what is grass and why is it important?

It’s that green stuff that grows in the field and on our lawns right?

And when it comes to horses, there’s always too much or too little.

But still, grass is just grass … right?

Actually, it’s estimated that there are over 12,000 species worldwide. Up to 160 of these species are found in the UK (and 158 of which are illustrated in Hubbard – generally accepted as one of the best field guides for ecologists conducting grassland surveys, and any of you that may want to refine your ID skills [although I wouldn’t recommend you dive straight in with Hubbard, there are some simpler introductory guides that can help get you started, if you’re interested then drop me a message or leave a comment below and I’ll be in touch to support you on your grass identification journey!]).

Have a look on your field and how many species can you see?

Since the onset of agricultural intensification and forage (hay/haylage/silage) production, most sown fields only have 6-7 species in their mix. These are dominated by rye grasses (Lolium species), Timothy (Phleum pratense), cocks foot (Dactylis glomerata) and fescue species (Festuca sp.) chosen for their fast growth profile and ease to manage intensively. Forming one of the largest ecosystems in the world, covering over 7,100 million ha (approximately 50% of terrestrial land) worldwide and up to 1.4 million ha in the UK it’s worth considering the implications of this –

• Does the species of grass really matter?
• Does it really matter if our management favours some species over others, and reduces grassland diversity?

I want to look at this from two perspectives, the health of our animals, and the health of our biodiversity. But first, let’s first answer the question of ‘what is grass’?

What is ‘grass’?

Grass is generally accepted as a type of monocotyledonous (single [seed] leaf) flowering plant with narrow leaves growing from the base belonging to the family Poaceae and often utilised for grazing animals and lawns. It is one of the largest plant families known .

Grasslands have been defined as occurring ‘where there is sufficient moisture for grass growth, but where environmental conditions, both climatic and anthropogenic, prevent tree growth. Its occurrence, therefore, correlates with a rainfall intensity between that of desert and forest and is extended by grazing and/or fire to form a plagioclimax in many areas that were previously forested’.

Why is it important?

Surprisingly, grass is recognised as the most economically important plant family. World Resources Institute have outlined the value of grassland to humans. This includes the importance of grass for food, as most major foodgrains originate in grasslands, and as the key to meat production (to graze and feed livestock).

They highlighted that grasslands store 33% of carbon in terrestrial ecosystems, most of this being found in the soil, perhaps surprisingly not far off what forests store (38-39%). They recognised that grasslands support some of the world’s greatest phenomena, such as mass migrations. And that it provides high economic values for recreation and tourism, being used extensively in recreational activities such as safari tours, hiking, hunting, fishing and religious or cultural activities.

They recognise that grasslands make up 15% of Centers of Plant Diversity, 11% of Endemic Bird Areas and 29% of ecoregions considered outstanding for biological distinctiveness. Yet in recent years grasslands have been reduced in range by nearly 90% and the threat of agriculture and urbanisation (including recreational pressure) is changing the extent, composition and structure. Some areas are nearly completely transformed.

I hope this helps you to understand the wide range of benefits that stem from grass and grasslands, and understand that how we manage our grassland is key to:

• biodiversity,
• reduce greenhouse gas emissions,
• support the health of our animals, ourselves and our livelihoods.

Table 1. Adapted from World Resources Institute (2000)

Grass and animal nutrition

Those 6-7 species mentioned above that dominant our agricultural landscape have been cultivated over the years to maximise production. But what does that mean? That means that species have been selected to provide the largest yield, in the shortest time, on lower nutrients (in the soil) and for those that are most resilient to seasonal variation - therefore require less tending and are capable of withstanding intense grazing pressures. It means that the grass puts all of its energy into growing as quickly as possible, that there is little nutritional value and the base of the stem (the crown), where the grass grows from, is full of water-soluble carbohydrates (WSC), or sugars. It is highly digestible and promoted as a mechanism to support the effective use of protein, thus supporting high growth rates and milk production (for dairy cattle). Perfect when we’re trying to produce high quantities of meat or dairy in a short time.

Cattle and sheep seem to fair ok on this sort of pasture. They are ruminants so their gut is capable of taking the sugar hit without it causing too many issues. But even so, this approach of monoculture high-sugar grass systems has demonstrated that the nutritional needs of animals are not met, and consequently the meat (or dairy) produced may be of low nutritional quality. Consumer panels have reportedly favoured the taste of produce from cattle grazed on species-rich grasslands , with research into blue-zones (those areas with the highest population of centenarians) showcasing higher nutritional value associated with meat from cattle grazed on biodiverse swards providing a direct line to our own health and longevity.

Horses aren’t quite so lucky. Naturally adapted to a high fibre, low sugar diet and to forage across rangelands scarce of food, being provided with an all you can eat buffet of sugar rich grass causes all sorts of issues. It can result in overeating and the development of metabolic issues, obesity, and at the same time nutritional deficits. For our native breeds, often renowned as ‘good doers’, evolved to cover 30-80km a day searching for food, this can be a real issue. And restricting grazing doesn’t help either. Recent research has found that ponies turned out for just 3 hours a day increase their intake rate to accommodate for the hours not at grass . Plus, there is little difference when we feed this type of forage cut, so eliminating grass and feeding hay isn’t the solution either.

But, what happens when we feed a diverse sward? There is little research into this, but we do know that species rich-grasslands have lower energy and protein levels than agriculturally improved grasslands, but the herbal components provide higher quantities of minerals . It is expected that the use of species rich grassland within agricultural systems will reduce the necessity of supplementary feeds needed to maintain healthy livestock. Some initial studies undertaken by Defra (the Diverse Forages Project ) demonstrate how feeding a diverse sward can improve the nutritional balance of a cows’ diet, consequently improving the health of the animal, reducing vet bills, antibiotic and steroid use and feed bills – and consequently improving our health for eating it (compared to meat reared intensively on monoculture grassland). We could expect the same from our horses, after all this is what they are naturally selected to do!

In fact there is a whole area of study dedicated to the ability for animals to self-select species as a form of medicine (Zoopharmacognosy), to natural support deficits in their diet, treat illnesses and reduce parasite burdens, but we’ll explore this another time.

Grass and biodiversity

The problem with these resilient agricultural grass species, is as our climate continues to change, providing us with warm, mild winters and dry summers, many species can no longer compete with the fast-growing agricultural species. This means that our strongholds of diverse grasslands are becoming ever smaller.

Many of these species thrive on nutritionally poor soils, so when you add the impact of inputs used on much of the agricultural land, fertilisers, pesticides, lime, these species take even more of a hit. This has consequences wider than just the grass present. With over 250 priority species relying on grasslands in the UK, it means we are losing many of our wildflowers, the pollinators that rely on them, the birds and small mammals that feed on the seeds, and those that feed on them . The whole ecosystem is at risk of collapse.

Now this is not just an issue on our farms, our farmers are struggling to do what they can to meet demand for produce. It’s also an issue with our monoculture lawns, the replacement of our grass with artificial grasses, and our ever-increasing demand for new houses which eat away at what bits of wild habitat we have left.

It doesn’t have to be this way.

We can work to improve our grassland diversity (and our soil health, but we’ll talk about that later). At the same time, we will improve the health of our horses and the health of our land, we will support flood resilience, reduce air pollutants, sequester carbon and even enhance our own health and wellbeing. And I want to help you achieve it.

references

1. Soreng, R.J., Peterson, P.M., Romschenko, K., Davidse, G., Zuloaga, F.O., Judziewicz, E.J., Filgueiras, T.S., Davis, J.I. and Morrone, O., 2015. A worldwide phylogenetic classification of the Poaceae (Gramineae). Journal of Systematics and Evolution, 53(2), pp.117–137.

2. Hubbard, C.E., 1984. Grasses: A Guide to their structure, Identification, Uses and Distribution in the British Isles. 3rd ed. Reprinted 1992. Penguin Books.

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14. Glunk, E.C., Pratt-Phillips, S.E. and Siciliano, P.D., 2013. Effect of restricted pasture access on pasture dry matter intake rate, dietary energy intake, and fecal pH in horses. Journal of Equine Veterinary Science, 33(6), pp.421-426. Available at: https://doi.org/10.1016/j.jevs.2012.07.014 [Accessed 27 March 2025].

15. Shellswell, C.H., 2017. Is the rye-grass always greener? An evidence review of the nutritional, medicinal and production value of species-rich grassland. Plantlife.

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