Plant Ecology and Conservation

Andrew Lack

• Publisher: Garland Science
• Year: 2022
• ISBN:
  9781000597882
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Environmental Conservation & Protection
• Index: Biological Sciences

Plant Ecology & Conservation is an introduction to the world of plant ecology. It includes the main areas of current research including ideas about plant populations, nutrition and plant community ecology and has a particular emphasis on the interactions of plants with animals, fungi and microorganisms whose important is being increasingly demonstrated. With the world's environmental problems having such a high profile, the book focusses on the human impact on the world's plant species. Conservation of the terrestrial world starts with plants as they form the basis of all ecosystems on land. We can only understand how best to conserve the world's biodiversity with an understanding of the central role of plant ecology. This theme runs throughout with numerous examples of the disruption of ecosystems by human activity emphasising the connection between plant ecology and conservation.

Key Features:

• Boxes present case studies, important statistics and interesting asides
• Full-colour photos depict key species and habitats and superb line drawings illustrate many concepts
• Important data are presented in Tables and Figures throughout
• Each chapter has Key Concepts and review questions to test a reader's grasp of the content
• Key References and Further Reading are given for each chapter to point the reader towards the most important and influential literature
• Jargon is kept to a minimum and a full Glossary of all technical terms is presented

The book is aimed primarily at undergraduate and graduate students in any aspect of ecology or plant science. It should also appeal to anyone interested in how plants function and are concerned about what is needed for the conservation of the world's ecosystems.

1 THE IMPORTANCE OF PLANTS AND PLANT ECOLOGY

DOI: 10.1201/9781003104711-1

As our world has become more populated and the demands of that population have steadily increased, the overall welfare of the living world has come to the forefront of our concerns. It is talked and written about every day throughout the media of the world, whether it is pollution, habitat destruction, invasions of introduced species, climate change or any number of related issues. In all these issues, plants are crucial. Our dependence on plants for our most basic needs is absolute, and it is plants that define all our terrestrial habitats. With the modifications that we have imposed on every habitat of the world, we have become aware of some of the complexity of the interactions of living organisms. These interactions include how the underlying bedrock affects the soil and the way this in turn affects, and is affected by, the plant cover and the way the plants interact between themselves and how they influence, and are influenced by, the animal life, the fungi and the microbial life. These interactions are the basis of ecology. Plants compete or cooperate with other plants and with other organisms; they form associations, sometimes intimate, with animals, fungi or bacteria, and a few even function as parasites or digest animals. My main aim in this book is to introduce some of the most important elements of plant ecology and discuss what we have studied so far and our understanding and show what we do not understand and provide some pointers to the next stages as well. There is much active research in plant ecology, and there is no immediate prospect of that slowing down.

One of the central aims of ecology is not just to understand how ecosystems work but to use this knowledge to conserve them. Ecology and conservation have been intertwined since the earliest days of ecology (Box 1.1). Ecology, as a discipline, derives from concerns about habitat change or outright destruction. Natural history was almost entirely a leisure pursuit until the end of the eighteenth century, but the industrial age saw much destruction of the countryside, and the whole study took on a much greater significance. By the end of the nineteenth century, we began to realise how much we treasured the natural world, and, with that, how little we understood about how it worked.

Since then, natural habitats have come under increasing threat, and many species are facing local or global extinction. We have little idea how important many habitats actually are, even for the most basic of purposes. But we know that they matter, and frequently they matter to us personally. Our lives are greatly enriched by the diversity of life around us, and indeed we are, to a large extent, defined by the places we know or have visited. The knowledge that there are many other places with different species and different interactions is both fascinating, in that there is much more to explore, and a great relief that we have not been entirely destructive. Conservation has become a major global effort with all parts of the world having to be involved. Ecology knows no national boundaries. Conserving the plants is, in many ways, a first step. If we do not conserve the plants, the entire ecosystem, with all its other living organisms, changes. Ecology grew

BOX 1.1 THE BEGINNINGS OF ECOLOGY AND CONSERVATION

Ecology was the name given by the German biologist, Ernst Haeckel, in the mid-nineteenth century to the study of the relationships of organisms with their environment. Haeckel was aiming to turn the amateur pursuit of natural history into something more scientific. Haeckel’s idea took hold, particularly in England. There was a long tradition of natural history in England, including contributions from luminaries such as John Ray in the seventeenth century (Figure B 1.1) and Gilbert White in the eighteenth, and it was Haeckel who dubbed Charles Darwin an ecologist. By the beginning of the twentieth century, it was achieving a stronger footing, and the scientific study of ecology, as we understand it today, started. The first of the world’s ecological societies, the British Ecological Society, was founded in 1913.

The British Ecological Society had its inception in 1904 as the Committee for the Survey and Study of British Vegetation. There had been a vegetation survey of Scotland in the 1890s, and this committee was formed following a widely perceived “need” or even “urgent need” to widen this to a comprehensive vegetation survey of the whole of Britain. There had, clearly, not been a perceived need before this time. The need, usually not stated, was that these places, the habitats that were an integral part of the British landscape, had seemed inviolable until industry and a burgeoning human population started to take over in the nineteenth century and, effectively, destroy them. The rapid rise in population, increased wealth, and improved transport across the country allowed industrial development almost anywhere. The landscapes and habitats of Britain were threatened, and, if we did not survey the vegetation before it disappeared, we would never have known what we had. We knew that some places had greater diversity than others, a fact that gave them greater apparent value, but these pioneers were extremely conscious of all the gaps in our knowledge, hence the “urgent need”.

Figure B1.1 John Ray (1627-1705), parson and pioneer naturalist. Ray wrote several volumes on the plants of Britain and Europe. He was concerned with systematics and paved the way for Linnaeus's system and a biological definition of species.

In the United States, the connection with conservation was just as direct. The Ecological Society of America had parallel, and almost contemporary, origins to that in Britain, being founded in 1915. It explicitly wanted to include botanists and zoologists, but perhaps its most influential early member, though never an officer, was F.E. Clements. Clements started by joining a survey of the vegetation of Nebraska in the 1890s. He did this because much of it was to be ploughed up. His pioneering work on succession came from a concern with habitat recovery and a fascination with the study of the plants on abandoned fields.

By the time the British Ecological Society was rounded, conservation organisations had already started, such as the Royal Society for the Protection of Birds in 1889 and the National Trust in 1895. The link between ecolegy and conservation was made explicit in Britain when The Nature Conservancy was founded in 1949 as a governmental body, as a result of the influence, among others, of the British Ecological Society’s founder, Sir Arthur Tansley. National Nature Reserves were to be outdoors research laboratories, and there was a strong ecological research element inherent in the organisation. The resulting data-driven ecology gave the organisation considerable influence. It was too much, as it turned out, since the research section was forcibly severed from the part directly involved with conservation in 1973 to the detriment of both sides.

Ecology becomes a very human story when we see its origins. It grows so clearly out of our desire to understand our position in the world. We should celebrate this desire rather than, as so often, feel apologedc about it. It is, in fact, the reason most of us went into ecology in the first place. Conservation and ecology go hand in hand.

I was, and still am, a keen naturalist, constantly looking for plants, birds and other wildlife. Several of my colleagues feel the same way. The natural world gives an unending thrill as we find unfamiliar or familiar organisms in new or unexpected places, as well as taking us into some of the loveliest places on earth. These are what we want to conserve and give us the best reasons to conserve them. They matter to the human spirit.

from a concern to conserve, and it started by examining, in broad-brush, the way that habitats work. Plant community ecology, as we now understand it, is, in many ways, the founding ecological discipline. It remains of vital importance.

Today, ecologists sit on town and county councils and in numerous voluntary organisations, and many are employed in environmental consultancies specifically to give an assessment of ecological value to places that are threatened with some form of development. The basis of these surveys is nearly always the plants. Ecology has grown to embrace many fields, but, for many ecologists, it retains its strong links with conservation. The motivation behind many ecologists’ work is the desire to retain as much as possible of the native species and their natural habitats. Conservation has been at the heart of ecological study since serious ecological study started, and although some branches of ecology do not address conservation directly, one does not need to look far to reinforce the link.

1.1 PLANTS ARE CENTRAL TO ANY TERRESTRIAL ECOLOGICAL STUDY

All terrestrial ecosystems and many in freshwater depend on plants for primary production. The latest estimates suggest that around 80 per cent of the world’s entire living biomass is plants, with a further 15 per cent being bacteria and archaea and 2 per cent fungi. Animals constitute about 0.4 per cent. Plants are the ultimate providers of most of our food, providing much of the oxygen we breathe and some of our clothing, building materials, medicines and numerous objects of surpassing beauty. Plants are instrumental in creating our soils, storing carbon, even as dead parts (in fact particularly as dead parts), and they influence our climate profoundly in many different ways.

Ihe oceans cover around 71 per cent ot the earth but have only about 1 per cent of the earth’s biomass. Some 60 species of flowering plants, usually known as “sea-grasses” although they are not true grasses, grow in the sea and can be the basis of important inshore marine ecosystems particularly on sandy substrates, but they are not the main photosynthesisers in the sea. In the oceans, the main photosynthetic organisms are planktonic diatoms, dinoflagellates and some other unicellular organisms, and, in inshore waters, the main photosynthetic organisms are the large and multicellular brown and red seaweeds. These organisms have sometimes been considered as plants, mainly because they are photosynthetic. It has become clear that they should not be classified as plants but derive from a range of different evolutionary backgrounds. The one group of algae that is sometimes being classified as a plant group is the green algae. These form a minor component of the inshore marine ecosystems and are important in some freshwater ecosystems. They are a diverse group and the group from which all other plants evolved. These and the seaweeds and planktonic groups will not be considered here. The oceanic autotrophs occupy only 0.2 per cent of the total living biomass of the world. Marine heterotrophs have a greater biomass than the autotrophs, unlike on land.

As well as being the primary building blocks of all terrestrial life, plants are wonderfully diverse. There are currently, 2020, about 400,000 species of plant described scientifically. Ninety-four per cent of these (370,000) are flowering plants, and flowering plants dominate most terrestrial ecosystems. The conifers are the second most important group ecologically, even though there are fewer than 700 described species, a mere 0.3 per cent of all plant species. They a...