Grazer movements: spatial and temporal responses to burning in a tall-grass African savanna

2004 ◽  
Vol 13 (3) ◽  
pp. 377 ◽  
Author(s):  
S. Archibald ◽  
W. J. Bond
Keyword(s):  
Grazing Pressure ◽  
Distribution Data ◽  
Wet Season ◽  
Tall Grass ◽  
Kwazulu Natal ◽  
Grazing Systems ◽  
Time Of Year ◽  
Grass Growth ◽  
Grass Sward ◽  
Burnt Areas

The consequences of burning on grazer distributions in the landscape were investigated in a savanna system in South Africa. Distribution and extent of fires can be highly variable within and between years, but how this influences patterns of grazing is not well understood. Three years of fire and grazer distribution data from Hluhluwe-Umfolozi Park, KwaZulu Natal were used to describe how animals respond to different burn situations. Animals were attracted to the burnt areas after fires and this resulted in a decrease in grazer densities in unburnt areas. This effect was more pronounced when a larger area of the park had burnt, and increased over time as area burnt increased. Thus, grazing pressure in an area will depend on the size, timing and distribution of fires in a larger spatial context. Fires also seem to promote a more uniform grazing environment: although grazer density overall is higher in areas that have burnt, the grazers are more dispersed in these areas, and grazing at any one point may be less intense than in the unburnt areas (which are grazed patchily). Therefore at the beginning of the wet season—a key time of year for grass growth—fires are acting to decrease grazing pressure at any one point in both burnt and unburnt areas. The presence of fire in grazing systems could affect grass community composition because fire alters the intensity and frequency of utilisation of the grass sward.

Occupancy of two forest specialist birds in the Southern Mistbelt Forests of KwaZulu-Natal and Eastern Cape, South Africa

2020 ◽  
pp. 1-16
Author(s):  
S. THOBEKA GUMEDE ◽  
DAVID A. EHLERS SMITH ◽  
YVETTE C. EHLERS SMITH ◽  
SAMUKELISIWE P. NGCOBO ◽  
MBALENHLE T. SOSIBO ◽  
...  
Keyword(s):  
South Africa ◽  
Camera Trap ◽  
Habitat Requirements ◽  
Stem Density ◽  
Grass Cover ◽  
Eastern Cape ◽  
Wet Season ◽  
Mature Trees ◽  
Natural Habitats ◽  
Kwazulu Natal

Summary Establishing the specific habitat requirements of forest specialists in fragmented natural habitats is vital for their conservation. We used camera-trap surveys and microhabitat-scale covariates to assess the habitat requirements, probability of occupancy and detection of two terrestrial forest specialist species, the Orange Ground-thrush Geokichla gurneyi and the Lemon Dove Aplopelia larvata during the breeding and non-breeding seasons of 2018–2019 in selected Southern Mistbelt Forests of KwaZulu-Natal and the Eastern Cape, South Africa. A series of camera-trap surveys over 21 days were conducted in conjunction with surveys of microhabitat structural covariates. During the wet season, percentage of leaf litter cover, short grass cover, short herb cover, tall herb cover and saplings 0–2 m, stem density of trees 6–10 m and trees 16–20 m were significant structural covariates for influencing Lemon Dove occupancy. In the dry season, stem density of 2–5 m and 10–15 m trees, percentage tall herb cover, short herb cover and 0–2 m saplings were significant covariates influencing Lemon Dove occupancy. Stem density of trees 2–5 m and 11–15 m, percentage of short grass cover and short herb cover were important site covariates influencing Orange Ground-thrush occupancy in the wet season. Our study highlighted the importance of a diverse habitat structure for both forest species. A high density of tall/mature trees was an essential microhabitat covariate, particularly for sufficient cover and food for these ground-dwelling birds. Avian forest specialists play a vital role in providing ecosystem services perpetuating forest habitat functioning. Conservation of the natural heterogeneity of their habitat is integral to management plans to prevent the decline of such species.

Resource selection by grazing herbivores on post-fire regrowth in a West African woodland savanna

2007 ◽  
Vol 34 (2) ◽  
pp. 77 ◽  
Author(s):  
Erik Klop ◽  
Janneke van Goethem ◽  
Hans H. de Iongh
Keyword(s):  
Resource Selection ◽  
West African ◽  
Tree Cover ◽  
Resource Selection Functions ◽  
Risk Of Predation ◽  
Savanna Fires ◽  
Grass Sward ◽  
Burnt Areas ◽  
Good Visibility ◽  
Selection Of

The preference of grazing herbivores to feed on grass regrowth following savanna fires rather than on unburnt grass swards is widely recognised. However, there is little information on which factors govern patterns of resource selection within burnt areas. In this study, we attempted to disentangle the effects of different habitat and grass sward characteristics on the utilisation of post-fire regrowth by nine species of ungulates in a fire-dominated woodland savanna in north Cameroon. We used resource-selection functions based on logistic regression. Overall, the resource-selection functions identified the time elapsed since burning as the most influential parameter in determining probability of use by ungulates, as most species strongly selected swards that were recently burned. This pattern might be related to nutrient levels in the grass sward. In addition, most species selected areas with high grass cover and avoided grass swards with high amounts of dead stem material. This is likely to increase bite mass and, hence, intake rates. The avoidance of high tree cover by some species may suggest selection for open areas with good visibility and, hence, reduced risk of predation. Body mass seemed to have no effect on differential selection of post-fire regrowth, irrespective of feeding style.

Grass Growth in Response to Time of Rainfall and Season Along a Climate Gradient in Australian Rangelands.

1997 ◽  
Vol 19 (1) ◽  
pp. 95 ◽  
Author(s):  
BH Walker ◽  
FR Mcfarlane ◽  
JL Langridge
Keyword(s):  
Soil Moisture ◽  
Perennial Grass ◽  
Management Strategies ◽  
The Other ◽  
Green Leaf ◽  
Grass Species ◽  
Seasonal Growth ◽  
Available Soil Moisture ◽  
Time Of Year ◽  
Grass Growth

Percentage green leaf and height of the major perennial grass species was estimated fortnightly at six locations along a rainfall predictability gradient from Katherine (most predictable) to Lake Mere near Cobar (aseasonal), and regressed on estimated plant available soil moisture (PASM) and time of year (T). Green leaf is more strongly related to T at Katherine and to PASM at Lake Mere with the other sites in-between. Differences between species in terms of seasonal growth phenology were minor, at all sites, and there were no meaningful patterns in percentage contributions by the species to sward biomass. A strong inter-seasonal rainfall pattern over the period of the study may have masked phenological differences between species, but it is also possible that changes in species composition very soon after livestock were introduced resulted in a decline in phenological differentiation. Whatever the reason, the differences observed in this study would ~ot warrant their use in the formulation of management strategies.

The use of fire to establish Townsville lucerne in the Northern Territory

1966 ◽  
Vol 6 (22) ◽  
pp. 277 ◽  
Author(s):  
GC Stocker ◽  
JD Sturtz
Keyword(s):  
Northern Territory ◽  
Wet Season ◽  
Seeding Rate ◽  
Stylosanthes Humilis ◽  
Grass Growth ◽  
Rainfall Region

During the wet season of 1964-65 two trials were established near Darwin to determine if Townsville lucerne (Stylosanthes humilis H.B.K.) could be established in undisturbed annual sorghum (Sorghum intrans F. Muell. ex Benth.) pastures after wet season burning had controlled grass growth. In the first trial, plots were burnt at intervals throughout the wet season. Townsville lucerne pods were broadcast immediately after burning. Grass control and Townsville lucerne establishment were satisfactory in plots burnt after December 6. The second trial examined the effect on Townsville lucerne establishment and S. intrans control of burning, seeding rate, superphosphate, and weedicide treatments. Burning had the most important effect ; seeding rate had little significant effect and superphosphate none. The weedicide treatment was ineffective. The trials indicate that provided wet season burning is used to control S. intrans, Townsville lucerne can be established cheaply over wide areas of the higher rainfall region of the Northern Territory.

Gastrointestinal nematode parasites and the stability and productivity of intensive ruminant grazing systems

1988 ◽  
Vol 321 (1207) ◽  
pp. 541-563 ◽  
Keyword(s):  
Plant Density ◽  
Gastrointestinal Nematode ◽  
Future Research ◽  
Feeding Rates ◽  
Nematode Parasites ◽  
Relevant Field ◽  
Grazing Systems ◽  
The Stability ◽  
Grass Growth ◽  
The Impact

This paper uses mathematical models, describing the transmission dynamics of directly transmitted gastrointestinal nematode parasites of sheep and cattle, to examine the impact of these parasites on the stability and productivity of ruminant grazing systems. Current models of the ecology of grass growth under grazing, and the epidemiology of trichostrongylid nematode parasites of ruminants, are combined in a formulation that captures the general features of the plant - (ruminant) herbivore - parasite interaction. The simplest case, in which herbivore numbers are constant and not food limited (the norm for m any agricultural systems) is considered in detail. T he effect of gastrointestinal parasitism in reducing herbivore feeding rates is shown to act as a potential density-dependent constraint on the parasite’s infection rate. T he process is manifested in the model as a progressive linearization of the relation between herbivore feeding rate and plant density at the parasite equilibrium . This effect acts to stabilize the dynamics of the model grazing system and significantly affects its predictions about the impact of parasite control and the pattern of host productivity. Model predictions are discussed in the light of relevant field observations, and areas for future research are identified.

Identifying the drivers of the pelagic ecosystem of an oligotrophic bight (KwaZulu–Natal, South Africa) using stable isotopes (δ13C, δ15N) and C : N ratio analysis

2016 ◽  
Vol 67 (11) ◽  
pp. 1750 ◽  
Author(s):  
Ander M. de Lecea ◽  
Rachel Cooper ◽  
Albertus J. Smit
Keyword(s):  
South Africa ◽  
East Coast ◽  
Austral Summer ◽  
Ratio Analysis ◽  
Wet Season ◽  
Terrestrial Organic Matter ◽  
Pelagic Ecosystem ◽  
Riverine Input ◽  
Kwazulu Natal ◽  
Marine System

The international literature highlights the importance of understanding the role and fate of terrestrial organic matter (OM) in the marine system, yet little is known about this on the oligotrophic east coast of South Africa. Within the Bight, three important processes make OM biologically available: (1) a topographically induced upwelling cell (north), (2) a Cyclonic Eddy (south), and (3) riverine input. We hypothesise that: (i) these OM sources differ substantially in their isotope ratios, and (ii) zooplankton at the inshore region has an isotope signature linked to localised fluvial fluxes. Particulate OM samples were collected at five locations along the Bight and in three main estuaries during austral summer and winter seasons in 2010 and subjected to isotopic and mixing model analysis. Riverine input played an important role in this ecosystem inshore during the wet season. Only marine OM played a role as a biological driver offshore and at all sites during the dry season. Although there were indications that the upwelling cell did occur, it was not confirmed as active in either season. The current study provides valuable insights into the Bight's biological functioning and principle insights into the fate of terrestrial organic carbon on the east coast of southern Africa.

Ecology of the Asian elephant in southern India. I. Movement and habitat utilization patterns

1989 ◽  
Vol 5 (1) ◽  
pp. 1-18 ◽  
Author(s):  
R. Sukumar
Keyword(s):  
Deciduous Forest ◽  
Habitat Preferences ◽  
Movement Pattern ◽  
Habitat Utilization ◽  
Asian Elephant ◽  
Southern India ◽  
Food Plants ◽  
Wet Season ◽  
Tall Grass ◽  
Utilization Patterns

ABSTRACTThe movement and habitat utilization patterns were studied in an Asian elephant population during 1981–83 within a 1130 km2 area in southern India (11° 30′ N to 12° 0′ N and 76° 50′ E to 77° 15′ E). The study area encompasses a diversity of vegetation types from dry thorn forest (250–400 m) through deciduous forest (400–1400 m) to stunted evergreen shola forest and grassland (1400–1800 m).Home range sizes of some identified elephants were between 105 and 320 km2. Based on the dry season distribution, five different elephant clans, each consisting of between 50 and 200 individuals and having overlapping home ranges, could be defined within the study area. Seasonal habitat preferences were related to the availability of water and the palatability of food plants. During the dry months (January-April) elephants congregated at high densities of up to five individuals km-2 in river valleys where browse plants had a much higher protein content than the coarse tall grasses on hill slopes. With the onset of rains of the first wet season (May-August) they dispersed over a wider area at lower densities, largely into the tall grass forests, to feed on the fresh grasses, which then had a high protein value. During the second wet season (September-December), when the tall grasses became fibrous, they moved into lower elevation short grass open forests.The normal movement pattern could be upset during years of adverse environmental conditions. However, the movement pattern of elephants in this region has not basically changed for over a century, as inferred from descriptions recorded during the nineteenth century.

Effects of seed bed conditions on the germination of four Stylosanthes species in the Northern Territory

1976 ◽  
Vol 27 (6) ◽  
pp. 811 ◽  
Author(s):  
JJ Mott ◽  
GM McKeon ◽  
CJ Moore
Keyword(s):  
Management Practices ◽  
Surface Soil ◽  
Soil Surface ◽  
Northern Territory ◽  
Perennial Species ◽  
Wet Season ◽  
Native Grasslands ◽  
Grass Sward ◽  
Moisture Conditions ◽  
Potential Rate

Since the proposed use of low input management practices in the Northern Territory will require the establishment of Stylosanthes species in the native grasslands with the least possible disturbance, the effects of soil surface, soil type and seed treatments on the germination of four Stylosanthes species were studied. The species were the annual S. humilis, the facultative perennial S. hamara cv. Verano, and two obligate perennials, S. scabra CPI 40289 and S. viscosa CPI34904. The study was carried out on microplots in burnt and unburnt pasture near Katherine in the Northern Territory. Although all species germinated in both burnt and unburnt grassland, germination was much better under the grass sward. The two perennial species germinated much more slowly than either S. humilis or S. hamata, and the removal of grass cover caused low germination of these species, especially under the poor moisture conditions existing on the surface of sandy soils. Under the existing method of establishment with burning late in the dry season followed by sowing in the early wet season, the germination of the perennials S. scabra and S. viscosa will not attain the same levels as that of S. hamata and S. humilis. Our results suggest that field germination of the perennials could be enhanced by either pretreating the seed to improve its potential rate of germination, or by sowing later in the wet season to take advantage of the greater probability of prolonged moisture conditions.

The nodulation of annual summer legumes sown on the far north coast of NSW

1967 ◽  
Vol 7 (25) ◽  
pp. 181 ◽  
Author(s):  
MJ Cloonan ◽  
MJ Vincent
Keyword(s):  
Field Trials ◽  
Sand Culture ◽  
North Coast ◽  
Far North ◽  
South Wales ◽  
Quantitative Basis ◽  
Dry Conditions ◽  
Grass Growth ◽  
Grass Sward ◽  
Annual Summer

Difficulty has been encountered in securing the nodulation of inoculated annual summer legumes (Dolichos lablab L, and Vigna sinensis (L) Endl, ex Hassk.) sown on the far north coast of New South Wales and using strains that had proved satisfactory in sand culture trials. Satisfactory nodulation by the inoculum strain, when applied at a normal level, was secured in only one of ten trials that involved a clean cultivated seed bed and in one out of eight that were seeded directly into the grass sward. Reduction of grass growth by prior treatment with herbicide did not improve nodulation. Four out of six trials where the inoculum was 10x 100x normal were satisfactorily nodulated by the applied strain; the two failures were associated with dry conditions after sowing. Later sowings (January-March) generally resulted in better nodulation than those in December, but restricted the growing season to too short a period. A more detailed glasshouse trial with a red basaltic soil and which simulated sod-seeding conditions provided a quantitative basis for the relationship between size of inoculum and success in establishment. The extent to which the difficulties encountered in this work are due to the nature of the host, the bacterium, or both, has yet to be more fully investigated, along with the possible influence of factors in the root environment. The results illustrate the importance of field trials in strain selection and recommendations for inoculant use.

Limitations to animal production imposed by seasonal fluctuations in pasture and by management procedures

1959 ◽  
Vol 10 (2) ◽  
pp. 248 ◽  
Author(s):  
WM Willoughby
Keyword(s):  
Grazing Pressure ◽  
Animal Production ◽  
Seasonal Fluctuations ◽  
Wool Production ◽  
Continuous Grazing ◽  
Management Procedures ◽  
Grazing Systems ◽  
The Individual ◽  
Stocking Rates

An experiment with Merino wethers on a Phalaris tuberosa-subterraneum clover-volunteer grass pasture has compared throughout an annual cycle the effects of: (a) Seasonal fluctuations in quantity and quality of pasture on liveweight gains and wool production in sheep. (b) Different grazing systems at equal stocking rates both on pasture growth and on liveweight and wool production in sheep. (a) Availability of dry pasture did not affect animal production so long as green pasture was present. Small increases in green pasture in the period of slow growth (winter) gave large increases in liveweight and wool production. Large increases in green pasture in the period of rapid growth (spring) had no effect on the animal. On dry pasture (summer) heavy sheep lost more weight than light sheep. Increasing the amount of dry pasture reduced liveweight loss only slightly but resulted in a greater rate of breakdown of plant material. An asymptotic relationship between availability of green pasture aid animal gain is presented, the asymptote in this instance occurring at a,pproxirnatnly 1400 lb dry matter per acre. The implications of the results are discussed with reference to methods of investigation of species, fertilizers, end management procedures aimed at 01-ercoming pasture limitations to animal production. The validity of investigations which do not take into account the relative constancy of grazing pressure throughout the year, and the continuing effects of plant on animal and animal on plant, is questioned. (b) Regardless of the degree to which pastures had been checked by grazing in spring, all dried out simultaneously on the onset of summer, and all sheep on all treatments reached their peak liveweight turning point on approximately the same date. Less than one-third of the liveweight gain potential of the pasture was attained on any one of the three grazing systems. The mean amounts of the individual pasture components, and of the total weight of pasture, were identical at any one time under the three grazing systems. The closer the systems approached towards continuous grazing the greater were the liveweight gains and wool production.

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