The intensification of agriculture is one of the most important global changes of the last century. Intensification of agriculture by use of high-yielding crop varieties, fertilization, irrigation, and pesticides has contributed to increased food production over the past 50 years. However, land conversion and intensification alter biotic interactions and patterns of resource availability in ecosystems and can have serious local, regional, and global environmental consequences. Agricultural intensification can have negative local consequences, such as increased erosion, lower soil fertility, and reduced biodiversity; negative regional consequences, such as pollution of ground water and eutrophication of rivers and lakes; and negative global consequences, including impacts on climate through greenhouse gas emissions. In contrast, appropriate agricultural management practices can increase food production while minimizing the negative impacts of agricultural activities.
In this talk, I will provide an overview of the contributions of agricultural production to greenhouse gas emissions across a range of agroecosystems, from annual crop monocultures in the temperate zone to small-holder mixed cropping systems in the tropics. These agricultural ecosystems show tremendous variation in structure and function, because they were designed by diverse cultures under diverse socioeconomic conditions in diverse climatic regions. This diversity of agricultural systems results in a highly variable suite of ecological processes and environmental impacts. I will provide examples of appropriate management of key processes that can substantially reduce the emissions of greenhouse gases from these agroecosystems and increase C storage, while preserving the ability of these systems to provide food to human communities. The tradeoffs that may occur between agricultural production and environmental impacts will be evaluated.