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Premium member Presentation Transcript Suitable plant species for rehabilitation of degraded land in South Africa: Suitable plant species for rehabilitation of degraded land in South Africa By Felix Nchu, PhD Percy FiztPatrick Institute of African Ornithology University of Cape TownSlide 2: Objectives of the lecture Understand the concept of soil degradation and rehabilitation Understand why soil rehabilitation is site-specific Acquire special knowledge on methods of selecting plant species that are suitable for any given site Motivate course participants to take soil degradation seriously and hopefully contribute in finding solutionOverview: Overview State of land degradation in South Africa Causes of sloping land degradation Embankment Methods of reducing erosion in sloping land and rehabilitation of sloping land Planting grasses and trees to fight erosion and improve land rehabilitation Propagation of useful plants species Opportunities for researchSlide 4: Land degradation can be defined as a sustained loss in the quality and the productive capacity of the land. In South Africa, it is estimated that about 400 million meter square of soil is lost annually. The most common indication of land degradation is soil erosion, bush encroachment and change in species composition. (Source: FAO, 2004)Slide 5: Source FAO AGL 2005Slide 6: Reduced vegetative cover-Drakensberg Mountains Source:Drynet, 2010Slide 7: Natural factors such as the characteristics of climate, soil, geology and landscape are important in soil erosion Anthropogenic land-use activities, especially deforestation, Mining of minerals urbanization and agricultural land-use impact negatively on sloping lands. Large-scale road works, construction of dams, water conservation projects or flood control projectsSlide 8: conservation tillage practices to reduce soil erosion Source: http://www.cesperieni.ro/page3.html Preventing soil erosion using tyres Source: http://sgp.undp.org/web/images/6142/tyre_bonding_underway_to_prevent_soil_erosion.html Methods of preventing soil erosion Windbreaks Conservation tillage Using tyres Terrace buildingWhy use plants?: Why use plants? Plants slow down water as it flows over the land and this allows much of the rain to soak into the ground. Plant roots hold the soil in position and prevent it from being blown or washed away. Vegetative cover breaks the impact of a raindrop before it hits the soil, reducing the soil's ability to erode. Some plant species helps to improve soil nutrient content Trees act as windbreaks, roosting and n esting sites for seed-eating birdsCharacteristics of suitable plants Grasses and trees for land rehabilitation: Grasses Perennial grasses Spreading Hardy Pioneer or sub-climax Not Palatable Indigenous Easy to propagate Characteristics of suitable plants Grasses and trees for land rehabilitationSlide 11: Trees Characteristics Pioneer Evergreen Medium size Indigenous Easy to propagate Adaptable to local environmental conditions Recruitment of other species Good roosting and nesting sites for birdsSlide 12: Eragrostis lehmanniana ( Lehmann’s love grass): It is native to South Africa. A hardy, tufted grass with 60-90 cm tall culms. and it is used for erosion control. prefers sandy soils. Erasgrostis curvula (weeping love grass): Increaser 2 plant. Sub-climax and found in high rainfall area. Stabilizes soil. Plant can be established from seeds and vegetative (nodes). A good seed-bed is preferred. Establishes easily. Persist well in poor soil and fire. Aristida canescens (Pale three-awn): Can survive difficult growing condition. It is not palatable. Good for stabilization of eroded soil. Found in the Eastern Cape. Cynodon dactylon (cough grass): This is a stoloniferous grass. It is a good pasture. It is a pioneer grass. The stolons makes it a good soil stabilizer. Can be propagated readily from seeds or vegetative (stolon pieces [sprigs]). Normally sown at 5-10 kg/ha dehulled seed. Can spread rapidly in fertile soil and become a weed.Slide 13: Hyperrhenia hirta (common thatching grass): It is grazed by livestock early in the growing season becomes less palatable with age. It is pollinated and seed dispersed by wind. Hyparrhenia hirta is self-fertile, enabling new populations to arise from a single plant. Good for soil stabilization. Plants for improving soil fertility Brachiaria spp. have very strong root systems that can penetrate very compact soils and can improve soil physicochemical and biological properties over a short period of time.Slide 14: Vetiveria zizanioides (L.) Nash) Vetiver and Phragmites australis (reeds) Acts as a pioneer plants growing where other plants would not survive and providing micro-climatic conditions where native species may become established. Both species can be planted across gullies. Caution The vetiver and reeds are non-native plants and may become invasivePropagation of grasses : Propagation of grasses Seeding - Planting grass seed in the soil Sodding - Laying out chunks of turf containing healthy grass plants Adding plugs or sprigs - Transplanting individual grass plants or small sections of grass and soil Watering is importantTrees: Trees Rhus ( Searsia ) lancea - Anacardiaceae It could thus be considered as a possible pioneer plant for establishing a new forest in an area that receives frost. Dense growth of the plant makes it suitable for use as a screen or barrier against wind. The karee ( R. lancea ) is an excellent shade tree especially in hot regions such as the Karoo and Kalahari since it is evergreen and drought resistant.Propagation: Propagation Rhus lancea can be propagated easily from seed, cuttings or layers. The ripe seed should be sown in seedling trays using a good seedling medium and transplanted into bigger containers when the seedlings reach the two leaf stage. Cuttings can be taken using young growth from September till October. The tree can grow up to 80 cm a year and is thus fairly fast growing. Because the tree is both drought and frost resistant it does not require any special attention once it has established its root system.Slide 18: Acacia nilotica (L.) Willd. ex Del. (subfamily Mimosoideae) Subspecies kraussiana prefers dry grasslands and savannas, especially on compacted sandy loam, shallow granite or clay soils along drainages and rivers, but away from flooding. Distribution and Habitat This tree occurs in a variety of woodland types, wooded grassland and scrub escarpment, forests and low-lying forest, in deep soil and along rivers. It is found in large areas of KwaZulu-Natal , eastern and northern Mpumalanga , the northern part of Gauteng , throughout Limpopo and the north-eastern part of the North-West .Slide 19: Propagation It is a pioneer species, easily regenerated from seed. The nutritious indehiscent pods have evolved for animal dispersal. Hard coated seeds can be extracted by pounding the pods or collected from animal pens after the pods have been eaten (Sheikh, 1989). Pre-treatment is needed. Pouring boiling water over the seeds and allowing them to cool are also effective. Cover lightly with sand and do not allow to dry out. It is a particularly good fodder tree, stock and game feed on the leaves, flowers and pods. Seed dispersal takes place this way Acacia species can cause bush encroachmentSlide 20: Acacia karoo (Fabaceae) Sub. Family Mimisoideae Acacia karroo has a life span of 30-40 years. It is an adaptable pioneer, able to establishing itself without shade, shelter or protection from grass fires. Once over a year old, seedlings can re-sprout after fire. Useful windbreak. The sweet thorn is very adaptable to soil types and is frost and drought hardy This tree has a long taproot which enables it to use water and nutrients from deep underground. It has ability to fix nitrogen, lead to grasses and other plants thriving in its shade.Slide 21: Conclusion Land rehabilitation is complex but can be achieved. However, careful environmental planning, and knowledge of ecosystems is key: Each ecosystem is unique Information on indigenous plant and animal species and species interaction is critical Information on soil biodiversity is important Knowledge on abiotic factors including climatic factors, hydrology is importantOpportunities for research: Opportunities for research More laboratory, greenhouse and small-scale field experiments are needed and universities, small-scale businesses and research institutes will play a critical role. Some possible research activities include: Indigenous plant propagation using modern technologies (tissue culture, plant hormones, improving soil fertility) Pest control (biological control, resistant plant varieties) Identify suitable plants species for soil rehabilitation purposes for the different ecological zones of SA Sustainable agriculture Carbon sequestration projectsSlide 23: Thank You You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.