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Dr Heidi-Jayne Hawkins


Dr. Heidi-Jayne Hawkins
Email: heidi-jane.hawkins@uct.ac.za

I am fascinated by how things work. My background is in nutritional physiology, root adaptations to oligotrophic soils, and soil-plant-microbe interactions in both indigenous and crop plants.  For the last six years as Director of Research and Technical Support at an NGO, Conservation South Africa, my research has informed questions around rangeland management and farming using ecological principles. In 2014, myself and colleagues at Stellenbosch and Wageningen Universities developed and implemented a curriculum on Sustainable Agriculture that draws on systems thinking, biological sciences, social sciences, conservation, agriculture and economics. My current research focuses on the physiological and ecophysiological impacts of herbivores on nutrient cycling and productivity in rangelands, using diverse approaches such as plant source-sink allocations, remote sensing and soil microbial analysis. 

Research highlights

Conservation biology and farming
Over ten years of the so-called Business and Biodiversity Initiatives such as Biodiversity and Wine Initiative, Right Rooibos, Flower Valley Conservation Trust, etc claim to have improved conservation of intermediate zones between farmed lowlands and unfarmed mountainous areas. However a spatial analysis revealed that while these initiatives have tremendous potential to conserve biodiversity, ca. 5000 ha of critical biodiversity areas have in fact been lost since their inception. In livestock farming, we are also testing the claims of Short Duration Grazing or Holistic Planned Grazing. This includes a meta-analysis (article in prep) and several multi-disciplinary field based student research projects in SA grasslands.

 

Mycorrhiza in the Fynbos Biome

Field and pot experiment data show that Fynbos species with mycorrhizal associations (ericoid and arbuscular) can access nitrogen from complex organic forms while non-mycorrhizal Proteaceae species could only access simple forms. (Article in prep).

Cluster roots
The various unique aspects of P nutrition in Proteaceae across the world are reviewed in a phylogenetic context, including the highly efficient acquisition of P via the exudation of carboxylates into the soil, and efficient use of P in ribosomal RNA.



See Lambers H, Shane MW, Clode P, Hawkins H-J, Laliberté E, Oliveira RS, Reddell P, Stitt M, Weston P 2015. Chapter 11: Metabolic adaptations of the non-mycotrophic Proteaceae to soil with a low phosphorus availability. In: Annual Plant Reviews, Volume 50: Phosphorus Metabolism in Plants in the Post-genomic Era: From Gene to Ecosystem, H Lambers, W Plaxton (eds.), pp 289-335, John Wiley & Sons, Ltd., New York, USA, ISBN 978-1-118-95885-8.

Nutritional physiology and mass flow
The demand that plants have for limiting nutrients such as nitrogen and phosphorus has been shown to drive the mass flow of water towards roots, bringing along other nutrients. Sometimes this can result in accumulation and cementation of excess nutrients, forming astonishing artifacts such as root casts. These castes can form at the scale of landscapes.



See Cramer MD, Hawkins H-J, Verboom GA 2009 The importance of nutritional regulation of plant water flux. Oecologia 161, 15-24
Cramer MD, Hawkins H-J 2009 A physiological mechanism for the formation of root casts. Palaeogeography, Palaeoclimatology, Palaeoecology 274: 125-133

Protea physiology: nutrition, hydraulic redistribution and P toxicity
Hawkins H-J, Hettasch H, West A Cramer MD 2009 Hydraulic redistribution by Protea ´Sylvia´ (Proteaceae) facilitates soil water replenishment and water acquisition by an understorey grass and shrub.
Functional Plant Biology 36: 752-760
Hawkins H-J, Hettasch H, Mesjasz-Przybylowicz J, Przybylowicz W, Cramer MD 2008 Phosphorus toxicity in the Proteaceae – a problem in post-agricultural lands. Hort Sci 117, 357-365

 

Current positions
Director of Technical Support & Research, Conservation South Africa
Honorary Research Association, University of Cape Town

Qualifications
BSc. (Nelson Mandela Metropolitan University)
BSc. Hons (Biochemistry; University of Cape Town)
MSc. (Botany; University of Cape Town)
PhD. (Biological Sciences & Agriculture Faculties; University of Hohenheim)

Current teaching
Sustainable Agriculture Masters Course (Stellenbosch University)

Current research students
Alexander Venter (MSc., PhD.)
Tshepo Morokong (MSc.)
Vanessa van Niekerk (MSc.)
Nompendulo Mgwali (MSc.)

Peer-reviewed publication list
Hawkins H-J, Jaffer MA, Graham M, Sewell BT 1990 Measurement of the diameters of chromatin fibres from chicken erythrocyte and sea urchin sperm. Electron Microscopy Society of Southern Africa 20, 185-186.
Hawkins H-J and Lewis OAM 1993 The effect of NaCl salinity, N form and Ca2+ on the growth, ionic content and gaseous exchange properties of Triticum aestivum cv. Gamtoos. New Phytologist 124, 161-170.
Hawkins H-J and Lewis OAM 1993 The effect of NaCl salinity, N form, Ca2+ and K+ concentration on uptake and kinetics in Triticum aestivum cv. Gamtoos. New Phytologist 124, 171-177.
Hawkins H-J and Lips SH 1997 Cell suspension cultures of Solanum tuberosum as a model system for N and salinity response: Effect of salinity on NO3- uptake and PM-ATPase activity. Journal of Plant Physiology 150, 103-109.
Hawkins H-J and George E 1997 Hydroponic culture of the mycorrhizal fungus Glomus mosseae with Linum usitatissimum L., Sorghum bicolor L. and Triticum aestivum L. Plant and Soil 196, 143-149.
Hawkins H-J, George E, Römheld V 1998 Beitrag der Mykorrhiza zur Aufnahme von anorganischem und organischem N in Weizen. In: 8. Borkheider Seminar zur Ökophysiologie des Wurzelraumes, Mikrobielle Leistungen in der Rhizosphäre, pp 109-114, W. Merbach (ed.) B.G. Teubner Verlagsgesellschaft Stuttgart, Leipzip.
Hawkins H-J and George E 1998 Substrate-free culture of mycorrhizal plants: Aeroponic, nutrient flow and hydroponic culture. In: Microbes: For Health, Wealth and Sustainable Environment, pp 809-826, A. Varma (ed.), Malhotra Publishing House, New Delhi.
Caris C, Hördt W, Hawkins H-J, Römheld V, George E 1998 Studies of iron transport by arbuscular mycorrhizal hyphae from soil to peanut and sorghum plants. Mycorrhiza 8, 35-39.
Hawkins H-J and George E 1999 Effect of plant nitrogen status on the contribution of arbuscular mycorrhizal hyphae to plant nitrogen uptake. Physiologia Plantarum 105, 694-700
Hawkins H-J, Cramer MD, George E 1999 Root respiratory quotient and nitrate uptake in hydroponically grown non-mycorrhizal and mycorrhizal wheat. Mycorrhiza 9, 57-60
Hawkins H-J, George E, Römheld V 2000 Contribution of arbuscular mycorrhiza to uptake of organic and inorganic N in wheat and carrot. In: Nitrogen in a sustainable ecosystem – from the cell to the plant, MA Martins-Loução (ed.), pp 45-50, Backhuys Publishers, Leiden, Netherlands
Karandashov VE, Kuzovkina I, Hawkins H-J, George E 2000 Growth and sporulation of the arbuscular mycorrhizal fungus, Glomus caledonium, in dual culture with transformed carrot roots. Mycorrhiza 10, 23-28
Hawkins H-J, Johansen A, George E  2000 Uptake and transport of organic and inorganic nitrogen by arbuscular mycorrhizal fungi. Plant and Soil 226, 275-285
Hawkins H-J, George E 2001 Reduced 15N-nitrogen transport through arbuscular mycorrhizal hyphae to Triticum aestivum L. supplied with ammonium versus nitrate nutrition. Annals of Botany 87, 303-311
Hawkins HJ and Grobicki A 2001 Guidelines for sustainable use, cultivation or construction of wetlands: site assessment and design. WRC Project No. K5/1054
Hawkins H-J, Wolf G, Stock WD 2005 Cluster roots of Leucadendron laureolum (Proteaceae) and Lupinus albus (Fabaceae) take up glycine intact: an adaptive strategy to low mineral N in soils? Annals of Botany 96, 1275-1282
Hawkins H-J, Hettasch H, Cramer MD 2007 Putting back what we take out, but how much? Phosphorus and nitrogen additions to farmed Leucadendron ‘Safari Sunset’ and Leucospermum ‘Succession’ (Proteaceae). Hort Sci 111, 378-388
Hawkins H-J, Hettasch H, Mesjasz-Przybylowicz J, Przybylowicz W, Cramer MD 2008 Phosphorus toxicity in the Proteaceae – a problem in post-agricultural lands. Hort Sci 117, 357-365
Cramer MD, Hawkins H-J 2009 A physiological mechanism for the formation of root casts. Palaeogeography, Palaeoclimatology, Palaeoecology 274: 125-133
Cramer MD, Hawkins H-J, Verboom GA 2009 The importance of nutritional regulation of plant water flux. Oecologia 161, 15-24
Hawkins H-J, Hettasch H, West A Cramer MD 2009 Hydraulic redistribution by Protea ´Sylvia´ (Proteaceae) facilitates soil water replenishment and water acquisition by an understorey grass and shrub. Functional Plant Biology 36: 752-760
Hawkins H-J, Cramer MD, Louw E, O’Brian C, Mesjasz-Przybylowicz J, Przybylowicz W 2010 Prevention and amelioration of phosphorus toxicity in Proteaceae grown on previously fertilized land. Proceedings IXth International Protea Research Symposium, International Society for Horticultural Science (ISHS), A Gerber, L Hoffman (eds), Acta Horticulturae 869, 37-46
Hawkins H-J 2010 Expert opinion: Mainstreaming biodiversity. In: The Environmental Handbook: A guide to green business in South Africa 2nd edition, pp 86-87, Trialogue, Cape Town, SA, ISBN 978-0-620-43696-0
Hawkins H-J, Malgas R, Biénabe E 2011 Ecotypes of wild rooibos (Aspalathus linearis (Burm. F) Dahlg., Fabaceae) are ecologically distinct. South African Journal of Botany 77, 360–370.

Published Conference Proceedings
Hawkins H-J, Luyt C, Smith E, Newman R, Bourne A, Martins Q, Frazee S 2012 Eco-Rangers:
Reducing livestock losses while improving farm management and skills in Namaqualand rangelands? Arid Zone Ecology Forum, Worcester, South Africa.
Hawkins H-J, Stanway R, Corcoran B, Mudalahothe T, Kotze I, von Bormann T, Burns A, Stephens A, Venter J, Frazee S 2013 The Veld-Raised Meat Standard: a cut above? 48th Annual Congress of the Grasslands Society of Southern Africa Annual Congress No. 48, Molemole, South Africa.
Kristine Teichman, Bogdan Cristescu, Quinton Martins, Heidi Hawkins 2013 Wildlife-human coexistence: Mitigation of livestock predation and biodiversity conservation in the Karoo. Arid Zone Ecology Forum, Worcester, South Africa.
Hawkins H-J, Nel G, Mgwali N, McLeod N, Matela S, Frazee S, Knight A 2014 Mapping social, ecological and production dimensions for targeted conservation opportunities. 49th Annual Congress of the Grassland Society of Southern Africa, Bloemfontein, South Africa.
Hawkins H-J 2015 Meta-analysis: Does short duration grazing work in the grasslands? 50th Annual Congress of the Grassland Society of Southern Africa, Bloemfontein, South Africa.

 

Peer-reviewed books, book chapters and books edited
De Beer EF 2009 Sustainable Mohair Industry Production Guidelines: Pre-farm gate 2009/2010 1st edition, H-J Hawkins (ed), SA Mohair Growers Association, Mohair SA, Cape Town, SA.
De Beer EF 2011 Sustainable Mohair Industry Production Guidelines: Pre-farm gate 2011/2012 2nd edition, H-J Hawkins (ed), SA Mohair Growers Association, Mohair SA, Cape Town, SA. DOI: 10.13140/RG.2.1.1658.3842
De Beer EF 2010 Code of Best Practice for Wool Sheep Farming in South Africa 2010/2011 edition, version 3, H-J Hawkins (ed), National Wool Growers Association, Cape Town, SA.
Goldblatt A, Kotze I, Corcoran B, Botha M, Brinkcate T, Hawkins H-J 2010 Agriculture: Facts and Trends South Africa, T von Bormann and M Rose (eds.), Refresh Creative Media, Cape Town, South Africa.
Hawkins H-J, Cramer MD 2011 The Protea Grower’s Manual: Sustainable Nutrition and Irrigation, v.1.1, Protea Producers of South Africa, Cape Town, South Africa, ISBN 978-0-620-59736-4. DOI: 10.13140/RG.2.1.3231.2484.
Pretorius G, Harley V, Ryser L 2011 n Handboek vir die implementering van volhoubaarhedistandaarde in Rooibosproduksie, Hawkins H-J en Rose M (eds.), Refresh Creative Media.
Pretorius G, Harley V, Ryser L 2011 Handbook for the implementation of sustainable Rooibos standards, Hawkins H-J en Rose M (eds.), Refresh Creative Media.
Hawkins H-J, Stanway R 2013 The Sustainable Dairy Handbook: For South African Dairy Farmers, Nestlé Printers, Bryanston, South Africa, ISBN 978-0-620-59372-4. DOI: 10.13140/RG.2.1.2838.0321
Lambers H, Shane MW, Clode P, Hawkins H-J, Laliberté E, Oliveira RS, Reddell P, Stitt M, Weston P 2015. Chapter 11: Metabolic adaptations of the non-mycotrophic Proteaceae to soil with a low phosphorus availability. In: Annual Plant Reviews, Volume 50: Phosphorus Metabolism in Plants in the Post-genomic Era: From Gene to Ecosystem, H Lambers, W Plaxton (eds.), pp 289-335, John Wiley & Sons, Ltd., New York, USA, ISBN 978-1-118-95885-8.

Peer-review papers in preparation:
Hawkins H-J and Stock W. Relative influence of source nitrogen, mycorrhiza, rainfall and foliar nitrogen on d15N foliar signatures of plants in the nitrogen-limited soils of the South African Cape Floristic Region.
Hawkins H-J, Rohwer, J, McKensie J, Cramer MD. Timing of organic acid synthesis, storage and exudation in roots of Proteaceae and Fabaceae using 31P- and 13C-NMR spectrometry in prep
Hawkins H-J, Stanway R, Pence GQK Contribution of ecoagriculture to critical biodiversity, landscape connectivity and ecological support areas in the Western Cape, South Africa. South African Journal of Botany, in prep.
Hawkins H-J, Coq S, Bienabe E. Cramer MD. Effects of farming practises on the biodiversity, community structure and root functional traits of vegetation remnants surrounding honeybush (Cyclopia spp.) and rooibos (Aspalathus linearis) farms in the Cape Floristic Region, South Africa. in prep
Hawkins H-J, Stanway R, Frazee S Accessible monitoring and evaluation of socio-economic and environmental indicators on South African farms. 2014. FarmLink in prep.

Transitional outputs: Technical reports, manuals, guides and pamphlets:
Douma M, Hawkins H-J, Vellema S 2011 Linking biodiversity conservation to market-led development: A case study of the Right Rooibos Initiative, South Africa. IChA Working Paper No. 2/Partnerships Resource Centre Working Paper, 1-40, Development Cooperation, Dutch Ministry of Foreign Affairs,  Netherlands.
Hawkins H-J 2011 Participatory monitoring enables agro-environmental initiative in the Cape Floristic Region, South Africa. IChA Working Paper 1, 1-22, Development Cooperation, Dutch Ministry of Foreign Affairs, Netherlands.
Hawkins H-J 2011 The Green Choice Brochure. Refresh Creative Media, Cape Town, South Africa.
Various fact sheets for the Rooibos, potato and wine industries.
Hawkins H-J, von Bormann T 2010 Living Landscapes Living Farms, A1 educational poster produced for GreenChoice Alliance, WWF-SA and Conservation South Africa in collaboration with LandCare, Department of Agriculture, Forestry and Fisheries, Refresh Creative Media, Cape Town, South Africa.
Hawkins H-J, Cramer MD 2008 Phosphorus toxicity in proteas: symptoms and amelioration. A4 booklet produced for PPSA, Cape Town, South Africa.
Morrow C, Matlhoahela T, Hawkins H-J, Cramer MD 2007 Nutrient deficiencies and toxicities in cultivated Proteaceae. A2 poster-pamphlet produced for PPSA, Paarl Print, Paarl, South Africa.
Hawkins H-J, Cramer MD, Hettasch H 2007 Protea nutrition: Food for thought, Farmers Weekly 23.02.07, 60-64