A century of woody plant encroachment in the dry Kimberley savanna of South Africa

References

• Archer S, Scifres C, Bassham CR, Maggio R. 1988. Autogenic succession in a subtropical savanna: conversion of grassland to thorn woodland. Ecological Monographs 58: 111–127.
   Web of Science ®Google Scholar
• Archer S, Schimel DS, Holland EA. 1995. Mechanisms of shrubland expansion: land use, climate or CO2? Climate Change 29: 91–99.
   Web of Science ®Google Scholar
• Bates BC, Kundzewicz ZW, Wu S, Palutikof JP (eds). 2008. Climate change and water. Technical paper of the Intergovernmental Panel on Climate Change. Geneva: IPCC Secretariat.
   Google Scholar
• Bezuidenhout H. 1994. An ecological study of the major vegetation communities of the Vaalbos National Park, Northern Cape. 1. The Than-Droogeveld section. Koedoe 37: 19–42.
   Google Scholar
• Bond WJ. 2008. What limits trees in C4 grasslands and savannas? Annual Review of Ecology, Evolution and Systematics 39: 641–659.
   Web of Science ®Google Scholar
• Bond WJ, Midgley GF. 2000. A proposed CO2-controlled mechanism of woody plant invasion in grasslands and savannas. Global Change Biology 6: 865–869.
   Web of Science ®Google Scholar
• Bond WJ, Midgley GF. 2012. Carbon dioxide and the uneasy interactions of trees and savannah grasses. Philosophical Transactions of the Royal Society B: Biological Sciences 367: 601–612.
   PubMed Web of Science ®Google Scholar
• Bond WJ, Midgley GF, Woodward FI. 2003. The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas. Global Change Biology 9: 973–982.
   Web of Science ®Google Scholar
• Booth CA. 1986. The effect of microtopography and woolly butt (Eragrostis eriopoda) competitiion on the survival of hopbush (Dodonaea attenuata) seedlings. In: Joss PJ, Lynch PW, Williams OB (eds), Rangelands: a resource under siege. Cambridge: Cambridge University Press. Adelaide; Cambridge University Press. pp 32–33.
   Google Scholar
• Bowman DMJS, Prior LD, Williamson G. 2010. The roles of statistical inference and historical sources in understanding landscape change: the case of feral buffalo in the freshwater floodplains of Kakadu National Park. Journal of Biogeography 37: 195–199.
   Web of Science ®Google Scholar
• Brando PM, Durigan G. 2004. Changes in cerrado vegetation after disturbance by frost (São Paulo State, Brazil). Plant Ecology 175: 205–215.
   Web of Science ®Google Scholar
• Britz ML, Ward D. 2007. Dynamics of woody vegetation in a semi-arid savanna, with a focus on bush encroachment. African Journal of Range and Forage Science 24: 131–140.
   Google Scholar
• Browning DM, Archer SR, Byrne AT. 2009. Field validation of 1930s aerial photography: what are we missing? Journal of Arid Environments 73: 844–853.
   Web of Science ®Google Scholar
• Buitenwerf R, Bond WJ, Stevens N, Trollope WSW. 2012. Increased tree densities in South African savannas: >50 years of data suggests CO2 as a driver. Global Change Biology 18: 675–684.
   Web of Science ®Google Scholar
• Cabral AC, de Miguel JM, Rescia AJ, Schmitz MF, Pineda FD. 2003. Shrub encroachment in Argentinean savannas. Journal of Vegetation Science 14: 145–152.
   Web of Science ®Google Scholar
• Centritto M, Lucas ME, Jarvis PG. 2002. Gas exchange, biomass, whole-plant water-use efficiency and water uptake of peach (Prunus persica) seedlings in response to elevated carbon dioxide concentration and water availability. Tree Physiology 22: 699–706.
   PubMed Web of Science ®Google Scholar
• Chamberlin TC. 1897. The method of multiple working hypotheses. Journal of Geology 5: 837–848.
   Google Scholar
• Condon RW. 1986. Scrub invasion on semi-arid grazing lands in western New South Wales – causes and effects. In: Joss PJ, Lynch PW, Williams OB (eds), Rangelands: a resource under siege. Cambridge: Cambridge University Press. p 40.
   Google Scholar
• Dean WRJ, Hoffman MT, Meadows ME, Milton SJ. 1995. Desertification in the semi-arid Karoo: review and reassessment. Journal of Arid Environments 30: 247–264.
   Web of Science ®Google Scholar
• Eamus D, Ceulemans R. 2001. Effects of greenhouse gases on the gas exchange of forest trees. In: Karnosky D, Ceulemans R, Scarascia-Mugnozza GE, Innes JL (eds), The impact of CO₂ and other greenhouse gases on forest ecosystems. Wallingford: CABI Publishing. pp 17–56.
   Google Scholar
• Eamus D, Palmer AR. 2007. Is climate change a possible explanation for woody thickening in arid and semi-arid regions?Research Letters in Ecology2007: Article ID 37364, 5 pp.
   Google Scholar
• Ehleringer JM, Monson RK. 1993. Evolutionary and ecological aspects of photosynthetic pathway variation. Annual Review of Ecology and Systematics 24: 411–439.
   Google Scholar
• Ellis JE, Swift DM. 1988. Stability of African pastoral ecosystems: alternate paradigms and implications for development. Journal of Range Management 41: 450–459.
   Google Scholar
• Etchberger RC, Krausman PR. 1997. Evaluation of five methods for measuring desert vegetation. Wildlife Society Bulletin 25: 604–609.
   Google Scholar
• Gordijn PJ, Rice E, Ward D. 2012. The effects of fire on woody plant encroachment are exacerbated by succession of trees of decreased palatability. Perspectives in Plant Ecology, Evolution and Systematics 14: 411–422.
   Web of Science ®Google Scholar
• Goslee SC, Havstad KM, Peters DPC, Rango A, Schlesinger WH. 2003. High-resolution images reveal rate and pattern of shrub encroachment over six decades in New Mexico, U.S.A. Journal of Arid Environments 54: 755–767.
   Web of Science ®Google Scholar
• Harralick RM, Shanmugam K, Dinstein I. 1973. Textural features for image classification. IEEE Transactions on Systems, Man and Cybernetics 3: 610–621.
   Web of Science ®Google Scholar
• Hibbard KA, Schimel DS, Archer S, Ojima DS, Parton W. 2003. Grassland to woodland transitions: integrating changes in landscape structure and biogeochemistry. Ecological Applications 13: 911–926.
   Web of Science ®Google Scholar
• Higgins SI, Bond WJ, Trollope WSW. 2000. Fire, resprouting and variability: a recipe for grass-tree co-existence in savanna. Journal of Ecology 88: 213–229.
   Web of Science ®Google Scholar
• Higgins SI, Bond WJ, February EC, Bronn A, Euston-Brown DIW, Enslin B, Govender N, Rademan L, O'Regan S, Potgieter ALF et al. 2007. Effects of four decades of fire manipulation on woody vegetation structure in savanna. Ecology 88: 1119–1125.
   PubMed Web of Science ®Google Scholar
• Higgins SI, Scheiter S. 2012. Atmospheric CO2 forces abrupt vegetation shifts locally, but not globally. Nature 488: 9–12.
   Web of Science ®Google Scholar
• Higgins SI, Scheiter S, Sankaran M. 2010. The stability of African savannas: insights from the indirect estimation of the parameters of a dynamic model. Ecology 91: 1682–1692.
   PubMed Web of Science ®Google Scholar
• Hobbs RJ, Mooney HA. 1986. Community changes following shrub invasion of grassland. Oecologia 70: 508–513.
   PubMed Web of Science ®Google Scholar
• Hoffman MT, Ashwell A. 2001. Nature divided: land degradation in South Africa. Cape Town: University of Cape Town Press.
   Google Scholar
• Hoffman MT, O'Connor TG. 1999. Vegetation change over 40 years in the Weenen/Muden area, KwaZulu-Natal: evidence from photopanoramas. African Journal of Range and Forage Science 16: 71–88.
   Google Scholar
• Hoffman MT, Rohde R. 2011. Rivers through time: historical changes in the riparian vegetation of the semi-arid, winter rainfall region of South Africa in response to climate and land use. Journal of the History of Biology 44: 59–80.
   PubMed Web of Science ®Google Scholar
• Holdo RM. 2006. Elephant herbivory, frost damage and topkill in Kalahari sand woodland savanna trees. Journal of Vegetation Science 17: 509–518.
   Web of Science ®Google Scholar
• Hudak AT, Wessman CA. 1998. Textural analysis of historical aerial photography to characterize woody plant encroachment in South African savanna. Remote Sensing of the Environment 66: 317–330.
   Web of Science ®Google Scholar
• Hudak AT, Wessman CA. 2001. Textural analysis of high resolution imagery to quantify bush encroachment in Madikwe Game Reserve, South Africa, 1955–1996. International Journal of Remote Sensing 22: 2731–2740.
   Web of Science ®Google Scholar
• Idso SB. 1992. Shrubland expansion in the American Southwest. Climatic Change 22: 85–86.
   Web of Science ®Google Scholar
• Jackson RB, Banner JL, Jobbágy EG, Pockman WT, Wall DH. 2002. Ecosystem carbon loss with woody plant invasion of grasslands. Nature 418: 623–626.
   PubMed Web of Science ®Google Scholar
• Jeltsch F, Milton SJ, Dean WRJ, van Rooyen N. 1997. Analysing shrub encroachment in the southern Kalahari: a grid-based modelling approach. Journal of Applied Ecology 34: 1497–1508.
   Web of Science ®Google Scholar
• Joubert DF, Rothauge A, Smit GN. 2008. A conceptual model of vegetation dynamics in the semiarid Highland savanna of Namibia, with particular reference to bush thickening by Acacia mellifera. Journal of Arid Environments 72: 2201–2210.
   Web of Science ®Google Scholar
• Joubert DF, Smit GN, Hoffman MT. 2012. The influence of rainfall, competition and predation on seed production, germination and establishment of an encroaching Acacia in an arid Namibian savanna. Journal of Arid Environments 87: 1–7.
   Web of Science ®Google Scholar
• Kanowski J. 2001. Effects of elevated CO2 on the foliar chemistry of seedlings of two rainforest trees from north-east Australia: implications for folivorous marsupials. Austral Ecology 26: 165–172.
   Web of Science ®Google Scholar
• Karl TR, Knight RW. 1998. Secular trends of precipitation amount, frequency, and intensity in the United States. Bulletin of the American Meteorological Society 79: 231–241.
   Web of Science ®Google Scholar
• Kennedy M. 2000. Understanding map projections. Redlands, California: Environmental Systems Research Institute.
   Google Scholar
• Kgope B, Bond WJ, Midgley GF. 2010. Growth responses of African savanna trees implicate atmospheric [CO2] as a driver of past and current changes in savanna tree cover. Austral Ecology 35: 451–463.
   Web of Science ®Google Scholar
• Knapp AK, Briggs JM, Collins SL, Archer SR, Bret-Harte MS, Ewers BE, Peters DP, Young DR, Shaver GR, Pendall E, Cleary MB. 2008. Shrub encroachment in North American grasslands: shifts in growth form dominance rapidly alters control of ecosystem carbon inputs. Global Change Biology 14: 615–623.
   Web of Science ®Google Scholar
• Körner C. 2006. Plant CO2 responses: an issue of definition, time and resource supply. New Phytologist 172: 393–411.
   PubMed Web of Science ®Google Scholar
• Kraaij T, Ward D. 2006. Effects of rain, nitrogen, fire and grazing on tree recruitment and early survival in bush-encroached savanna, South Africa. Plant Ecology 186: 235–246.
   Web of Science ®Google Scholar
• Laliberte AS, Rango A, Havstad KM, Paris JF, Beck RF, McNeely R, Gonzalez AL. 2004. Object-oriented image analysis for mapping shrub encroachment from 1937 to 2003 in southern New Mexico. Remote Sensing of the Environment 93: 198–210.
   Web of Science ®Google Scholar
• Lawler IR, Foley WJ, Woodrow IE, Cork SJ. 1997. The effects of elevated CO2 atmospheres on the nutritional quality of Eucalyptus foliage and its interaction with soil nutrient and light availability. Oecologia 109: 59–68.
   Web of Science ®Google Scholar
• Leakey ADB, Bishop KA, Ainsworth EA. 2012. A multi-biome gap in understanding of crop and ecosystem responses to elevated CO2. Current Opinion in Plant Biology 15: 1–9.
   PubMed Web of Science ®Google Scholar
• Leakey ADB, Lau JA. 2012. Evolutionary context for understanding and manipulating plant responses to past, present and future atmospheric [CO2]. Philosophical Transactions of the Royal Society B: Biological Sciences 367: 613–629.
   PubMed Web of Science ®Google Scholar
• Loik ME, Nobel PS. 1993. Freezing tolerance and water relations of Opuntia fragilis from Canada and the United States. Ecology 74: 1722–1732.
   Web of Science ®Google Scholar
• Londo G. 1976 The decimal scale for relevés of permanent quadrats. Vegetatio 33: 61–64.
   Google Scholar
• Mattson WJ, Kuokkanen K, Niemelä P, Julkunen-Tiitto R, Kellomäki S, Tahvanainen J. 2004. Elevated CO2 alters birch resistance to lagomorpha herbivores. Global Change Biology 10: 402–1413.
   Web of Science ®Google Scholar
• Mentis MT. 1981. Evaluation of the wheel-point and step-point methods of veld condition assessment. Proceedings of the Annual Congress of the Grassland Society of Southern Africa 16: 89–94.
   Google Scholar
• Meyer KM, Ward D, Moustakas A, Wiegand K. 2005. Big is not better: small Acacia mellifera shrubs are more vital after fire. African Journal of Ecology 43: 131–136.
   Web of Science ®Google Scholar
• Meyer KM, Wiegand K, Ward D, Moustakas A. 2007a. SATCHMO: a spatial simulation model of growth, competition, and mortality in cycling savanna patches. Ecological Modelling 209: 377–391.
   Web of Science ®Google Scholar
• Meyer KM, Wiegand K, Ward D, Moustakas A. 2007b. The rhythm of savanna patch dynamics. Journal of Ecology 95: 1306–1315.
   Web of Science ®Google Scholar
• Moleele NM, Perkins J. 1998. Encroaching woody plant species and boreholes: is cattle density the main driving factor in the Olifants Drift communal grazing lands, Botswana? Journal of Arid Environments 40: 245–253.
   Web of Science ®Google Scholar
• Morgan JL, Gergel SE, Coops NC. 2010. Aerial photography: a rapidly evolving tool for ecological management. BioScience 60: 47–59.
   Web of Science ®Google Scholar
• Moustakas A, Sakkos K, Wiegand K, Ward D, Meyer KM, Eisinger D. 2009. Are savannas patch-dynamic systems? A landscape model. Ecological Modelling 220: 3576–3588.
   Web of Science ®Google Scholar
• Mucina L, Rutherford MC (eds). 2006. The vegetation of South Africa, Lesotho and Swaziland. Strelitzia19. Pretoria: South African National Biodiversity Institute.
   Google Scholar
• Nelson JA, Morgan JA, LeCain DR, Mosier AR, Milchunas DG, Parton BA. 2004. Elevated CO2 increases soil moisture and enhances plant water relations in a long-term field study in the semiarid shortgrass steppe of Colorado. Plant and Soil 259: 169–179.
   Web of Science ®Google Scholar
• O'Connor TG. 1995. Acacia karroo invasion of grassland: environmental and biotic effects influencing seedling emergence and establishment. Oecologia 10: 214–223.
   Web of Science ®Google Scholar
• O'Connor TG, Crow VRT. 1999. Rate and pattern of bush encroachment in Eastern Cape savanna and grassland. African Journal of Range and Forage Science 16: 26–31.
   Google Scholar
• Petty AM, Werner PA. 2010. How many buffalo does it take to change a savanna? A response to Bowman et al. (2008). Journal of Biogeography 37: 193–195.
   Web of Science ®Google Scholar
• Phoenix GK, Hicks WK, Cinderby S, Kuylenstierna JCI, Stock WD, Dentener FJ, Giller KE, Austin AT, Lefroy RDB, Gimeno BS et al. 2006. Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts. Global Change Biology 12: 470–476.
   Web of Science ®Google Scholar
• Platt JR. 1964. Strong inference. Science 146: 347–353.
   PubMed Web of Science ®Google Scholar
• Puttick JR, Hoffman MT, Gambiza J. 2011. Historical and recent land-use impacts on the vegetation of Bathurst, a municipal commonage in the Eastern Cape, South Africa. African Journal of Range and Forage Science 28: 9–20.
   Web of Science ®Google Scholar
• Rango A, Huenneke L, Buonopane M, Herrick JE, Havstad KM. 2005. Using historic data to assess effectiveness of shrub removal in southern New Mexico. Journal of Arid Environments 62: 75–91.
   Web of Science ®Google Scholar
• Rappole JH, Russell CE, Norwine JR, Fulbright TE. 1986. Anthropogenic pressures and impacts on marginal, neotropical, semiarid ecosystems: the case of south Texas. Science of the Total Environment 55: 91–99.
   Web of Science ®Google Scholar
• Rohde RF, Hoffman M. 2012. The historical ecology of Namibian rangelands: vegetation change since 1876 in response to local and global drivers. Science of the Total Environment 416: 276–288.
   PubMed Web of Science ®Google Scholar
• Roques KG, O'Connor TG, Watkinson AR. 2001. Dynamics of shrub encroachment in an African savanna: relative influences of fire, herbivory, rainfall and density dependence. Journal of Applied Ecology 38: 268–280.
   Web of Science ®Google Scholar
• Scanlan JC, Archer S. 1991. Simulated dynamics of succession in a North American subtropical Prosopis savanna. Journal of Vegetation Science 2: 625–634.
   Web of Science ®Google Scholar
• Scholes RJ, Archer SR. 1997. Tree-grass interactions in savannas. Annual Review of Ecology and Systematics 28: 517–544.
   Google Scholar
• Schulze RE, Maharaj M. 2003. Development of a database of gridded daily temperatures for southern Africa. ACRUcons Report 41. Pietermaritzburg: University of Natal.
   Google Scholar
• Shantz HL, Turner BL. 1958. Photographic documentation of vegetational changes in Africa over a third of a century. Tucson: University of Arizona Press.
   Google Scholar
• Silberbauer-Gottsberger I, Morawetz W, Gottsberger G. 1977. Frost damage of cerrado plants in Botucatu, Brazil, as related to geographical distribution of species. Biotropica 9: 253–261.
   Web of Science ®Google Scholar
• Skarpe C. 1990a. Shrub layer dynamics under different herbivore densities in an arid savanna, Botswana. Journal of Applied Ecology 27: 873–885.
   Web of Science ®Google Scholar
• Skarpe C. 1990b. Structure of the woody vegetation in disturbed and undisturbed arid savanna, Botswana. Plant Ecology 87: 11–18.
   Web of Science ®Google Scholar
• Stock WD, Ludwig F, Morrow C, Midgley GF, Wand SJE, Allsopp N, Bell TL. 2005. Long-term effects of elevated atmospheric CO2 on species composition and productivity of a southern African C4 dominated grassland in the vicinity of a CO2 exhalation. Plant Ecology 178: 211–224.
   Web of Science ®Google Scholar
• Stoddard JL, Jeffries DS, Lükewille A, Clair TA, Dillon PJ, Driscoll CT, Forsius M, Johannessen M, Kahl JS, Kellogg JH et al. 1999. Regional trends in aquatic recovery from acidification in North America and Europe. Nature 401: 575–578.
   Web of Science ®Google Scholar
• Tans PP. 2014. Atmospheric CO2 at Mauna Loa observatory. Available at http://www.esrl.noaa.gov/gmd/ccgg/trends/ [accessed 23 May 2014].
   Google Scholar
• Teague WR, Smit GN. 1992. Relations between woody and herbaceous components and the effects of bush-clearing in southern African savannas. Journal of the Grassland Society of Southern Africa 9: 60–71.
   Google Scholar
• van Langevelde F, van der Vijver CADM, Kumar L, van de Koppel J, de Ridder N, van Andel J, Skidmore AK, Hearne JW, Stroosnijder L, Bond WJ et al. 2003. Effects of fire and herbivory on the stability of savanna ecosystems. Ecology 84: 337–350.
   Web of Science ®Google Scholar
• van Rooyen N, Bredenkamp G. 1996. Kimberley thorn bushveld. In: Low AB, Rebelo AG (eds), Vegetation of South Africa, Lesotho and Swaziland. Pretoria: Department of Environmental Affairs and Tourism. pp 19–36.
   Google Scholar
• Vitousek PM. 1994. Beyond global warming: ecology and global change. Ecology 75: 1861–1876.
   Web of Science ®Google Scholar
• Volder A, Tjoelker MG, Briske DD. 2010. Contrasting physiological responsiveness of establishing trees and a C4 grass to rainfall events, intensified summer drought, and warming in oak savanna. Global Change Biology 16: 3349–3362.
   Web of Science ®Google Scholar
• Vorster CJ. 2003. Simplified geology: South Africa, Lesotho and Swaziland. Pretoria: Council for Geoscience.
   Google Scholar
• Waisel Y, Fahn A. 1965. A radiological method for the determination of cambial activity. Physiologia Plantarum 18: 44–46.
   Web of Science ®Google Scholar
• Wakeling JL, Cramer MD, Bond WJ. 2012. The savanna-grassland ‘treeline’: why don't savanna trees occur in upland grasslands? Journal of Ecology 100: 381–391.
   Web of Science ®Google Scholar
• Walker BH, Noy-Meir I. 1982. Aspects of the stability and resilience of savanna ecosystems. In: Huntley BJ, Walker BH (eds), Ecology of tropical savannas. Berlin: Springer-Verlag. pp 577–590.
   Google Scholar
• Walter H. 1939. Grasland, Savanne und Busch der arideren Teile Afrikas in ihrer ökologischen Bedingtheit. Jahrbuch der wissenschaftliche Botanik 87: 750–860.
   Google Scholar
• Ward D. 2005. Do we understand the causes of bush encroachment in African savannas? African Journal of Range and Forage Science 22: 101–105.
   Google Scholar
• Ward D. 2009. The biology of deserts. Oxford: Oxford University Press.
   Google Scholar
• Ward D. 2010. A resource ratio model of the effects of changes in CO2 on woody plant invasion. Plant Ecology 209: 147–152.
   Web of Science ®Google Scholar
• Ward D, Esler KJ. 2011. What are the effects of substrate and grass removal on recruitment of Acacia mellifera seedlings in a semi-arid environment? Plant Ecology 212: 245–250.
   Web of Science ®Google Scholar
• Ward D, Rohner C. 1997. Anthropogenic causes of high mortality and low recruitment in three Acacia tree taxa in the Negev desert, Israel. Biodiversity and Conservation 6: 877–893.
   Web of Science ®Google Scholar
• Ward D, Wiegand K, Getzin S. 2013. Walter's two-layer hypothesis revisited: back to the roots!. Oecologia 172: 617–630.
   PubMed Web of Science ®Google Scholar
• Wells R, Lloyd S, Turner C. 1996. National air pollution source inventory. In: Held G, Gore BJ, Surridge AD, Tosen GR, Turner CR, Walmsley RD (eds), Air pollution and its impacts on the South African highveld. Cleveland: Environmental Scientific Association. pp 3–9.
   Google Scholar
• Wenig M, Spichtinger N, Stohl A, Held G, Beirle S, Wagner T, Jähne B, Platt U. 2003. Intercontinental transport of nitrogen oxide pollution plumes. Atmospheric Chemistry and Physics 3: 387–393.
   Web of Science ®Google Scholar
• Widodo W, Vu JCV, Boote KJ, Baker JT, Allen LH. Jr 2003. Elevated growth CO2 delays drought stress and accelerates recovery of rice leaf photosynthesis. Environmental and Experimental Botany 49: 259–272.
   Web of Science ®Google Scholar
• Wiegand K, Saltz D, Ward D. 2006. A patch-dynamics approach to savanna dynamics and woody plant encroachment – insights from an arid savanna. Perspectives in Plant Ecology, Evolution and Systematics 7: 229–242.
   Web of Science ®Google Scholar
• Wiegand K, Ward D, Saltz D. 2005. Multi-scale patterns and bush encroachment in an arid savanna with a shallow soil layer. Journal of Vegetation Science 16: 311–320.
   Web of Science ®Google Scholar
• Wigley BJ, Bond WJ, Hoffman MT. 2009. Bush encroachment under three contrasting land-use practices in a mesic South African savanna. African Journal of Ecology 47: 62–70.
   Web of Science ®Google Scholar
• Wigley BJ, Bond WJ, Hoffman MT. 2010. Thicket expansion in a South African savanna under divergent land use: local vs. global drivers? Global Change Biology 16: 964–976.
   Web of Science ®Google Scholar
• Wolfe DW, Erickson JD. 1993. Carbon dioxide effects on plants: uncertainties and implications for modeling crop responses to climate change. In: Kaiser H, Drennen T (eds), Agricultural dimensions of global climate change. Delray Beach: St Lucie Press. pp 153–178.
   Google Scholar
• Zak DR, Holmes WE, Finzi AC, Norby RJ, Schlesinger WH. 2003. Soil nitrogen cycling under elevated CO2: a synthesis of forest FACE experiments. Ecological Applications 13: 1508–1514.
   Web of Science ®Google Scholar
• Zhu XG, Long SP, Ort DR. 2008. What is the maximum efficiency with which photosynthesis can convert solar energy into biomass? Current Opinions in Biotechnology 19: 153–159.
   PubMed Web of Science ®Google Scholar