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5 results on '"Cromsigt, Joris PGM"'

1. Fatal attraction: vegetation responses to nutrient inputs attract herbivores to infectious anthrax carcass sites

Author

Turner, Wendy C, Kausrud, Kyrre L, Krishnappa, Yathin S, Cromsigt, Joris PGM, Ganz, Holly H, Mapaure, Isaac, Cloete, Claudine C, Havarua, Zepee, Küsters, Martina, Getz, Wayne M, and Stenseth, Nils Chr

Subjects
Rare Diseases, Infectious Diseases, Anthrax, Emerging Infectious Diseases, 2.2 Factors relating to the physical environment, Aetiology, Good Health and Well Being, Animals, Bacillus anthracis, Cadaver, Equidae, Feeding Behavior, Longitudinal Studies, Namibia, Poaceae, Soil, Species Specificity, anthrax, camera traps, disease transmission, foraging ecology, host-pathogen contact, parasite avoidance, host–pathogen contact, Biological Sciences, Agricultural and Veterinary Sciences, Medical and Health Sciences
Abstract

Parasites can shape the foraging behaviour of their hosts through cues indicating risk of infection. When cues for risk co-occur with desired traits such as forage quality, individuals face a trade-off between nutrient acquisition and parasite exposure. We evaluated how this trade-off may influence disease transmission in a 3-year experimental study of anthrax in a guild of mammalian herbivores in Etosha National Park, Namibia. At plains zebra (Equus quagga) carcass sites we assessed (i) carcass nutrient effects on soils and grasses, (ii) concentrations of Bacillus anthracis (BA) on grasses and in soils, and (iii) herbivore grazing behaviour, compared with control sites, using motion-sensing camera traps. We found that carcass-mediated nutrient pulses improved soil and vegetation, and that BA is found on grasses up to 2 years after death. Host foraging responses to carcass sites shifted from avoidance to attraction, and ultimately to no preference, with the strength and duration of these behavioural responses varying among herbivore species. Our results demonstrate that animal carcasses alter the environment and attract grazing hosts to parasite aggregations. This attraction may enhance transmission rates, suggesting that hosts are limited in their ability to trade off nutrient intake with parasite avoidance when relying on indirect cues.

Published
2014

2. Long-term frequent fires do not decrease topsoil carbon and nitrogen in an Afromontane grassland

Author

Findlay, Nicola, Manson, Alan, Cromsigt, Joris PGM, Gordijn, Paul, Nixon, Cathy, Rietkerk, Max, Thibaud, Guy, Wassen, Martin J, Beest, Mariska te, Environmental Sciences, Spatial Ecology and Global Change, Environmental Sciences, and Spatial Ecology and Global Change

Subjects
fire regime, montane grassland, soil, montane grassland, Ecology, Animal Science and Zoology, fire regime, soil
Abstract

Fire has been an integral evolutionary force shaping and maintaining grassy biomes, such as the Afromontane grasslands of South Africa. Afromontane grasslands represent a large carbon reservoir, but it is uncertain how fire affects their long-term C storage. We investigated the effect of fire regime on soil organic C and N (SOC; SON) in a long-term (39-year) burning experiment in the Maloti-Drakensberg Park, South Africa. We compared SOC and SON sampled in 2004 and 2019 from six treatments differing in fire frequency (annual, biennial, five-year, infrequent) and season (spring, autumn). Average SOC increased significantly between 2004 and 2019. Average SON increased slightly, resulting in a significant increase in C:N ratio, indicating that soil organic matter is becoming less N-eutrophic. Importantly, burning annually in spring increased SOC and SON. This unexpected response is attributed to the aluandic (acidic, high organic matter) properties of Drakensberg soils. Burning in autumn did not increase SOC and SON. The lowest C stocks were observed in infrequently burnt plots. Average C sequestration across all fire treatments was 0.30 Mg ha���1 y���1. The observed increase in SOC under frequent fires is contrary to many findings from other studies in grassy ecosystems and notably driven by fire season.

Published
2022

3. Long-term frequent fires do not decrease topsoil carbon and nitrogen in an Afromontane grassland

Author

Environmental Sciences, Spatial Ecology and Global Change, Findlay, Nicola, Manson, Alan, Cromsigt, Joris PGM, Gordijn, Paul, Nixon, Cathy, Rietkerk, Max, Thibaud, Guy, Wassen, Martin J, Beest, Mariska te, Environmental Sciences, Spatial Ecology and Global Change, Findlay, Nicola, Manson, Alan, Cromsigt, Joris PGM, Gordijn, Paul, Nixon, Cathy, Rietkerk, Max, Thibaud, Guy, Wassen, Martin J, and Beest, Mariska te

Published
2022

4. Pictures or pellets? Comparing camera trapping and dung counts as methods for estimating population densities of ungulates

Author

Pfeffer, Sabine E, Spitzer, Robert, Allen, A.M., Hofmeester, Tim R, Ericsson, Göran, Widemo, Fredrik, Singh, Navinder J, Cromsigt, Joris PGM, Pfeffer, Sabine E, Spitzer, Robert, Allen, A.M., Hofmeester, Tim R, Ericsson, Göran, Widemo, Fredrik, Singh, Navinder J, and Cromsigt, Joris PGM

Abstract

Contains fulltext : 179057.pdf (publisher's version ) (Open Access)

Published
2017

5. Restoration of a megaherbivore : landscape-level impacts of white rhinoceros in Kruger National Park, South Africa

Author

Cromsigt, Joris PGM, te Beest, Mariska, Cromsigt, Joris PGM, and te Beest, Mariska

Abstract

Megaherbivores have been lost from most ecosystems world-wide, and current increases in poaching of rhino and elephant spp. threaten their status in the systems where they still occur. Although megaherbivores are said to be key drivers of ecosystem structure and functioning, empirical evidence is strongly biased to studies on African elephant. We urgently need a better understanding of the impact of other megaherbivore species to predict the consequences of megaherbivore loss. We used a unique 'recolonization experiment' to test how a megagrazer, white rhinoceros, is affecting the structure of savanna grasslands in Kruger National Park (KNP). With a 30-year record of rhinoceros distribution, we quantified how they recolonized KNP following their re-introduction. This allowed us to identify landscapes with high rhino densities and long time since recolonization versus landscapes with low rhino densities that were recolonized more recently but were otherwise biophysically similar. We recorded grassland heterogeneity on 40transects covering a total of 30km distributed across both landscapes. We used two proxies of grassland heterogeneity: % short grass cover and number of grazing lawn patches. Grazing lawns are patches with specific communities of prostrate-growing stoloniferous short grass species. Short grass cover was clearly higher in the high rhino impact (17.5%) than low rhino impact landscape (10.7%). Moreover, we encountered ~20 times more grazing lawns in the high rhino impact landscape. The effect of rhino on number of lawns and on short grass cover was similar to the two dominant geologies in KNP, basalt-derived versus granite-derived soils. Synthesis. We provide empirical evidence that white rhinoceros may have started to change the structure and composition of KNP's savanna grasslands. It remains to be tested if these changes lead to other ecological cascading effects. However, our results highlight that the current rhino poaching crisis may not only affec

Published
2014
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