Rainfall trends and variation in the Maasai Mara ecosystem and their implications for animal population and biodiversity dynamics

Bartzke, Gundula; Ogutu, Joseph O.; Mukhopadhyay, Sabyasachi; Mtui, Devolent; Dublin, Holly T.; Piepho, Hans‐Peter

doi:10.1371/journal.pone.0202814

Cited by 79 publications

(63 citation statements)

References 108 publications

(170 reference statements)

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“…, Bartzke et al. ). Droughts will not only influence herbivores indirectly through changes in food availability, but also directly through decreased surface water availability (Gaylard et al.…”

Section: Introductionmentioning

confidence: 98%

Quantifying water requirements of African ungulates through a combination of functional traits

Kihwele

Mchomvu

Owen‐Smith

et al. 2020

Ecological Monographs

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Citation: Kihwele, E. S., V. Mchomvu, N. Owen-Smith, R. S. Hetem, M. C. Hutchinson, A. B. Potter, H. Olff, and M. P. Veldhuis. 2020. Quantifying water requirements of African ungulates through a combination of functional traits. Ecological Monographs 90(2):Abstract. Climate and land use change modify surface water availability in African savannas. Surface water is a key resource for both wildlife and livestock and its spatial and temporal distribution is important for understanding the composition of large herbivore assemblages in savannas. Yet, the extent to which ungulate species differ in their water requirements remains poorly quantified. Here, we infer the water requirements of 48 African ungulates by combining six different functional traits related to physiological adaptations to reduce water loss, namely minimum dung moisture, relative dung pellet size, relative surface area of the distal colon, urine osmolality, relative medullary thickness, and evaporation rate. In addition, we investigated how these differences in water requirements relate to differences in dietary water intake. We observed strong correlations between traits related to water loss through dung, urine and evaporation, suggesting that ungulates minimize water loss through multiple pathways simultaneously, which suggests that each trait can thus be used independently to predict water requirements. Furthermore, we found that browsers and grazers had similar water requirements, but browsers are expected to be less dependent on surface water because they acquire more water through their diet. We conclude that these key functional traits are a useful way to determine differences in water requirements and an important tool for predicting changes in herbivore community assembly resulting from changes in surface water availability.

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Section: Introductionmentioning

confidence: 98%

Quantifying water requirements of African ungulates through a combination of functional traits

Kihwele

Mchomvu

Owen‐Smith

et al. 2020

Ecological Monographs

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“…In the Serengeti-Mara ecosystem straddling Kenya and Tanzania, rainfall primarily drives population dynamics [11,12], aggregate population biomass [7,8], recruitment dynamics [13], phenology, synchrony and prolificacy of calving [14,15,16], seasonal dispersal and migration of large herbivores [17,18]. However, increasing frequency and intensity of droughts [19,20], widening variation of river flows [21] and rising temperatures [19] hasten the need to advance our understanding of how anticipated climate changes will likely affect larger herbivore populations. Such understanding can be gained by studying rainfall influences on large herbivore population dynamics using long-term monitoring data from protected areas with relatively little human influence, such as the Ngorongoro Crater, in northern Tanzania.…”

Section: Introductionmentioning

confidence: 99%

Long-term historical and projected herbivore population dynamics in Ngorongoro crater, Tanzania

et al. 2020

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The Ngorongoro Crater is an intact caldera with an area of approximately 310 km 2 located within the Ngorongoro Conservation Area (NCA) in northern Tanzania. It is known for the abundance and diversity of its wildlife and is a UNESCO World Heritage Site and an International Biosphere Reserve. Long term records (1963-2012) on herbivore populations, vegetation and rainfall made it possible to analyze historic and project future herbivore population dynamics. NCA was established as a multiple use area in 1959. In 1974 there was a perturbation in that resident Maasai and their livestock were removed from the Ngorongoro Crater. Thus, their pasture management that was a combination of livestock grazing and fire was also removed and 'burning' stopped being a regular occurrence until it was resumed in 2001 by NCA management. The Maasai pasture management would have selected for shorter grasses and more palatable species. Vegetation mapping in 1966-1967 recorded predominately short grasslands. Subsequent vegetation mapping in the crater in 1995 determined that the grassland structure had changed such that mid and tall grasses were dominant. After removal of the Maasai pastoralists from the Ngorongoro Crater in 1974, there were significant changes in population trends for some herbivore species. Buffalo, elephant and ostrich numbers increased significantly during 1974-2012. The zebra population was stable from 1963 to 2012 whereas population numbers of five species declined substantially between 1974 and 2012 relative to their peak numbers during 1974-1976. Grant's and Thomson's gazelles, eland, kongoni, and waterbuck (wet season only) declined significantly in the Crater in both seasons after 1974. In addition, some herbivore species were consistently more abundant inside the Crater during the wet than the dry season. This pattern was most evident for the large herbivore species requiring bulk forage, i.e., buffalo, eland, and elephant. Even with a change in grassland structure, total herbivore biomass remained relatively stable from 1963 to 2012, implying that the crater has a stable carrying capacity. Analyses of rainfall indicated that there was a persistent cycle of 4.83 years for the annual component. Herbivore population size was correlated with rainfall in both the wet and dry

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“…There is an increasing body of evidence supporting that climate change and variability have significant impact on ecosystem health (Bartzke et al 2018) and agricultural production (Craparo et al 2015;Niles et al 2015;Lobell et al 2011). Future projections in the East and Southern Africa (ESA) region points to wetter climate (Otte et al 2017;IPCC 2014) although erratic rainfall patterns and frequent extreme events such as droughts and floods are common (Nicholson 2016;Guan et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Long-term spatial-temporal trends and variability of rainfall over Eastern and Southern Africa

Muthoni

Odongo

Ochieng

et al. 2018

Theor Appl Climatol

116

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This study investigates the spatial-temporal trends and variability of rainfall within East and South Africa (ESA) region. The newly available Climate Hazards group Infrared Precipitation with Stations (CHIRPS-v2) gridded data spanning 37 years (1981 to 2017) was validated against gauge observations (N = 4243) and utilised to map zones experiencing significant monotonic rainfall trends. Standardised annual rainfall anomalies revealed the spatial-temporal distribution of below and above normal rains that are associated with droughts and floods respectively. Results showed that CHIRPS-v2 data had a satisfactory skill to estimate monthly rainfall with Kling-Gupta efficiency (KGE = 0.68 and a high temporal agreement (r = 0.73) while also preserving total amount (β = 0.99) and variability (γ = 0.8). Two contiguous zones with significant increase in annual rainfall (3-15 mm year −1) occurred in Southwest Zambia and in Northern Lake Victoria Basin between Kenya and Uganda. The most significant decrease in annual rainfall (− 20 mm year −1) was recorded at Mount Kilimanjaro in Tanzania. Other significant decreases in annual rainfall ranging between − 4 and − 10 mm year −1 were observed in Southwest Tanzania, Central-South Kenya, Central Uganda and Western Rwanda. CHIRPS-v2 rainfall product provides reliable high spatial resolution information on amount of rainfall that can complement sparse rain gauge network in rain-fed agricultural systems in ESA region. The observed spatial-temporal trends and variability in rainfall are important basis for guiding targeting of appropriate adaptive measures across multiple sectors.

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Rainfall trends and variation in the Maasai Mara ecosystem and their implications for animal population and biodiversity dynamics

Cited by 79 publications

References 108 publications

Quantifying water requirements of African ungulates through a combination of functional traits

Quantifying water requirements of African ungulates through a combination of functional traits

Long-term historical and projected herbivore population dynamics in Ngorongoro crater, Tanzania

Long-term spatial-temporal trends and variability of rainfall over Eastern and Southern Africa

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