Short- and long-term control of water lettuce (Pistia stratiotes) on seasonal water bodies and on a river system in the Kruger National Park, South Africa

Hydrobiologia ◽  
1996 ◽  
Vol 340 (1-3) ◽  
pp. 173-179 ◽  
Author(s):  
Catharina J. Cilliers ◽  
D. Zeller ◽  
G. Strydom
Keyword(s):  
South Africa ◽  
National Park ◽  
River System ◽  
Kruger National Park ◽  
Water Bodies ◽  
Pistia Stratiotes ◽  
Water Lettuce ◽  
Short And Long Term

Alien Invasive Aquatic Plant Species in Botswana: Historical Perspective and Management

2016 ◽  
Vol 9 (1) ◽  
pp. 1-40 ◽  
Author(s):  
C. N. Kurugundla ◽  
B. Mathangwane ◽  
S. Sakuringwa ◽  
G. Katorah
Keyword(s):  
South Africa ◽  
Biological Control ◽  
Plant Species ◽  
Water Hyacinth ◽  
Water Bodies ◽  
Pistia Stratiotes ◽  
Okavango Delta ◽  
Aquatic Weeds ◽  
Water Lettuce ◽  
The Government

Aquatic ecosystems in Botswana have been under threat by the aquatic alien invasive plant species viz., salvinia Salvinia molesta Mitchell, water lettuce Pistia stratiotes L., and water hyacinth Eichhornia crassipes (Mart.) Solms-Laub. While salvinia has been termed the major threat to the Botswana wetlands, water lettuce and water hyacinth are considered to be of minor importance. This review presents the species biology, distribution, historical spread, negative impacts, control achieved right from their discovery in the country by referring to their control and management in the world. Having infested the Kwando-Linyanti-Chobe Rivers in the 1970s, salvinia was initially tried by the use of herbicides, paraquat and glyphosate, between 1972 and 1976. With the discovery of the host specific biological control weevil Cyrtobagous salviniae Calder and Sands in 1981, the weevil was introduced by Namibians on Kwando and Chobe Rivers in 1983 and by Botswana in 1986 in the Okavango Delta. While the control was slowly establishing in Kwando-Linyanti-Chobe Rivers, it became apparent that lakes and perennial swamps within and outside Moremi Game Reserve of the Okavango Delta were infested with salvinia from 1992 onwards. With continuous and sustained liberation of the weevil in the Kwando-Linyanti-Chobe Rivers and in the Okavango Delta between 1999 and 2000, salvinia control was achieved by 2003, and since then the weevil constantly keeps the weed at low levels. The success is mainly due to sustainable monitoring through the application of physical and biological control methods. However, salvinia is still threatening the Okavango Delta due to factors such as tourism activities, boat navigation fishing and transporttion by wild animals. The first occurrence of water lettuce was recorded on Kwando and Chobe Rivers in 1986. Its biocontrol weevil Neohydronomous affinis Hustache was released in the year 1987. The weevil became extinct in Selinda Canal and Zibadianja Lake on Kwando River due to dry and wet events for over 10 years and the weed had been under control biologically on Chobe River. Having surface covered the Selinda and a part of the Zibadianja in high flood and rainfall in 1999/2000 season, research was undertaken to contain water lettuce, which led to its eradication by 2005. Regular physical removal of the water lettuce prior to fruit maturity is an effective method of control or eradicating the weed in seasonal water bodies. The Limpopo Basin (shared by Botswana, South Africa, Zimbabwe and Mozambique) has become vulnerable to water hyacinth infestation. Water hyacinth infested the trans-boundary Limpopo River in 2010 sourced from Hartbeesport Dam on Crocodile River in South Africa. Botswana and South Africa have been consulting each other to implement integrated control of the weed jointly in the Limpopo River. Water hyacinth could be a continuous threat to the dams and the rivers in the Limpopo basin if its control is not taken seriously. These three species are found growing in Botswana in a range of pH between 4.5 and 10.3 and in the range of conductivities between 20 and 580 µS cm-1. Range of soluble nitrates, phosphates and potassium in the habitats of salvinia infestations were 0.02 to 1.5, 0.01 to 1.78 and 0.3 to 6.92 mg L-1 respectively. Water lettuce infestation in the seasonal Selinda Canal had a maximum of 4.7 mg L-1 nitrates, 2.8 mg L-1 phosphates and 7.9 mg L-1 potassium. Nevertheless, these three nutrients were in the range of 0.41 to 9.56 mg L-1, 0.2 to 2.9 mg L-1, and 7.7 to 11.53 mg L-1 respectively in the Limpopo River where water hyacinth infestations were observed. These nutrients were considerably high during decomposition phase of biological control of weeds. The Government of Botswana “regulates the movement and importation of boats and aquatic apparatus, to prevent the importation and spread of aquatic weeds both within and from the neighboring countries” by “Aquatic Weed (Control) Act” implemented in 1986. These measures, combined with communities, conservation groups, NGOs and public awareness campaigns, have highlighted the gravity of aquatic weeds spreading into wetlands, dams and other water bodies. In conclusion, the Government of Botswana is committed and supportive through the Department of Water Affairs in protecting the wetlands of the country efficiently and prudently.

scholarly journals The contribution of fire research to fire management: a critical review of a long-term experiment in the Kruger National Park, South Africa

2007 ◽  
Vol 16 (5) ◽  
pp. 519 ◽  
Author(s):  
Brian W. van Wilgen ◽  
Navashni Govender ◽  
Harry C. Biggs
Keyword(s):  
South Africa ◽  
National Park ◽  
Fire Management ◽  
Basic Research ◽  
Kruger National Park ◽  
Management Policy ◽  
Wet Season ◽  
Long Term Experiment ◽  
Faunal Communities

The present paper reviews a long-term fire experiment in the Kruger National Park, South Africa, established in 1954 to support fire management. The paper’s goals are: (1) to assess learning, with a focus on relevance for fire management; (2) to examine how findings influenced changes in fire management; and (3) to reflect on the experiment’s future. Results show that fire treatments affected vegetation structure and biomass more than species composition. Effects on vegetation were most marked in extreme treatments (annual burning, burning in the summer wet season, or long periods of fire exclusion), and were greater in areas of higher rainfall. Faunal communities and soil physiology were largely unaffected by fire. Since the inception of the experiment, paradigms in savanna ecology have changed to encompass heterogeneity and variability. The design of the experiment, reflecting the understanding of the 1950s, does not cater for variability, and as a result, the experiment had little direct influence on changes in management policy. Notwithstanding this, managers accept that basic research influences the understanding of fundamental ecosystem function, and they recognise that it promotes appropriate adaptive management by contributing to predictive understanding. This has been a major reason for maintaining the experiment for over 50 years.

scholarly journals Seven decades of institutional learning: managing alien plant invasions in the Kruger National Park, South Africa

Oryx ◽  
2007 ◽  
Vol 41 (2) ◽  
pp. 160-167 ◽  
Author(s):  
Llewellyn C. Foxcroft ◽  
Stefanie Freitag-Ronaldson
Keyword(s):  
South Africa ◽  
National Park ◽  
Invasive Plant ◽  
Current Control ◽  
Kruger National Park ◽  
Plant Management ◽  
Plant Interactions ◽  
Alien Plant ◽  
Invasive Plant Management

AbstractLong-term ecological and economic sustainability will ultimately determine the outcome of any conservation management programme. Invasive alien plants, first recorded in the Kruger National Park, South Africa, in 1937, are now recognized as one of the greatest threats to the biodiversity of this Park. Such plants have been managed in the Park since 1956, with control advancing mainly through a process of trial and error. Refinement of invasive plant management strategies has resulted in an understanding of the target plants' biology and ecology, herbicide use and herbicide-plant interactions, as well as the plant-insect interactions of biological control. Careful integration of different control methods has proved essential to ensure the most appropriate use of techniques to deliver the best possible results from the resources available and achieve long-term sustainability. We outline the development of control efforts and current control programmes and the process of their incorporation into the institutional memory of Kruger National Park over the last 7 decades.

scholarly journals Long-term effects of fire frequency and season on herbaceous vegetation in savannas of the Kruger National Park, South Africa

2012 ◽  
Vol 6 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Melinda D. Smith ◽  
Brian W. van Wilgen ◽  
Catherine E. Burns ◽  
Navashni Govender ◽  
Andre L. F. Potgieter ◽  
...  
Keyword(s):  
South Africa ◽  
National Park ◽  
Fire Frequency ◽  
Kruger National Park ◽  
Long Term Effects ◽  
Herbaceous Vegetation

scholarly journals Comparing efficacy of a sweep net and a dip method for collection of mosquito larvae in large bodies of water in South Africa

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 713 ◽  
Author(s):  
Katherine K. Brisco ◽  
Anthony J. Cornel ◽  
Yoosook Lee ◽  
Joel Mouatcho ◽  
Leo Braack
Keyword(s):  
South Africa ◽  
Significant Role ◽  
National Park ◽  
Kruger National Park ◽  
Water Bodies ◽  
Mosquito Larvae ◽  
Wilderness Area ◽  
Bodies Of Water ◽  
Field Setting ◽  
Sweep Net

In this study we tested an alternative method for collecting mosquito larvae called the sweep net catch method and compared its efficiency to that of the traditional dip method. The two methods were compared in various water bodies within Kruger National Park and Lapalala Wilderness area, South Africa. The sweep net catch method performed 5 times better in the collection of Anopheles larvae and equally as well as the dip method in the collection of Culex larvae (p =8.58 x 10-5). Based on 15 replicates the collector’s experience level did not play a significant role in the relative numbers of larvae collected using either method. This simple and effective sweep net catch method will greatly improve the mosquito larval sampling capacity in the field setting.

scholarly journals Online appendix 1:A geomorphic and soil description of the long-term fire experiment in the Kruger National Park, South Africa

Koedoe ◽  
2012 ◽  
Vol 54 (1) ◽  
Author(s):  
Frederik J. Venter ◽  
Navashni Govender
Keyword(s):  
South Africa ◽  
Fire Ecology ◽  
National Park ◽  
Fire Regimes ◽  
Kruger National Park ◽  
Spatial And Temporal Scales ◽  
Online Appendix ◽  
Soil Variation ◽  
Fire Experiments

In 1954, the experimental burning programme into fire research was initiated in the Kruger National Park (KNP), South Africa. It is viewed as one of the last remaining long- term landscape fire experiments in Africa. Throughout the more than five decades of fire treatments in the experiment, numerous surveys (expanding various spatial and temporal scales), research projects (covering biotic and abiotic components) and analyses have been conducted with the aim to assess the impacts of different fire regimes on the savannah biome. The design of the experiment intended to test the effect of season and frequency of burning on vegetation within four major landscapes in the KNP. However, these effects have been partly obscured by factors not fully taken into account by the experimental design, namely, herbivory, artificial water provision and soil variation. Soil variation between replicates in the same landscape, as well as within individual replicates, has raised the issue of the representivity of the trial. This paper provided a description and ranking of the experimental burning trial according to the geomorphic and soil characteristics of each plot in comparison to the surrounding landscape.Conservation implications: The KNP burn plots are one of the largest and longest-running fire experiments on fire ecology in African savannahs. However, studies need to consider the underlying geomorphic and soil template when designing experiments and interpreting results. This work describes the representivity of the plots across, and within, treatments.

scholarly journals Long-term rainfall regression surfaces for the Kruger National Park, South Africa: a spatio-temporal review of patterns from 1981 to 2015

2018 ◽  
Vol 38 (5) ◽  
pp. 2506-2519 ◽  
Author(s):  
Sandra MacFadyen ◽  
Nick Zambatis ◽  
Astrid J. A. Van Teeffelen ◽  
Cang Hui
Keyword(s):  
South Africa ◽  
National Park ◽  
Kruger National Park ◽  
Spatio Temporal

scholarly journals Invasive alien freshwater snail species in the Kruger National Park, South Africa

Koedoe ◽  
2008 ◽  
Vol 50 (1) ◽  
Author(s):  
Kenné N. De Kock ◽  
Cornelius T. Wolmarans
Keyword(s):  
South Africa ◽  
Species Diversity ◽  
National Park ◽  
Negative Impact ◽  
Freshwater Snail ◽  
Kruger National Park ◽  
Water Bodies ◽  
Snail Species ◽  
Physa Acuta ◽  
Tarebia Granifera

An account is given of all invasive alien freshwater snail species samples found in the Kruger National Park currently on record in the National Freshwater Snail Collection(NFSC) database. This report mainly focuses on samples collected during surveys of selected water bodies in the Kruger National Park (KNP) during 1964, 1995, 2001 and 2006. The progress made by four alien invasive freshwater snail species, Lymnaea columella, Physa acuta, Aplexa marmorata and Tarebia granifera, in colonising water bodies since first being recorded in the KNP is addressed. The results clearly show that all four species are in the process of becoming more widespread than they were when first recorded. However, T. granifera is the only one of these species of which exceptionally dense populations were encountered in several water bodies. All indications are that this species could already have had a negative impact on the species diversity of molluscs in these water bodies, and it is recommended that the situation be closely monitored.

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