Large herbivores transform plant-pollinator networks in an African savanna

2021 ◽  
Author(s):  
Travis J. Guy ◽  
Matthew C. Hutchinson ◽  
Katherine C.R. Baldock ◽  
Elisha Kayser ◽  
Benjamin Baiser ◽  
...  
Keyword(s):  
African Savanna ◽  
Large Herbivores ◽  
Plant Pollinator

Dispersal ofAcaciaseeds by ungulates and ostriches in an African savanna

1996 ◽  
Vol 12 (3) ◽  
pp. 345-356 ◽  
Author(s):  
Maxine F. Miller
Keyword(s):  
South Africa ◽  
Seed Dispersal ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Tree Crown ◽  
African Savanna ◽  
Large Herbivores ◽  
Mammalian Herbivores ◽  
Open Environments ◽  
Presence And Absence

ABSTRACTThe dispersal of AfricanAcaciaseeds in the presence and absence of large mammalian herbivores and ostriches was assessed in a savanna ecosystem in South Africa. In the absence of large herbivores,A. tortilisandA. niloticapods were mainly dispersed in the shade, directly beneath the tree crown and seeds remained in pods for over 18 months. In the presence of large herbivores,A. tortilis, A. niloticaandA. karrooseeds were freed from pods and were dispersed into open, non-shaded habitats. Impala dispersed mostA. tortilisseeds (18,900 ha−1), giraffe mostA. niloticaseeds (1060 ha−1) and giraffe and kudu mostA. karrooseeds (452 and 448 ha−1, respectively). Seedling survival in dung in open environments may exceed that of seedlings in soil shaded beneath the tree crown. It appears that seed dispersal by large herbivores may be advantageous to future seedling recruitment.

Large herbivores suppress liana infestation in an African savanna

2021 ◽  
Vol 118 (41) ◽  
pp. e2101676118
Author(s):  
Tyler C. Coverdale ◽  
Ryan D. O’Connell ◽  
Matthew C. Hutchinson ◽  
Amanda Savagian ◽  
Tyler R. Kartzinel ◽  
...  
Keyword(s):  
Stable State ◽  
Life Forms ◽  
Tree Canopy ◽  
Alternative Stable State ◽  
African Savanna ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Woody Vines ◽  
Plant Life Forms ◽  
Canopy Area

African savannas are the last stronghold of diverse large-mammal communities, and a major focus of savanna ecology is to understand how these animals affect the relative abundance of trees and grasses. However, savannas support diverse plant life-forms, and human-induced changes in large-herbivore assemblages—declining wildlife populations and their displacement by livestock—may cause unexpected shifts in plant community composition. We investigated how herbivory affects the prevalence of lianas (woody vines) and their impact on trees in an East African savanna. Although scarce (<2% of tree canopy area) and defended by toxic latex, the dominant liana, Cynanchum viminale (Apocynaceae), was eaten by 15 wild large-herbivore species and was consumed in bulk by native browsers during experimental cafeteria trials. In contrast, domesticated ungulates rarely ate lianas. When we experimentally excluded all large herbivores for periods of 8 to 17 y (simulating extirpation), liana abundance increased dramatically, with up to 75% of trees infested. Piecewise exclusion of different-sized herbivores revealed functional complementarity among size classes in suppressing lianas. Liana infestation reduced tree growth and reproduction, but herbivores quickly cleared lianas from trees after the removal of 18-y-old exclosure fences (simulating rewilding). A simple model of liana contagion showed that, without herbivores, the long-term equilibrium could be either endemic (liana–tree coexistence) or an all-liana alternative stable state. We conclude that ongoing declines of wild large-herbivore populations will disrupt the structure and functioning of many African savannas in ways that have received little attention and that may not be mitigated by replacing wildlife with livestock.

scholarly journals Water availability, bedrock, disturbance by herbivores, and climate determine plant diversity in South-African savanna

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Martin Hejda ◽  
Jan Čuda ◽  
Klára Pyšková ◽  
Guin Zambatis ◽  
Llewellyn C. Foxcroft ◽  
...  
Keyword(s):  
Species Richness ◽  
South African ◽  
Plant Diversity ◽  
Water Availability ◽  
Large Scale ◽  
Woody Species ◽  
Plant Species Richness ◽  
African Savanna ◽  
Shrub Species ◽  
Large Herbivores

AbstractTo identify factors that drive plant species richness in South-African savanna and explore their relative importance, we sampled plant communities across habitats differing in water availability, disturbance, and bedrock, using the Kruger National Park as a model system. We made plant inventories in 60 plots of 50 × 50 m, located in three distinct habitats: (i) at perennial rivers, (ii) at seasonal rivers with water available only during the rainy season, and (iii) on crests, at least ~ 5 km away from any water source. We predicted that large herbivores would utilise seasonal rivers’ habitats less intensely than those along perennial rivers where water is available throughout the year, including dry periods. Plots on granite harboured more herbaceous and shrub species than plots on basalt. The dry crests were poorer in herb species than both seasonal and perennial rivers. Seasonal rivers harboured the highest numbers of shrub species, in accordance with the prediction of the highest species richness at relatively low levels of disturbance and low stress from the lack of water. The crests, exposed to relatively low pressure from grazing but stressed by the lack of water, are important from the conservation perspective because they harbour typical, sometimes rare savanna species, and so are seasonal rivers whose shrub richness is stimulated and maintained by the combination of moderate disturbance imposed by herbivores and position in the middle of the water availability gradient. To capture the complexity of determinants of species richness in KNP, we complemented the analysis of the above local factors by exploring large-scale factors related to climate, vegetation productivity, the character of dominant vegetation, and landscape features. The strongest factor was temperature; areas with the highest temperatures reveal lower species richness. Our results also suggest that Colophospermum mopane, a dominant woody species in the north of KNP is not the ultimate cause of the lower plant diversity in this part of the park.

scholarly journals Habitat selection by large herbivores in a southern African savanna: the relative roles of bottom-up and top-down forces

Ecosphere ◽  
2013 ◽  
Vol 4 (11) ◽  
pp. art139 ◽  
Author(s):  
Deron E. Burkepile ◽  
Catherine E. Burns ◽  
Craig J. Tambling ◽  
Elizabeth Amendola ◽  
Greg M. Buis ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Top Down ◽  
African Savanna ◽  
Large Herbivores ◽  
Bottom Up

scholarly journals Naïve plant communities and individuals may initially suffer in the face of reintroduced megafauna: An experimental exploration of rewilding from an African savanna rangeland

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0248855
Author(s):  
Truman P. Young ◽  
Duncan M. Kimuyu ◽  
Wilfred O. Odadi ◽  
Harry B. M. Wells ◽  
Amelia A. Wolf
Keyword(s):  
Plant Communities ◽  
Human Impacts ◽  
Experimental Manipulation ◽  
Grass Species ◽  
Native Plant ◽  
African Savanna ◽  
Large Herbivores ◽  
Native Communities ◽  
Exclosure Experiment ◽  
Rich Diversity

Excluding large native mammals is an inverse test of rewilding. A 25-year exclosure experiment in an African savanna rangeland offers insight into the potentials and pitfalls of the rewilding endeavor as they relate to the native plant community. A broad theme that has emerged from this research is that entire plant communities, as well as individual plants, adjust to the absence of herbivores in ways that can ill-prepare them for the return of these herbivores. Three lines of evidence suggest that these “naïve” individuals, populations, and communities are likely to initially suffer from herbivore rewilding. First, plots protected from wild herbivores for the past 25 years have developed rich diversity of woody plants that are absent from unfenced plots, and presumably would disappear upon rewilding. Second, individuals of the dominant tree in this system, Acacia drepanolobium, greatly reduce their defences in the absence of browsers, and the sudden arrival of these herbivores (in this case, through a temporary fence break), resulted in far greater elephant damage than for their conspecifics in adjacent plots that had been continually exposed to herbivory. Third, the removal of herbivores favoured the most palatable grass species, and a large number of rarer species, which presumably would be at risk from herbivore re-introduction. In summary, the native communities that we observe in defaunated landscapes may be very different from their pre-defaunation states, and we are likely to see some large changes to these plant communities upon rewilding with large herbivores, including potential reductions in plant diversity. Lastly, our experimental manipulation of cattle represents an additional test of the role of livestock in rewilding. Cattle are in many ways ecologically dissimilar to wildlife (in particular their greater densities), but in other ways they may serve as ecological surrogates for wildlife, which could buffer ecosystems from some of the ecological costs of rewilding. More fundamentally, African savannah ecosystems represent a challenge to traditional Western definitions of “wilderness” as ecosystems free of human impacts. We support the suggestion that as we “rewild” our biodiversity landscapes, we redefine “wildness” in the 21st Century to be inclusive of (low impact, and sometimes traditional) human practices that are compatible with the sustainability of native (and re-introduced) biodiversity.

scholarly journals Large herbivores promote habitat specialization and beta diversity of African savanna trees

Ecology ◽  
2016 ◽  
Vol 97 (10) ◽  
pp. 2640-2657 ◽  
Author(s):  
Robert M. Pringle ◽  
Kirsten M. Prior ◽  
Todd M. Palmer ◽  
Truman P. Young ◽  
Jacob R. Goheen
Keyword(s):  
Beta Diversity ◽  
Habitat Specialization ◽  
African Savanna ◽  
Large Herbivores

scholarly journals Plant community response to loss of large herbivores differs between North American and South African savanna grasslands

Ecology ◽  
2014 ◽  
Vol 95 (4) ◽  
pp. 808-816 ◽  
Author(s):  
Sally E. Koerner ◽  
Deron E. Burkepile ◽  
Richard W. S. Fynn ◽  
Catherine E. Burns ◽  
Stephanie Eby ◽  
...  
Keyword(s):  
South African ◽  
Plant Community ◽  
North American ◽  
Community Response ◽  
African Savanna ◽  
Large Herbivores

scholarly journals Man and Environment during the Early Peopling of Northeastern Caucasus

2019 ◽  
Vol 18 (5) ◽  
pp. 50-63
Author(s):  
A. A. Anoikin
Keyword(s):  
Material Culture ◽  
Early Pleistocene ◽  
Human Populations ◽  
African Savanna ◽  
Large Herbivores ◽  
The Caucasus ◽  
Western Asia ◽  
Human Habitation ◽  
Early Human ◽  
Small Tool

Purpose. Archaeological findings on the western Caspian coast indicate that this part of the Caucasus was populated throughout the Pleistocene. The earliest human habitation in the region is dated back to around 2 million years ago (2 Ма), which corresponds to the period of initial expansion of early Homo beyond Africa. Information on the environment and the features of the early human material culture is crucial for our understanding of the Caucasus’ earliest history. It was alternating processes of transgression and regression of the Caspian Sea throughout the Pleistocene that determined the paleoenvironment in the eastern Caucasus. The Early Pleistocene landscape of the southeastern part of Eastern Europe and northeastern Caucasus was similar to African open landscapes nowadays. The Khapry faunal complex characterizes the environment of that period. Its vertebrate composition is close to that typical for African savanna. Both animal communities included similar types of large herbivores: the elephant, rhinoceros, antelope, giraffe, ostrich and others. The African savanna carnivore community included the lion, guepard, hyena and jakal. The Khapry complex included the hyena, large sabre toothed Felidae, guepard and others. The earliest artifact collections in the Northeastern Caucasus are the artifact assemblage from stratum 5 at Rubas-1 in southeastern Dagestan and the archaeological materials from Ainikab-1, Mukhai-1 and 2 in Central Dagestan. The artifact age has been estimated in the range of ~ 2.3–1.8 Ma. Results. The initial stage of human habitation of the Northeastern Caucasus is characterized by two distinct lithic industries: the small tool industry (Rubas-1, stratum 5) and the Oldowan / pebble-flake industry (the Akushinski group of sites). Early human populations dispersed rather rapidly over the low-altitude savannas in the relative proximity to the seashore under the favorable environmental conditions of the initial Pleistocene. After the initial peopling stage, human communities set apart in particular regions where lithic industries were formed and developed. The first major region represents the Caspian shores (the small tool industry: Rubas-1); the second zone is the higher plateaus at the altitude not exceeding 1 500 m asl (pebble-flake industry: Dmanisi, Central Dagestan sites). Conclusion. It is asserted that the early human populations migrating out of Africa through Western Asia to the Caucasus, and its eastern part in particular, remained in the habitual environment, and it did not require any substantial changes in the adaptation strategies including stone working techniques and lithic tool production.

Elephant-induced structural changes in the vegetation and habitat selection by large herbivores in an African savanna

2011 ◽  
Vol 144 (2) ◽  
pp. 902-912 ◽  
Author(s):  
Marion Valeix ◽  
Hervé Fritz ◽  
Rodolphe Sabatier ◽  
Felix Murindagomo ◽  
David Cumming ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Structural Changes ◽  
African Savanna ◽  
Large Herbivores
Sign in / Sign up

Export Citation Format

Share Document