Bibliography: Land Degradation in South Africa project

indicate that its role should include information sharing and/or consultation,

more than 80% also indicate that the Forum should allow for participatory

approaches and/or lobbying. In addition, various other roles are suggested. It

should also be noted that a variety of concerns were expressed by people

appreciative of the constraints and difficulties: above all that, as a meeting

place of constituencies, it must be fully representative of all role players.

In discussing a possible focus for a new structure such as a National

Environmental Forum, note should be taken of the roles played by the various

organisations already active in the environmental field and the process of

restructuring which is already underway. A Forum must bring 'added value'. To

be meaningul, it must establish clear goals, undertake to deliver on specific

tasks and actions, and be prepared to evaluate its progress and measure its

achievements. National priorities suggest other possible objectives for a

National Environmental Forum: such as, giving effect to the clause in the

interim constitution which deems that every person shall have the right to an

environment which is not detrimental to his or her health or well being; and

giving environmental perspectives to the Reconstruction and Development

Programme or the work of the National Economic Forum. Taking into consideration

international trends, the Forum could focus on promoting the concept of

'sustainable development' - integrating considerations of the environment, the

economy and equity - and effectively ensuring that environmental factors are

built into policy formulation and decision-making throughout society. A focus

on sustainable development would lend itself toward the Forum involving itself

in formulating a 'sustainable development strategy' and on establishing 'action

plans', which would provide opportunities for participation from all its

constituent members. A focus on sustainable development would also require the

involvement of a broad spectrum of society and the accommodation of perspectives

ranging from the local to the international. If there is consensus that this

Forum should reach beyond dealing with the environment in isolation and aspire

toward integrating environment and development, then consideration should be

given to a name that better reflects this role. To establish a full sense of

participation and legitimacy, it is recommended that the structure and role of

the Forum should be confirmed by convening a plenary session of consituencies.

The organisation of such a plenary should be undertaken by a convening

committee, sensitive to the needs of the various stakeholders. The convening

committee should aim to develop and present alternative ideas to the plenary, as

well as source the ressources necessary to begin and continue to operate the

Forum. To advance the process within a reasonable time frame, the work of the

convening committee should be supported by an acceptable champion/will carrier.

Ref ID : 547

301. Archer, F.M. Current and future land use in Namaqualand rural reserves.

Final report.Anonymous Athlone:Surplus People Project. , 1995.

Reprint : Not in File,

Keywords : LAND USE; NORTHERN CAPE; SUSTAINABLE AGRICULTURE

Ref ID : 1594

302. Archer, S. The Distribution of Photosynthetic Pathway Types on a Mixed-

grass Prairie Hillside. American Midland Naturalist 111(1):138-142, 1919.

Reprint : In File,

Keywords : GRASSLAND; INTERNATIONAL ASPECTS; SOIL PROPERTIES; IRRIGATION

Abstract : Plant distributions were examined on a N-facing, mixed-grass prairie

hillside near Fort Collins, Colorado. Three plant communities were recognised

along the hillside. An Agropyron smithii-dominated community was found at the

hilltop, while a Poa-Hordeum-dominated community was located at the base of the

slope. Midslope areas supported a Bouteloua-Agropyron-dominated community.

Each topographic location had different soil moistures and textures. Grasses

with the C4 photosynthetic pathway had highest importance values on well-drained

sites where soil moisture was lowest and soils were soil moisture was lowest and

soils were coarsest. C3 graminoids predominated on the relatively moist upper

and lower portions of the hillside.

Ref ID : 1596

303. Archer, S. Have Southern Texas Savannas been Converted to Woodlands in

Recent History? The American Naturalist 134(4):545-561, 1989.

Reprint : In File,

Keywords : SAVANNA; MODELS; POPULATION; PLANT PHYSIOLOGY; VEGETATION CHANGE;

CLIMATE CHANGE; GRAZING EFFECTS; ENVIRONMENTAL HISTORY

Notes : At savanna woodland sites in southern Texas, discrete clusters of woody

plants form in herbaceous clearings following the invasion of mesquite (Prosopis

glandulosa var. glandulosa), an arborescent legume. The growth rate of these

clusters has been shown to vary with precipitation and size. Based on field

data and knowledge of mechanisms of woody-plant successional processes, a

simulation model was developed to estimate the rates of growth and development

of these woody-plant assemblages on sandy-loam uplands under different

precipitation regimes. In the simulation, the establishment of other woody

species beneath invading Prosopis occurred within 10-15 yrs. As a cluster

developed around the Prosopis nucleus, species richness increased rapidly for

35-45 yrs. and become asymptotic at 10 species per cluster. The estimated age

of the oldest Prosopis plant found in clusters was 172-217 yrs. However, model-

derived size-age relationships predicted that most (90%) clusters and mesquite

plants at the site are less than 100yrs. old. A lack of field evidence of

mortality among large clusters and Prosopis plants suggests that populations are

young and expanding geometrically. There was no evidence of density-dependent

restrictions on recruitment or expansion. Thus, as new clusters are initiated

and existing clusters expand, coalescence to continuous canopy woodlands may

eventually occur. Predicted long-term mean radial trunk growth of Prosopis

(0.8-1.9 mm/yr) was reasonable in comparison with short-term field measurement

on Prosopis in other, more-mesic systems (2-4 mm/yr). Model output was also

consistent with historical observations suggesting that the conversion of

savannas to woodlands in the Rio Grande Plans has been recent and coincident

with both heavy grazing by livestock and seasonal shifts in precipitation that

began in the late 1800s. This is in agreement with woody-plant invasions

documented in other North American arid and semiarid systems by the direct aging

of woody plants.

Ref ID : 1595

304. Archer, S. Development and stability of grass/woody mosaics in a

subtropical savanna parkland, Texas, USA. Journal of Biogeography 17:453-462,

1990.

Reprint : In File,

Keywords : SAVANNA; GRASSLAND; ENVIRONMENTAL HISTORY; VEGETATION CHANGE; PLANT

PHYSIOLOGY

Abstract : The potential natural vegetation of southern Texas and northern

Mexico has been classified by plant geographers as savanna. However, many of

the present landscapes in this subtropical region are dominated by thorn

woodlands. Evidence for replacement of grasslands and savannas by woodlands is

based largely on historical accounts, many of which are conflicting. This paper

reviews and integrates a series of recent studies addressing the following

questions: (1) Have woodlands replaced grasslands or savannas? (2) If there was

a physiognomic conversion (a) what successional processes were involved; (b)

what time scale would have been required; and (c) what were the causes?

Ref ID : 932

305. Archer, S. Poverty and production in a rural microcosm: Hanover, Cape.

Africa 60(4):471-496, 1990.

Reprint : In File,

Keywords : POVERTY; AGRICULTURAL PRODUCTION; ECONOMIC ASPECTS; NAMA KAROO;

LABOUR; POPULATION; LAND TENURE

Notes : In the popular consciousness, South African poverty is a phenomenon of

the homeland or urban township and ghetto, more rarely of rural areas in the

core economy. Such a perspective is determined largely by the higher visibility

of the poor in the former localities in the recent past, for reasons of

geography and political sensitivity. This study aimed to redress the balance,

starting from two broad premises: first, that the technical and organisational

changes in production and growth of surplus labour observable in Hanover on a

microscale are representative of secular trends in commercialised agriculture

in the Karoo region as a whole; and, second, that the causes of poverty

generation in that region cannot be satisfactorily examined in isolation from

the wider political and economic processes within which they are embedded.

There is no evidence to suggest that the findings from this study are unique to

the time or place in which it was conducted. Poverty in the region is to be

found among the unemployed residents in villages and small towns; among the

working poor comprising seasonal, itinerant and part-time workers, including a

proportion of the self-employed; and among some regular employees on certain

farms and in urban work places. They all have no access to the main regional

resource, neither owning land nor cultivating or grazing land owned by others -

whether private individuals, the community or the state - under lease or tenancy

arrangements. They have low levels of formal education, coupled with severely

limited opportunities for learning-by-doing. And they are powerles to influence

these conditions. One can conclude with reasonable confidence that to sustain

the present population on the gravel plans and uplands of the central Karoo at

even moderately higher levels of welfare is inconceivable in the absence of far-

reaching alternations in land tenure, in production techniques and organisation,

and in social priorities.

Ref ID : 1602

306. Archer, S. Tree-grass dynamics in a Prosopis-thornscrub savanna parkland:

Reconstructing the past and predicting the future. Ecoscience 2(1):83-99, 1995.

Reprint : In File,

Keywords : SAVANNA; GRASSLAND; MODELS; MICROCLIMATE; VEGETATION DYNAMICS;

VEGETATION CHANGE; VELD CONDITION

Abstract : Although trends toward increased woody plant abundance in grasslands

and savannas in recent history have been reported worldwide, our understanding

of the processes involved is limited. Here I review and integrate a series of

studies which quantify the rates, dynamics, spatial patterns and successional

processes involved in tree patch and woody plant community development at a

savanna parkland site in southern Texas, USA. Stable carbon isotope ratios of

soil organic carbon indicate C3 woody plants currently occupy sites once

dominated by C4 grasses. Historical aerial photographs (1941-1990), tree ring

analysis and plant growth models all indicate this displacement has occurred

over the past 100 to 200 years. Succession from grass- to woody plant -

domination occurs when the N2-fixing arborescent, honey mesquite (Prosopis

glandulosa (Torr.) var. glandulosa), invades and establishes in herbaceous

patches. Over time, this plant modifies soils and microclimate to facilitate

the ingress and establishment of additional woody species. The result is a

landscape comprised of shrub clusters of varying ages organized around a

Prosopis nucleus. As new clusters form and existing clusters enlarge,

coalescence occurs. This process appears to be in progress on upland portions

of the landscape and has progressed to completion on lowlands. Rates of cluster

development and patterns of distribution appear regulated by subsurface

variations in clay concession from grassland to woodland steady states would

require 400 - 500 years, with the most dramatic changes occurring over a 200-

year period. The shrubs initially facilitated by Prosopis appear to contribute

to its demise and prevent its re-establishment. Structure and function of

future communities may therefore depend on how remaining woody plants react to

changes in microclimate and nitrogen cycling that occur after Propsopis is gone.

Ref ID : 1601

307. Archer, S. Ecological Implications of Livestock Herbirory in the West,

1998.pp. 13-68.

Reprint : In File,

Keywords : GRASSLAND; SAVANNA; VEGETATION CHANGE; FIRE; CLIMATE; MODELS; GRAZING

EFFECTS; PLANT-ANIMAL INTERACTIONS; ENVIRONMENTAL HISTORY; DESERTIFICATION

ASSESSMENT; CLIMATE CHANGE; SUSTAINABLE DEVELOPMENT; VELD CONDITION

Abstract : Warm temperature grasslands and savannas which characterised many

landscapes in southwestern North America at the time of European settlement have

been replaced by shrublands and woodlands. These changes in plant life-form

composition were coincident with the introduction of large numbers and high

concentrations of livestock. While a cause-effect relationship is implied, it

is difficult to demonstrate, since most evidence is based on anecdotal

historical accounts or descriptions from localized long-term studies, many of

which are conflicting. Case studies documenting the rate, pattern and extent of

vegetation change are summarized and used to illustrate how historical

inconsistencies might be resolved. Where vegetation history is reasonably known,

causes for change are evaluated. Explanations for the proliferation of woody

plants and the associated decline of graminoids have typically centered around

alterations in climatic, grazing and fire regimes. Each of these factors is

addressed individually and in combination. It is argued that : (1) Atmospheric

CO2 enrichment and directional shifts in climate may have occurred, but have not

been sufficient, to cause the vegetation changes observed to date; (2) Fire is

not necessarily required to maintain grasslands or savannas; and (3) Although

herbivory, lack of fire, atmospheric CO2 enrichment and climate have interacted

to produce recent vegetation change, selective grazing by large numbers and high

concentrations of livestock has been the primary force in altering plant life-

form interactions to favour unpalatable woody species over graminoids.

Conceptual models illustrating the role of grazers in directing plant succession

are presented in the context of ecosystem resilience, multiple steady states and

positive feedbacks.

Ref ID : 1604

308. Archer, S., Schimel, D.S., and Holland, E.A. Mechanism of shrubland

expansion: land use, climate or CO2? Climatic Change 29:91-99, 1995.

Reprint : In File,

Keywords : LAND USE; CLIMATE; GRASSLAND; SAVANNA; FIRE; BUSH ENCROACHMENT;

VEGETATION CHANGE; CLIMATE CHANGE; GRAZING EFFECTS

Abstract : Encroachment of trees and shrubs into grasslands and the

'thickenization' of savannas has occurred worldwide over the past centry. These

changes in vegetation structure are potentially relevant to climatic change as

they may be indicative of historical shifts in climate and as they may influence

biophysical aspects of land surface-atmosphere interactions and alter carbon and

nitrogen cycles. Traditional explanations offered to account for the historic

displacement of grasses by woody plants in many arid and semi-arid ecosystems

have centered around changes in climatic, livestock grazing and fire regimes.

More recently, it has been suggested that the increase in atmospheric CO2 since

the industrical revolution has been the driving force. In this paper we

evaluate the CO2 enrichment hypotheses and argue that historic, positive

correlations between woody plant expansion and atmopheric CO2 are not cause and

effect.

Ref ID : 1605

309. Archer, S., Scifres, C., Bassham, C.R., and Maggio, R. Autogenic succession

in a subtropical savanna:conversion of grassland to thorn woodland. Ecological

Monographs , 1998.

Reprint : In File,

Keywords : VEGETATION DYNAMICS; GRASSLAND; SAVANNA; DROUGHT; ENVIRONMENTAL

HISTORY; PLANT PHYSIOLOGY; STATISTICS

Abstract : Dense thorn woodlands occupy what are thought to have been grasslands

and savannas prior to settlement of the Rio Grande Plains of Texas. However,

the tenet that grasslands have been converted to shrublands and woodlands in

recent history is controversial and based largely upon conflicting historical

accounts. Our objective was to determine how the presumed physiognomic

converstion from grassland or savanna to woodlands might have occurred. Some

upland landscapes are dominated by closed-canopy woodlands in southern Texas,

whereas others have a two-phase pattern of discrete shrub clusters scattered

throughout a grassland. More mesic sites are dominated by closed-canopy

woodlands. We hypothesized the two-phase landscapes represented an intermediate

stege in the coversion of grassland to woodland. As new shrub clusters were

initiated and existing clusters expanded and coalesced, a gradual shift from

grassland to savanna to woodland would occur. To address this hypothesis, we

inventoried herbaceous interspaces for woody colonizers, quantified the

composition and distribution of shrub clusters on upland sites, and compared the

structure of clusters to that of adjacent, more mesic areas with continuous

woody plant cover. To assess the physiognomic stability of the two-phase

landscapes, cluster size, density, and cover were quantified for 1941, 1960 and

1983 from aerial photographs. A lone mesquite (Prosopis glandulosa) plant

occurred in >80% of the upland clusters, where it was typically the largest

individual in terms of basal area, height, and canopy area. The number of woody

species per cluster ranged from 1 to 15 and was strongly related to mesquite

basal diameter (R2 = 0.86). Cluster diversity, evenness, and size were also

significantly correlated with mesquite size. The data suggest that mesquite

plants invaded grasslands and served as recruitment foci for bird-disseminated

seeds of other woody species previously restricted to other habitats. The result

was a landscape composed of discrete chronosequences of woody plant assemblages

organized about a mesquite nucleus. Within the two-phase portion of the

landscape, 50% of the clusters were within 5 m of another and 95% were within 15

m of another. Analysis of the size class distribution of clusters suggested

that most had yet to realize their growth potential. Moreover, the herbacious

clearings between clusters contained high densities of woody seedlings, mostly

(>70%) mesquite, which occurred in 85% of the clearings, with a mean density of

350 plants/ha. Coalescence will become increasingly probable if new clusters

are initiated and existing clusters expand. This phenomenon appeared to be in

progress on one portion of the landscape and had apparently already occurred on

others. As clusters developed on the two-phase portion of the landscape, their

species composition, dominance, and size class structure became increasingly

similar to that of adjacent closed-canopy woodlands on more mesic sites. Mean

cluster size increased from 494 m2 in 1941 ro 717 m2 in 1983. Growth rates of

clusters were a function of cluster size and precipitation. During the 1941 -

1960 period characterized by severe drought, there was a slight decrease in

total woody plant cover resulting primarily from the formation of gaps among

clusters on the periphery of the site and a 35% decrease in density of clusters

<5 m2. These cover losses offset the areal expansion of small (<100 m2)

clusters which had an average relative growth rate (RGR) of 0.10 m2.m-2.yr-1.

Post-droughtwoody plant cover increased from 8% in 1960 to 36% in 1983 as new

clusters were initiated (density increased from 16 to 26 clusters/ha), and the

RGR of small clusters increased to 0.16 m2.m-2.yr-1. Numerous clusters coalesced

during this period. RGRs of clusters > 100 m2 were an order of magnitude lower

than those of clusters < 100 m2 in each time period. The RGR of large clusters

following the drought was not significantly increased, except in the largest

size class (clusters > 1,000 m2). Our results indicate 1. mesquite invaded

grasslands and served as the nucleus of cluster organisation on upland sites; 2.

woody plant commuinty development has been highly punctuated by variations in

precipitation; 3. clusters > 5 m2 in area are persistent features of the

landscape; and 4. the present two-phase pattern is moving toward a monophasic

woodland as new clusters are initiated and existing clusters expand and

coalesce. As a result, 5. shrub clusters on uplands represent an intermediate

stage in the converstion of grassland to where this has already occurred.

Because the conversion of grasslands and savannas to woodlands in the Rio Grande

Plains is initated by mesquite, factors regulating its dispersal, establishment,

and role as a facilitator of woody community development are emphasized.

Ref ID : 1607

310. Archer, S. and Smeins, F.E. Grazing management: an ecological perspective,

Oregon:Timber Press, 1919.pp. 109-138.

Reprint : In File,

Keywords : CLIMATE; POLICY; LIVESTOCK PRODUCTION; GRAZING EFFECTS; VELD

MANAGEMENT; AGRICULTURAL PRODUCTION; PLANT-ANIMAL INTERACTIONS; CLIMATE CHANGE;

SOIL PROPERTIES; FIRE; DESERTIFICATION ASSESSMENT; ENVIRONMENTAL POLICY

Notes : Most grazed systems in arid and semiarid regions are expansive and

heterogeneous. Plant production is limited by climatic and edaphic factors.

Because of the numerous, interactive, and to a large extent stochastic processes

that regulate species composition and productivity in natural systems, it is

difficult and misleading to propose standard prescriptions for vegetation

management. Agronomic approaches, with their heavy emphasis on expensive

cultural inputs and treatments, have a high rate of failure in arid and semiarid

situations and are typically not economically feasible even when successfully

implemented. It is therefore essential to acquire a functional understanding of

the basic ecological processes that drive natural systems and develop flexible

management strategies that work within constraints dictated by soils and a

highly variable and unpredictable climate. The traditional concept of single