Tolman, Tom:Photographic Guide to the Butterflies of Britain & Europe
- edition reliée, livre de poche 2005, ISBN: 9780198506072
Timber Press, Incorporated. Very Good. 9 x 0.8 x 6 inches. Hardcover. 2005. 176 pages. <br>Informative and entertaining, this book will stimu late experimentation and encourage gard… Plus…
Timber Press, Incorporated. Very Good. 9 x 0.8 x 6 inches. Hardcover. 2005. 176 pages. <br>Informative and entertaining, this book will stimu late experimentation and encourage gardeners to review and improv e their current gardening practices. Once gardeners learn how pla nts are constructed, it is easier to envision how they'll grow an d flourish. An understanding of the structure behind good, health y soil gives clues as to how to improve one's own garden tilth. T his practical guide helps readers identify what plants need to su rvive and how these fundamental scientific facts are at the heart of good plant care. A chapter on seeds and germination will enco urage gardeners at any level to try their hand at propagation, wh ile discussion of soil, pests, and diseases adds to the skills of all gardeners. The final sections of the book take a closer look at biodiversity, ecology, genetic engineering, and nomenclature. For the enthusiastic beginner or the master gardener, Practical Science for Gardeners unravels the mysterious inner life of plant s. Editorial Reviews Book Description Packed full of tips about how to use science to achieve healthier plants and better garden s, this informative and entertaining book will appeal to gardener s at all levels. Includes information on what plants need to surv ive, seeds and germination, soil, and pests and diseases. From t he Publisher Packed full of tips about how to use science to achi eve healthier plants and better gardens, this informative and ent ertaining book will appeal to gardeners at all levels. Includes i nformation on what plants need to survive, seeds and germination, soil, and pests and diseases. About the Author Mary Pratt gradu ated in zoology from Oxford University and went on to gain a Mast er's degree in biology at Keele University. She lectured on adult education programs and worked in nature conservation, including a stint for the Wildlife Trusts. More recently she taught biology at secondary school level before retiring to Devon with her musi cian husband. Excerpt. ® Reprinted by permission. All rights res erved. Nature's arms race and how to negotiate a peace deal Neit her 'mother nature' nor 'nature red in tooth and claw' are really appropriate epithets for the non-human world. 'Nature's arms rac e', in which gardeners and farmers become intimately involved, is nearer to the mark. I suppose motherly qualities come to mind be cause all our nutritional needs have ultimately been met from wil d plants and animals. But nature is not in the least motherly to its own offspring. Out there, be it in wilderness or garden, it's 'each one for itself'. This, of course, leads to the 'red in too th and claw' concept but, curiously, things are not as bad as the y may appear. Ecological research has shown that individual spec ies tend to occupy their own little niches, their particular way of 'making a living', to which they are well adapted, and in whic h they can avoid direct competition with other species for scarce resources. For example, several species of bird live on coastal mudflats, each endowed with a particular length of beak adapted t o feeding on creatures found at different depths in the mud. They can thus all live happily together without having to squabble ov er their next meal. Admittedly the creatures living in the mud ar e being preyed upon but, at least, the birds aren't fighting each other for access to food. Plants, like animals, occupy their ow n special niches - adapted to particular conditions. They are ost ensibly docile and peaceable, quietly minding their own business. They just get on with making their own food, and are fortunate i n their ability to survive nibbling by herbivorous animals. But m any of them are remarkably good at fending off potential enemies - you'll have noticed that there are certain plants which slugs w on't touch. Some of them are not at all innocent, entering the fr ay with a vengeance. There are some pretty nasty weapons in their armoury, stinging cells, spines, alkaloid poisons to name but a few. So, if 'red in tooth and claw' conjures up snarling carnivor es, nature could equally well be described as 'green in thorn and killer chemicals'! There is thus a constant arms race going on - organisms needing to feed, but also having to avoid being preyed upon or outwitted in competition. We, as gardeners, are very muc h part of that arms race because we are in the business of manipu lating things to suit our needs. It makes sense to think of the living world, the biosphere, as an intricate and miraculously sel f-sustaining network. The expression 'the balance of nature' is s ometimes used in connection with this network, but it's not neces sarily a balance in the sense of a see-saw which is poised, equal ly weighted at either end. It is, rather, a constantly fluctuatin g balance - a see-saw being played on and moving up and down. Som etimes, due to some cataclysmic event or to human mismanagement, the fluctuations can get out of hand, drastic crashes occur (and the players may fall off!). Humans have not treated the biosphere well, so gardeners, being intimately involved in the network, ha ve a particular responsibility to be constructive and careful in their management of it. This chapter is about being involved in t he arms race but achieving a sensible balance without being too d estructive. Because plants and animals, and their relationships with their environment, are so complex, the science of the topics in this chapter is by no means precise. What follows is, I hope, a guide through a somewhat tortuous maze. Food webs Ecologists - who study living things in relation to their environment - hav e tried to work out the way in which species fit into their niche s and to unravel the complex interactions between them. Feeding r elationships are important here. Who feeds on what can be determi ned by direct observation, or by analysing the contents of a pred ator's digestive system. A picture emerges of networks of feeding relationships, referred to as food webs. An example of a garden food web might be depicted as in Figure 5-1. It must be emphasize d that most diagrams like this are gross over-simplifications. Th ere are more creatures in our gardens than we might suppose, and finding out all their feeding habits would be a challenge indeed. Weeds, pests and diseases In the food web in Figure 5-1 there are plants to be cherished, a plant which is not welcome, animals which can be tolerated, animals which are a nuisance, and animal s which are positively beneficial. This is just a very small sele ction of the kinds of creatures and their feeding relationships w hich might exist in a garden. There is also a myriad of micro-org anisms, busy being parasites, often causing nasty diseases; some, on the other hand, are going about their business harmlessly, an d some are being really helpful. Organisms which we call pests or weeds are simply those which militate against our efforts to pro duce beautiful flowers, immaculate foliage, and copious, unblemis hed vegetables. In Figure 5-1 they are the cabbage white butterfl y caterpillar, the tortrix moth caterpillar, the aphid, the snail and the dandelion. There is no point in listing the numerous di fferent kinds of nuisances and ways of identifying them. There ar e excellent books available and you will find some suggestions in the Further Reading list. If they are not obviously available on your library shelves, or in the local garden centre, remember th at libraries will order things for a small fee. Preserving the c herished, the tolerable and the beneficial, whilst keeping at bay the undesirables There is a school of thought which insists tha t it must all be done 'organically', relying on natural predators and parasites, using hand or mechanical removal of weeds or othe r nasties, and spraying only with substances which occur naturall y or are approved by the Soil Association. Others think this is a load of nonsense - a visit to the chemicals section of a garden centre demonstrates that there is a vast army of gardeners who sp ray all manner of man-made concoctions on their plants. Scientifi c evidence would suggest, though, that - as with soil management - the most sensible approach is to keep an open mind and adopt a combination of both. The next few sections contain guidelines to wards achieving a compromise - the use of a combination of biolog ical and man-made chemical agents. This kind of approach is techn ically called Integrated Pest Management (IPM). In general it mak es sense to use the predators and parasites in natural food webs to keep things under control. This is particularly so in a garden where the scale of operation is fairly small. They are not, howe ver, likely to eradicate a pest species completely, for reasons I shall explain. If things are really troublesome, modern science offers well-tested alternatives, though man-made pesticides are n ot without their problems - not least the fact that pests become resistant to them. Some people worry about the human health and s afety aspects of pesticides but the Food and Environment Protecti on Act, 1985, the Pesticides Safety Directorate, and European leg islation are there to safeguard us. In the USA there is the Feder al Environmental Pesticide Control Act of 1972. All products lega lly permitted for use in agriculture and horticulture have been t horoughly tested for safety. It is therefore technically illegal to attack the aphids on your roses by spraying them with diluted washing-up liquid; detergents haven't been tested with their gard ening safety in mind! One of the themes of this book, though, is that science isn't perfect - scientists do the best they can. It 's worth remembering that just as, in medicine, there may be chan ges of treatment in the light of new discoveries, so scientists w orking on pesticides may change their tune in view of new evidenc e. What was once thought safe may be deemed no longer so, and pro ducts are taken off the market (as has happened recently under Eu ropean rules). The range of pesticides available to gardeners is now very limited. It's my view that the danger which this small s election poses to humans, domestic animals and the environment is utterly insignificant compared with other risks of modern life. Controlling animal pests without artificial chemicals This sect ion covers those methods which are commonly termed biological, ph ysical and cultural - those which rely on the use of other living organisms, traps and barriers, or particular cultivation practic es. Predators and parasites There are many examples of predator s or parasites which make their living by consuming undesirables in the garden. Blue tits, ladybirds and lacewing larvae eat aphid s. There are tiny parasitic wasps which have the unpleasant habit of laying their eggs inside the larvae of moths or flies, so tha t the grubs consume their host from the inside - Encarsia, used i n glasshouses to control white fly, is an example. But there are snags about counting on these agents. One factor is the relations hip between predator and prey, a topic which has been much studie d by ecologists. Interactions between predators and prey The re lationship between a single predator and its prey often follows a particular pattern. At first the predator has an abundance of pr ey and is able to reproduce so successfully that its numbers incr ease in parallel with prey numbers. But there comes a point where predation begins to reduce the numbers of prey, there is less fo od available for the predator, and its numbers begin to decline. After a phase of reduction in predator numbers the prey species b egins to recover and the pattern repeats itself. Scientific evid ence for this effect comes from situations where the ecosystem is a simple one. An example is a Canadian study, published as long ago as 1937, which collected and collated hunting and trapping re cords of the numbers of lynx (predator) and snowshoe hare (prey) caught over a period of almost 100 years. The results show a stri king picture of approximately 10-year cycles; as numbers of hare increased so, after a brief delay, did the numbers of lynx, but t here always came a point where hare numbers started to decrease f ollowed by a crash in lynx numbers. Then hares recovered and so d id the lynx. I won't bother you with the graph - but it shows a v ery pretty and obvious 'boom-and-bust' pattern, with the lines fo r lynx and hare running up and down in parallel with a slight lag of lynx behind hare. Another more recently studied example is th at of lemmings and their predators on the arctic tundra of northe rn Europe. Here lemmings are the main small herbivores, and the c arnivores which prey on them are arctic fox, snowy owl, long-tail ed skua and stoat. Lemming numbers have long been known to fluctu ate markedly, leading to various myths, including mass suicide, a nd hypotheses to do with weather and availability of food plants. Over a 15-year period these animals have been closely studied, a nd the 'boom-and-bust' story has been shown to hold good for them too. As lemming numbers increase so do the numbers of predators, reaching a point where the pressure on the lemmings is such that their numbers start to decrease. With not enough food around the foxes, owls and skuas apparently move off to search for other pr ey species which, in the arctic, are not numerous, and the stoats , which feed only on lemmings, die off. The lemmings then begin t o do better and the cycle starts again. In a garden similar cycl es may occur. An example is the potential interaction between aph ids and their predators. Ladybird larvae might come across an abu ndant supply of food on your rose bushes. A veritable feast ensue s and the ladybirds do so well that they multiply prodigiously. T hen there comes a point when aphids are beginning to be in short supply and the ladybirds can no longer support so many offspring. But as soon as predator numbers die down, the aphids begin to ha ve a field day again and return to their former abundance. So you are back to square one. Parasites The story is simple. To be a successful parasite you mustn't kill your source of food straigh t away. A parasite is an organism which feeds from a living plant or animal - its host. Much of the time the thieving beast sits h appily consuming nice nutritious juices from its host's body, occ asionally producing vast numbers of offspring, eggs, seeds or spo res, which are specially designed to invade a new host. The cruci al thing is that a successful parasite doesn't immediately f, Timber Press, Incorporated, 2005, 3, Oxford UK: Oxford University Press, 2001. Hardcover. Near Fine with no dust jacket. This new concept field guide aims to promote interest in butterflies while encouraging their conservation--enabling straightforward identifications to be madw without interfering with the insects in any way." 305 pages, color photos.; 5 5/8 x 8 3/4, Oxford University Press, 2001, 4<
