indicators as assessed within the national park.

Figure 8. The range condition short termitaria vegetation type based on the occurrence of five indicators as assessed the national park and game management area.

important factors for site stability relevant to the site potential [27] and our results suggest that this vegetation type is largely susceptible to accelerated wind and water erosion. Two factors seem important to have caused this.

Firstly, Termitaria vegetation type does not regularly flood and floods may cover this area only during high flood peaks and in exceptional years, and secondly much grazing occurs in this vegetation type by large herbivores, mainly buffalo and roan antelope. Litter amount is a measure of dead plant material that

Figure 9. Percent herbage standing crop biomass production and percent grazing intensity in each vegetation type.

covers the soils and most important for decomposing and soil formation and significant for detrital food chain. The wide and even distribution of litter in all vegetation types sampled as shown in our results can only be explained by the lack of movement of litter amount in this low gradient wetland. However, this aspect requires further investigations.

Herbaceous ground cover describes the proportion of soil surface covered by grasses and forbs. These plants are most important for grazing and can either be perennial or annual and the low presence of grass cover in the area can be explained as being due to excessive grazing and that the rangeland is dominated by high presence of annual grasses which being evaders reproduce by seed and live only for one growing season.

With regard to utilization, it was evident that considerable research has been devoted to this [25] , which in essence refers to the degree to which animals have consumed the annual usable forage production expressed in percentages [29] . This is important in rangeland management primarily for estimating carrying capacity and stocking rates. As our results have revealed over 40% of the herbage produced per year is consumed by wild herbivores. Whether or not this amount could be accepted as allowable use for wildlife in Kafue Flats rangeland remains largely speculative and inconclusive. We hypothesized that Kafue Flats north bank was overstocked during the period before the construction of the Itezhi-Tezhi dam. While this view may appear conjectural, various studies [33] [34] [35] have provided sufficient discussion on spatial and temporal differences in structures of wetland landscape and the impact of grazing in a rangeland. Flood patterns, plant diversity and food availability are important determinants of the distribution of animals and these require considerable empirical evidence before conclusions can be made.

The significance of these findings however, is that we now know that Kafue Flats wetland was under severe land degradation even before the construction of the Itezhi-Tezhi dam and there are several reasons and speculations which may require discussions and future research.

First, Kafue Flats as a flood plain rangeland assumes the wetland ecological character, and understanding the relationship between grazing and wetland conditions is essential for effective management of a wetland grassland [34] [36] . The data presented in this study are an important description of the Kafue Flats state before the construction of the Itezhi-Tezhi (“Meshi Teshi” as was known) dam, but full interpretation would require discussion of linkages between wetland condition and rangeland condition. Wetland condition as might apply to the Kafue Flats, refers to the health of an ecosystem that primarily supports habitats and viable native animals and plant populations similar to those present before any disturbance [37] , and that it is able to return to its pre-existing condition after disturbance, whether natural or human induced and that annual flood pulse, channel forming floods, and infrequent droughts remain major driving factors in flood plain river ecosystem.

Secondly, knowledge of hydrology of the ecosystem and its processes is fundamental and critical for sustainable development, in particular, if dam development and operations are to become part of an integrated management in such sensitive ecosystems that would need environmental protection. Emerging issues on the impact of dams have been widely debated and well documented [9] [10] [38] , however the main focus of concern on Kafue flats centred on limited water for the wetland and currently coupled with water regulation and altered environmental flows. The primary question is how much water is required to sustain the ecosystem in Kafue Flats wetlands-Essentially, environmental flows are understood to be the quantity, quality and timing or water flow required to sustain fresh water ecosystems and livelihood and wellbeing that depend on these ecosystem [39] . However, water requirement or ecological flow needs are levels required in a water body for flora and fauna and habitat process present within that water and its margins [40] , and aware of our inability to make meaningful evaluation of environmental flow requirement, but in trying to explain and understand the hydrology of the Kafue Flats wetland, we want to propose a number of hypotheses.

We argue that Kafue Flats sub-catchment of 45,526 km2 had much of its recharge function substantially reduced. This is because the streams within this sub-catchment are seasonal and may flow only for three to four months in a year, and in addition increasing human settlements and excessive deforestation [14] [41] have resulted in recharge function largely being dysfunctional. The relationship between water and forests has well been studied and widely discussed [41] and clearly the vegetation around the Kafue flats is an integral part of the Kafue Flats landscape. As earlier pointed out [42] forests play a significant role in the interaction between ground water of wetland ecosystem and through the recharge function as well as controlling flood flows, water quality and erosion control.

Thirdly, the use of plants to measure water requirements or wetland ecosystem condition has been an established science [39] [43] . Plant species presence and absence, plant vigour, plant diversity and invasiveness are among reliable indicators and tools in evaluating wetland condition. Similarly, plant response to altered and regulated water regimes have also been well investigated [44] [45] [46] . These tools are available for research in Kafue Flats monitoring.

Fourthly, water regime of a flood plain is its characteristic pattern of flooding, drying and water level changes and these water level changes have specific needs to ensure plant species maintenance and regeneration. The flood pulse ecology has emerged as the new science that has adequately provided explanations to such wetland processes. The basic claim of the flood pulse principle is that it refers to a river discharge, the flood, as the major force controlling biota in a river flood plain as the river and the flood conduct exchanges laterally between them [47] . Since then the principle has been well researched and discussed elsewhere [48] [49] [50] . This principle is of great interest to the Kafue Flats because of its implication on the primary production of the rangeland. The reduction on the environmental flows coupled with regulated flood pulsing through timing, duration and magnitude could have serious consequences on the annual life cycles particularly the annual grass species in this wetland [51] . However, this view would require detailed investigations and further substantiation.

Furthermore, although fires are known to be of great significance and a tool extensively used in wetland and rangeland management, their effects are not well understood. Whether or not fires cause changes in the structure of vegetation has been a subject of investigation and debate for a long time [28] [52] . Numerous and well documented studies that have been done on the effects of fires have revealed fires as an integral part of wetland and rangeland landscapes and a management tool [53] [54] [55] , and that the effects of fire generally depend upon fire intensity, frequency, and time of the year [56] [57] . Although fires may remove much of the vegetation in a wetland and can change the structure and configuration of a wetland, the removal of organic soils and change in water chemistry may have a negative effect on other organisms. We believe that research on this aspect should be pursued further.

5. Conclusions and Recommendations

5.1. Conclusions

This study provides earlier information of the rangeland condition of the Kafue Flats wetland before the construction of the Itezhi-Tezhi dam. Nevertheless, its significance will depend on detailed subsequent research in the future, in particular, rangeland health and pasture dynamics, environmental and ecological flows, pulse ecology and fire ecology.

For now, it is firmly establishment that rangeland research and monitoring programmes are essential to adaptive management of vegetation dynamics.

These results have also given the picture that the rangeland in Kafue Flats north bank is largely at high risk as demonstrated by high values of bare ground of the soils and that there is high possibility of the rangeland being over grazed since the recorded 40% is unsustainable in flood pulse ecosystems.

5.2. Recommendations

1) We recommend the establishment of regular rangeland and wetland health assessment and monitoring providing for determination of causes of plant succession most likely directing change and for managers to consider repair or restoration.

2) We also propose detailed research on both wetland and rangeland health and provide answers or suggestions in view of disturbances involving multiple factors such as environmental flow, flood pulse and human impact.

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1] Chabwela, H.N. (1992) The Ecology and Resource Use of the Bangweulu Basin and the Kafue Flats. In: Jeffery, R.C.V., Chabwela, H.N., Howard, G. and Dugan, P.J., Eds., Managing the Wetlands of Kafue Flats and Bangweulu Bassin, IUCN, Gland, 11-24.
[2] Godet, F. and Pfister, S. (2007) Case Study on the Itezhi-tezhi and the Kafue Gorge Dam: The Science and Politics of International Water Management.
[3] Drjver, C.A. and Marchand, M. (1985) Taming the Floods: Environmental Aspects of Plan Development in Africa. CES State University of Leiden, Leiden.
[4] Joyce, C.B., Simpson, M. and Casanova, M. (2016) Future Wet Grasslands: Ecological Implications of Climate Change. Ecosystem Health and Sustainability, 2, e01240.
https://doi.org/10.1002/ehs2.1240
[5] Gordon, E. and Meentemeyer, R.K. (2006) Effects of Dam Operation and Land Use on Stream Channel Morphology and Riparian Vegetation. Geomorphology, 82, 412-429.
http://www.elsevier.com/locate/geomorph
https://doi.org/10.1016/j.geomorph.2006.06.001
[6] Cowardin, L.M., Carter, V., Golet, F.C. and LaRoe, E.T. (1979) Classification of Wetlands and Deep-Water Habitats of the United States. U.S. Fish and Wildlife Service, FWS/OBS-79/31, Washington DC.
[7] UNFAO (1968) Wildlife, Fisheries and Livestock Production. Multipurpose Survey of the Kafue River Basin, Zambia. Vol. 5, UNFAO, Rome, 94 p.
[8] McCartney, M.P., Sullivan, C. and Acreman, M.C. (2001) Ecosystem Impacts of Large Dams, Background Paper Nr. 2 Prepared for IUCN/UNEP/WCD. International Union for Conservation of Nature and Natural Resources and the United Nations Environmental Programme.
[9] Richter, B.D., Postel, S., Revenga, C., Scudder, T., Lehner, B. and Churchill, A. (2010) The Downstream Human Consequences of Dams. Water Alternatives, 3, 14-42.
http://www.water-alternatives.org
[10] Wildi, W. (2010) Environmental Hazards of Dams and Reservoirs. NEAR Curriculum in Natural Environmental Science. Terre et Environment, 88, 187-197.
[11] UNFAO (1968) Soil Surveys. Multipurpose Survey of the Kafue River Basin, Zambia. Vol. 2, UNFAO, Rome, 309 p.
[12] UNFAO (1968) Climatology and Hydrology Multipurpose Survey of the Kafue River Basin, Zambia. Vol. 3, UNFAO, Rome, 46 p.
[13] Chabwela, H.N. and Siwela, A. (1986) The Vegetative Structure of the Kafue Flats, North Bank, after the Construction of the Dams. In: England EWRS/AAB Symposium on Aquatic Weeds, Loughborough University, Loughborough, 61-72.
[14] Ellenbroek, G.A. (1987) Ecology and Productivity of an Africa Wetland System. In: The Kafue Flats, Zambia, Dr. W. Junk Publishers, Boston, 266 p.
https://doi.org/10.1007/978-94-009-4051-2
[15] Chabwela, H.N. and Mumba, W. (1998) Integrating Water Conservation and Population Strategies on the Kafue Flats. In: de Shebinin, A. and Dompka, V., Eds., Water & Population Dynamics: Case Studies and Policy Implications, American Association for Advancement of Science, Washington DC, 25-48.
[16] Hedberg, O. (1971) Kafue River Hydroelectric Power Development Stage II. SWECO, Lusaka.
[17] DHV Consulting Engineers (1979) Kafue Flats Hydrological Studies. Final Report, DHV Consulting Engineers, Amersfoort, 198 p.
[18] ZACPLAN (1994) Water Resources Assessment Study: Appendices. Zambezi River System Action Plan. ZACPRO 6, ELMS/DANIDA.
[19] Trapnell, C.G. (1959) Ecological Results of Woodland Burning Experiments in Northern Rhodesian. Journal of Ecology, 47, 129-168.
[20] Thompson, K. (1985) Emergent Plants of Permanent and Seasonally-Flooded Wetlands. In: Denny, P., Ed., The Ecology and Management of African Wetland Vegetation. A Botanic Account of African Swamps and Water Bodies, Dr. W. Junk Publishers, Boston, 1-18.
[21] Gaudet, J.J. (1992) Structure and Function of African Floodplains. Journal of the East Africa Natural History Society and National Museum, 82, 1-32.
[22] Fynn, R.W.S., Murray-Hudson, M., Dhliwayo, M. and Scholte, P. (2015) African Wetlands and Their Seasonal Use by Wild and Domestic Herbivores. Wetlands Ecology Management, 23, 559-581.
https://doi.org/10.1007/s11273-015-9430-6
[23] Chomba, C., Nyirenda, V., Shanungu, G., Simukonda, C., Nyirenda, M.A. and Chaka, K. (2015) An Updated Population Status of the Endemic Kafue lechwe (Kobus leche kafuensis) on the Kafue Flats, Zambia, for the Period 1931-2015 Global. Journal of Biology, Agriculture, and Health Sciences, 4, 154-164.
[24] Cummings, J. and Smith, D. (2000) The Line-Intercept Method: A Tool for Introductory Plant Ecology Laboratories. In: Karcher, S.J., Ed., Tested Studies for Laboratory Teaching, Clemson University, Clemson, Vol. 22, 234-246.
[25] Holechek, J.L., de Gomes, H. and Gait, G. (1998) Grazing Surveys: Problems, Experiences, and Ideas. Rangelands, 20, 9-11.
[26] Salo, E.D., Higgins, K.F., Patton, B.D., Bakker, K., Barker, K., William, T., Kreft, B. and Paul, E. (2004) Grazing Intensity Effects on Vegetation, Livestock and Non-Game Birds in North Dakota Mixed-Grass Prairie. Proceedings of the North American Prairie Conferences, Madison, 8-12 August 2004, Paper 88.
http://digitalcommons.unl.edu/napcproceedings/88
[27] Pellant, M., Shaver, P., Pyke, D.A. and Herrick, J.E. (2005) Interpreting Indicators of Rangeland Health, Version 4. Technical Reference 1734-6, U.S. Department of the Interior, Bureau of Land Management, National Science and Technology Center, Denver, 122 p.
[28] Herrick, J.E., Van Zee, J.W., Havstad, K.M., Burkett, L.M. and Whitford, W.G. (2005) Monitoring Manual for Grassland, Shrubland and Savanna Ecosystems Volume I: Quick Start USDA-ARS Jornada Experimental Range.
[29] Smith, L., Ruyle, G., Maynard, J., Barker, S., Meyer, W., Stewart, D., Coulloudon, B., Williams, S. and Dyess, J. (2005) Principles of Obtaining and Interpreting Utilization Data on Rangelands. College of Agriculture and Life Sciences, Arizona Cooperative Tension, The University of Arizona, Tucson.
[30] Bureau of Land Management. Interagency Technical Reference (1996) Utilization Studies and Residual Measurements. Technical Reference 1734-3 Copies Available from Bureau of Land Management National Business Center, Denver.
[31] Sheley, R.L., James, J.J., Vasquez, E.A. and Svejcar, T.J. (2011) Using Rangeland Health Assessment to Inform Successional Management. Invasive Plant Science and Management, 4, 356-366.
https://doi.org/10.1614/IPSM-D-10-00087.1
[32] Mitchell, J.E. (2010) Criteria and Indicators of Sustainable Rangeland Management. University of Wyoming, Laramie, Extension Publication No. SM-56, 227 p.
[33] Krausman, P.R.D., Naugle, D.E., Frisina, M.R., Northrup, R., Bleich, V.C., Block, W.M., Wallace, M.C., Wright, J.D. and Paul, R. (2009) Livestock Grazing, Wildlife Habitat, and Rangeland Values. Society for Range Management.
[34] Morris, K. and Reich, P. (2013) Understanding the Relationship between Livestock Grazing and Wetland Condition. Arthur Rylah Institute for Environmental Research Technical Report Series No. 252, Department of Environment and Primary Industry, Heidelberg, Victoria 253.
[35] USDA (2016) Grazing Management and Soil Health Keys to Better Soil, Plant, Animal, and Financial Health. Natural Resources Conservation Service.
[36] SANBI (2013) Grasslands Ecosystem Guidelines: Landscape Interpretation for Planners and Managers. South African National Biodiversity Institute, Pretoria, 139 p.
[37] Lubinski, K. (1998) Floodplain River Ecology and the Concept of River Ecological Health. Floodplain River Ecology. Ecological Status and Trends of the UMRS Division of Applied River Sciences, USGS Environmental Management Technical Center, Onalaska.
[38] Braatne, J.H., Rood, S.B., Goater, L.A. and Blair, C. (2008) Analyzing the Impacts of Dams on Riparian Ecosystems: A Review of Research Strategies and Their Relevance to the Snake River through Hells Canyon. Environmental Management, 41, 267-281.
https://doi.org/10.1007/s00267-007-9048-4
[39] U.S. EPA (2002) Methods for Evaluating Wetland Condition, Using Vegetation to Assess Environmental Conditions in Wetlands. Office of Water, U.S. Environmental Protection Agency, Washington DC, EPA-822-R-02-020.
[40] Acreman, M.C., Farquharson, F.A.K., McCartney, M.P., Sullivan, C., Campbell, K., Hodgson, N., Morton, H.J., Smith, D., Birley, M., Knott, D., Lazenby, J., Wingfield, E.B. and Barbier, E.B. (2000) Managed Flood Releases from Reservoirs: Issues and Guidance. Report to DFID and the World Commission on Dams, Centre for Ecology and Hydrology, Wallingford.
[41] Mumeka, A. (1986) Effect of Deforestation and Subsistence Agriculture on Runoff of the Kafue River Headwaters, Zambia. Hydrological Sciences Journal, 31, 543-554.
https://doi.org/10.1080/02626668609491073
[42] Chabwela, H., Chomba, C. and Thole, L. (2017) The Habitat Structure of Lukanga Ramsar Site in Central Zambia: An Understanding of Wetland Ecological Condition. Open Journal of Ecology, 7, 406-432.
http://www.scirp.org/journal/oje
https://doi.org/10.4236/oje.2017.76029
[43] Faber-Langendoen, D., Rocchio, J., Thomas, S., Kost, M., Hedge, C., Nichols, B., Walz, K., Kittel, G., Menard, S. and Muldavin, E. (2012) Assessment of Wetland Ecosystem Condition across Landscape Regions: A Multi-Metric Approach. Part B. Ecological Integrity Assessment Protocols for Rapid Field Methods (L2). U.S. Environmental Protection Agency Office of Research and Development, Washington DC, 111 p.
[44] Alldredgea, B. and Moore, G. (2012) Assessment of Riparian Vegetation Sensitivity to River Hydrology Downstream of a Major Texas Dam. River Research and Applications, 30, 230-244.
[45] Allington, D.A. and Winemiller, K.O. (2006) Habitat Affinity, the Seasonal Flood Pulse, and Community Assembly in the Littoral Zone of a Neotropical Floodplain River. Journal of North American Benthological Society, 25, 126-141.
https://doi.org/10.1899/0887-3593(2006)25[126:HATSFP]2.0.CO;2
[46] Drinkard, M.K., Kershner, M.W., Romito, A., Nieset, J. and de Szalay, F.A. (2011) Responses of Plants and Invertebrate Assemblages to Water-Level Fluctuation in Headwater Wetlands. Journal of the North American Benthological Society, 30, 981-996.
[47] Junk, W., Bayley, P.B. and Sparks, R.E. (1989) The Flood Pulse Concept in River-Floodplain Systems. Canadian Journal of Fisheries and Aquatic Sciences, 106, 110-127.
https://www.researchgate.net/publication/256981220
[48] Zalewski, M. (2006) Flood Pulses and River Ecosystem Robustness. In: Tchiguirinskaia, I., Thein, K.N.N. and Hubert, P., Eds., Frontiers in Flood Research, Kovacs Colloquium, UNESCO, Paris, 43.
[49] Rebelo, L.M., Senay, G.B. and McCartney, M.P. (2010) Flood Pulsing in the Sudd Wetland: Analysis of Seasonal Variations in Inundation and Evaporation in South Sudan. Earth Interactions, 16, 1-19.
https://doi.org/10.1175/2011EI382.1
[50] Arias, M.E., Cochrane, T.A., Norton, D., Killeen, T.J. and Kho, P. (2013) The Flood Pulse as the Underlying Driver of Vegetation in the Largest Wetland and Fishery of the Mekong Basin. AMBIO, 42, 864-876.
https://doi.org/10.1007/s13280-013-0424-4
[51] Benke, A.C., Chaubey, I., Ward, G.M. and Dunn, E.L. (2000) Flood Pulse Dynamics of an Unregulated River Floodplain in the Southeastern U.S. Coastal Plain. Ecology, 81, 2730-2741.
https://doi.org/10.1890/0012-9658(2000)081[2730:FPDOAU]2.0.CO;2
[52] Lugo, A.E. (1995) Fire and Wetland Management. In: Cerulean, S.I. and Engstrom, R.T., Eds., Fire in Wetlands: A Management Perspective, No. 19, Tall Timbers Research Station, Tallahassee, 1-9.
[53] Robertson, M.M. (1997) Prescribed Burning as a Management and Restoration Tool in Wetlands of the Upper Midwest. Student on Line Journal, 2, 1-6.
[54] Mapiye, M., Mwale, N. and Chikumba, N. (2008) Fire as a Rangeland Management Tool in the Savannas of Southern Africa: A Review. Tropical and Subtropical Agroecosystems, 8, 115-124.
[55] Kotze, D.C. (2013) The Effects of Fire on Wetland Structure and Functioning. African Journal of Aquatic Science, 38, 237-247.
https://doi.org/10.2989/16085914.2013.828008
[56] Trollope, W.S.W. and Trollope, A.L. (2004) Prescribed Burning in African Grasslands and Savannas for Wildlife Management Arid Lands Newsletter.
[57] Bixby, R.J., Cooper, S., Gresswell, R.E., Clifford, L.E.B., Dahm, N. and Dwire, K.A. (2015) Fire Effects on Aquatic Ecosystems: An Assessment of the Current State of the Science. Freshwater Science, 34, 1340-1350.
https://doi.org/10.1086/684073

  
comments powered by Disqus
OJE Subscription
E-Mail Alert
OJE Most popular papers
Publication Ethics & OA Statement
OJE News
Frequently Asked Questions
Recommend to Peers
Recommend to Library
Contact Us

Copyright © 2020 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.