Different nitrogen acquirement and utilization strategies might determine the ecological competition between ferns and angiosperms

Abstract

Background and Aims The abundance or decline of fern populations in response to environmental change has been found to be largely dependent on specific physiological properties that distinguish ferns from angiosperms. Many studies have focused on water use efficiency and stomatal behaviors, but the effects of nutrition acquirement and utilization strategies on niche competition between ferns and flowering plants are rarely reported. Methods We collected 34 ferns and 42 angiosperms from the Botanic Garden of Hokkaido University for nitrogen (N), sulfur (S), NO3−, and SO42− analysis. We then used a hydroponic system to compare the different N and S utilization strategies between ferns and angiosperms in N deficiency conditions. Key Results Ferns had a significantly higher NO3 −-N concentration and NO3 −-N/N ratio than angiosperms, although the total N concentration in ferns was remarkably lower than in the angiosperms. Meanwhile, a positive correlation between N and S was found, indicating that nutrient concentration is involved in assimilation. Pteris cretica, a fern species subjected to further study, maintained a slow growth rate and lower N requirement in response to low N stress, while the biomass and N concentration in wheat (Triticum aestivum) both quickly responded to N deficiency conditions. Conclusions The different nutritional strategies employed by ferns and angiosperms mainly depended on the effects of phylogenetic and evolutionary diversity. Ferns tend to adopt an opportunistic strategy of limiting growth rate to reduce N demand and store more pooled nitrate, whereas angiosperms likely utilize N nutrition to ensure as much development as possible under low N stress. Identifying the effects of mineral nutrition on the evolutionary results of ecological competition between plant species remains a challenge.

Time will tell: Taxonomic and functional diversity of monilophyte ferns in native forests and abandoned silviculture systems

“…We found that functional richness was lower in the silviculture systems, with only Blechnum austrobrasilianum being identified as an indicator species. This result is in line with the fact that systems with low habitat diversity, such as silviculture, tend to have fewer species occupying the space, which leads to a decrease in functional richness (Riaño & Moulatlet, 2022;Zhang et al, 2023), but may increase the functional evenness. B. austrobrasilianum showed characteristics that are influenced by environmental factors, such as its height, which can reach up to 3 m (Ramos Giacosa et al, 2009).…”

“…As expected, we observed a high richness (α diversity), abundance, and functional richness in the native forest compared to silviculture systems. Generally, the greater taxonomic and functional diversity observed in native forests may be related to a high habitat diversity (Biassi et al., 2022; Qin et al., 2016), which could lead to increased complementarity in resource utilization by the plant species of the monilophytic community (Riaño & Moulatlet, 2022; Zhang et al., 2023). Moreover, species specialization and occupation of specific microhabitats may increase species richness (Jin et al., 2021), as well as functional diversity (Aros‐Mualin et al., 2021; Kessler et al., 2011), explaining why Asplenium claussenii , Ctenitis falciculata , Doryopteris patula , Campyloneurum nitidum , Doryopteris concolor , and Doryopteris pentagona are indicators for native forest systems.…”

“…The high acidity of silviculture systems (Baradwal et al, 2023;Powers et al, 2013), combined with a higher degree of canopy opening and lower soil moisture (Hogan et al, 2022), may negatively affect the development of monilophytes' foliage (Kessler et al, 2007). In addition, the uniform and fast growth rates of monocultures in silviculture systems may increase competition among plants for nutrients and water absorption (Zhang et al, 2023), while decreasing competition for sunlight due to the high degree of canopy openness (Dani et al, 2021). This supports the observed effect of leaf division, which is an important trait in silviculture systems (Kessler et al, 2007;Salazar et al, 2023), as it reduces the pressure caused by high luminosity (Dani et al, 2021;Jin et al, 2021), in line with the mass ratio theory (Finegan et al 2005;Castro-Díez et al, 2016).…”