Ecological consequences of large herbivore exclusion in an African savanna: 12 years of data from the UHURU experiment

Diverse communities of large mammalian herbivores (LMH), once widespread,
are now rare. LMH exert strong direct and indirect effects on community
structure and ecosystem functions, and measuring these effects is
important for testing ecological theory and for understanding past,
current, and future environmental change. This in turn requires long-term
experimental manipulations, owing to the slow and often nonlinear
responses of populations and assemblages to LMH removal. Moreover, the
effects of particular species or body-size classes within diverse LMH
guilds are difficult to pinpoint, and the magnitude and even direction of
these effects often depends on environmental context. Since 2008, we have
maintained the Ungulate Herbivory Under Rainfall Uncertainty (UHURU)
experiment, a series of size-selective LMH exclosures replicated across a
rainfall/productivity gradient in a semi-arid Kenyan savanna. The goals of
the UHURU experiment are to measure the effects of removing successively
smaller size classes of LMH (mimicking the process of size-biased
extirpation) and to establish how these effects are shaped by spatial and
temporal variation in rainfall. The UHURU experiment comprises three
LMH-exclusion treatments and an unfenced control, applied to 9 randomized
blocks of contiguous 1-ha plots (n = 36). The fenced treatments are:
“MEGA” (exclusion of megaherbivores, elephant and giraffe); “MESO”
(exclusion of herbivores ≥40 kg); and “TOTAL” (exclusion of herbivores ≥5
kg). Each block is replicated three times at three sites across the 20-km
rainfall gradient, which has fluctuated over the course of the experiment.
The first five years of data were published previously (Ecological
Archives E095-064) and have been used in numerous studies. Since that
publication, we have (a) continued to collect data following the original
protocols, (b) improved the taxonomic resolution and accuracy of plant and
small-mammal identifications, and (c) begun collecting several new data
sets. Here, we present updated and extended raw data from the first 12
years of the UHURU experiment (2008–2019). Data include daily rainfall
data throughout the experiment; annual surveys of understory plant
communities; annual censuses of woody-plant communities; annual
measurements of individually tagged woody plants; monthly monitoring of
flowering and fruiting phenology; every-other-month small-mammal
mark-recapture data; and quarterly large-mammal dung surveys.