Remote sensing of vegetation: principles, techniques and applications. By Hamlyn G. Jones and Robin A Vaughan


  • Ranjani Wasantha Kulawardhana ( PhD Student (Rangeland Ecology and Management), Department of Ecosystem Science and Management, Texas A & M University, 2138 TAMU, College Station, Texas 77843

Oxford University Press , Oxford, NY, 2010 xxiii+365pp. ISBN978-0-19-920779-4, $66.95

In this book, Jones and Vaughan have brought together comprehensive material to provide readers a thorough understanding of the basic physics and fundamental principles underlying the use of remote sensing data and techniques for vegetation studies. Their main emphasis is to describe applications of remote sensing for the study of plants and vegetation canopies. The book includes a great deal of preparatory material including a fairly comprehensive introduction to basic radiation physics, image analysis and remote sensing technology as well as an outline of the physiological basis of key aspects of plant functioning.

The authors state that the book is specifically aimed at senior undergraduates and new postgraduates to help them appreciate the ways in which remote sensing can be used for the study and monitoring of vegetation. In general, this book could be an entry-level text. This 365 pages (including 12-page color plate section) are divided in to 11 chapters. The authors have organized the content of the book to provide first the basic understanding of radiation physics, the fundamentals of plant functioning and a general introduction to remote sensing technology and processing of data. The latter half of the book discusses specific applications of remote sensing data and techniques for deriving information about physical and biological characteristics of vegetation. Each chapter is organized to have a proper flow of information. Extensive use of Illustrations and equations throughout the book help the reader to better understand the explanations given in the text. Additional sections are included at the end of the chapters (where necessary) to provide details on further readings and related websites. These sections suggest suitable texts for particular aspects of each chapter to guide researchers to in depth knowledge on specific subjects. To help the reader appreciate some of the quantitative materials discussed, 3 to 6 sample problems are included at the end of each chapter. Answers for the sample problems are provided at the end of the book. The overall organization of the book facilitates better understanding of the subject specifically for beginners with minimal or no prior knowledge of remote sensing. The book also provides definitions of the symbols used in the text, abbreviations and acronyms, an index and three appendices. Throughout the book, the authors have extensively cited relevant studies to provide detailed explanations in the text as well as to provide example applications where necessary. Hence, this book could also be considered as a comprehensive review of remote sensing applications in vegetation studies.

Chapter 1 provides a brief and a very basic introduction to the development of satellite remote sensing and its potential applications for use in vegetation studies. This chapter provides readers with an overall understanding of the capabilities and applicability of remote sensing techniques for vegetation and environmental studies while providing some background information on the parallel development in two fields: plant environmental physiology and remote sensing of vegetation.

The second chapter provides readers with a detailed understanding of the basics of radiation physics that is vital in understanding nearly all remote sensing techniques and their applications. Included is a comprehensive explanation on the properties of electromagnetic radiation and its interactions with the surface materials and the atmosphere. This chapter mostly provides key concepts, theories and definitions that are vital in understanding remote sensing data acquisition and their characteristics. However, explanations are provided to relate these theoretical concepts with the underlying principles of remote sensing data acquisition so that readers benefit from this basic understanding.

Chapter three discusses how different earth surfaces: vegetation, water and soil interact with incoming radiation to generate reflected signal that is recorded as remote sensing data. This information is important in inferring properties of these surfaces from remotely sensed data. This chapter has three major sections. Each section discusses radiative properties in three regions of the electromagnetic spectrum: optical, thermal and microwave. Even though most remote sensing applications have been based on studies of radiation in the broader optical reflective region, with the recent advances in microwave and thermal remote sensing in vegetation studies makes it vital to understand these applications, as well. The chapter first discusses the radiative properties of individual components of vegetation surfaces including leaves, soil and water. The discussion then extends to individual components as a whole and illustrates how the radiation properties of vegetation canopies are affected by the spatial arrangements of individual components. Extensive use of simple illustrations and examples drawn from past studies clarifies the comprehensive explanations given in the text.

Chapter four is on the main non-radiative ways in which vegetation interacts with the aerial environment. Recently, remote sensing data have been extensively used to infer plant functions and their interactions with the aerial environment, such as estimates of vegetation productivity via remote sensing. Hence, understanding these natural processes is vital to the proper application of remote sensing in vegetation studies. The chapter first highlights commonality in structure and functioning of most terrestrial plants with an emphasis on transfer of matter (CO2 and water during photosynthesis and respiration), heat and momentum during the natural processes of plant functioning. This is a comprehensive coverage of topics that is highly relevant to almost all remote sensing applications in vegetation studies over recent decades.

Chapter five provides readers a basic yet comprehensive understanding of the process of remote sensing data acquisition and recording. It explains how remote sensing systems are designed to include a wide range of instruments for data acquisition and recording, and platforms on which the instruments are mounted. It also introduces the basic concepts that are important in understanding specific characteristics of remote sensing data. Such understanding will provide the readers the ability to distinguish and make selections on appropriate data for their specific fields of interest.

Chapter six provides entry-level materials on remote sensing data handling, processing, visualization and interpretation that are vital in preparing raw data for presentation and subsequent analysis. The chapter starts with basic steps generally used to correct remotely sensed data, including geometric and radiometric errors that are introduced by the atmosphere and/or the instruments and platforms during the process of data acquisition. The second half of the chapter introduces the concepts and techniques that are used for visualization of remote sensing data. This includes the basics of remote sensing techniques generally used in interpretation of data. Materials included in further readings are highly relevant to the topics discussed and therefore of particular value for those interested in methodological details.

Chapter seven explains the analysis and interpretation of spectral response (mainly in the optical region) to derive useful information about biophysical characteristics of vegetation, which is of great interest to most researchers. This chapter discusses how the complexities in characteristic spectra of different surfaces could be handled to determine key biophysical parameters of vegetation. Details on key approaches generally applied in vegetation and other remote sensing applications are given. These include use of empirical indices and their relationships to vegetation biophysical properties and image classification techniques that are applied mostly in remote sensing applications. A comprehensive discussion of the fundamental principles involved in each technique and their applicability in vegetation studies is included.

In chapter eight, the authors introduce the concept of multiangular sensing of vegetation structure, an approach that enables extraction of canopy biophysical parameters such as Leaf Area Index (LAI), Leaf Area Density (LAD), radiation interception and chlorophyll content from remote sensing images acquired using sensors with multiple view angles. The first part of the chapter introduces the basic principles and terminology related to the treatment of anisotropy in canopy reflectance. This is followed by an outline of some of the approaches used in collection of multiangular data. Better understanding of multiangular sensing of vegetation canopies is important for the appropriate use of remote sensing data in radiation transfer models, which is a relatively advanced and complex level of remote sensing application in vegetation studies. The latter half of the chapter describes the integration of radiation transfer modeling and anisotropy in canopy reflectance for inferring canopy structure and related biophysical characteristics. The authors provide a wealth of practical knowledge in the discussion of approaches commonly used in inversion of radiation transfer models for the extraction of canopy biophysical parameters.

Remote sensing applications further extend beyond the vegetation studies at local scales to ecosystem level applications where remote sensing data and techniques are used in combination with appropriate biosphere-atmosphere models for the estimation of ecosystem fluxes including CO2. In chapter nine the authors discuss general principles and terminology related to remote sensing of heat and mass exchange. A wide range of models is presented that can be used to estimate or interpolate ecosystem variables that are not directly measurable from the remotely sensed canopy biophysical parameters. These range from estimates of surface radiative and heat fluxes to estimates of vegetation primary production.

The validity and applicability of remotely sensed information depends both on accurate measurements of relevant parameters and use of appropriate analytical and statistical techniques. In each chapter authors provide detailed discussions on accuracy, applicability and errors related to remote sensing methods. Chapter 10 emphasizes sampling, data collection and the use of in situ data in analysis and interpretation of remotely sensed data. Detailed discussions are included to highlight the impacts of changing scale of observations, the necessity of calibrating data generated from different instruments, and the importance of validating remote sensing based estimates to increase accuracy and interpretability. It also highlights the necessity of geospatial statistical techniques rather than conventional statistics in validating remotely sensed data using field estimates.

The final chapter introduces a wide range of remote sensing applications and approaches that can be applied to answer questions related to vegetation structure and functioning. Example applications are discussed to illustrate the principles involved in these approaches and to highlight the ways in which different remote sensing approaches can be combined to answer the research questions of interest. The examples cover a range of applications applied at leaf, plant and canopy scales to landscape and ecosystem scales. In each section, an introduction to the topic is followed by details regarding its importance, variables measured, remote sensing techniques used and their strengths and weaknesses. Given the vast range of potential applications of remote sensing in vegetation studies, the authors cannot be expected to completely cover them all in a single book. However, the author's attempt to compile a representative set of examples in a single chapter is commendable.

In a summary, this book is a comprehensive coverage of entry-level material for beginners in both the fundamental principles and potential applications of remote sensing to answer questions relating to vegetation structure and functioning at the individual leaf scale to complex landscapes and ecosystems. Some readers may find the introductory chapters on remote sensing and plant physiology to be less concise than desired. However, as one reads through the text the fundamental information and background presented up front help to clarify the detailed information presented in later chapters.