Native herbivore browsing alters plant physical and chemical traits in a eucalypt forest understory

Macropods exhibit selective herbivory on plant traits within and between
species and hence can alter plant trait variation. In this study we asked,
what are the effects of macropod herbivory on intraspecific variation in
plant traits of forest understorey species? We tested the effects of
herbivory by macropods on eight plant traits, in nine understorey species
using a herbivore exclusion experiment. Generalised linear mixed models
were used to test for differences between herbivory treatments in trait
means as well as variation within species and at the community level.
Macropod herbivory resulted in differences in either the mean trait value
or trait variance within a species for seven of the eight tested plant
traits. Macropod exclusion resulted in larger dimensions of size for most
species, as well as changes in specific leaf area, moisture content, and
carbon content of leaves. Further, community-weighted means of specific
leaf area, moisture content, and leaf nitrogen were lower in the presence
of macropods. Plant trait variance was altered for three of the seven
community weighted traits. This study demonstrates a mechanism through
which macropods can drive changes in the traits of understorey plant
species. Plant traits have been linked to various larger scale ecological
processes including ecosystem flammability, nutrient cycling, response to
global change and habitat suitability for other organisms. Therefore,
herbivore-induced changes in plant trait variation and community
composition could have important flow on effects for other environmental
processes and hence should be considered in management decisions regarding
fire-prone ecosystems.