Where the work of others has been used, it is duly acknowledged in the text. NUFU – Norwegian Program for Development, Research and Education One year, three years and six years – refers to the three fire exemption periods north of the Manzengwenya offices, unless otherwise indicated.
Introduction
Previously, however, large parts of the East Coast were forested with Pinus elliottii, which effectively precluded the use of fire in the surrounding grasslands. Management is also concerned about the reduction of coastal dune forest of the Coastal Forest Reserve due to frequent fires.
Literature review
The edaphic grasslands have been shown to be rich in perennial grass species compared to the hygrophilous grasslands (Siebert et al. 2004). Head fires result in a greater top kill of stems and branches compared to ridge fires (de Ronde et al. 2004;.
Study area
C LIMATE
Maputaland is located on the southernmost part of the Mozambican Coastal Plain and is bounded by the Lebombo Mountains to the west and the Indian Ocean to the east (Matthews et al. 2001), with a coastal dune range present along the entire coastline (Tinley 1985). Maud (1980) provides a concise summary of the succession of both rocks and unconsolidated sediments underlying the Maputaland region and is presented in Table 3.1.
S OILS
Groundwater and associated groundwater movements play an important role in determining vegetation patterns in most of the Maputaland region. Coastal dunes play a key role in augmenting groundwater through lateral seepage and during times of severe drought can produce as much as ten percent of the freshwater entering Lake St Lucia (Hutchinson & Pitman 1976).
Trials
However, the burning was done to coincide with the burning of the recently felled pine plantation block within which the trial is located. As opposed to implementing a third 'burning' and shearing trial at another site in the iSimangaliso Wetland Park (IWP), the unburned part of block two on the Eastern Shores mentioned above was used.
Prior to the wildfire, the biomass of the surface fuel consisting of the standing grassland was determined using the disc grazing meter (DPM) (Bransbury & Tainton 1977) for a site both on the eastern shore of Lake St Lucia and north of the Manzengwenya Offices. This was an estimate of the extent to which the grassland directly below the DPM was hardened.
Typical plot with vegetation around the Helichrysum kraussii plants removed by clipping
R ESULTS
A further increase in the fire exclusion period results in a relatively disproportionate reduction in plant density change. Grass species within areas with a three-year fire exclusion period show a different trend although a similar species response is evident. The main difference compared to sites with a one-year fire exemption period is the reduction in total plant density.
This species response to catenal position was evident at sites with a one-year fire exclusion, but not as pronounced. The number of herbaceous species increased in locations with a fire exclusion period of three years (Figure 4.5.8) compared to locations with a one-year exclusion period. Cyperus natalensis had increased density for lower sites, a reversal from the 1-year fire exclusion.
Twenty-three of the 28 woody species were present for sites with a one-year fire exclusion period (Figure 4.5.10). The following woody species were not present within the one year fire exclusion period: Eriosema saligna, Isoglossa ovata, Kraussia floribunda, P.
View south towards the Manzengwenya Offices (left of number 3). Note the appreciable difference in vegetation structure between annual burning (1), three year fire
These two sites are both downstream from a three (MBP 6 B) and six year (MBP 9 B) fire exemption period. The three-year fire exception resulted in above-average abundance for a number of woody species for east- and west-facing sites. For this fire exemption period (three years) the western areas (MBP 4 W) have a greater abundance of these species compared to the east facing sites (MBP 5 E) the largest of which is the grass species I .
Locations with a one-year fire exclusion period have greater evenness compared to the other two fire exclusion periods. Aboveground biomass for unpruned plots with a one-year fire exclusion period was dominated by grass. Soil sites with a one-year fire exclusion period had the greatest biomass and this decreased to west-facing sites.
This was also observed for east- and west-facing sites with a one-year fire exclusion period. A one-year fire exclusion promoted an increase in herbaceous biomass compared to a three-year fire exclusion period. Interestingly, sites with a six-year fire exclusion period had a greater number of herbaceous species with increased abundance for these sites.
Diversity was greatest within sites with a six-year fire exclusion period and decreased with an increase in fire exclusion.
Areas regenerating following complete defoliation due to the clipping treatment for the trials and cool point source burning
Aerial photography
- R ESULTS
Determine and describe historical changes in both the relative proportions and spatial variations of grassland, bushveld/savannah and dune forest over time (1937 to present) for selected locations on the east coast of Lake St. Lucia and adjacent Tewate Wilderness Area. As a result, central portions that include hygrophilous grasslands are located in the center of the Tewate area, but form the western boundary for the east coast. A clear trend is visible for the vegetation categories digitized for the east coast area (Table 5.1).
It is also interesting to note that this area increases more for the eastern part of the study area compared to the western side. Also note the location of the shades representing the vegetation categories Grassland (shades of red) and Scattered trees (shades of blue). Between 1937 and 1975, the majority of the areas that contained scattered trees progressed to Duinbos (Blue) and the lower lying parts of Grassveld to Scattered Trees (Red).
Compared to the eastern coast where Dune Forest has increased to dominate 60% of the vegetation, these increases within Tewate are minimal. For the eastern coast, scattered trees increased and then decreased with a change through to Duinbos and grassland decreased drastically. Of this particular area of study that was not so obvious for the East Coast is the influence of the water table on woody species establishment and expansion.
This is highly exaggerated for the examined section on the east coast and can be attributed to active fire exclusion.
Conclusions
The grasses were negatively correlated with the fire exclusion period, with an increase in the exclusion period resulting in a decrease in the number of grass species within the grassland. As a result, the field condition also decreased with increased fire exclusion and therefore adversely affected the carrying capacity. Therefore, sites with a reduction in fire exclusion period were characterized by an abundance of a few palatable grass species and a less than average abundance of herb and tree species.
The response of plant biomass to fire exclusion, catenal position and clipping highlighted the improvement in grass species vigor when regularly defoliated, and this decreased as the fire exclusion period increased. The distribution of this species is restricted to areas above the influence of the water table and is rapidly lost from the system among larger, closed, covered woody species. H. In terms of species response to management regimes, researchers should take note of the short woody species. within the turf, especially if wood density is considered as response variation.
The soil locations were significantly denser, indicating differences within the fire exclusion period that require further investigation. Clipping trials have been halted, but it is recommended that fire exclusion periods north of the Manzengwenya offices continue for three and one.
55 Figure 4.5.6 Density (plants ha-1) for selected grass species (ordered by species location, local average) for sites with a six-year fire exclusion period, Manzengwenya Offices, South Africa. 56 Figure 4.5.7 Density (plants ha-1) for selected herbaceous species (ordered by species, local average) for sites with a one-year fire exclusion period, Manzengwenya Offices, South Africa. 58 Figure 4.5.8 Density (plants ha-1) for selected herbaceous species (ordered by species, local average) for sites with a three-year fire exclusion period, Manzengwenya Offices, South Africa.
59 Figure 4.5.9 Density (plants ha-1) of selected herbaceous species (ordered by species. site mean) for sites with a fire exclusion period of six years, Manzengwenya Offices, South Africa. 60 Figure 4.5.10 Density (plants ha-1) of selected tree species (ordered by species. site mean value) for sites with a fire exclusion period of one year, Manzengwenya Offices, South Africa. 63 Figure 4.5.11 Density (plants ha-1) of selected tree species (ordered by species . site mean value) for sites with a fire exclusion period of three years, Manzengwenya Offices, South Africa.
64 Figure 4.5.12 Density (plant ha-1) for selected woody species (sorted by species. Local area average) for sites with a six-year fire exemption period, Manzengwenya Offices, South Africa. 147 Figure 5.4.14 Total surfaces (expressed in percentage) remain constant. unchanged) for different vegetation categories and time intervals within the Tewate Wilderness Area, South Africa.
List of tables
Categories amp; 19 (bold and italics) have been excluded from the analysis and are the result of digitization errors. Categories 1, 2, 3 and 21 (bold and italicized) were excluded from the analysis and are the result of digitization errors. Categories 1, 2, 6 and 12 (bold and italicized) were excluded from the analysis and are the result of digitization errors.
List of plates
Note Dichrostachys cinerea and Syzygium cordatum growing from within the canopy of Helichrysum kraussii and showing a form of relief (top right and bottom).
List of appendices
Rhodes University and the Natal Branch of the Wildlife Society of Southern Africa, Grahamstown and Durban, ch 34, pp Research note: the short-term effect of fire on the woody component of the Sourish Mixed Bushveld. Effects of disturbance on seedling germination and establishment in a coastal prairie grassland: a test of the competitive release hypothesis.
Rhodes University og Natal-afdelingen af Wildlife Society of Southern Africa, Grahamstown og Durban, kap. 1, s. Rhodes University og Natal-afdelingen af Wildlife Society of Southern Africa, Grahamstown og Durban, kap. 6, s. I: Allsopp N, Palmer AR, Milton SJ, Kirkman KP, Kerley GIH, Hurt CR & Brown CJ (red.) Proceedings of the VIIth International Rangelands Congress.
Disturbance regimes as determinants of seed banks in coastal dune vegetation in the southeastern Cape. United Nations Educational, Scientific and Cultural Organization: convention for the protection of the world's cultural and natural heritage.
