Ecological significance of standing dead phytomass: marcescence as a puzzle piece to the nutrient cycle in temperate ecosystems

The plant economics spectrum (PES) drives nutrient cycling through effects
on soil decomposers. However, dead phytomass may remain standing or unshed
(marcescent), hardly accessible to decomposers, and be photodegraded. In
arid zones, the significant part of marcescent phytomass can be decomposed
without touching the ground. In temperate zones, photodegradation of
marcescent phytomass is low but prompts important chemical changes, which
affect its subsequent decomposability in the soil and alters the
surrounding environment. It is unknown, however, how common marcescence is
among different taxa and in which habitats, and how it is coordinated by
PES traits. We sampled standing (marcescent) and lying (shed) dead
phytomass from a broad spectrum of 127 herbaceous temperate species in a
common garden experiment and related these parameters to PES traits,
species ecological preferences, and phylogeny. Nearly all species (97%)
kept their phytomass marcescent. Tall species with a small leaf area and
high leaf carbon had a high level of marcescence. Marcescent species also
preferred sites affected by severe (but not necessarily frequent)
disturbance. The degree of marcescence was considerably conserved in
phylogeny. Synthesis. Marcescence extends PES trait effects on ecosystems,
particularly in immature habitats, being a common but overlooked
phenomenon of the temperate flora.