Data from: Effects of two key plant trait spectra on litter layer properties and habitat provision functions

Plant litter harbours a wide range of organisms, such as soil animals,
microbes, vascular plants (including their seeds and seedlings), mosses,
and lichens. While it is well-recognised that litter drives carbon and
nutrient cycling through their traits related to the plant resource
economics spectrum (PES), their explanatory power for predicting the
litter-dwelling biological community has been very low. In this era of
biodiversity change, litter habitat provisioning functions for myriad
organisms should receive more research attention.  A conceptual
multivariate trait space defined by a physical trait axis related to the
litter size and shape spectrum (SSS) and a biochemical trait axis (PES)
has been proposed to explain habitat as well as nutrition functions for
soil organisms. We aim to improve the explanatory power of litter traits
for the litter-dwelling animal communities by testing this concept, and by
connecting fundamental traits related to size and shape of single litter
particles (i.e., leaf litter units) with litter and litter layer
properties more directly related to habitat quality (e.g., moisture
regime, habitat space).  We tested the concept by using 16 woody
species commonly observed in NW Europe, and examined how different traits
or trait axes determine the litter and litter layer properties directly
related to habitat quality for soil animals. In addition, we assessed in a
field experiment with litter layers in mesocosms how this new trait
framework explains the soil invertebrate community as an actual example of
linking litter traits and host function to other organisms.  The
two plant trait spectra together accounted for > 60% of the
variance in litter quality in a principal component analysis. SSS-related
traits strongly explained litter layer habitat-related properties, such as
water-holding capacity and litter bulk density. The SSS axis and these
SSS-associated properties more strongly determined soil animal communities
assembled over seven weeks in the field experiment, surpassing the effects
of the PES axis.  Synthesis. This study has provided the first
empirical evidence for the litter trait space defined by both SSS and PES
spectra occupied by wide-ranging plant species, and its utility to explain
litter layer properties related to the physical environment and associated
habitat provisioning function. We suggest that this trait-based SSS-PES
framework will help us to disentangle mechanisms underpinning real-world
interactions between aboveground vegetation and belowground communities.