Veld Condition Assessment

The procedure for analysing benchmarks and sample sites involves taking 200-point positions within a demarcated sample site of 0.1 ha to provide data on the botanical composition and basal cover. Each of the recorded species is allocated to a species category (Decreaser, Increaser I, Increaser II, or Increaser III) depending on its ecological status in the community.

The species categories are defined as follows:

Other features of the sample site are also rated visually on a 1 (excellent) to 5 (very poor) scale. Such features may include the presence of poisonous plants, the poor age distribution of the component plants, vigour of the Decreaser species, obvious soil erosion or any other features which may be considered appropriate.  Also, if the assessment is to be used to determine current grazing capacities appropriate to the area, then the general topography of the grazing unit represented by the sample site and the inherent erodibility of the soil of the site should be recorded. The condition of any particular sample of veld is then rated by comparing it with the benchmark, whose condition is assured to represent the potential of the area concerned.

The method which is currently in use is shown, using a practical example, for the humid grassland of KwaZulu-Natal. After having obtained the necessary data from the sample site, and from the benchmark site, the following procedure is followed:

1. The composition of the benchmark site is listed as shown in the table below.

Computation sheet for the determination of the composition score

Although the sample site recorded 20% Brachiaria serrata, only 16% (the maximum limit) is scored. The same applies to the Increaser species Bothriochloa insculpta, Eragrostis plana, Hyparrhenia hirta, Sporobolus pyramidalis, the spring aspect forbs and Elionurus muticus.

The score in each species class is totalled to provide the composition score in this example 59%. The interpretation of this score is discussed in conjunction with the Veld Condition scoresheet.

Limits are then imposed on the excess of individual species in subsequent veld assessment may be recognised and penalised. The limits are more severe for Increasers than Decreasers. The limits for Increasers are taken as the percentage contributed by the individual species in the benchmark. For the Decreasers, the limits are the benchmark values plus ten percentage units.

2. The sample site is then scored against the benchmark, as in the Table below:

Veld Condition scoresheet

	Benchmark	Sample site
Composition score (%)	100	59
Decreasers (%)	70	41
Increaser I (%)	10	2
Increaser II (%)	15	50
Increaser III (%)	5	7
Cover (%)	14	9
Abundance of poisonous plants	1	1
Vigour of grass plants	1	2
Age distribution of grass plants	1	2
Soil erosion	1	3

From the table above, the following conclusions can be drawn:

• The species composition rates only 59% relative to the optimum composition of well-managed veld in the same ecological area;
• The percentage of Decreaser (fire/grazing climax) species in the sample site is only 41, relative to 70 in the benchmark so the sample site has lost a large proportion of the Decreaser species of the fire ‘grazing climax award;
• The sample site is composed of only 2% Increaser I species relative to 10% in the benchmark sit, so under-utilisation (which encourages Increaser I species) is not a cause of the decline in the composition score to 59%;
• The site has an abnormally high proportion of Increaser II species (50% relative to 15% in the benchmark site) so over-utilisation (which encourages Increaser II species) has caused the deterioration in the composition of the veld;
• The cover of the sample site has declined from a potential of 14%, as in the benchmark, to 9%;

In the system which was originally proposed by Foren et al, (1978) the basal cover data was combined with the composition data to derive the veld condition score, but it is now considered advisable to present these data separately. The basall cover is binomially distributed so that a sample size of only 200 for an event which has a low probability (up to about 0.15) yields a wide confidence interval (Mentis, Collinson and Wright in preparation). Observer differences also render basal cover measured at different times and places irrelative. Further, the correlation between the composition score and the basal cover is weak. In 132 sample sites in Moist Tall Grassveld, the correlation coefficient was only 0.58 (Dillon, 1979). Whether this poor correlation is real or an artefact of imprecise measurement of basal cover is not known.

In contrast to basal cover, determining the species composition seems relatively free of theoretical and practical weaknesses, and results are highly repeatable (Mentis et al, in preparation).

It is recommended therefore that in interpreting the results of veld condition assessment, more weight be attached to the measured composition than the basal cover of the veld.

There is no reason why each operator cannot define his benchmark sites. Such sites should represent stable and productive communities within the same ecological zone and with as many general features (soil type, slope, aspect) as possible identical to those of the sample site which is being investigated. Where such sites are not available, recourse may be made to previously established benchmark data, examples of which are presented in the table below:

Example of benchmark data for different veld types in KwaZulu-Natal

Species   Class	Species	Highland sourveld		Moist Tall grassveld		Dry Tall grassveld		Lowveld
		Group 4f		Group 6		Group 8		Grp 10a
		a	b	a	b	a	b	a	b
Decreaser	Brachiaria serrata	1	11	0	10	1	11	–	–
	Cenchrus ciliaris	–	–	–	–	–	–	1	11
	Digitaria eriantha	–	–	–	–	–	–	1	11
	Diheteropogon amplectens	1	11	1	11	0	10	–	–
	Eragrostis capensis	–	–	6	16	3	13	–	–
	Eragrostis racemosa	O	–	2	12	2	12	–	–
	Eustachys paspaloides	–	–	–	–	–	–	4	14
	Heteropogon contortus	4	14	2	12	2	12	2	12
	Monocymbium ceresiiforme	2	12	0	10	0	10	–	–
	Panicum deustum	–	–	–	–	–	–	1	11
	Panicum maximum	–	–	–	–	–	–	6	16
	Rhynchelytrum setifolium	0	10	1	11	0	1-	–	–
	Schima gapinii	–	–	–	–	–	–	14	24
	Themeda triandra	45	55	53	63	67	77	60	70
	TOTAL	53		65		75		89
Increaser I	Alloteropsis semialata	2		–		–
	Tristachya leucothrix	21		13		3		–
	Cymbopogon excavates	–		1		–		–
	Eulalia villosa	1		–		–		4
	Harpochloa flax	3		–		–		–
	Setaria nigrirostris	–		1		–		–
	Trachypogon spicatus	2		–		–		–
	TOTAL	28		15		3		4
Increaser II	Aristida congesta var. barbicollis	–		1		–		–
	Aristida congesta var. congesta	–		–		–		1
	Bothriochloa insculpta	–		–		–		1
	Digitaria monodactyla	–		–		1		–
	Eragrostis capensis	1		–		–		–
	E. chloromelas	–		–		2		–
	E. curvula	1		–		–		1
	E. plana	1		–		–		–
	E racemosa	1		–		–		–
	E. superba	–		–		1		1
	Hyparrhenia hirta	1		2		2		3
	Microchloa caffra	1		–		2		–
	Setaria flabellate	–		5		5		–
	Sporobolus africanus	–		1		–		–
	S. pyramidalis	–		2		–		–
	S. stapfianus	–		–		4		–
	Spring aspect forbs	5		4		1		–
	Sedges	1		5		4		–
	TOTAL	12		20		22		7
Increaser III	Diheteropogon filifolius	2		–		–		–
	Elionurus muticus	5		–		–		–
	TOTAL	7		–		–		–
Cover (%)		12		14		12		9

a = actual percentages of Decreaser species in benchmark

b = limit to which decreasers may contribute to composition score

Veld conditions in the bushveld areas are dependent on the condition of both the herbaceous layer and the shrub–tree community. The method devised for the humid grasslands seems to apply equally well to the analysis of the herbaceous layer of bushveld communities, but additional assessments are necessary to describe the overall community adequately. It is possible that, in time, the tree species may be classified into the same categories as the grass species, and attempts are currently being made to derive such a classification. In the interim, however, the system which is being used requires a count of the typically encroaching (Increaser) species or, if the availability of browse is a factor, the amount of the valuable browse species, or a plot large enough to include at least 200 individual plants, and the presentation of the density of such species in three categories, as shown later. Where the browsing capacity is relevant, browse and non-brose species should be distinguished.

Characteristics of tree layer in a bushveld site (plants/ha)

Species	Benchmark			Sample site
	Coppice growth	Seedlings 2m	Trees 2m	Coppice growth	Seedlings 2 m	Trees 2 m
Browse species:
Acacia Karroo	6	15	30	43	161	12
Acacia tortilis	2	3	15	6	15	5
Dichrostachys cinerea	9	18	23	17	137	1
Sub-totals, numbers:	17	36	66	66	213	18
Non-browse species:
Maytenus heterophylla	2	5	21	11	25	1
Euclea divinorum	1	2	9	15	23	2
Sub-total	3	7	30	26	48	3
TOTAL	20	43	98	92	261	21

Assuming that this sample site had been burnt recently to control encroaching bush and to provide acceptable browse at an available level, the interpretation of the tabulated results might be as follows:

• The lower density of mature trees (2 m tall) on the sample site than on the benchmark might imply, for example, that the sample site was previously bush-cleared;
• The higher density of seedlings on the sample site than on the benchmark indicates that bush encroachment is occurring;
• The higher density of coppicing plants on the sample site than on the benchmark indicates that the fire alone was inadequate in controlling the bush (counting the number of plants killed by fire and/or browsing provides an additional useful statistic);
• The relatively high density of seedling and coppicing browse species indicates a large food resource for browsers
• The relatively high density of seedling and coppicing non-browse species indicates that this un-utilisable component of the veld is increasing, perhaps because grazing is excessive and fires are too infrequent or of insufficient intensity.

Such an assessment of the condition of the herbaceous and tree communities of an area should provide valuable information on the condition of the site. From such a description, it should be possible to devise corrective grazing and burning management procedures, where these are necessary.