of the elevational profile, especially above the forest line, conditions become more extreme, likely promoting trait convergence and reducing functional diversity within bryophyte communities. We anticipate more uniformity of traits and decreasing functional diversity within these communities (Cornwell et al. 2006; Grime 2006; Baldeck et al. 2013). Habitat filtering results in a relatively narrower range of trait values occurring in specific environmental conditions, i.e. species co-existing in communities under habitat filtering usually exhibit similarity in life history, morphology, and physiology (Grime 2006). Alternatively, competition and the resulting limiting similarity may lead to communities containing dissimilar species. Therefore, the co-existence of species in any given community likely results from the combined effect of habitat filtering and niche differentiation (Kraft et al. 2009; Jung et al. 2010).

This study addresses the following questions: (1) How do species and functional diversity components vary along the elevational gradient? (2) How do traits measured at species and community level respond to environmental changes along the gradient? (3) How do bryophyte species interact functionally with their abiotic and biotic environments?, and (4) How do habitat filtering and niche differentiation influence bryophyte assemblages along the elevational gradient?

# MATERIAL AND METHODS

## Study site

This study was carried out in Marojejy National Park in the Sava Region of north-eastern Madagascar and centred on the Marojejy massif. The mountain spans a wide elevational gradient from 250 to 2132 m, making it
<table><caption>**Table 1.** Description of 12 morphological traits in liverworts, including 7 size related traits, and their ecological function.</caption><thead><tr><th>Traits</th><th>Category</th><th>Description</th><th>Function</th></tr></thead><tbody><tr><td>Oil bodies</td><td>Binary</td><td>Unique to liverworts, these are true membrane-bound organelles that contain terpenoid oils suspended in a carbohydrate and/or protein-rich matrix. Ninety percent of liverworts develop them.</td><td>Thought to deter herbivores or provide protection from cold and/or UV radiation (He et al. 2013).</td></tr><tr><td>Ocelli</td><td>Binary</td><td>Specialized leaf cells that contain one larger-than-usual oil body and lack chloroplasts.</td><td>Like oil bodies, these are thought to deter herbivores or provide protection from cold and/or UV radiation (He et al. 2013).</td></tr><tr><td>Lobule</td><td>Binary</td><td>Smaller lobes of a complicated-bilobed leaf or a sac formed by an enrolled rear leaf margin (Malcolm and Malcolm 2000).</td><td>Lobules have long been interpreted as water sacs allowing the plant to remain physiologically active when the colonies are subjected to persistent desiccating conditions.</td></tr><tr><td>Leaf surface papillae</td><td>Binary</td><td>A minute, solid protuberance on a cell surface. Developed in some liverwort species.</td><td>These are thought to increase and maintain water uptake. By creating capillary channels on the leaf surface they appear to aid in retaining water and protecting regions of active cell division from dehydration (Proctor 2008).</td></tr><tr><td>Trigones</td><td>Binary</td><td>Wall thickenings where three adjacent cells meet.</td><td>The presence of trigones seems to be a xerophytic adaptation in liverworts (Watson 1914).</td></tr><tr><td>Underleaves</td><td>Binary</td><td>Leaves on ventral stem surfaces.</td><td>Their presence against the stem could favor the storage of intercepted water through capillarity in order to keep the plant moist and photosynthetically active (Ah-Peng et al. 2017).</td></tr><tr><td rowspan="5">Size related traits</td><td rowspan="5">Continuous</td><td>Gametophyte length</td><td rowspan="5">These traits appear to be related to growth and nutrient retention (Proctor and Tuba 2002).</td></tr><tr><td>Gametophyte width</td></tr><tr><td>Stem diameter</td></tr><tr><td>Leaf length</td></tr><tr><td>Leaf width</td></tr><tr><td></td><td></td><td>Elongation index (gametophyte length/width ratio)</td><td></td></tr></tbody></table>

an ideal site for examining trait filtering across elevations. The rugged topography of the massif creates diverse habitats that transition quickly with changes in altitude. The moist evergreen forests occurring at lower elevations gradually transition at about 1200 m into montane cloud forest, marked by its lower canopy and more dense understory and, finally, a forest line occurs around 1800 m and ericoid montane thickets occur to the peak at 2132 m. Rainfall is abundant, and almost no dry season has been recorded on the eastern slope of the massif. Across this slope, average annual temperatures range from 14.9 to 21.8°C, with relative humidity consistently high, averaging between 94.8% and 98.9% throughout the year (Marline et al. 2023).

## Sampling design and data collection

Bryophytes were collected along an elevational transect at 200 m intervals from 250 to 2050 m and following the hierarchical sampling method described in Ah-Peng et al. (2007) and Marline (2018). At each elevation, two plots of 10 × 10 m were established. Within each plot, three quadrats of 2 × 2 m were selected randomly. In each quadrat, three trees were randomly chosen, and 5 × 10 cm epiphytic bryophyte samples (microplots) were collected

at three heights: 0–50 cm, 50–100 cm, and 100–200 cm above ground level.

Temperature and relative humidity were monitored using MadgeTech RHTemp1000 data loggers, installed at five elevations (450, 850, 1250, 1650, and 2050 m) in December 2013. These loggers recorded temperature and humidity continuously at hourly intervals from December 2013 to December 2014. To estimate temperature and relative humidity at locations without data loggers, a calibration curve based on elevation was applied. For each elevation, vapor pressure deficit (VPD) was calculated as the difference between saturated vapor pressure (SVP) and actual vapor pressure (VP) following Monteith and Unsworth (2013). Minimum and maximum canopy height were also recorded at each site. A summary of the environmental variables, including temperature, relative humidity, vapor pressure deficit, and canopy height across elevations, is presented in Supplementary material 1.

For the species found on the transect, we compiled data on 12 morphological traits (Table 1) that are likely to be related to resource use, life history, species defense, resistance to desiccation, and photosynthetic activity, and could be obtained for at least 95% of the collected taxa. Trait values for each taxon were collected from the literature or by direct measurements on herbarium specimens.
## Data analyses

Two multidimensional indices, functional evenness (FEve) and functional dispersion (FDis), were used to characterize functional diversity, following the framework proposed by (Botta-Dukát 2005; Mason et al. 2005; Villéger et al. 2008; Laliberté and Legendre 2010). FEve, a measure of the evenness of species abundance distributions in functional trait space (Mason et al. 2005; Villéger et al. 2008) reflects the degree to which a community can effectively utilize the entire range of resources available to it. FDis measures the weighted (by relative abundance) mean distance of individual species to their weighted community centroid and describes the functional similarity of species in a community in trait space. Its variation across species indicates the degree of functional redundancy, typically measured across multiple traits, among species within a given spatial scale (Laliberté and Legendre 2010).

We used linear regressions to evaluate the relationship between functional diversity indices and species richness across altitudes.

To investigate potential functional responses underlying the process of community assembly along the elevational gradient, we measured the community-weighted means (CWM) and community-weighted variances (CWV) for each trait along the elevational transect. The CWM for each trait is the mean across species present in the community weighted by their relative abundance (Violle et al. 2007; Bernard-Verdier et al. 2012), in this case the frequency of species occurrence across the smallest sampling units (microhabitat). Similarly, CWVᵢ is calculated following Bernard-Verdier et al. (2012) and Sonnier et al. (2010). For binary traits, CWMᵢ estimates the total frequency of species sharing the attribute, and CWVᵢ estimates the variance in this frequency.

A null model approach was used to test whether the observed trait metrics differ from random expectation. Species abundances were randomized across elevations in order to divide existing relationships between trait values and species abundance. Random assemblages were constrained to observed species richness per elevation. Weighted community traits were computed at each iteration, and the 2.5th and 97.5th percentiles were obtained from the null distribution to produce null confidence intervals across the elevation gradient.

Comparing the estimated CWM and CWV values to expectations from randomized data allows detection of significant functional structuring in observed patterns. Higher values of CWM compared to random simulations indicate higher trait values at the community level, or higher frequency of species with a given attribute for binary traits. Conversely, values lower than expected provide evidence of ecological filtering towards high or low trait values (Hulshof and Swenson 2010; Bernard-Verdier et al. 2012), analogous to directional selection in evolution. Compared to random expectations, higher CWV values indicate significantly high variability in trait

values or, for binary traits, high variability in frequency among species sharing similar attributes. Conversely, lower CWV values suggest reduced variability. Such patterns reflect ecological convergence/divergence for the considered traits and, indirectly, are evidence of competition or ecological filtering (Hulshof and Swenson 2010; Kang et al. 2017).

In order to understand the possible drivers of community functional traits, we built statistical models that relate either elevation only, or a combination of elevation and other environmental variables to each functional diversity measure and CWM. A multiple general linear model was used to select the best combinations of environmental variables associated with community functional composition. For the sake of simplicity, we restrict the analyses to metrics related to average functional composition (CWM) and not variability (CWV). AIC scores were compared among three model types: linear, cubic, and quadratic polynomial, to determine the best fit. The model with the lowest AIC score and highest R² value was taken as best explaining the relationship between the observed CWM trait values and environmental variables. CWM for binary traits was logit-transformed prior to analysis, allowing the consideration of models in a classical Gaussian framework for all response variables.

All analyses were conducted with the statistical software R v.2024.12. (R Core Team 2024) and the packages ade4 v.1.7-23 (Dray 2016), permute v.0.9-7 (Simpson 2016), vegan v.2.6-10 (Oksanen et al. 2015), and FD v.1.0-12.3 (Laliberté and Legendre 2010; Laliberté et al. 2015).

# RESULTS

## Elevational pattern of floristic and functional diversity

The epiphytic leafy liverwort flora along the altitudinal transect comprises 149 species, distributed among 44 genera and 18 families (Supplementary material 2). Lejeuneaceae are the most species-rich family and comprise nearly half of the total species diversity (70 species in 19 genera). Species richness peaks at 1250 m (69 species) and lowest species richness was found at 650 m (19 species) and 2050 m (19 species).

FEve shows a significant increase with altitude (R² = 0.405, p < 0.05), as does FDis (R² = 0.632, p < 0.01) (Fig. 1). Neither of the two functional diversity indices shows a significant relationship with species richness (Fig. 2).

## Variation in community means of traits along the elevational gradient

Community weighted means (CWM) for size-related traits (i.e. leaf length, leaf width, gametophyte length, gametophyte width, and stem diameter), as well as for papillae and trigone presence increase significantly with increasing elevation. CWMs for lobule, ocelli, and oil
<table><caption>**Table 2.** AIC for models of CWM. Cubic elevation models were retained only for papillae and trigone presence. Multiple general linear model analysis was performed to select multiple combinations of environmental variables that could predict CWM with the lowest Akaike Information Criteria (AIC). R² is shown for models with climate variables AIClin (linear model), AICquad (quadratic polynomial model), and AICcub (cubic model). Est.: estimate; Std.Err.: standard error; T: T-statistic; * p value < 0.05, ** p value < 0.01, *** p value < 0.001, ns not significant.</caption><thead><tr><th>Traits</th><th>AICclin</th><th>AICquad</th><th>AICcub</th><th>R<sup>2</sup></th><th>adjusted.R<sup>2</sup></th><th>Est.</th><th>Std.Err.</th><th>T</th><th>p</th></tr></thead><tbody><tr><td>Leaf length</td><td>-10.95</td><td>-9.54</td><td>-10.48</td><td>0.9</td><td>0.89</td><td>0.000524</td><td>6.38E-05</td><td>8.2</td><td>***</td></tr><tr><td>Leaf width</td><td>-11.24</td><td>-9.57</td><td>-8.57</td><td>0.73</td><td>0.7</td><td>0.000259</td><td>6.29E-05</td><td>4.12</td><td>**</td></tr><tr><td>Papillae presence</td><td>12.16</td><td>13.22</td><td>14.05</td><td>0.57</td><td>0.52</td><td>0.000631</td><td>0.000203</td><td>3.12</td><td>*</td></tr><tr><td>Gametophyte length</td><td>69.11</td><td>70.73</td><td>71.07</td><td>0.92</td><td>0.88</td><td>0.0166</td><td>0.00349</td><td>4.74</td><td>**</td></tr><tr><td>Gametophyte width</td><td>1.73</td><td>3.61</td><td>3.64</td><td>0.77</td><td>0.74</td><td>0.000607</td><td>0.00012</td><td>5.04</td><td>***</td></tr><tr><td>Elongation index</td><td>73.05</td><td>60.66</td><td>60.4</td><td>0.7</td><td>0.61</td><td>0.0445</td><td>0.0103</td><td>4.31</td><td>**</td></tr><tr><td>Stem diameter</td><td>-42.12</td><td>-42.5</td><td>-42.49</td><td>0.75</td><td>0.72</td><td>6.49E-05</td><td>1.34E-05</td><td>4.83</td><td>**</td></tr><tr><td>Underleaf presence</td><td>6.12</td><td>6.96</td><td>8.45</td><td>0.5</td><td>0.35</td><td>0.000167</td><td>0.00015</td><td>1.11</td><td>ns</td></tr><tr><td>Lobule presence</td><td>23.48</td><td>16.24</td><td>18.24</td><td>0.74</td><td>0.7</td><td>-0.00511</td><td>0.00112</td><td>-4.57</td><td>**</td></tr><tr><td>Trigone presence</td><td>19.94</td><td>20.62</td><td>20.69</td><td>0.87</td><td>0.85</td><td>0.00158</td><td>0.000299</td><td>5.28</td><td>***</td></tr><tr><td>Ocelli presence</td><td>10.88</td><td>8.73</td><td>10.08</td><td>0.7</td><td>0.66</td><td>-0.00221</td><td>0.000769</td><td>-2.88</td><td>*</td></tr><tr><td>Oil body presence</td><td>20.49</td><td>22.26</td><td>20.41</td><td>0.5</td><td>0.44</td><td>-0.00081</td><td>0.000307</td><td>-2.64</td><td>*</td></tr></tbody></table>

<figure><img src="image_6.png" /><figcaption>**Figure 1.** Pattern of functional diversity metrics with elevation. **A.** Functional evenness. **B.** Functional dispersion. R² value from a linear regression. * p value < 0.05, ** p value < 0.01. Note that vertical axes start above 0.</figcaption></figure>

body presence decrease significantly with elevation (Fig. 3, Table 2). CWM for underleaf presence did not show a significant relationship with elevation. A hump-shaped relationship with elevation was found for the elongation index (Fig. 3, Table 2).

Considering the intraspecific variability did not improve these relationships except for lobule presence and trigone presence, where the trigone presence decreases with increasing elevation and lobule presence increases with increasing elevation (Fig. 3). The traits showing the strongest relationships with environmental variables are leaf length (R² = 0.9, p < 0.001), gametophyte length (R² =

0.92, p < 0.001) and trigone presence (R² = 0.87, p < 0.001) (Table 2).

## Effect of environmental variables on community trait means

Leaf length, leaf width, gametophyte length, gametophyte width, papillae presence, and trigone presence exhibited significant negative correlations with mean canopy height (cmea). Conversely, oil body presence showed a significant positive correlation with cmea. Stem diameter and underleaf presence were negatively correlated with the mean temperature (temp.m), whilst lobule and
<table><caption>**Table 3.** Regression coefficients for linear models of CWM with environmental variables. cmea = mean canopy height, vpd = vapor pressure deficit, temp.m = mean temperature, rh.m = mean relative humidity. (.) p value < 0.1, * p value < 0.05, ** p value < 0.01, *** p value < 0.001, ns not significant.</caption><thead><tr><th>Traits</th><th></th><th>Est.</th><th>Std.Err</th><th>T</th><th>p</th></tr></thead><tbody><tr><td>Leaf length</td><td>cmea</td><td>-4.08E-02</td><td>0.00471</td><td>-8.65</td><td>***</td></tr><tr><td>Leaf width</td><td>cmea</td><td>-2.08E-02</td><td>0.00446</td><td>-4.67</td><td>**</td></tr><tr><td>Papillae presence</td><td>cmea</td><td>-4.99E-02</td><td>0.01532</td><td>-3.26</td><td>*</td></tr><tr><td rowspan="3">Gametophyte length</td><td>cmea</td><td>-1.73E+00</td><td>0.22753</td><td>-7.61</td><td>***</td></tr><tr><td>rh.m</td><td>1.47E+01</td><td>6.07085</td><td>2.42</td><td>.</td></tr><tr><td>I(vpd<sup>2</sup>)</td><td>3.96E-03</td><td>0.00187</td><td>2.12</td><td>.</td></tr><tr><td>Gametophyte width</td><td>cmea</td><td>-4.73E-02</td><td>0.00916</td><td>-5.16</td><td>***</td></tr><tr><td rowspan="2">Elongation index</td><td>I(vpd<sup>2</sup>)</td><td>-5.53E-03</td><td>0.00218</td><td>-2.54</td><td>*</td></tr><tr><td>rh.m</td><td>-1.60E+01</td><td>7.04997</td><td>-2.26</td><td>.</td></tr><tr><td>Stem diameter</td><td>temp.m</td><td>-1.69E-02</td><td>0.00341</td><td>-4.96</td><td>**</td></tr><tr><td rowspan="2">Underleaf presence</td><td>I(temp.m<sup>2</sup>)</td><td>-2.46E-03</td><td>0.00096</td><td>-2.57</td><td>*</td></tr><tr><td>I(vpd<sup>2</sup>)</td><td>-1.82E-05</td><td>1E-05</td><td>-1.81</td><td>ns</td></tr><tr><td>Lobule presence</td><td>I(temp.m<sup>2</sup>)</td><td>1.07E-02</td><td>0.00227</td><td>4.72</td><td>**</td></tr><tr><td>Trigone presence</td><td>cmea</td><td>-1.29E-01</td><td>0.01803</td><td>-7.17</td><td>***</td></tr><tr><td>Ocelli presence</td><td>I(temp.m<sup>2</sup>)</td><td>5.38E-03</td><td>0.00125</td><td>4.29</td><td>**</td></tr><tr><td>Oil body presence</td><td>cmea</td><td>6.51E-02</td><td>0.02307</td><td>2.82</td><td>***</td></tr></tbody></table>

<figure><img src="image_7.png" /><figcaption>**Figure 2.** Linear regression between functional diversity measures and species richness. A. Functional evenness. B. Functional dispersion. R² value from a linear regression and 95% confidence level.</figcaption></figure>

ocelli presence exhibited significant positive correlation with this variable. Only the elongation index showed a significant correlation with vapor pressure deficit (vpd) and a weak correlation with relative humidity (rh.m) (Table 3). This indicates that a high percentage of variation in these traits is explained by the corresponding environmental variables.

## Trait filtering along the elevational gradient

Trait filtering is indicated when the mean value of a trait within a community deviates from null expectations.

This occurs when certain environmental conditions at a given elevation selectively favour species with specific traits, causing the community's trait composition to diverge from what would be expected under random assembly. All traits that we studied, with the exception of the presence/absence of underleaf and ocelli, exhibited departures from the null model at at least one elevational band (Fig. 4). Filtering for lobule absence is evident at 1250–1650 m and oil body presence at 1250–1650 m, and at lower elevation for low values of stem diameter (250–850 m) and gametophyte width (250 m, 560–850 m).
<figure><img src="image_8.png" /><figcaption>**Figure 3.** Distribution of community-weighted means (CWM) of traits (black dots) along the elevational gradient and values estimated by linear models from climatic variables (grey squares). Vertical lines indicate the 95% confidence interval for modeled values.</figcaption></figure>
<figure><img src="image_9.png" /><figcaption>**Figure 4.** Distribution of community-weighted means (CWM) of traits (black dots) along the elevational gradient. Envelope (grey) shows the 95% confidence interval under the null model of random community assembly. Diamonds (grey) indicate values estimated by linear models against elevation with 95% confidence interval.</figcaption></figure>
<figure><img src="image_10.png" /><figcaption>**Figure 5.** Distribution of community-weighted variances (CWV) of traits (black dots) along the elevational gradient. The envelope (grey) shows the 95% confidence interval under the null model of random community assembly.</figcaption></figure>
m). Observed values of community-weighted means (CWM) were higher than expected at higher elevation for leaf length (1250–2050 m), leaf width (1650–1850 m), gametophyte length (1250–2050 m), gametophyte width (1650–1850 m), stem diameter (1250–1650 m), papillae presence (1450–2050 m), and trigone presence (1250–2050 m). Only the elongation index at mid elevation showed significant deviation above the null model.

## Trait divergence along the elevational gradient

Community weighted variances (CWV) for all traits except gametophyte width and stem diameter also departed significantly from those expected under a null model at least at some elevations. Thus, leaf length (1650–1850 m), leaf width (450 m), papillae presence (1420–2050 m), elongation index (450–1250 m), gametophyte length (1250–1650 m and 2050 m), ocelli presence (250 m), and oil body presence (1250–1650 m) were more variable than expected, indicating that those traits have scattered distributions within communities. This means that abundant species tend to exhibit dissimilar functional trait values in communitites along the elevational gradient. By contrast, trait convergence, indicated by lower-than-random CWV values, is detected at 850–1250 m for underleaf presence, 1250–2050 m for trigone presence, and 250–850 m for lobule presence (Fig. 5).

## DISCUSSION

Patterns and changes in the range and distribution of functional trait values in a community provide information on spatial and temporal variation in trait diversity, as well as on processes that drive species assemblages and whether such assemblages are likely to contain redundant species (Tilman 2001). Neither community-weighted means (CWM) of trait values nor functional trait diversity metrics have often been incorporated in assessments of ecosystem services, but to better understand species interaction and community assembly they have recently been incorporated in biodiversity experiments (Holden and Cahill 2024; Palacio et al. 2024).

The trait-based analyses presented here show that (1) functional evenness and functional dispersion increase significantly with elevation, (2) the pattern of distribution and variance of traits within communities along the elevational gradient are dependent on the nature of the considered traits, (3) canopy height and temperature are the most powerful environmental variables shaping the pattern of CWM distribution, and (4) habitat filtering and niche differentiation both explained observed species abundance in communities; habitat filtering (associated with trait convergence) is strongest at lower elevations and niche differentiation (associated with trait divergence) occurs at higher elevation and is highest at the most species-rich sites.

## Functional evenness, functional dispersion, and floristic composition

Much attention has been focused on the use of functional traits, and their abundance and distribution in communities, in the exploration of relationships between biodiversity and ecosystem functioning (Halpern and Floeter 2008; Cadotte et al. 2009; Mouillot et al. 2011; Roscher et al. 2012; Correia and Lopes 2023). The positive relationship between functional evenness and elevation found here suggests a more regular functional distance among species as elevation increases (Villéger et al. 2008). The fact that more individuals of the common species are recorded as elevation increases suggests that liverwort functional traits are not evenly distributed along the elevational gradient. Functional dispersion quantifies the extent of functional similarity among species in the trait space. The increase in functional dispersion with elevation indicates low redundancy in the liverwort community. This is consistent with the idea that new species added at each elevation are less similar than the existing species and reflects dissimilar functional traits across abundant species (Karadimou et al. 2015; Ferrara et al. 2024).

## Trait variation at different ecological scales

A main goal of this work was to determine which environmental factor(s) influence the variation and distribution of CWM of liverworts traits across the elevational gradient. This study suggests that canopy height and temperature are the most powerful environmental variables shaping the pattern of trait distributions. Relative humidity and vapor pressure deficit, on the other hand, have a weaker effect on trait variation and distribution among communities.

The leafy liverwort communities showed a clear functional response along the elevational gradient, as demonstrated by the observed clear pattern in community-weighted means for nine of the 12 traits (Fig. 3). The abundance-distribution of all traits related to plant size significantly increased with elevation, indicating that at high elevation there is more variation in plant size (Henriques et al. 2017). Papillae and trigone presence are thought to be related to water retention and xerophytic adaptation respectively. Papillae may facilitate water uptake by creating capillary spaces (Proctor 1979), whilst elongated cells with trigones enhance water uptake from the surrounding environment (Vitt et al. 2014). This study shows that the abundance of species with those traits also increases significantly with elevation, potentially as a response to the more challenging environmental conditions at elevations higher than 1800 m. Lobules are often referred to as water sacs and, like papillae and trigones, an increasing CWM for lobule presence would have been expected. However, its CWMs were negatively related to increasing elevation. A similar result was found for ocelli presence, although the functional role of this feature is yet to be elucidated. Since the lobules and ocelli are characteristic of Lejeuneaceae, this pattern
can be related to the fact that the Lejeuneaceae are most
abundant at lower and mid-elevations.

Habitat filtering and niche differentiation

Both habitat filtering and niche differentiation appear
to be involved in structuring species abundances in the
communities studied here. Our results add to the growing
body of evidence for the joint effect of these two processes
on community structure (Cornwell and Ackerly 2009;
Jung et al. 2010; Mason et al. 2011; Maire et al. 2012).

In the system studied herein, trait filtering appears to
occur toward both ends of the elevational gradient. This
is in line with hypothesised (Mayfield and Levine 2010)
ecological filtering at the extremities of environmental
gradients. According to Bernard-Verdier et al. (2012), this
is due to the differential filtering of dissimilar traits along
a gradient. The detection of ecological filtering is critically
dependent on the studied trait. Different traits, related to
various functional roles, exhibited filtering at different
parts of the elevational gradient. At low elevation, where
diversity is lower, the range of traits directly linked to
growth and nutrient acquisition (gametophyte and leaf
size) exhibits filtering (Herben and Goldberg 2014). This
can be related to competition for light, given the fact
that at low elevations in a tropical forest the canopy is
continuous, and the canopy height is the greatest. This may
account for the abundance of small and narrow species at
these elevations. At low elevations, for instance, the most
abundant species include: *Bazzania nitida* (F.Weber)
Grolle, *Ceratolejeunea papuliflora* Steph., *Cololejeunea
appressa* (A.Evans) Benedix, *Lejeunea abyssinica* (Gola)
Cufod., and *Prionolejeunea grata* (Gottsche) Schiffn.

None of the studied traits, except for lobule and oil
body presence, were specifically filtered at mid-elevation,
suggesting that these provide the most favorable habitats
for epiphytic liverworts. Nearly all liverworts, except
complex thalloid species, possess oil bodies, their
filtering at mid-elevations is unexpected and suggests an
ecological or physiological constraint. This pattern may
result from environmental factors and selective pressure,
leading to a shift in survival strategies. Understanding this
anomaly may require further understanding and study
of the functional role of oil bodies for liverworts and
the selective pressures shaping their distribution along
elevational gradients.

Interestingly, at mid-elevations trait variation is either
randomly distributed or divergent (elongation index
only) due perhaps to the relaxation of environmental
constraints allowing for the coexistence of a wide range
of functional strategies and therefore a peak of diversity at
the center of the gradient. Trait range reduction detected
at mid-elevation suggests that trait filtering may also occur
in more stable habitats (Bernard-Verdier et al. 2012).

Towards higher elevations, leaf length, leaf width, and
gametophyte length tend to be divergent in communities.
This suggests that traits related to plant size coexist
successfully, and species are less similar to each other

(Funk et al. 2008). This trend can be explained by the
wide range in size exhibited by the most abundant species.
Tall liverwort species such as *Herbertus dicranus* (Taylor
ex Gottsche et al.) Trevis, *Mastigophora diclados* (Brid. ex
F.Weber) Nees, and *Conoscyphus trapezioides* (Sande Lac.)
Mitt. ex Schiffn. are about as abundant as small species
such as *Drepanolejeunea physaefolia* (Gottsche) Steph. at
higher elevations.

The divergence in leaf length, leaf width, gametophyte
length, papillae presence, elongation index, and oil body
presence provide strong evidence of niche differentiation,
although mechanisms such as limiting similarity or
facilitation cannot be inferred here.

CONCLUSION

This study provides evidence that assemblage of the
epiphytic liverwort community on a massif in the wet
tropical north of Madagascar is driven by variation in
climatic conditions and vegetation structure, affecting the
occurrence of species among and within communities. It
demonstrates that traits tend to shift from convergent to
divergent with increasing elevation. Higher temperature
and taller vegetation appear to have driven a strong
functional convergence of size-related traits (except
for leaf width) at lower elevations but have allowed for
divergence in these at higher elevations.

This is the first study to investigate bryophyte
functional trait variation along an elevational gradient
in Madagascar. Only morphological traits potentially
related to resource use, life history, species defense,
resistance to desiccation, and photosynthetic activity
were studied. However, other physiological traits related
to features such as photosynthetic capacity and carbon
fixation, superimposed on phylogenetic relatedness,
need to be considered for further study and for a better
understanding of the relationship between species
composition and ecosystem processes in this ecologically
important but grossly understudied plant group.

ACKNOWLEDGEMENTS

This paper is part of the first author's PhD project, which
was funded by the Organization for Women in Science
from Developing Countries (OWSD). We are grateful
for the comments of Steve Goodman on this manuscript,
conducted in the context of the Fulbright U.S. Scholar for
Madagascar in 2023-2024. The authors also acknowledge
financial support from the BRYOLAT project (French
Foundation for Research in Biodiversity), FEDER
POE 3.21, MOVECLIM (ANR Net Biome), and the
International Foundation for Sciences (Grant number:
IFS-3388F589). The second author would like to thank
the project Biodiversa BioMonI, Biodiversity monitoring
of island ecosystems (ANR-23-EBIP-0009-05) for
support. We thank Ministère de l'Environnement et
du Développement Durable for issuing the necessary
collecting permits (No. 253/09/MEF/SG/DGF/DCBSAP/
SLRSE) and Madagascar National Park for granting us permission to conduct research in the Marojejy Park. Additionally, we are grateful to the assistance of the BRYOLAT team, including Roger Lala Andriamiarisoa, Nicholas Wilding, Min Chuah Petiot, Jacques Bardat, and Jurgen Kluge, as well as Lanto Andriamanantena from DUKE Lemur SAVA, during the fieldwork.

REFERENCES

Ah-Peng C, Chuah-Petiot M, Descamps-Julien B, Bardat J, Staménoff P, Strasberg D (2007) Bryophyte diversity and distribution along an altitudinal gradient on a lava flow in La Réunion. Diversity and Distributions 13: 654–662. https://doi.org/10.1111/j.1472-4642.2007.00393.x

Ah-Peng C, Cardoso AW, Flores O, West A, Wilding N, Strasberg D, Hedderson TAJ (2017) The role of epiphytic bryophytes in interception, storage, and the regulated release of atmospheric moisture in a tropical montane cloud forest. Journal of Hydrology 548: 665–673. https://doi.org/10.1016/j.jhydrol.2017.03.043

Baldeck CA, Harms KE, Yavitt JB, John R, Turner BL, Valencia R, Navarrete H, Bunyavejchewin S, Kiratiprayoon S, Yaacob A, Supardi MNN, Davies SJ, Hubbell SP, Chuyong GB, Kenfack D, Thomas DW, Dalling JW (2013) Habitat filtering across tree life stages in tropical forest communities. Proceedings of the Royal Society of London B: Biological Sciences 280: 20130548. https://doi.org/10.1098/rspb.2013.0548

Bergamini A, Unghricht S, Hofmann H (2009) An elevational shift of cryophilous bryophytes in the last century – an effect of climate warming? Diversity and Distributions 15: 871–879. https://doi.org/10.1111/j.1472-4642.2009.00595.x

Bernard-Verdier M, Navas M-L, Vellend M, Violle C, Fayolle A, Garnier E (2012) Community assembly along a soil depth gradient: contrasting patterns of plant trait convergence and divergence in a Mediterranean rangeland. Journal of Ecology 100: 1422–1433. https://doi.org/10.1111/1365-2745.12003

Botta-Dukát Z (2005) Rao's quadratic entropy as a measure of functional diversity based on multiple traits. Journal of Vegetation Science 16: 533–540. https://doi.org/10.1658/1100-9233(2005)16[533:RQEAAM]2.0.CO;2

Cadotte MW, Carscadden K, Mirotnick N (2011) Beyond species: functional diversity and the maintenance of ecological processes and services. Journal of Applied Ecology 48: 1079–1087. https://doi.org/10.1111/j.1365-2664.2011.02048.x

Cadotte MW, Cavender-Bares J, Tilman D, Oakley TH, Tackenberg O (2009) Using phylogenetic, functional and trait diversity to understand patterns of plant community productivity. PLoS ONE 4: e5695. https://doi.org/10.1371/journal.pone.0005695

Correia AM, Lopes LF (2023) Revisiting biodiversity and ecosystem functioning through the lens of complex adaptive systems. Diversity 15: 895. https://doi.org/10.3390/d15080895

Cornwell WK, Ackerly DD (2009) Community assembly and shifts in plant trait distributions across an environmental gradient in coastal California. Ecological Monographs 79: 109–126. https://doi.org/10.1890/07-1134.1

Cornwell WK, Schwilk DW, Ackerly DD (2006) A trait-based test for habitat filtering: convex hull volume. Ecology 87: 1465–1471. https://doi.org/10.1890/0012-9658(2006)87[1465:ATTFHF]2.0.CO;2

Davies TJ, Meiri S, Barraclough TG, Gittleman JL (2007) Species co-existence and character divergence across carnivores. Ecology Letters 10: 146–152. https://doi.org/10.1111/j.1461-0248.2006.01005.x

Díaz S, Lavorel S, de Bello F, Quétier F, Grigulis K, Robson TM (2007) Incorporating plant functional diversity effects in ecosystem service assessments. PNAS 104: 20684–20689. https://doi.org/10.1073/pnas.0704716104

Dray S (2016) Package “ade4” analysis of ecological data: exploratory and euclidean methods in environmental science. https://doi.org/10.32614/CRAN/package.ade4

Ferrara A, Bricca A, Alberti D, Sabatini FM, Chiarucci A (2024) Elevation differentially shapes functional diversity patterns in understorey forest communities when considering intraspecific and interspecific trait variability. Journal of Vegetation Science 35: e13277. https://doi.org/10.1111/jvs.13277

Funk JL, Cleland EE, Suding KN, Zavaleta ES (2008) Restoration through reassembly: plant traits and invasion resistance. Trends in Ecology & Evolution 23: 695–703. https://doi.org/10.1016/j.tree.2008.07.013

Gehrig-Downie C, Obregón A, Bendix J, Gradstein SR (2011) Epiphyte biomass and canopy microclimate in the tropical lowland cloud forest of French Guiana. Biotropica 43: 591–596. http://doi.org/10.1111/j.1744-7429.2010.00745.x

Gignac LD (2001) Bryophytes as indicators of climate change. The Bryologist 104: 410–420. https://doi.org/10.1639/0007-2745(2001)104[0410:BAIOCC]2.0.CO;2

Govindapyari H, Leleeka M, Nivedita M, Uniyal P (2010) Bryophytes: indicators and monitoring agents of pollution. NeBIO 1: 35–41.

Gradstein SR, Pócs T (1989) Bryophytes. In: Lieth H, Werger MJA (Eds) Tropical Rainforest Ecosystems. Elsevier, Amsterdam, 311–325. https://doi.org/10.1016/B978-0-444-42755-7.50022-5

Grime JP (2006) Trait convergence and trait divergence in herbaceous plant communities: mechanisms and consequences. Journal of Vegetation Science 17: 255–260. https://doi.org/10.1111/j.1654-1103.2006.tb02444.x

Gross N, Börger L, Duncan RP, Hulme PE (2013) Functional differences between alien and native species: do biotic interactions determine the functional structure of highly invaded grasslands? Functional Ecology 27: 1262–1272. https://doi.org/10.1111/1365-2435.12120

Halpern BS, Floeter SR (2008) Functional diversity responses to changing species richness in reef fish communities. Marine Ecology Progress Series 364: 147–156. https://doi.org/10.3354/meps07553

He X, Sun Y, Zhu R-L (2013) The oil bodies of liverworts: unique and important organelles in land plants. Critical Reviews in Plant Sciences 32: 293–302. https://doi.org/10.1080/07352689.2013.765765

Henriques DSG, Rigal F, Borges PAV, Ah-Peng C, Gabriel R (2017) Functional diversity and composition of bryophyte water-related traits in Azorean native vegetation. Plant Ecology & Diversity 10: 127–137. https://doi.org/10.1080/17550874.2017.1315839

Herben T, Goldberg DE (2014) Community assembly by limiting similarity vs. competitive hierarchies: testing the consequences of dispersion of individual traits. Journal of Ecology 102: 156–166. https://doi.org/10.1111/1365-2745.12181

Hinz H, Törnroos A, de Juan S (2021) Trait-based indices to assess benthic vulnerability to trawling and model loss of ecosystem functions. Ecological Indicators 126: 107692. https://doi.org/10.1016/j.ecolind.2021.107692

Holden EM, Cahill Jr JF (2024) Plant trait dissimilarity increases competitive interactions among co-occurring plants. Functional Ecology 38: 1464–1474. https://doi.org/10.1111/1365-2435.14561

Holz I, Gradstein RS (2005) Cryptogamic epiphytes in primary and recovering upper montane oak forests of Costa Rica - species richness, community composition and ecology. Plant
Ecology 178: 89–109. https://doi.org/10.1007/s11258-004-2496-5

Hulshof CM, Swenson NG (2010) Variation in leaf functional trait values within and across individuals and species: an example from a Costa Rican dry forest. Functional Ecology 24: 217–223. https://doi.org/10.1111/j.1365-2435.2009.01614.x

Jung V, Violle C, Mondy C, Hoffmann L, Muller S (2010) Intraspecific variability and trait-based community assembly. Journal of Ecology 98: 1134–1140. https://doi.org/10.1111/j.1365-2745.2010.01687.x

Kang S, Niu J, Zhang Q, Li D, Ren H, Ren J, Zhang X, Dong J (2017) Environmental filtering does not necessarily prevent trait divergence: a case study of the Xilin River Basin in Inner Mongolia, China. Journal of Plant Ecology 10: 497–509. https://doi.org/10.1093/jpe/rtw050

Karadimou E, Tsiripidis I, Kallimanis AS, Raus T, Dimopoulos P (2015) Functional diversity reveals complex assembly processes on sea-born volcanic islands. Journal of Vegetation Science 26: 501–512. https://doi.org/10.1111/jvs.12255

Kraft NJB, Valencia R, Ackerly DD (2009) Functional traits and niche-based tree community assembly in an Amazonian forest. Science 322: 580–582. https://doi.org/10.1126/science.1160662

Laliberté E, Legendre P (2010) A distance-based framework for measuring functional diversity from multiple traits. Ecology 91: 299–305. https://doi.org/10.1890/08-2244.1

Laliberté E, Legendre P, Shipley B (2015) FD: measuring functional diversity from multiple traits, and other tools for functional ecology. R package version 1.0-12. https://doi.org/10.32614/CRAN/package.FD

Liu C, Li Y, Yan P, He N (2021) How to improve the predictions of plant functional traits on ecosystem functioning? Frontiers in Plant Science 12: 622260. https://doi.org/10.3389/fpls.2021.622260

Maire V, Gross N, Börger L, Proulx R, Wirth C, Pontes LS, Soussana J-F, Louault F (2012) Habitat filtering and niche differentiation jointly explain species relative abundance within grassland communities along fertility and disturbance gradients. New Phytologist 196: 497–509. https://doi.org/10.1111/j.1469-8137.2012.04287.x

Malcolm B, Malcolm N (2000) Moss and Other Bryophytes: an Illustrated Glossary. Micro-Optics Press, Nelson, 1–220.

Marline L (2018) Diversity and biogeography of Madagascan bryophytes with an analysis of taxic and functional diversity along an elevational gradient in Marojey National Park. PhD Thesis, University of Cape Town, South Africa. http://hdl.handle.net/11427/29263

Marline L, Randrianarimanana R, Patel ER (2023) Elevation variation of temperature and relative humidity on Marojey National Park, Madagascar. Malagasy Nature 17: 32–40.

Mason NWH, Mouillot D, Lee WG, Wilson JB (2005) Functional richness, functional evenness and functional divergence: the primary components of functional diversity. Oikos 111: 112–118. https://doi.org/10.1111/j.0030-1299.2005.13886.x

Mason NWH, de Bello F, Doležal J, Lepš J (2011) Niche overlap reveals the effects of competition, disturbance and contrasting assembly processes in experimental grassland communities. Journal of Ecology 99: 788–796. https://doi.org/10.1111/j.1365-2745.2011.01801.x

Mayfield MM, Levine JM (2010) Opposing effects of competitive exclusion on the phylogenetic structure of communities. Ecology Letters 13: 1085–1093. https://doi.org/10.1111/j.1461-0248.2010.01509.x

Montheith JL, Unsworth MH (2013) Principles of Environmental Physics. Fourth edition. Academic Press, Oxford, 1–401. https://doi.org/10.1016/C2010-0-66393-0

Mouillot D, Villéger S, Scherer-Lorenzen M, Mason NWH, Richers BT (2011) Functional structure of biological

communities predicts ecosystem multifunctionality. PLoS ONE 6: e17476. https://doi.org/10.1371/journal.pone.0017476

Muchura HM, Chuah-Petiot MS, Mworia JK, Gichuki NN (2014) Role of bryophytes and tree canopy in mist trapping in Mt. Marsabit forest. Journal of Environment and Earth Science 4: 128–138.

Oksanen J, Blanchet GF, Kindt R, Legendre P, Minchi PR, O'Hara RB, Simpson GL, Solymos P, Stevens MHM, Wagner H (2015) vegan: community ecology package. R package version 2.3-0. https://doi.org/10.32614/CRAN/package. vegan

Palacio FX, Ottaviani G, Mammola S, Graco-Roza C, de Bello F, Carmona CP (2024) Integrating intraspecific trait variability in functional diversity: an overview of methods and a guide for ecologists. Preprint, EcoEvoRxiv repository. https://doi.org/10.32942/X2B02G

Pardow A, Lakatos M (2013) Desiccation tolerance and global change: implications for tropical bryophytes in lowland forests. Biotropica 45: 27–36. https://doi.org/10.1111/j.1744-7429.2012.00884.x

Pardow A, Gehrig-Downie C, Gradstein R, Lakatos M (2012) Functional diversity of epiphytes in two tropical lowland rainforests, French Guiana: using bryophyte life-forms to detect areas of high biodiversity. Biodiversity and Conservation 21: 3637–3655. https://doi.org/10.1007/s10531-012-0386-z

Pócs T (1982) Tropical forest bryophytes. In: Smith AJE (Ed.) Bryophyte Ecology. Springer, Dordrecht, 59–105. https://doi.org/10.1007/978-94-009-5891-3_3

Proctor MCF (1979) Structure and eco-physiological adaptation in bryophytes. In: Clarke GCS, Duckett JG (Eds) Bryophyte Systematics. Academic Press, London, 479–509.

Proctor MCF (2008) Physiological ecology. In: Shaw AJ, Goffinet B (Eds) Bryophyte Biology. Cambridge University Press, Cambridge, 237–268. https://doi.org/10.1017/CBO9781139171304.009

Proctor MCF, Tuba Z (2002) Poikilohydray and homoihydray: antithesis or spectrum of possibilities? New Phytologist 156: 327–349. https://doi.org/10.1046/j.1469-8137.2002.00526.x

Proctor MCF, Oliver MJ, Wood AJ, Alpert P, Stark LR, Cleavitt NL, Mishler BD (2007) Desiccation-tolerance in bryophytes: a review. The Bryologist 110: 595–621. https://doi.org/10.1639/0007-2745(2007)110[595:DIBAR]2.0.CO;2

R Core Team (2024) R: a Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/[accessed 08.05.2025]

Roscher C, Schumacher J, Gubsch M, Lipowsky A, Weigelt A, Buchmann N, Schmid B, Schulze E-D (2012) Using plant functional traits to explain diversity-productivity relationships. PLoS ONE 7: e36760. https://doi.org/10.1371/journal.pone.0036760

Simpson GL (2016) permute: functions for generating restricted permutations of data. R package version 0.9-4. https://doi.org/10.32614/CRAN/package.permute

Sonnier G, Shipley B, Navas M-L (2010) Quantifying relationships between traits and explicitly measured gradients of stress and disturbance in early successional plant communities. Journal of Vegetation Science 21: 1014–1024. https://doi.org/10.1111/j.1654-1103.2010.01210.x

Swenson NG (2011) The role of evolutionary processes in producing biodiversity patterns, and the interrelationships between taxonomic, functional and phylogenetic biodiversity. American Journal of Botany 98: 472–480. https://doi.org/10.3732/ajb.1000289

Tilman D (2001) Functional diversity. Encyclopedia of Biodiversity 3: 109–120. https://doi.org/10.1016/B0-12-226865-2/00132-2
Villéger S, Mason NWH, Mouillot D (2008) New multidimensional functional diversity indices for a multifaceted framework in functional ecology. Ecology 89: 2290–2301. https://doi.org/10.1890/07-1206.1

Violle C, Navas M-L, Vile D, Kazakou E, Fortunel C, Hummel I, Garnier E (2007) Let the concept of trait be functional! Oikos 116: 882–892. https://doi.org/10.1111/j.2007.0030-1299.15559.x

Vitt DH, Crandall-Stotler BJ, Wood AJ (2014) Bryophytes: survival in a dry world through tolerance and avoidance. In: Rajakaruna N, Boyd RS, Harris TB (Eds) Plant Ecology

and Evolution in Harsh Environments. Nova Publishers, Hauppauge, New York, 267–295.

Watson W (1914) Xerophytic adaptations of bryophytes in relation to habitat. New Phytologist 13: 149–169. https://doi.org/10.1111/j.1469-8137.1914.tb05747.x

Wang N, Lv T, Wang L, Chen S, Xie L, Fang Y, Ding H (2024) Leaf functional traits and ecological strategies of common plant species in evergreen broad-leaved forests on Huangshan Mountain. Journal of Forestry Research 35: 130. https://doi.org/10.1007/s11676-024-01780-0

# SUPPLEMENTARY MATERIALS

## Supplementary material 1

Description of environmental conditions at each plot along the elevational gradient in the Marojejy National Park. https://doi.org/10.5091/plecevo.139573.suppl1

## Supplementary material 2

Checklist of epiphytic liverworts recorded along the elevational gradient transect in Marojejy National Park, indicating species occurrences at each elevation. https://doi.org/10.5091/plecevo.139573.suppl2