Post on 07-Apr-2018
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Data collection: vegetationData collection: vegetat ion
Flip Breytenbach
LADA Regional Training Workshop
Pumulani Lodge5 Aug 2010
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INTRODUCTIONINTRODUCTIONINTRODUCTION
Vegetation degradation is an important aspect of land degradation.
Vegetation degradation can occur in:
Grasslands and rangelands
Forests and woodlands
Croplands
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More emphasis is placed on assessing vegetation degradation in grasslands
and rangelands.
Detailed assessments of forests and woodlands are not covered though can be
added if important at an assessment site.
Detailed tools are not provided for assessing crops or other vegetation incroplands can be visually assessed using Tool 15 (Part 2: Page 112)
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INDICATORSINDICATORSINDICATORS
The most important indicators of vegetation degradation are (Part 1: Page 29):
Reduced vegetation cover
Changes in vegetation structure and plant community composition
Decline in species and habitat diversity
Changes in abundance of indicator species
Land productivity in terms of biomass, quality of products and livestock
production
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Plant and litter cover
Directly affects:
Infiltration
Runoff rate
Erosion rate
Soil organic matter and nutrient
restoration
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Vegetation structure and composition
Multi storey system (trees, shrubs, dwarf shrubs,
grasses) better use of rainwater and higher
protection against erosion
Wooded savanna provide shade and a cooler
microclimate
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Vegetation diversity
Biodiversity degradation can be assessed at three levels:
Reduced habitat diversity
Loss of or reduced species diversity
Loss of or reduced varietal/land-race diversity
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Vegetation quality and productivity
Pasture and rangelands direct linked to livestock productivity
After assessing vegetation degradation in rangeland and pasture it is important
to look at the effects of this degradation on livestock productivity
(Tool 13.2- Part2: Page 90)
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Seasonality and inter-annual variability
Vegetation growth is dynamic (meteorological, geological, topographical)
Good understanding is required of variation in plant growth and characteristics
between seasons, months and years will influence data recorded
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Assessment indicators and methods are described in:
Tool 4 Part 2: Page 22
Tool 13 Part 2: Page 87
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VEGETATION ASSESSMENTVEGETATION ASSESSMENTVEGETATION ASSESSMENT
There are two stages of vegetation assessment namely:
A rapid assessment of vegetation and land use
More detailed vegetation assessment at selected sites in
the study area
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Assessment of the overall state of the vegetation (Tool 4.B.
Part 2: Page 23)
A rapid assessment of:
vegetation type
vegetation cover
Structure
species composition
Undertaken through the reconnaissance visits.
Table 3 Page 24 can be used as a basis for the vegetation overview
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VEGETATION ASSESSMENTVEGETATION ASSESSMENTVEGETATION ASSESSMENT
Part 2: Page 87
The following tools provide a rapid assessment of vegetation.
Tool 13.1 Interviews and focus group discussions on vegetation resources
Tool 13.2 Visual assessment of vegetation status, quality and trends in
pasture/rangeland
Tool 13.3 Assessing vegetation status, quality and trends in
forests/woodland
Tool 13.4 Assessing vegetation condition in croplands
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VISUAL ASSESSMENTVISUAL ASSESSMENTVISUAL ASSESSMENT
Changes in species composition combined with decline in plant vigour leading
to lower forage biomass production, will result in the affected rangeland
having a reduced livestock carrying capacity.
A set of proposed indicators is outlined in Table 15 (Part2: Page91)
Once the rapid assessment has been conducted the vegetation condition can
be scored (Table 16 Part 2: Page 93)
Scoring should be accompanied by a description of reasons for the current
vegetation status management practices
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Rapid assessment of the vegetation status, quality and trends in
forest/woodlands (Tool 13.3) indicators Table 18 on Page 96: Part 2
Rapid assessment of vegetation condition in croplands (Tool 13.4) -
indicators Table 19 on Page 98: Part 2
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VEGETATION ASSESSMENTVEGETATION ASSESSMENTVEGETATION ASSESSMENT
Further information on vegetation assessment methods (Annex 2 Part 2:Page
118)
Vegetation cover
Basal cover
Folial cover
Canopy cover
Plant residues and litter amount
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Method: 200m line transect. At each metre a hit or a miss is recorded.
Number of hits divided by 2 percentage basal cover.
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ADDITIONAL DETAILADDITIONAL DETAILADDITIONAL DETAIL
Species composition
How to determine the species composition of veld
At each sample site a 200-point survey method is applied.
Working downslope.
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At each metre the hit of a species or the
nearest plant species is recorded. If it is a hit on
the base of a species, it is recorded as such.
No plant species in a radius of 50cm bare
soil is recorded.
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CARRYING CAPACITYCARRYING CAPACITYCARRYING CAPACITY
Potential of an area to support livestock through grazing/browsing production
over an extended number of years without deterioration to the overall
ecosystem. (Part 2: Page 119)
Determining the carrying capacity
It must be repeated over time to obtain a proper norm.
Dry material production is determined via harvesting (clipping 1m2 quadrates,
weighing the dried grass and converting the obtained production to kg/ha) or
by using a disc pasture meter.
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The following formula is then used:
CC = 365 / {(Production X Utilisation factor) / Daily intake}
Where : 365 = days/year
Production = production of palatable species (kg/ha)
Utilisation factor = 35% = 0.35. (Only 35% of all grass is considered to
be utilised. The rest is wasted).
Daily intake = 3% of body weight = 10 -12 kg/day
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VELD CONDITIONVELD CONDITIONVELD CONDITION
Determination of veld condition (Part 2; Page 120)
To conserve our grasslands, we must know in what condition it is.
Different methods are described to determine veld condition. Some of these
methods have a difficult scientific basis, while others are easy to use.
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Visual, subjective methods
Veld is evaluated by using pre-determined characteristics listed on a form,
which is completed while walking through the veld. These methods are
totally subjective, the accuracy depending on the judgement of the operator.
These methods need no in-depth knowledge of the veld and is easily applied.
They are scientifically inaccurate.
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Ecological classification methods
These are the most general methods used to determine veld condition.
The veld condition of a camp is compared with that of a benchmark, which is
a similar veld type taken to be in a good condition. The benchmark is chosen
by the operator and remains the same for future comparisons. On the basis
of botanical surveys, comparisons are made between different camps,
relative to the condition of the benchmark, by determining a veld condition
index for the benchmark and each camp. The surveys are repeated over time
to give an indication of veld condition trend.
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THANK YOU