Book Reviews Agroecology: Ecological Processes in Sustainable Agriculture

A s the title implies, this book offers an ecological viewpoint of agriculture. The reader will come away with an understanding of the basic ecological processes and principles that govern the structure and function of agroecosystems, and— more importantly—an awareness of how these principles can be applied to solve the environmental and sustainability crisis of modern agriculture. Guided by his plant ecology background, as Gliessman explains in the preface, the first part of the book is basically an autoecological treatise. It describes the interactions of crops and abiotic factors such as temperature, radiation, fire, and soil, all important relationships that regulate water, light, and nutrient use in crop communities. Perhaps some readers would have liked a deeper look at the ecophysiological responses of crops to environmental factors. For example, can guidelines be developed on how to optimize photosynthesis at the crop field level rather than at the level of an individual plant? The second half of the book is a synecological treatise that delves into aspects of community ecology at the agroecosystem level and focuses on questions such as How complex are biotic interactions in agroecosystems? What are the ecological roles of biodiversity and genetic diversity? What is the relationship between agroecosystem diversity and stability of production? What are the ecological effects and benefits of diversified cropping systems such as polycultures and agroforestry systems? Gliessman makes it clear that ecosystem processes in agriculture require an understanding of smalland large-scale (landscape-level) interactions between crops, arthropods, microorganisms, and their environment. This is why a landscape perspective is required and why agroecologists should borrow tools from the emerging science of landscape ecology to analyze the dynamics of agroecosystems and their interactions with natural systems. One of the final chapters delineates the ecological basis needed to guide the conversion of agroecosystems to sustainable management. After going through the initial steps of input use efficiency and input substitution, the final goal of the conversion process is the design of diversified farming systems that can sponsor their own fertility, protection, and production. Parameters that could measure the level of sustainability attained after the conversion are offered, but methodologies on how to use them are lacking. Finally, Gliessman argues that we need to focus beyond ecological sustainability at the farm level and move toward a sustainable food system. Processing, distribution, marketing, and access are all key issues in addition to food production. Although the book depicts the varied interplay in defining the global food system, no scenario is offered of an alternative social organization, policy framework, or economic system that could make such global food systems more equitable. Overall, the book is an important contribution; if the price does not impede it, Gliessman’s book should become a major agroecology textbook throughout the United States.