Skip to main content Accessibility help

We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.

Close cookie message
×
Hostname: page-component-cb9f654ff-k7rjm Total loading time: 0 Render date: 2025-08-06T00:49:16.251Z Has data issue: false hasContentIssue false

16 - Savannas

from Section Four - Case Studies

Published online by Cambridge University Press:  05 June 2016

Derek Eamus ,
Alfredo Huete  and
Qiang Yu
Derek Eamus
Affiliation:
University of Technology, Sydney
Alfredo Huete
Affiliation:
University of Technology, Sydney
Qiang Yu
Affiliation:
University of Technology, Sydney
Get access

Summary

Introduction

Savannas are biomes with a discontinuous tree layer and a grass understorey. They are generally tropical or sub-tropical with a distinctly seasonal distribution of rainfall. The two major plant functional types (trees and grasses) have contrasting strategies for surviving the dry season and this is reflected in the seasonality of productivity, leaf area index and patterns in water-use. Woody thickening, whereby the standing biomass of trees increases over time, is a globally observed phenomenon which has implications for carbon (C) storage and catchment water balances of savannas.

Key questions addressed in this case study include: How do tree and grass productivities vary at daily, seasonal and inter-annual time-scales? What are the major drivers of variability in C uptake and water-use at a single site and along rainfall gradients? What is causing woody thickening globally?

A range of field based studies at leaf, canopy and plot scales are discussed in this chapter to illustrate the relationships among meteorological variables at hourly, daily, seasonal and inter-annual time-scales. Remotely sensed data are used to examine: (a) the relative importance of various environmental drivers in explaining differences in productivity; and, (b) large spatial and temporal patterns in phenology along an aridity gradient in north Australia.

Variation in soil moisture content and vapour pressure deficit are vitally important as drivers of daily and seasonal patterns of water-use and C fluxes of savannas. Explanations for inter-annual variations in phenological patterns differ according to aridity and the relative dominance of monsoonal versus convective storm rainfall. Productivity of savannas is very strongly influenced by water availability and much of this is related to changes in LAI of the understorey.

What Are Savannas?

Savannas are characterised by: (i) a high degree of predictability in the occurrence of wet and dry seasons (although timing and amount of rainfall can vary and this can have important impacts on savanna function); (ii) moderate to high temperatures; (iii) the coexistence of a tree dominated overstorey and grass dominated understorey; (iv) the occurrence of fire as a frequent disturbance; and, (v) for tropical and sub-tropical savannas, only small variation in day length. This is contrast to Boreal forests Chapter 14), which are characterised by winters of extreme cold and short day length, and arid and semi-arid grasslands (Chapter 15), which are characterised by very low inputs of rain and extreme variability in the timing and amount of rainfall received each year.

Information

Type
Chapter
Information
Vegetation Dynamics
A Synthesis of Plant Ecophysiology, Remote Sensing and Modelling
 , pp. 383 - 414
Publisher: Cambridge University Press
Print publication year: 2016

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Book purchase

Temporarily unavailable

References

Arneth, A, Veenendaal, EM, Best, C, Timmermans, W, Kolle, O and Montagnani, L, (2006). Water-use strategies and ecosystem-atmosphere exchange of CO2 in two highly seasonal environments. Biogeosciences Discussion 3, 421–437.Google Scholar
Baldocchi, DD, (2008). Breathing of the terrestrial biosphere: lessons learned from a global network of carbon dioxide flux measurement systems. Australian Journal of Botany 56, 1–26.Google Scholar
Baldocchi, DD and Ryu, Y, (2011). Synthesis of Forest Evaporation Fluxes–from Days to Years–as Measured with Eddy Covariance. In Forest Hydrology and Biogeochemistry: Synthesis of Past Research and Future Directions, Levia, DF and Carlyle-Moses, D (Eds.), Ecological Studies, 216, Springer Science Business Media. DOI 10.1007/978-94-007-1363-5.
Berry, Sl and Roderick, ML, (2002). CO2 and land-use effects on Australian vegetation over the last two centuries. Australian Journal of Botany 50, 511–531.Google Scholar
Berryman, CA, Eamus, D and Duff, GA, (1993). The influence of carbon dioxide enrichment on growth, nutrient content and biomass allocation of Maranthes corymbosa. Australian Journal of Botany 41, 195–209.CrossRefGoogle Scholar
Bruemmer, C, Falk, U, Papen, H, Szarzynski, J and Wassmann, R, (2008). Diurnal, seasonal and interannual variation in carbon dioxide and energy exchange in shrub savanna in Burkina Faso (West Africa). Journal of Geophysical Research-Biogeosciences 113, GO2030.Google Scholar
Bucci, SJ, Scholz, FG, Goldstein, G, Hoffmann, WA, Meinzer, FC, Franco, AC, Giambelluca, T and Miralles-Wilhelm, F, (2008). Controls on stand transpiration and soil water utilization along a tree density gradient in a Neotropical savanna. Agricultural and Forest Meteorology 148, 839–849.Google Scholar
Buis, GM, Blair, JM, Burkepile, DE, Burns, CE, (2009) Controls of above-ground net primary production in mesic savanna grassland: an inter-hemispheric comparison. Ecosystems 12, 982–995.Google Scholar
Campo-Bescos, MA, Munoz-Carpena, R, Kaplan, DA, Southworth, J, Zhu, L, Waylen, PR, (2013). Beyond precipitation: physiographic gradients dictate the relative importance of environmental drivers on savanna vegetation. PLOS One 8, e72348. DOI: 10.1371/journal.pone.0072348CrossRefGoogle Scholar
Cernusak, LA, Hutley, LB, Beringer, J, Holtum, JAM, Turner, BLet al., (2011). Photosynthetic physiology of eucalypts along a sub-continental rainfall gradient in northern AustraliaAgricultural and Forest Meteorology 151, 1462–1470.Google Scholar
Ciais, P, Piao, S-L, Cadule, P, Friedlingstein, P and Chedin, A, (2009). Variability and recent trends in the African terrestrial carbon balance. Biogeosciences 6, 1935–1948.Google Scholar
Cowan, IR and Farquhar, GD, (1977). Stomatal function in relation to leaf metabolism and environment. Symposium of the Society for Experimental Biology 31, 471–505.Google Scholar
Do, FC, Rocheteau, A, Diagne, AL, Goudiaby, V, Granier, AL and Homme, JP, (2008). Stable annual pattern of water-use by Acacia tortilis in Sahelian Africa. Tree Physiology 28, 95–104.Google Scholar
Dye, PJ, (1996). Climate, forests and streamflow relationships in South African afforested catchments. Commonwealth Forestry Review 75, 31–38.Google Scholar
Eamus, D and Ceulemans, R, (2001). Effects of greenhouse gases on the gas exchange of forest trees. In The Impact of CO2 and Other Greenhouse Gases on Forest Ecosystems, Karnosky, D and Ceulemans, R (Eds.), CABI Publishing, UK, pp. 17–56.
Eamus, D, Cleverly, J, Boulain, N, Grant, N, Faux, R and Villalobos-Vega, R, (2013). Carbon and water fluxes in an arid-zone Acacia savanna woodland: An analyses of seasonal patterns and responses to rainfall events. Agricultural and Forest Meteorology 182–183, 225–238.Google Scholar
Eamus, D and Cole, SC, (1997). Diurnal and seasonal comparisons of assimilation, phyllode conductance and water potential of three Acacia and one eucalypt species in the wet−dry tropics of Australia. Australian Journal of Botany 45, 275–290.Google Scholar
Eamus, D, Duff, G and Berryman, CA, (1995). The effects of increased atmospheric CO2 concentration on the response of assimilation to temperature, LAVPD, light flux density and CO2 concentration of Eucalyptus tetrodonta. Environmental Pollution 68, 133–140.Google Scholar
Eamus, D, Hutley, LB and O'Grady, A, (2001). Daily and seasonal patterns of carbon and water fluxes above a north Australian savanna. Tree Physiology 21, 977–988.Google Scholar
Eamus, D and Jarvis, PG, (1989). The direct effects of increase in the global atmospheric CO2 concentration on natural and commercial temperate trees and forests. Advances in Ecological Research 19, 1–55.Google Scholar
Eamus, D, O'Grady, A and Hutley, L, (2000). Dry season conditions determine wet season water-use in the wet-dry tropical savannas of northern Australia. Tree Physiology 20, 1219–1226.Google Scholar
Eamus, D and Palmer, AR, (2007). Is climate change a possible explanation for woody thickening in arid and semi-arid regions?Research Letters in Ecology DOI: 10.1155/2007/37364.CrossRefGoogle Scholar
Eldridge, DJ, Bowker, MA, Maestre, FT, Roger, E, Reynolds, JF and Whitford, WG, (2011). Impacts of shrub encroachment on ecosystem structure and functioning: towards a global synthesis. Ecology Letters 14, 709–722.Google Scholar
Franco, AC, (1998). Seasonal patterns of gas exchange, water relations and growth of Roupala montana, an evergreen savanna species. Plant Ecology 136, 69–76.Google Scholar
Gedney, N, Cox, PM, Betts, RA, Boucher, O, Huntingford, C and Stott, PA, (2006). Detection of a direct carbon dioxide effect in continental river runoff records. Nature 439, 835–838.CrossRefGoogle Scholar
Gifford, RM, (2005). (Ed) Pan evaporation: An example of the detection and attribution of trends in climate variables. Proceedings of a workshop held at the Shine Dome, Australian Academy of Science, Canberra 22–23 November 2004.
Givnish, J, (1988). Adaptation to sun and shade–a whole plant perspective. Australian Journal of Plant Physiology 15, 63–92.Google Scholar
Gu, LH, Baldocchi, DD, Wofsy, SC, Munger, JW, Michalsky, JJ, Urbanski, SP and Boden, TA, (2003). Response of a deciduous forest to the Mount Pinatubo eruption: enhanced photosynthesis. Science 299, 2035–2038.Google Scholar
Hubbard, RM, Bond, BJ, Ryan, MG, (1999) Evidence that hydraulic conductance limits photosynthesis in old Ponderosa trees. Tree Physiology 19, 165–172.Google Scholar
Kanniah, KD, Beringer, J and Hutley, LB, (2011). Environmental controls on the spatial variability of savanna productivity in the Northern Territory. Agricultural and Forest Meteorology 151, 1429–1439.Google Scholar
Kanniah, KD, Beringer, J, North, P and Hutley, L, (2012). Control of atmospheric particles on diffuse radiation and terrestrial plant productivity: A review. Progress in Physical Geography 36, 209–237.Google Scholar
Keeling, C, Whort, TP, Wahlen, M and Plicht, J van der, (1995). Interannual extremes in the rate of rise of atmospheric carbon dioxide since 1980. Nature 375, 666–670.Google Scholar
Kutsch, WL, Hanan, N, Schoiles, B, McHugh, I, Kubheka, W, Eckhardt, H and Williams, C, (2008). Response of carbon fluxes to water relations in a savanna ecosystem in South Africa. Biogeosciences 5, 1797–1808.Google Scholar
Labat, D, Godderis, Y, Probst, JL and Guyot, JL. (2004). Evidence for global runoff increase related to climate warming. Advances in Water Resources 27, 631–642.Google Scholar
Leuning, R, Cleugh, HA, Zegelin, SJ and Hughes, D, (2005). Carbon and water fluxes over a temperate Eucalyptus forest and a tropical wet/dry savanna in Australia: measurements and comparison with MODIS remote sensing estimates. Agricultural and Forest Meteorology 129, 151–173.Google Scholar
Ma, S, Baldocchi, DD, Xu, L and Hehn, T, (2007). Inter-annual variability in carbon dioxide exchange of an oak/grass savanna and open grassland in California. Agricultural and Forest Meteorology 147, 157–171.Google Scholar
Ma, X, Huete, A, Yu, Q, Coupe, N Restrepo, Davies, K, Broich, M, Ratana, P, Beringer, J, Hutley, LB, Cleverly, J, Boulain, N and Eamus, D, (2013). Spatial patterns and temporal dynamics in savanna vegetation phenology across the North Australian Tropical Transect. Remote Sensing of Environment 139, 97–115.Google Scholar
Macinnis-Ng, C, Zeppel, M, Williams, M and Eamus, D, (2011). Applying a SPA model to examine the impact of climate change on GPP of open woodlands and the potential for woody thickening. Ecohydrology 4, 379–393.CrossRefGoogle Scholar
Medlyn, BE, Duursma, RA, Eamus, D, Ellsworth, DS, Prentice, CI, Barton, CVM, Crous, KY, Angelis, P de, Freeman, M and Wingate, L, (2011). Reconciling the optimal and empirical approaches to modelling stomatal conductance. Global Change Biology 17, 2134–2144.CrossRefGoogle Scholar
Merbold, L, Ardo, J, Arneth, A, Scholes, RJ, Nouvellon, Y, Grandcourt, A de, Archibald, S, Bonnefond, JM, Boulain, N, Brueggemann, N, Bruemmer, C, Cappelaere, B, Ceschia, E, El-Khidir, HAM, El-Tahir, BA, Falk, U, Lloyd, J, Kergoat, L, Dantec, V Le, Mougin, E, Muchinda, M, Mukelabai, MM, Ramier, D, Roupsard, O, Timouk, F, Veenendaal, EM and Kutsch, KL, (2009). Precipitation as driver of carbon fluxes in 11 African ecosystems. Biogeosciences 6, 1027–1041.CrossRefGoogle Scholar
Miller, JM, Williams, RJ and Farquhar, GD, (2001). Carbon isotope discrimination by a sequence of Eucalyptus species along a sub-continental rainfall gradient in Australia. Functional Ecology 15, 222–232.Google Scholar
Miranda, AC, Miranda, HS, Lloyd, J, Grace, J, Francey, RJ, McIntyre, JA, Meir, P, Riggan, P, Lockwood, R and Brass, J, (1997). Fluxes of carbon, water and energy over Brazilian cerrado: an analysis using eddy covariance and stable isotopes. Plant, Cell and Environment 20, 315–328.CrossRefGoogle Scholar
Myers, BA, Duff, GA, Eamus, D, Fordyce, IR, O'Grady, A and Williams, RJ, (1997). Seasonal variation in water relations of trees of differing leaf phenology in a wet–dry tropical savanna near Darwin, northern Australia. Australian Journal of Botany 45, 225–240.Google Scholar
Pitman, JE, (1996). Ecophysiology of tropical dry evergreen forest, Thailand: measured and modelled stomatal conductance of Hopea ferrea, a dominant canopy emergent. Journal of Applied Ecology 33, 1366–378.CrossRefGoogle Scholar
Prior, L and Eamus, D, (2000). Seasonal changes in hydraulic conductance, xylem embolism and leaf area in Eucalyptus tetrodonta and E. miniata saplings in a north Australian savanna. Plant, Cell and Environment 23, 800–810.Google Scholar
Prior, LD, Bowman, DMJS and Eamus, D, (2005). Intra-specific variation in leaf attributes of four savanna tree species across a rainfall gradient. Australian Journal of Botany 53, 323–335.Google Scholar
Prior, LD, Eamus, D and Duff, GA, (1997). Seasonal trends in carbon assimilation, stomatal conductance, pre-dawn leaf water potential and growth in Terminalia ferdinandiana, a deciduous tree of northern Australian savannas. Australian Journal of Botany 45, 53–69.Google Scholar
Roderick, ML and Farquhar, GD, (2002). The cause of decreased pan evaporation over the past 50 years. Science 298, 1410–1411.Google Scholar
Roderick, ML and Farquhar, GD, (2004). Changes in Australian pan evaporation from 1970 to 2002. International Journal of Climatology 24, 1077–1090.CrossRefGoogle Scholar
Jose, J San, Montes, R, Grace, J and Nikonova, N, (2008). Land-use changes alter CO2 flux patterns of a tall-grass Andropogon field and a savanna-woodland continuum in the Orinoco lowlands. Tree Physiology 28, 437–450.Google Scholar
Scholes, RJ and Hall, DO, (1996). The carbon budget of tropical savannas, woodlands and grasslands. In Global Change: Effects on Coniferous Forests and Grasslands, SCOPE, Vol. 56, Breymeyer, AI, Hall, DO, Melillo, JM and Agren, GI (eds). Wiley: Chichester; pp. 69–100.
Schulze, ED, William, RJ, Farquhar, GD, Schulz, ED, Langridge, J, Miller, JM, Walker, BH. (1998). Carbon and nitrogen isotope discrimination and nitrogen nutrition of trees along a rainfall gradient in northern Australia. Australian Journal of Plant Physiology 25, 413–425.CrossRefGoogle Scholar
Schymanski, SJ, Roderick, ML, Sivapalan, M, Hutley, LB and Beringer, J, (2007). A test of the optimality approach to modelling canopy properties and CO2 uptake by natural vegetation. Plant, Cell and Environment 30, 1586–1598.CrossRefGoogle Scholar
Thomas, DS, Eamus, D and Shanahan, S, (1999). Influence of season, drought and xylem ABA on stomatal responses to leaf-to-air vapour pressure difference of trees of the Australian wet-dry tropics. Australian Journal of Botany 48, 143–151.Google Scholar
Tognetti, R, Michelozzi, M and Giovannelli, A, (1997). Geographical variation in water relations, hydraulic architecture and terpene composition of Aleppo pine seedlings from Italian provenances. Tree Physiology 17, 241–250.CrossRefGoogle Scholar
Tyree, MT and Ewers, FW, (1996). Hydraulic architecture of woody tropical plants. In Tropical Forest Plant Ecophysiology. Mulkey, SS, Chazdon, RL and Smith, AP (Eds). Chapman and Hall, New York, pp 217–243.
Veenendaal, EM, Mantlana, KB, Pammenter, NW, Weber, P, Huntsman-Mapoila, P and Lloyd, J, (2008). Growth form and seasonal variation in leaf gas exchange of Colophospermum mopane savanna trees in northwest Botswana. Tree Physiology 28, 417–424.CrossRefGoogle Scholar
Whitley, RJ, Macinnis-Ng, CMO, Hutley, LB, Beringer, J, Zeppel, M, Williams, M, Taylor, D and Eamus, D, (2011). Is productivity of mesic savannas light limited or water limited? Results of a simulation study. Global Change Biology 17, 3130–3149.CrossRefGoogle Scholar
Williams, RJ, Myers, BA, Muller, MJ, Duff, GA and Eamus, D, (1997). Leaf phenology of woody species in a north Australian tropical savanna. Ecology 78, 2542–2558.CrossRefGoogle Scholar
Wright, IJ, Reich, PB, Westoby, M and Ackerly, DD, et al., (2004). The worldwide leaf economics spectrum. Nature 428, 821–827.Google Scholar
Wullschleger, SD, Gunderson, CA, Hanson, PJ, Wilson, KB and Norby, RJ, (2002a). Sensitivity of stomatal and canopy conductance to elevated CO2 concentration–interacting variables and perspectives of scale. New Phytologist 153, 485–496.Google Scholar
Wullschleger, SD, Tschaplinski, TJ and Norby, RJ, (2002b). Plant water relations at elevated CO2 implications for water-limited environments. Plant, Cell and Environment 25, 319–331.Google Scholar
Yi, C, Ricciuto, D, Li, R, Wolbeck, J, Xu, X, Nilsson, M and Aires, L, (2010). Climate control of terrestrial C exchange across biomes and continents. Environmental Research Letters 5, 034007.Google Scholar

Accessibility standard: Unknown

Accessibility compliance for the PDF of this book is currently unknown and may be updated in the future.

Save book to Kindle

To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

  • Savannas
  • Derek Eamus, University of Technology, Sydney, Alfredo Huete, University of Technology, Sydney, Qiang Yu, University of Technology, Sydney
  • Book: Vegetation Dynamics
  • Online publication: 05 June 2016
  • Chapter DOI: https://doi.org/10.1017/CBO9781107286221.017
Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

  • Savannas
  • Derek Eamus, University of Technology, Sydney, Alfredo Huete, University of Technology, Sydney, Qiang Yu, University of Technology, Sydney
  • Book: Vegetation Dynamics
  • Online publication: 05 June 2016
  • Chapter DOI: https://doi.org/10.1017/CBO9781107286221.017
Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Savannas
  • Derek Eamus, University of Technology, Sydney, Alfredo Huete, University of Technology, Sydney, Qiang Yu, University of Technology, Sydney
  • Book: Vegetation Dynamics
  • Online publication: 05 June 2016
  • Chapter DOI: https://doi.org/10.1017/CBO9781107286221.017
Available formats
×