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 semiarid 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 nine 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 5 years of data were published previously (Ecological Archives E095-064) and have been used in numerous studies. Since that publication, we have (1) continued to collect data following the original protocols, (2) improved the taxonomic resolution and accuracy of plant and small-mammal identifications, and (3) 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. There are no copyright restrictions; notification of when and how data are used is appreciated and users of UHURU data should cite this data paper when using the data.

Impacts of Decentralized Environmental Governance on Andean Bear Conservation in Colombia.

Decentralized environmental governance has become increasingly common across much of Latin America and in developing countries more generally, yet the impacts of decentralization on wildlife conservation remain unclear. Decentralized environmental governance is thought to improve efficiency, local compliance, and democratic potential of natural resource management. However, wildlife conservation, especially that of large mammals, poses unique challenges in the context of decentralized governance: wildlife conservation is often expensive, requires large expanses of contiguous habitat, and often offers few economic benefits. We analyzed Colombia's decentralized environmental governance and its performance in conserving a contentious and border-crossing wildlife species, the Andean bear (Tremarctos ornatus). We considered both decentralized institutions and nongovernmental organizations (NGOs). This analysis is informed by 67 semi-structured interviews with conservation practitioners in Colombia. We found inconsistent program implementation across the country and little information exchange among institutions. These issues quite likely contribute to exacerbated human-bear conflict and thus more Andean bear deaths suggesting that the successful coordination of large-scale wildlife conservation may yet require the leadership of strong central institutions. A few international NGOs were working to improve Andean bear conservation in Colombia, but we saw little involvement at the national level of Colombian NGOs-some of whom felt they were being unfairly outcompeted by international elites. We recommend a greater engagement with Colombian NGOs (by both donors and international NGOs) as a means through which to ensure the integrity of Andean bear conservation into the future.

Low functional redundancy among mammalian browsers in regulating an encroaching shrub (Solanum campylacanthum) in African savannah.

Large herbivorous mammals play an important role in structuring African savannahs and are undergoing widespread population declines and local extinctions, with the largest species being the most vulnerable. The impact of these declines on key ecological processes hinges on the degree of functional redundancy within large-herbivore assemblages, a subject that has received little study. We experimentally quantified the effects of three browser species (elephant, impala and dik-dik) on individual- and population-level attributes of Solanum campylacanthum (Solanum incanum sensu lato), an encroaching woody shrub, using semi-permeable exclosures that selectively removed different-sized herbivores. After nearly 5 years, shrub abundance was lowest where all browser species were present and increased with each successive species deletion. Different browsers ate the same plant species in different ways, thereby exerting distinct suites of direct and indirect effects on plant performance and density. Not all of these effects were negative: elephants and impala also dispersed viable seeds and indirectly reduced seed predation by rodents and insects. We integrated these diffuse positive effects with the direct negative effects of folivory using a simple population model, which reinforced the conclusion that different browsers have complementary net effects on plant populations, and further suggested that under some conditions, these net effects may even differ in direction.