will be looking great! There is just one little problem though; the increases in temperature are leading to faster plant and soil organism respiration rates, releasing more guess what? Some areas are also experiencing reduced rainfall so we get a reduction in photosynthesis. Water is just a tad important to land plants.


The basic answer is you cannot go pumping vast amounts of carbon into the system and expect it to carry on without getting a bit unbalanced. We are therefore being urged to reduce our output of carbon.


Many of the people who are urging us to do this regularly fly all over the world in very large jet planes to discuss their policies!


It would appear that we will, therefore, at least face some changes to the climate in the years to come.


Grass and the climate


If we are going to experience higher temperatures and reduced rainfall what are the effects on our choices of grasses for amenity areas? Most grasses in average lawn use are, believe it or not. going to recover from drought with very little significant damage. There is actually no scientific evidence to suggest that the average lawn will fail to cope with the current climatic changes. Grasses have evolved and dominated due to their ability to cope with drought. This goes back over eons when the lack of water availability denied trees the conditions to flourish. So, we may well owe our survival to grasses. The longest drought in recent history lasted thirty five days and most areas of grass recovered. Researchers at the University of Cambridge subjected grasses to high temperatures and drought for sixty days and they still recovered. (Ref: Grasses and drought: University of Cambridge Professor John Parker (Plant Cytogenetics) and Angus Jefferey.)


Highly maintained areas such as golf courses and sports pitches do present a problem. People do not expect them to be a nice brown colour and unplayable. Within fine turf areas the fine fescues still have the potential to provide


excellent drought tolerance and good recovery. This is particularly true of slender creeping red fescue, sheeps fescue and hard fescue. Cezanne, Reggae, Quatro and Carioca are excellent examples of some of the latest varieties.


Chewings fescues also recover well.


Regular over seeding will help to increase the populations of resilient grasses. For photosynthesis to occur the plant has to transport water to the chloroplasts in the leaf. A consequence of photosynthesis is loss of moisture through the stomata to ensure a continuous supply of water to the chloroplasts. Increased temperatures and light intensity leads to the cytoplasm streaming causing a cyclic movement of the chloroplasts. This further increases the rate of photosynthesis by continuously bringing the chloroplast to the light source to maximise the process.


So what strategies are these fine grasses adopting to survive in low moisture situations?


The leaves are very fine and rounded in cross section; this reduces the surface area and reduces water loss. The rate of growth of the fine fescues


is slow; this means the overall energy input is lower. Less moisture and less mineral uptake


is required than the more rapidly growing species. Narrow fine leaves provide a lower surface area both in terms of heat absorption and water loss. Some species will actually curl the leaf surface to further reduce water loss. This occurs due to differential distribution of tissues which shrink as water is lost. The root systems are reticulate,


spreading finely through the soil and presenting a very large surface area to absorb whatever moisture is available. The root mass is very high in proportion to the leaf mass. The size and distribution of stomata (leaf pores) is also reduced compared to broader leaved species and some grass species have stomata which are sunk below the ridges


in the venation of the leaf. Their root systems, whilst not necessarily penetrating deeply, are highly efficient. Rhizomatous species such as slender and strong creeping red fescue can regenerate from these underground stems. Rhizomes act as a storage system allowing vegetative regeneration after damage has occurred. The broader leaved species, such as amenity ryegrass, used in high wear sports areas are, by their nature, more demanding in both water utilisation and fertiliser input; they are not as well adapted to reducing water loss. The larger surface areas of the leaf absorb more light and heat and, as a consequence, they lose large amounts of moisture.


They tend to grow more rapidly and the stomata, at the leaf surface, are numerous. These rapid growth characteristics are actually desirable in very high wear situations. Newer varieties such as Hugo, Churchill and Bizet are distinctly finer leaved than their forebears. They still however provide high wear tolerance.


Conclusions


Where water input is needed we are going to have to look at ways of conserving, storing and recycling. We do, however, need to consider the fact that we live in a temperate country with little major climatic variance in each region. So let’s not get too carried away with regional mixtures and start considering highly drought tolerant grasses which have no cold tolerance! When seeking information please look for independent data from recognised research centres relevant to the United Kingdom. We also need to lobby for better management of water with more efficient systems of collection, storage and distribution of this vital resource. Finally don’t forget to let people know how vital our green spaces are, both aesthetically and environmentally. Grassed areas absorb toxic gasses, heat, carbon dioxide, release oxygen and provide us with pleasant and relaxing recreational areas. Throw in a few trees and we can lock up a bit more carbon!


“We also need to lobby for better management of water collection, storage and distribution”


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