Bibliography: Land Degradation in South Africa project

savannas, had received attention in the literature. It has contributed to some

understanding of the nature and dynamics of the vegetative growth, reproduction

and browse production (including animal-plant interactions) of woody plants in

various savanna ecosystems. It has also demonstrated the complexity and

heterogeneity of the different savanna ecosystems. Gaps in our knowledge,

linked to specific options of land use, were identified. Within the context of

the importance of woody plants, some recommendations on future research in

savanna are made.

Ref ID : 2080

1837. Smit, H.A.P. and De Kock, G.L. Ruimtelike diffusie van die indringerplant

Pinus pinaster teen die hange van Stellenboschberg. South African Forestry

Journal 129:10-16, 1984.

Reprint : Not in File,

Ref ID : 1817

1838. Smith, F.R. and Tainton, N.M. Effects of season of burn on shrub survival,

regeneration and structure in the Natal Drakensberg. Journal of the Grasslands

Society of Southern Africa 2(2):4-10, 1985.

Reprint : In File,

Keywords : GRASSLAND; FIRE

Abstract : Four shrub species which tend to invade unburnt grassland were

studied in field-burning trials at Cathedral Peak in the Natal Drakensberg.

Results showed that neither hot winter burns, nor cool summer burns, affected

the ability of Buddleia salviifolia, Leucosidea sericea, Widdringtonia nodiflora

or Philippia evansii to survive fire. The first three species resprouted

following damage to their root systems. The winter burns damaged more canopy,

resulting in proportionally more basal resprouting and higher net gains in new

stems. Summer burns, on the other hand, resulted in proportionally more

defoliated stems developing aerial resprouts. P. evansii, in contrast, was

sensitive to fire and the species regenerated from seed, with larger recruitment

of seedlings following winter than summer rains. Season of burn was shown to be

important insofar as it affected shrub structure and the nature and amount of

regeneration. Management objectives would therefore influence the way in which

fire is used in these shrublands.

Ref ID : 1292

1839. Smith, M. Te min word gedoen om woestyne te keer, waarsku kenners.

Volksblad , 1998.

Reprint : In File,

Keywords : DESERTIFICATION ASSESSMENT; LAND DEGRADATION

Notes : There is a small mention of the work that is being done by the National

Botanical Institute. The author states that too little is being said and at too

slow a pace regarding the struggle against desertification in SA. She makes

mention of the immensity of the problem, its implications and mentions some of

the people and organisations which are involved in fighting its spread in SA.

Ref ID : 1961

1840. Smithen, A. Procedure for soil loss estimation. 199.

Reprint : Not in File,

Notes : Undated, unpublished internal memo, of the Department of Agriculture,

KZN region.

Ref ID : 1962

1841. Smithen, A. Soil loss estimates for ecotope trial run -KZN region. 199.

Reprint : Not in File,

Keywords : KWAZULU NATAL

Notes : Undated, unpublished internal memo, of the Department of Agriculture in

KwaZulu-Natal.

Ref ID : 492

1842. Smithen, A. Characteristics of rainfall erosivity in South

Africa.University of Natal, Pietermaritzburg. , 1981. Master of Science.

Reprint : Not in File,

Keywords : SOIL EROSION; RAINFALL EROSIVITY

Ref ID : 493

1843. Smithen, A. and McPhee, P.J. Developing factors for the Universal Soil

Loss Equation in South Africa. Poster presented at the International Symposium

on Agricultural Engineering, Pretoria. 1986.

Reprint : Not in File,

Keywords : SOIL EROSION; MODELS

Ref ID : 356

1844. Smithen, A.A. Characteristics of rainfall erosivity in South

Africa.University of Natal, Pietermaritzburg. , 1981. Master of Science.

Reprint : In File,

Keywords : SOIL EROSION; HYDROMETEOROLOGY; RAINFALL EROSIVITY; RAINFALL; AID;

ENERGY; RUNOFF

Notes : Only Summary and one figure (fig. 7.4) photocopied. For a country such

as SA all the factors of soil loss equations except rainfall erosivity can

generally be obtained from published design aids. Rainfall erosivity, however,

is a function of regional rainfall characteristics and as such can only be

evaluated using regionally available data. Rainfall kinetic energy, E, has been

shown to be easily extrapolated from daily rainfall data since it is generally

well correlated with total rainfall amount, either on a monthly or annual basis.

The rainfall and runoff factor in general use in USA, however, combines energy

with sustained intensity in the interaction term EI30. This term is not

generally as well correlated with rainfall amount as rainfall kinetic energy is,

however, and more complex methods of estimation had to be devised to generate

EI30 data for SA. Techniques were therefore investigated whereby EI30 could be

related to rainfall parameters available from daily rainfall data. Use of these

parameters, which could be linearly related to annual EI30, provided a means of

generating EI30 data for some 400 stations with, in some cases, up to 100 years

of record. Data thus generated could be used tentatively for design purposes.

The application of extrapolated EI30 values to research projects is an

additional use for the extrapolation techniques. Following the development of

estimation techniques and the application of these techniques, aspects of the

EI30 term were examined in some detail. Data from the key stations provided a

means of investigating the temporal distribution of the term, its relationship

with rainfall kinetic energy and the possibility of defining rainfall erosivity

domains in terms of rainfall intensity distributions. The temporal distribution

is required for design purposes. Since soil loss has been shown to be directly

proportional to EI30 the relationship between EI30 and E was used to investigate

possible differences in the soil loss: E relationship for different parts of SA.

EI30 data generated by the estimation techniques facilitated the computation of

long term average annual EI30 values. These values are of fundamental

importance in the application of the USLE. Extreme values of annual EI30 were

also computed for 2, 5, 10, 25, 50 and 100 year return periods although these

values are not required for standard applications of the USLE. Extrapolated

EI30 values were used to test the term against recorded soil loss data from

Pretoria and Glen where significant soil loss: EI30 relationships were obtained.

Ref ID : 357

1845. Smithen, A.A. Crop cover management as a soil conservation tool - An

investigation with maize. Agricultural Engineering in South Africa 17(1):41-45,

1997.

Reprint : Not in File,

Keywords : SOIL EROSION; CULTIVATION; FARMING SYSTEMS; DESERTIFICATION CONTROL;

SOIL CONSERVATION

Ref ID : 358

1846. Smithen, A.A. and Schulze, R.E. The spatial distribution in Southern

Africa of rainfall erosivity for use in the universal soil loss equation. Water

SA 8(2):74-78, 1982.

Reprint : In File,

Keywords : SOIL EROSION; HYDROMETEOROLOGY; RAINFALL EROSIVITY; RAINFALL; MAPS;

SOUTHERN AFRICA

Abstract : Rainfall erosivity parameters are essential in soil loss modelling.

Parameters reflecing the effects of soil, vegetation and topography can be

estimated from tables and nomographs which are currently available. Rainfall

erosivity, however, is a climatic factor which can only be determined from local

rainfall data. The derivation of the rainfall erosivity factor EI30 from four

parameters based on daily rainfall values is discussed and design values of the

term currently used in the Universal Soil Loss Equation are presented in the

form of an iso-erodent map for Southern Africa. Annual values of rainfall

erosivity which may be expected for a 25 year return period are also given.

Ref ID : 1467

1847. Smuts, B. Drought and flood damage in South Africa. Africa Wildlife

39(1):92, 1985.

Reprint : Not in File,

Keywords : DROUGHT; FLOODS; DESERTIFICATION CONTROL; IRRIGATION

Ref ID : 2180

1848. Snaddon, C.D. Some of the ecological effects of a small inter-basin water

transfer on the receiving reaches of the Upper Berg River, Western

Cape.University of Cape Town. , 1998.

Reprint : Not in File,

Keywords : WESTERN CAPE

Notes : Unpublished M.Sc. thesis.

Ref ID : 2181

1849. Snaddon, C.D. and Davies, B.R. An analysis of the effects of inter-basin

water transfers in relation to the New Water Law.Anonymous , 1997.

Reprint : Not in File,

Keywords : FORESTRY

Notes : Report prepared for the Department of Water Affairs and Forestry.

Ref ID : 2182

1850. Snaddon, C.D. and Davies, B.R. A preliminary assessment of the effects of

a small-basin water transfer, the Riviersonderend-Berg River Transfer Scheme,

Western Cape, South Africa, on discharge and invertebrate community structure.

Regulated Rivers: Research and Management 14:421-441, 1998.

Reprint : Not in File,

Keywords : WESTERN CAPE

Ref ID : 1474

1851. Snyman, A. In the beginning. Farming in South Africa 46(9):30-31, 1970.

Reprint : Not in File,

Keywords : ENVIRONMENTAL HISTORY

Ref ID : 1782

1852. Snyman, D.D. and Grossman, D. Tekortkominge van die naasteplantmetode en

Dyksterhuis-verwante klassifikasiesisteme om veldtoestand in semi-ariede gebiede

te bepaal. Journal of the Grasslands Society of Southern Africa 7(4):273-276,

1990.

Reprint : In File,

Keywords : VELD CONDITION

Abstract : Shortcomings of the nearest plant methods and Dyksterhuis-related

classification systems for assessing veld condition in the semi-arid regions.

Veld condition was determined on seven farms in the Mopane veld, during two

seasons using the nearest plant method and a Dyksterhuis-related classification

system. During wet periods, Increasers 2c increased faster than Increasers 2b,

2a and Decreasers and this resulted in lower veld condition scores during wet

periods. The limitations of this method are discussed in the light of other

driving forces.

Ref ID : 359

1853. Snyman, H.A. Swak veldbestuur bevorder erosie/(Bad veld management

promotes erosion). Golden Fleece 15(12):12-15, 1986.

Reprint : Not in File,

Keywords : SOIL EROSION; VELD MANAGEMENT

Ref ID : 360

1854. Snyman, H.A. Grondverliese as gevolg van reenwaterafloop van veld/Soil

loss as a result of rainfall runoff. Glen Agric 16(1):3-6, 1987.

Reprint : Not in File,

Keywords : SOIL EROSION; HYDROMETEOROLOGY; VELD MANAGEMENT; VELD CONDITION;

RUNOFF

Ref ID : 650

1855. Snyman, H.A. Bepaling van waterverbruiksdoeltreffendheid van veld in die

sentrale Oranje-Vrystaat vanaf evapotranspirasiemetings/Determining water-use

efficiency of veld in the central Orange Free State from evapotranspiration

measurements. Water SA 14(3):153-158, 1988.

Reprint : In File,

Keywords : SOIL EROSION; PLANT PHYSIOLOGY; GRASSLAND; FREE STATE; VELD CONDITION

Abstract : Hydraulic non-floating lysimeters were used to determine

evapotranspiration (Et) and water use efficiency of veld in different

successional stages, over a four-year period. The mean yearly Et from the

climax, subclimax and pioneer communities were respectively 614,95; 603,58 and

557,15 mm. On average the daily Et from climax, subclimax and pioneer

communities was respectively 1,73; 1,71 and 1,55 mm. Measured evaporation (Es)

from bare soil lysimeters was 31,6% less than Et from climax grass community.

Statistically significant differences (P<0,01) in water use efficiency between

the climax, subclimax and pioneer communities were recorded with averages of

2,6830; 1,5840 and 0,9339 kg/ha above-ground dry matter accumulation for each mm

of water evapotranspired.

Ref ID : 639

1856. Snyman, H.A. Evapotranspirasie en waterverbruiksdoeltreffendheid van

verskillende grasspesies in die sentrale Oranje-Vrystaat/Evapotranspiration and

water use efficiency of different grass species in the central Orange Free

State. Tydskrif.Weidingsveren.S.Afr. 6(3):146-152, 1989.

Reprint : In File,

Keywords : SOIL EROSION; VELD MANAGEMENT; VELD CONDITION; GRAZING EFFECTS; PLANT

PHYSIOLOGY; GRASSLAND

Abstract : Evapotranspiration (Et) and water use efficiency (WUE) were

determined for each of seven grass species during the 1986/87 and 1987/88

seasons. The highest and lowest mean daily Et of 2,39 and 1,66 mm were recorded

respectively for Themeda triandra and Sporobolus fimbriatus. Between species,

the average Et for the two seasons did not differ significantly. On average the

highest level and lowest WUE of 7,83 and 4,72 kg/ha above-ground phytomass

produced for each mm water evapotranspired, were recorded respectively for

Cymbopogon plurinodis and Panicum stapfianum. The average WUE of C. plurinodis,

Digitaria eriantha and T. triandra was 38% (P<0,01) higher than that of the

other four species. Under conditions of moisture stress the WUE of the above-

mentioned three species was the lowest and that of Eragrostis chloromelas the

highest.

Ref ID : 1433

1857. Snyman, H.A. The influence of range conditions on the hydrological

characteristics in a semi-arid rangeland.Anonymous Anonymous South

Africa:University of Orange Free State. 2(23):23-1-23-2, 1994. Herbage

production, water-use efficiency (i.e. above-ground phytomass production per

unit of evapotranspiration), surface runoff, deep percolation, soil loss and

soil organic matter content were determined on rangeland in three different

ecological conditions, viz. poor, moderate and good, for 20 years. Hydraulic

non-floating lysimeters were used to determine evapotransiration (Et), soil

evaporation (E) and deep percolation. Runoff and soil loss were recorded on

runoff plots. Above-ground phytomass production, water-use efficiency, deep

percolation and soil organic matter content decreased (P < 0.01) when plant

cover was reduced or range and soil condition delined. The dense plant cover of

veld in good condition provides a situation in which surface runoff and soil

loss rates are lower (P < 0.01) than that from veld in poor condition.

Reprint : In File,

Keywords : RUNOFF; VEGETATION DYNAMICS; SOIL NUTRIENTS; HYDROLOGY; PLANT

PHYSIOLOGY; VELD CONDITION; GRASSLAND

Ref ID : 977

1858. Snyman, H.A. The influence of range condition on the hydrological

characteristics in a semi-arid rangeland. Proceedings of the XVIII International

Grassland Conference, Canada 2(23):1-2, 1995.

Reprint : In File,

Keywords : VELD CONDITION; HYDROLOGY; GRAZING EFFECTS; SOIL PROPERTIES; LAND

DEGRADATION; RUNOFF

Abstract : Herbage production, water-use efficiency (i.e. above-ground phytomass

production per unit of evapotranspiration), surface runoff, deep percolation,

soil loss and soil organic matter content were determined on rangeland in three

different ecological conditions, viz. poor, moderate and good, for 20 years.

Hydraulic non-floating lysimeters were used to determine evapotranspiration

(Et), soil evaporation (E) and deep percolation. Runoff and soil loss were

recorded on runoff plots. Above-ground phytomass production, water-use

efficiency, deep percolation and soil organic matter content decreased (P<0.01)

when plant cover was reduced or range and soil condition declined. The dense

plant cover of veld in good condition provides a situation in which surface

runoff and soil loss rates are lower (P<0.01) than that from veld in poor

condition.

Ref ID : 968

1859. Snyman, H.A. Die dinamika en volhoubare benutting van die

weidingekosisteem/The dynamics and sustainable utilization of the grazing

ecosystem. 1997.

Reprint : In File,

Keywords : VEGETATION DYNAMICS; SUSTAINABLE AGRICULTURE; PRODUCTION POTENTIAL

Notes : The author states that the world, with all its natural resources, as we

know it today, has come to exist as it is as a result of millions of years

development through natural processes. Living organisms, on the other hand,

cannot be viewed independently from the context in which they live - they are

constantly being affected by it, as the context itself is again affected by the

organisms which live in it. This ecosystem and an understanding of it is of

fundamental importance to humans' environmental problems. SA is blessed with an

enormous variety of natural resources of which soil, the atmosphere, and flora

are probably some of the most noteworthy as regards the continued survival of

its people. Depending on how these resources are taken care of, their

advantages can be used by South Africans for many years to come. The aim of

this paper is to bring some thoughts to bear in this respect. The talk will

deal with varying topics, including scientific ideas on grazing, and challenges

and opportunities to sustainable production.

Ref ID : 873

1860. Snyman, H.A. Dynamics and sustainable utilization of the rangeland

ecosystem in arid and sem-arid climate of South Africa. Unpublished Inaugural

Address, Department of Grassland Scienses, University of the Orange Free State.

1997.

Reprint : Not in File,

Keywords : VELD CONDITION; LAND DEGRADATION; HYDROLOGY; RUNOFF; VELD MANAGEMENT;

VEGETATION DYNAMICS; GRAZING EFFECTS; GRASSLAND; FREE STATE; CLIMATE; RAINFALL

Abstract : This paper examines the protection, security, productivity, viability

and acceptability aspects of range management ecology as it relates to

sustaining rangeland ecosystems in specific arid and semi-arid climate. The

efficiency, cost-effectiveness and risk with which rainfall is converted into

plant production and eventually gross farming income, without deterioration of

natural resources, form the essence of sustainability of the rangeland ecosystem

in these areas. Range and soil degradation can dramatically influence soil

water balance, nutrient cycling, soil loss, production and the economics of a

farm unit. With respect to deterioration and the loss of productivity of

natural vegetation, a co-ordinated approach is needed towards getting a

comprehensive inventory of the condition of the natural vegetation resources on

a geographically and scientifically sound basis.

Ref ID : 1697

1861. Snyman, H.A. Dynamics and sustainable utilization of rangeland ecosystems

in arid and semi-arid climates of southern Africa. Journal of Arid Environments

39:645-666, 1998.

Reprint : In File,

Keywords : CLIMATE; SOUTHERN AFRICA; DESERTIFICATION ASSESSMENT; VELD CONDITION;

VELD MANAGEMENT; WATER CONSERVATION; RUNOFF; EROSION; CARRYING CAPACITY;

ECONOMIC ASPECTS; GRASSLAND; HYDROLOGY; RANGELAND DEGRADATION; SOIL NUTRIENTS;

STOCKING RATE; CONSERVATION; RAINFALL

Abstract : This review examines the conservation, risk, productivity, viability

and acceptability of range management technology as it relates to sustaining

rangeland ecosystems specifically in arid and semi-arid climates. The

efficiency, cost effectiveness and risk with which rainfall is converted into

plant production, and eventually gross farming income, without deterioration of

natural resources form the essence of sustainability of rangeland ecosystems in

these areas. Range and soil degradation can dramatically influence soil water

balance, nutrient cycling, soil loss, production and the economics of a farm

unit. Mangement for long-term sustainability often requires sacrifice of short-

term welfare. With respect to deterioration and loss of productivity of natural

vegetation, a co-ordinated approach is needed towards establishing a

comprehensive inventory of the condition of national vegetation resources on a

geographically and scientifically sound basis.

Ref ID : 640

1862. Snyman, H.A. and Fouche, H.J. Production and water-use efficiency of semi-

arid grasslands of South Africa as affected by veld condition and rainfall.

Water SA 17(4):263-268, 1991.

Reprint : In File,

Keywords : SOIL EROSION; PLANT PHYSIOLOGY; PRODUCTION POTENTIAL; VELD CONDITION;

GRAZING EFFECTS; CLIMATE; GRASSLAND; RUNOFF; DROUGHT; RAINFALL

Abstract : Water is one of the most important determinants of plant production,

especially under semi-arid conditions. In the past, pasture science researchers

in SA paid very little attention to water-balance studies under semi-arid

conditions, thus identifying the needs for this study. Plant production, runoff

and water-use efficiency (i.e. above-ground phytomass production per unit of

evapotranspiration) were determined on runoff plots on veld (rangeland) in 3

different conditions, over a period of 12 years. Evapotranspiration was

calculated using the soil water-balance equation. Runoff, water-use efficiency

and plant production differed significantly (P<0.01) among the veld conditions.

High runoff and low water-use efficiency of veld in a poor condition resulted in

apparent droughts, even during periods of average rainfall. Veld condition,

rather than rainfall, appeared to be the more important factor controlling

runoff and water-use efficiency.

Ref ID : 634

1863. Snyman, H.A. and Van Rensburg, W.L.J. Hidrologiese siklus van natuurlike

veld in die sentrale Oranje-Vrystaat/Hydrological cycle of natural veld in the

central Orange Free State. SA Tydsrif vir Natuurwetenskap en Tegnologie

5(4):181-185, 1986.

Reprint : In File,

Keywords : SOIL EROSION; HYDROLOGY; VELD CONDITION; VELD MANAGEMENT; GRASSLAND;

FREE STATE; RUNOFF; RAINFALL

Abstract : The hydrological cycle, which determines the water balance of the

grazing ecosystem, is discussed. This cycle can be separated into a number of

intermediate processes, each of which influences the water balance. These

intermediate processes include surface runoff, evapotranspiration, percolation,

infiltration and the storage of water in the ecosystem. Practical guidelines to

increase the effectivity of the available rainfall for aboveground phytomass

production, in arid and semi-arid regions, are discussed.

Ref ID : 635

1864. Snyman, H.A. and Van Rensburg, W.L.J. Invloed van helling en plant