Determinants of fern and angiosperm herb community structure in lower montane rainforest in Indonesia

Abstract

Questions: Do ferns, which are physiologically less well adapted to conserve water than angiosperms but have more efficient propagule dispersal, show different vegetation-environment relationships than co-occurring angiosperm herbs? We hypothesized that ferns should show closer relationships to local environmental conditions and might be more closely associated with humid and shady microhabitats.Location: Pono and Bariri, two sites in lower montane primary tropical forest, Lore Lindu National Park, Central Sulawesi, Indonesia.Methods: At each site, all terrestrial herbaceous plants were sampled in 200 plots of 5 m 9 5 m. Sixteen environmental factors describing soils, topography and canopy openness were recorded. Correlations were calculated to test the degree of similarity in the species richness and turnover of ferns and angiosperms, and their relationships with environmental factors. Species optima were calculated on each environmental axis and compared between plant groups via randomization tests.Results: In total, 184 herb morphospecies were encountered at Pono and 135 at Bariri, of which almost 60% at each site were ferns. At both sites, fern species turnover showed closer correlations with soil variables than did angiosperm turnover. At the more topographically heterogeneous site (Bariri) fern species turnover was also more closely associated with topographic differences than was angiosperm turnover. Habitat preferences of ferns and angiosperms appeared more similar at Bariri than Pono, with both tending towards lower topographic positions and richer soils, but steeper slopes, than expected at random. At Bariri, neither plant group tended towards shady microsites, whereas at Pono ferns were better represented than angiosperms in microhabitats with open canopies.Conclusions: As expected, ferns showed closer correlations with environmental factors than angiosperm herbs. Ferns did not, however, consistently favour humid microhabitats at both sites, and were not significantly associated with shady microhabitats at either site. Furthermore, it appears that physiological differences in water use do not lead to marked divergence in fern and angiosperm herb distributions in the humid understorey of this lower montane rainforest.

Community assembly of the ferns of Florida

“…While these authors did not find direct evidence of physiological differences between the two groups, they did find that community composition and species turnover between sites was tied more closely to local environmental conditions for ferns than for flowering plants. This study and many others have also shown that ferns are very sensitive to soil traits (Karst et al., ; Zuquim et al., , ; Jones et al., , ; Tuomisto et al., ; Lehtonen et al., ), which can vary extensively over small spatial scales. If ferns are highly sensitive to local environmental and soil conditions, we might expect these abiotic factors to override competitive interactions in terms of importance at the local scale.…”

“…Jones et al. () reached this conclusion in a study of fern and angiosperm herb‐layer communities in Indonesia. While these authors did not find direct evidence of physiological differences between the two groups, they did find that community composition and species turnover between sites was tied more closely to local environmental conditions for ferns than for flowering plants.…”

Diversity and community composition of herbaceous plants in different habitat types in south‐east Cameroon

“…Herbaceous plants represent a significant proportion of the forest biodiversity, but they remain largely understudied despite their ecological relevance: they contribute to ecological processes, serve as ecological indicators of habitat quality and provide food and shelter for numerous wildlife species (reviewed in Ruben, Bolger, Peart, & Ayres, ; Wyatt & Silman, ; Jones, Cicuzza, van Straaten, Veldkamp, & Kessler, ; Willie, Tagg, Petre, Pereboom, & Lens, ). Studies on herbaceous plant abundance, distribution, diversity and composition in forest stands at different successional stages can inform biodiversity conservation policy and forest management practices (Allen, Platt, & Coker, ; Duffy & Meier, ; Fraser, Jentsch, & Sternberg, ; Willie, ; Wyatt & Silman, ).…”

“…Herbaceous plant species diversity and composition are affected by forest structure, tree species composition and topographic and environmental variables (Akhtar & Bergmeier, ; Berger & Puettmann, ; Ellum, Ashton, & Siccama, ; Jones et al., ; McKenzie, Halpern, & Nelson, ). In habitats such as light gaps, herbaceous plant species richness or density can be high due to a conducive environment (Qin et al., ; Willie, Petre, Tagg, & Lens, ).…”

“…Several herbaceous plant species may initially be present at early stages of succession but later display different successional dynamics due to idiosyncratic differences among species and habitat characteristics (Ohtsuka, Sakura, & Ohsawa, ). Abiotic factors and forest stand structure can have different effects on the herbaceous plant community development during various phases of the succession trajectory (Gilliam & Turrill, ), and some forest understorey herb species seem to be more sensitive to variations in ecological conditions than others (Jones et al., ; Qin et al., ). The species diversity and composition of herbaceous plant communities can therefore vary depending on habitat settings.…”