Vegetation Description and Data Analysis

A Practical Approach

Martin Kent

• Publisher: Wiley-Blackwell
• Year: 2011
• Print ISBN: 9780471490937, 9780471490920
• eBook ISBN: 9781119962397
• Edition: 2
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

Vegetation Description and Data Analysis: A PracticalApproach, Second Edition is a fully revised and up-datededition of this key text. The book takes account of recent advancesin the field whilst retaining the original reader-friendly approachto the coverage of vegetation description and multivariate analysisin the context of vegetation data and plant ecology.

Since the publication of the hugely popular first edition therehave been significant developments in computer hardware andsoftware, new key journals have been established in the field andscope and application of vegetation description and analysis hasbecome a truly global field. This new edition includes fullcoverage of new developments and technologies.
This contemporary and comprehensive edition of this well-known andrespected textbook will prove invaluable to undergraduate andgraduate students in biological sciences, environmental science,geography, botany, agriculture, forestry and biologicalconservation.
* Fully international approach
* Includes illustrative case studies throughout
* Now with new material on: the nature of plant communities;transitional areas between plant communities; induction anddeduction of plant ecology; diversity indices and dominancediversity curves; multivariate analysis in ecology.
* Accessible, reader-friendly style
* Now with new and improved illustrations

Chapter 1

The nature of quantitative plant ecology and vegetation science

THE NATURE OF VEGETATION

Dictionary definitions usually describe vegetation as ‘plants collectively’ or ‘plant growth in the mass’. To the plant ecologist and vegetation scientist, this definition is completely inadequate and perhaps conforms to the view of many students (and teachers and lecturers!), who see it as ‘a frightening and unknown mass of green, shrouded in technical terms and Latin Names’ (Randall, 1978: p. 3). This book is concerned with the techniques for both collecting and analysing data on vegetation with the primary aim of making sense of the ‘frightening and unknown mass of green’. As such, it is a text on quantitative plant ecology, which is a clearly recognisable subdiscipline of ecology and biogeography. The field of quantitative plant ecology is also related to an area of research known as vegetation science, which in addition to vegetation description and analysis, also includes plant population biology, species strategies and vegetation dynamics (successional processes and vegetation change) (van der Maarel, 1984a, 2005a,b). Most researchers and students take the phrase ‘vegetation description and data analysis’ to mean the collection of vegetation data, followed by analysis, usually using complex mathematical methods. However, in the 1980s and 1990s, there was a distinct tendency for the processes of analysis to become an end in themselves. An important aim of the previous edition of this book was to show that quantitative plant ecology and vegetation description and data analysis can and perhaps should be primarily ecological rather than mathematical in emphasis. The only way that variations in vegetation and plant species distributions can be properly understood and explained is within an ecological framework. This introduces the fundamental point that vegetation is always an integral part of an ecosystem (Tansley, 1935; Waring, 1989; Willis, 1997; Dickinson and Murphy, 1998; Leuschner, 2005) and can only be studied by fully exploring its role within that ecosystem. Vegetation cannot be isolated as a separate entity from the ecosystem within which it exists.

The building blocks of vegetation are individual plants. Each plant is classified according to a hierarchical system of identification and nomenclature using carefully selected criteria of physiognomy and growth form. The individuals of a species, taken together, form a species population, and within the local area of a few square metres to perhaps as much as a square kilometre, groups of plant species populations that are found growing together are known as plant communities or plant species assemblages. Much more will be said of plant communities and species assemblages later in Chapter 2, but within plant communities, the presence or absence of particular species is of primary importance. After this, the amount or abundance of each species present is of interest. Although most vegetation data are still collected at the species level, one of the more interesting developments of the past 20 years has been in alternative methods of describing vegetation, such as plant functional types and taxonomic, morphological and structural surrogates (Ramsay et al., 2006). This book is concerned with reasons and methods for collecting data of these kinds, and with techniques for their analysis.

The importance of vegetation within ecology is three-fold. Firstly, in most terrestrial parts of the world, with the exception of the hot and cold deserts, vegetation is the most obvious physical representation of an ecosystem. When ecologists talk about different ecosystem types, they usually equate these with different vegetation types and the dominant species life-forms within them. Secondly, most vegetation is the result of primary production, where solar energy is transformed through photosynthesis by different plant species into green plant tissue. The net primary production, which is the amount of green plant tissue accumulated within the area of a particular vegetation type over a given period of time, represents the base of the trophic pyramid. All other organisms in both the grazing and detrital food webs are ultimately dependent upon that base for their food supply. Thirdly, vegetation also acts as the habitat within which the organisms live, grow, reproduce and die. In the case of the grazing food web, it is among the above-ground parts of plants. With the detrital web, it is on the surface and below ground among the roots. Taken together, these three points show the central importance of vegetation to ecology and demonstrate the need for methods to assist with both description and data analysis (Anderson and Kikkawa, 1986; Cherrett, 1989; Barbour et al., 1999; van der Maarel, 2005a,b).

WHY STUDY VEGETATION?

There are many situations where vegetation merits study. The commonest examples of the use of vegetation description are in the recognition and definition of different vegetation types and plant communities, which is known as the science of phytosociology, the mapping of vegetation communities and types, the study of relationships between plant species distributions, environmental controls and their interactions with humans and animals, and the study of vegetation as a habitat for animals, birds and insects. Change in vegetation over time may also need to be described using concepts of succession and climax.

Information on vegetation may be required to help to solve an ecological problem, for biological conservation and management purposes, as an input to environmental impact statements, to monitor management practices, or to provide the basis for prediction of possible future changes in plant species distributions and linked to both human impacts on habitats via land use practices and also climate.

A useful distinction is into aspects of study that are academic, as opposed to those which can be termed applied. In the academic case, vegetation may be described and data analysed largely for their own sake. Applied studies are where vegetation data are collected and analysed with the aim of providing information of relevance to some ecological problem, often to do with environmental conservation and ecosystem management or the prediction of future environmental and ecological change. Many examples of research include elements of both.

CASE STUDIES

Throughout this book, many different examples of the application of methods for the description and analysis of vegetation will be presented. A brief introduction to four contrasted case studies serves to demonstrate the diversity of situations where vegetation may need to be surveyed and data collected and analysed.

Case Study 1: Evergreen broad-leaved forest in Eastern China: its ecology and conservation and the importance of resprouting in forest restoration (Wang et al., 2007)

Evergreen broad-leaved forest (EBLF) is now recognised as an important global vegetation formation type that contributes to both the biodiversity and the sustainable development of the subtropical regions of China. Discussion of the forests is omitted in Archibold (1995), although they are mapped as EBLF in the more recent overview of world vegetation types by Box and Fujiwara (2005). While its biogeographical status in China still remains a matter of debate, unfortunately, the extent of the EBLF has decreased very significantly due to long-term anthropogenic disturbance, including deforestation, logging and fire, and much of the forest is now degraded to plantation, secondary forests, shrub and grassland communities. Song (1988, 1995) provided the most valuable review in English of both the position of the Chinese EBLF within the world vegetation formation types and the overall characteristics of the forest. In China, it occurs between 24°–32°N and 99°–123°E and formerly covered around 25% of the area of the country (Figure 1.1). It lies within areas dominated by a subtropical monsoon climate and the forests occupy mountainous and hilly areas across the south and east of China (Plate 1.1). The forests are extremely diverse, particularly in terms of tree and shrub species (phanerophytes 50–80% of species – see Chapter 3), ranging from over 100 vascular plant species/400 m2 in the south, to 30–45 species in the north of its distribution (Song, 1988). The dominant species of the EBLF come from only a few genera, together with some ancient coniferous species, many of which have ‘broad leaves’.

To inform forest conservation and management, Wang et al. (2007) described research into major plant community types and underlying environmental gradients (see Chapter 2) of degraded EBLF around Tiantong and Dongqian Lake near Ningbo in Eastern China (Figure 1.1; Plate 1.1), and examined the importance of vegetative resprouting as a key mechanism in secondary succession following forest clearance. Species composition was described from 199 10 m × 10 m plots (Chapter 3) and analysed using various methods presented later in this book (Two-Way Indicator Species Analysis [TWINSPAN] – Chapter 8; and canonical correspondence analysis [CCA] ordination – Chapter 6). Some 22 degraded and mature forest community types were identified, while CCA indicated that a primary vegetation gradient was related to the distance of sample plot from mature forest, which was closely linked to altitude and slope. The secondary gradient corresponded to successional stage and disturbance. The roles of resprouting and reseeding characteristics in forest regeneration were researched firstly by 10 m × 10 m plots taken from selected TWINSPAN groups, and secondly by 20 m × 20 m plots in representative areas of forest at different ages – 1, 20, 43 and 60 years, and in an area of mature forest – 100+ years.

Figure 1.1 The distribution of evergreen broad-leaved forest (EBLF) in China and the separation of forest into the Western semi-moist and Eastern moist forest types (after Song, 1988; Wang et al., 2007: reproduced with kind permission of Elsevier).

The importance of resprouting in the regeneration of many EBLF tree and shrub species was demonstrated, a process linked to ideas of the persistence niche – resprouting from stumps is an important means of persistence for many species. Existing remnant forests should be conserved, but forest restoration is also essential and will benefit from understanding of the importance of tree/shrub resprouting, as well as seedling recruitment in forest regeneration. Further work is in progress on seedbanks, germination success and both inter- and intra-specific competition within Chinese EBLF to assist with successful conservation and management of this rare forest type (Chapter 6 – Case studies).

Case Study 2: Pioneer vegetation on glacier forelands in southern Norway (Robbins and Matthews, 2009, 2010)

Climate change and its ecological impact is one of the most important and also controversial environmental topics at the present time. A widely observed phenomenon in Europe and Scandinavia over the past 100 years has been the retreat of mountain glaciers in response to increased summer temperatures and relatively low winter precipitation, and Nesje et al. (2008) have predicted that up to 98% of Norwegian glaciers may have disappeared by 2100. Robbins and Matthews (2009) saw the retreat of such glaciers as a valuable opportunity to study the earliest stages of vegetation colonisation (primary succession) and the manner in which plant species are responding the availability of new terrain on glacier forelands (Plate 1.2). They were concerned firstly to examine the species com...

Table of contents

• Cover
• Title Page
• Copyright
• Dedication
• Preface to the second edition
• Acknowledgements
• Safety in the field
• Chapter 1: The nature of quantitative plant ecology and vegetation science
• Chapter 2: Environmental gradients, plant communities and vegetation dynamics
• Chapter 3: The description of vegetation in the field
• Chapter 4: The nature and properties of vegetation data
• Chapter 5: Basic statistical methods for understanding multivariate analysis
• Chapter 6: Ordination methods
• Chapter 7: Phytosociology and the Zürich-Montpellier (Braun-Blanquet) school of subjective classification
• Chapter 8: Numerical classification, cluster analysis and phytosociology
• Chapter 9: Computer software for the analysis of vegetation and environmental/biotic data
• Chapter 10: Future developments in vegetation science and quantitative plant ecology
• References
• Plates
• Index