Data from: Remote sensing reveals that wild herbivores limit senescent vegetation accumulation on dryland conservation reserves

Wild herbivores threaten vegetation recovery on dryland conservation
reserves globally. Monitoring herbivore impacts in remote drylands is
difficult because vegetation biomass transitions between living and
senescent states in response to irregular precipitation events. However,
land managers need a detailed understanding of the impacts that wild
herbivores have on vegetation to develop and refine herbivore management
strategies. Remote sensing provides the ability to assess grazing impacts
on living and senescent vegetation with high temporal and spatial
resolution. Here, we use Sentinel-2 satellite imagery to investigate how
grazing by kangaroos and rabbits impacted the fractional cover of
photosynthetic (PV) and non-photosynthetic (NPV) vegetation over 7 years
on three dryland reserves with experimental herbivore exclusion plots. We
compared PV and NPV cover in plots that were accessible to all herbivores,
accessible to kangaroos only, and inaccessible to both rabbits and
kangaroos. Generalized linear mixed models were used to determine if the
grazing impacts of rabbits and kangaroos varied from each other, between
reserves, and in response to variable rainfall patterns. Grazing impacts
varied between each herbivore, conservation reserve, and between PV and
NPV. PV was only weakly limited by kangaroos across all reserves and
antecedent rainfall totals. NPV was limited by rabbits and kangaroos, with
grazing having stronger impacts on NPV than PV. The grazing impacts of
rabbits and kangaroos varied spatially, with evidence that
NPV was limited by kangaroos only, by rabbits only, and by both
species across different reserves. Both herbivores had stronger impacts on
NPV as antecedent rainfall decreased. Our results show that the
impact of herbivores on vegetation biomass is greatest during periods of
dry climatic conditions. These findings contribute to a growing body of
evidence showing that grazing by wild herbivores can have detrimental
impacts on dryland ecosystems by disrupting ecological processes supported
by NPV. Our results highlight the importance of herbivore management
during productive periods to ensure NPV is retained during periods of low
rainfall.