NEWS
How ecologists put Orapa
vegetation on the map
Erik Verreynne, from Oxbow Investments, reports on how two teams of
ecologists undertook the vegetation community classification
in Orapa Game Park
Erik Verreynne
Current Address: Oxbow Investments
Reprinted From: http://bit.ly/2S0KWBQ
T
he perimeter fence of the northern
extension of the Orapa Game Park
has been completed, allowing the
vegetation to recover after a few years of
erratic rainfall and heavy livestock graz-
ing pressure. Following the revision of
the plant community classification and
veld condition assessment of the park
and buffer zones in 2014, the fieldwork
of the vegetation community classifica-
tion for the northern extension was com-
pleted in May 2017.
Two teams of ecologists have spent
weeks in the park and the park exten-
sion over the past 12 months. They got
stuck in mud during thunderstorms,
spent hours in the relentless summer
sun and walked kilometres every day to
reach the outlying points. They needed
to avoid small groups of elephants and
solitary lions that had recently moved
into the area, and endure mosquito and
tick bites, as well as bashing their way
through thorny thickets. However, the
beautiful landscape changing moods
every day, crimson sunsets and the starry
expanse at night made the fieldwork an
enjoyable experience.
In the absence of detailed soil analyses
or previous vegetation community as-
sessments for the extension area, recent
satellite imagery was used with Normal-
ised Difference Vegetation Index (NDVI)
software to differentiate and identify
vegetation types within each rangeland
type. Based on the NDVI images, 106
plots were identified and surveyed by
the teams in May 2017. The landscape in
the extension features a sand dune, two
large pan systems with one a large cal-
crete saline pan similar to the pans in the
Makgadikgadi system, and a third pan
system consisting of small pans with ver-
tic floors fringed by large knobthorn and
leadwood trees, towering termitaria and
a marula forest.
The fieldwork resulted in a vegetation
map classifying the vegetation commu-
nities into three main and six sub-com-
munities. It further resulted in a compre-
hensive catalogue of plants occurring
in the area, recording among others
five Grewia species, five Commiphora
species, three Terminalia species, three
Combretum species, 11 Acacia species,
a Gardenia species, two Albizia species,
and a large variety of grasses, shrubs and
forbs.
Figure 2: An unusual Marula forest in the
Orapa Game Park northern extension
Earlier this year, the teams consolidated
the vegetation maps of the northern ex-
tension and Orapa Game Park into one
map, merging the different plant com-
munities and allowing the extended park
to be managed as a unit.
This was followed by a veld condition as-
sessment of the total unit in April. The
teams of ecologists visited 114 plots over
the entire park to assess both the woody
component (trees and bushes) and the
grass sward.
The information collected was pro-
cessed into management information
that will be used to determine the brows-
ing and grazing potentials, tree densities
and phytomass, erosion potential, graz-
ing capacity, optimal stocking rates, and
fire management requirements of each
management unit.
The survey showed the severe impact
of the erratic rainfall since 2014 coupled
with the protection of a significant popu-
lation of white rhinos.
Figure 1: A magnificent sunset over the salt pan
09
The vegetation information paved the
way for the utilisation of the northern
extension to relieve the pressure on the
original Orapa Game Park. This will re-
sult in the optimal use of the extended
Orapa Game Park as a unit.
Grassroots
Vol 18
No 4
December 2018