Plant leaf litter is an important source of soil chemicals that are essential for the ecosystem and changes in leaf litter chemical traits during decomposition will determine the availability of multiple chemical elements recycling in the ecosystem. However, it is unclear whether the changes in litter chemical traits during decomposition and their similarities across species can be predicted, respectively, using other leaf traits or using the phylogenetic relatedness of the litter species. Here we examined the fragmentation levels, mass losses, and the changes of 10 litter chemical traits during 1-yr decomposition under different environmental conditions (within/above surrounding litter layer) for 48 temperate tree species and related them to an important leaf functional trait, i.e. leaf toughness. Leaf toughness could predict the changes well in terms of amounts, but poorly in terms of concentrations. Changes of 7 out of 10 litter chemical traits during decomposition showed a significant phylogenetic signal notably when litter was exposed above surrounding litter. These phylogenetic signals in element dynamics were stronger than those of initial elementary composition. Overall, relatively hard-to-measure ecosystem processes like element dynamics during decomposition could be partly predicted simply from phylogenies and leaf toughness measures. We suggest that the strong phylogenetic signals in chemical ecosystem functioning of species may reflect the concerted control by multiple moderately conserved traits, notably if interacting biota suffer microclimatic stress and spatial isolation from ambient litter.
Saltmarshes are valued as key buffering ecosystems against global climate change and sea level rise. However, the knowledge deficit regarding links between colonization of saltmarsh fringes by plants and mud cracking in the lateral dimension considerably limits our understanding of marsh resilience. Here, the role of mud cracks in colonization by saltmarsh plants was investigated. A combination of field experiments, remote sensing, and experimental results revealed that: (1) potential mud cracking zones were formed at the seaward edge of saltmarshes under the influence of tide-induced wetting–drying cycles, where mud cracks were extensively distributed and colonized by new seedlings. (2) The seedling density in the mud cracks was higher than that in the patches, and seedlings in the mud cracks sprouted earlier than those in the patches. The results implied that mud cracking enhanced colonization by saltmarsh plants, rather than being a water stressor. (3) The two main ecological functions of mud cracks in saltmarsh colonization were acting as “seed traps” and “seedling growth promoters.” (4) Mud cracking could be a key factor influencing saltmarsh resilience, especially by promoting the colonization and dispersal of saltmarsh plants. Rapid colonization of potential zones with mud cracks could occur as soon as seeds are available. Our results could facilitate the development of appropriate saltmarsh rehabilitation strategies.
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