TITLE:
Soil Factors That Influence the Abundance and Distribution of Threatened and Endangered Species in the Okavango Delta; with Particular Emphasis on Eulophia angolensis
AUTHORS:
Sandra K. Middleton, Kelebogile B. Mfundisi, Naidu Kurugundla
KEYWORDS:
Eulophia angolensis, Okavango Delta, Soil Macronutrients, Soil Organic Carbon (SOC), Endangered Species
JOURNAL NAME:
Natural Resources,
Vol.6 No.5,
May
19,
2015
ABSTRACT: Eulophia angolensis is an endangered
plant species found in the Okavango Delta. Generally, there is lack of
botanical information on this species in Botswana, which is necessary for its in-situ and ex-situ conservation. The objectives of this research are to map
areas where E. angolensis occurs,
determine the species that co-exist with it, and establish soil factors that
influence its abundance and distribution in the Okavango Delta. A survey of the
area where the plant was sighted in 2004 was carried out using recorded GPS points.
Soil samples were collected at 0 - 20 cm depth from the floodplain where the
species occurred to determine the macronutrients: total nitrogen, phosphorus, potassium
(N, P, and K) and soil organic carbon (SOC) contents. The researchers could not
find the plant at all GPS locations where the plant was sighted in 2004, but discovered
a new unrecorded site for the species. The species was very close to the water
channel; approximately 40 cm away, with only one plant about 60 cm away. The
mean macronutrients concentrations in the site that contained E. angolensis were total N = 2.61 ± 0.61
mg/L, P = 7.02 ± 0.8 mg/L and K = 14.41 ± 4.28 mg/L. SOC concentration was 40.1
± 10.28 mg/L. Furthermore, there was K biogeochemical
gradient within the E. angolensis habitat, with more concentrations directly around the plant. Therefore, E. angolensis needs critical amounts of
N, P, K and SOC, with K, SOC and water requirement being the crucial factors.
Frequent monitoring of the endangered species found in the Okavango Delta is
required, and ex-situ conservation of
the species in the country in the form of a botanical garden should be
established for future generations.