Agroecology: The Ecology of Sustainable Food Systems, Second Edition
Stephen R. Gliessman
Format: PDF / Kindle (mobi) / ePub
Providing the theoretical and conceptual framework for this continually evolving field, Agroecology: The Ecology of Sustainable Food Systems, Second Edition explores environmental factors and complexities affecting agricultural crops and animals. Completely revised, updated, and reworked, the second edition contains new data, new readings, new issues and case studies, and new options. It includes two completely new chapters, one on the role of livestock animals in agroecosystems and one on the cultural and community aspects of sustainable food systems.
The author clearly delineates the importance of using an ecosystem framework for determining if a particular agricultural practice, input, or management decision contributes or detracts from sustainability. He explains how the framework provides the ecological basis for the functioning of the chosen management strategy over the long-term. He also examines system level interactions, stressing the need for understanding the emergent qualities of populations, communities, and ecosystems and their roles in sustainable agriculture. Using examples of farming systems in a broad array of ecological conditions, the book demonstrates how to use an ecosystem approach to design and manage agroecosystems for sustainability.
opportunities for combining our understanding of the environment with our understanding of the population dynamics of the organisms we are dealing with. By focusing this knowledge on both crop and noncrop species, we can plan our agricultural activities accordingly. ECOLOGICAL NICHE The concept of life history strategy helps us understand how a population maintains a role and place in an ecosystem over time. An additional conceptual framework is required for understanding what that role and
pattern is triggered by a hormone that is activated by blue light. Leaves can be oriented toward the sun to capture more light, or away from the sun in high light environments. Sunflowers receive their name from the characteristic orientation of the disc of the inflorescence toward the morning sun. Photoperiod Because the earth is tilted on its axis, the relative proportion of daylight and nighttime hours varies from one time of year to another. Because of the correlation of hours of light or
and warmer temperatures beneficial to agriculture, atmospheric models indicate that other regions, including South and Southeast Asia, Latin America, and sub-Saharan Africa, would likely suffer from the increased heat and disrupted rainfall. Another concern is that prime agricultural land in low-lying coastal regions throughout the world will be flooded by the continued melting of the polar ice caps and the rise in water levels associated with the expansion of water as it warms. Although
market, some phosphorus goes with it. In the third pathway, there is little chance of the phosphorus returning to the soil from which it was extracted (except in much of China, where human excreta is used as fertilizer). Much of the phosphorus consumed by humans in the form of plant biomass or the flesh of grazing animals is essentially lost from the system. An example of what may happen to phosphorus in the third (human consumption) pathway may serve to illustrate the problem: phosphate is mined
surface. When these “mulches” are spread directly over planted beds, slits or holes can be made for the crop plants. Moisture loss is greatly reduced and crop yields, very often, are increased. Some plastics provide a concentrated greenhouse effect as well, raising soil temperatures several degrees. This is a very important benefit for crops that are planted during the colder time of the year, such as strawberries in coastal California (Figure 9.12). Crop Residues and Reduced Tillage By leaving a