Why Grasses?


I am fascinated by grasses.

Most people associate the term "grass" with the lawns that dot the artificial suburban and urban landscape, but the grass family (Poaceae) actually is composed of a lot more species than that.

Personally, my very life is interwoven with one of the world's most important grasses, rice. Not only are grasses the most important plant family to mankind, but by many measures grasses are the world's most successful angiosperm family (Linder et al. 2017).

Some notable facts about grasses:

  • Economically, grasses are by far the most important plant family. For example, 60% of human energy intake is derived from just three cereal species (rice, wheat, maize/corn; FAO, 1995). Most forage for domestic animals and most of the world's sugar (from Sugar cane or Saccharum officinarum) are also derived from grasses. Grasses like bamboos  are heavily used in construction and its use is increasing by leaps and bounds. Finally, the use of fast growing grasses such as species of Miscanthus, Arundo, Phalaris and others as biomass for energy production is growing.


  • Grasses were intimately involved in the evolution of humanity. The spread of grasslands created the environment where our most essential human traits developed -  flexible diets, large brains, complex social structures and the ability to walk and run on two legs (Uno et al, 2016; Polissar et al, 2019). Without the grasses, our species might not have evolved and developed intelligence.


  • Ecologically, grasses are by far the most dominant plant family. Areas dominated by grasses cover up to 43% of the surface of the world (Gibson, 2009), and they are found in almost every ecological habitat, including Antarctica. Up to 37% of the land area of the USA is dominated by grasses!


  • Although grasses account for only 3% of plant species on Earth, grass-dominated landscapes contribute 33% of global primary productivity, the amount of CO2 removed from the atmosphere every year to fuel photosynthesis (Beer et al., 2010)


  • Grasslands are a more reliable carbon sink than even forests under certain conditions (Dass et al, 2018).


  • Grasses are the fifth most species-rich angiosperm family with about 11,000 species (Clayton et al., 2015)


  • Grasslands have higher plant diversity than even rainforests at the smaller scales (Wilson et al, 2012)


  • Grasses have the ability to survive in the widest range of temperatures among plants, with Deschampsia antartica able to live down to -10 degrees C (with an optimum of 10 degrees), and Dichanthelium thermale able to tolerate up to 65 degrees C in the active geothermal areas of Yellowstone National Park.


  • Ornamental grasses are becoming very popular in landscape plantings and gardens They contribute movement to a static scenery, and are easy to grow and pest resistant.


  • Grasses are coolly difficult. It takes a special kind of masochist to want to try to learn to ID some of them ;-)

REFERENCES

Beer, C., Reichstein, M., Tomelleri, E., Ciais, P., Jung, M., Carvalhais, N., Rodenbeck, C., Arain, M. A., Baldocchi, D., Bonan, G. B., Bondeau, A., Cescatti, A., Lasslop, G., Lindroth, A., Lomas, M., Luyssaert, S., Margolis, H., Oleson, K. W., Roupsard, O., Veenendaal, E., Viovy, N., Williams, C., Woodward, F. I. & Papale, D. (2010). Terrestrial gross carbon dioxide uptake: global distribution and covariation with climate. Science 329,
834–838

Clayton, W. D., Vorontsova, M. S., Harman, K. T. & Williamson, H. (2015). GrassBase – The Online World Grass Flora. Royal Botanic Gardens Kew, Kew.

Pawlok Dass, Benjamin Z Houlton, Yingping Wang, David Warlind. Grasslands may be more reliable carbon sinks than forests in California. Environmental Research Letters, 2018; 13 (7): 074027 DOI: 10.1088/1748-9326/aacb39

Gibson, D. J. (2009). Grasses and Grassland Ecology. Oxford University Press, Oxford.

Linder, H Peter; Lehmann, Caroline E R; Archibald, Sally; Osborne, Colin P; Richardson, David M (2018). Global grass (Poaceae) success underpinned by traits facilitating colonization, persistence and habitat transformation. Biological Reviews of the Cambridge Philosophical Society, 93(2):1125-1144.

Pratigya J. Polissar, Cassaundra Rose, Kevin T. Uno, Samuel R. Phelps & Peter deMenocal (2019). Synchronous rise of African C4 ecosystems 10 million years ago in the absence of aridification. Nature Geosciencevolume 12, pages 657–660

Kevin T. Uno, Pratigya J. Polissar, Kevin E. Jackson, Peter B. deMenocal. Neogene biomarker record of vegetation change in eastern Africa. Proceedings of the National Academy of Sciences, 2016; 113 (23): 6355 DOI: 10.1073/pnas.1521267113

Wilson, J. Bastow; Peet, Robert K.; Dengler, Jürgen; Pärtel, Meelis (1 August 2012). "Plant species richness: the world records". Journal of Vegetation Science. 23 (4): 796–802.

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