Urbanization drastically alters the ecosystems structure and functions, disrupts cycling of C and other elements along with water. It alters the energy balance and influences climate at local, regional and global scales. In 2008, urban population exceeded the rural population. In 2050, 70% of the world population will live in urban centers. The number of megacities (10 million inhabitants) increased from three in 1975 to 19 in 2007, and is projected to be 27 in 2025. Rapid urbanization is altering the ecosystem C budget. Yet, urban ecosystems have a large C sink capacity in soils and biota. Judicious planning and effective management can enhance C pool in urban ecosystems, and off-set some of the anthropogenic emissions. Principal components with regards to C sequestration include home lawns and turfs, urban forests, green roofs, park and recreational/sports facilities and urban agriculture.

The book looks at the history and existence of trees, the importance of trees to the existence of humans and animals that utilize oxygen in their respiratory systems, the habitat that they have provided for all species of life over millennia, the food that they provide to all species, their impact upon existence of the hydrological system, the preservation of soil and the prevention of desertification, human relationships with forest and trees, the solace and the many other social benefits that they provide to humans and all species given to contemplation. The book highlights the many human activities, ancient and current, that are considered vital to human life, past, present and future inclusive of agriculture, mining, forestry for timber and paper products and energy production and the impact that they have had on forests and trees and consequently on the lives and health of humans and the other occupants of the planet. It also examines the many things, apart from human activities, that negatively impact forest and trees inclusive of natural events such as natural fires, floods, wind, disease, and salinization due to storm surges or rising seawater levels. The final chapters review and attempt to provide some solutions to the many problems associated with feeding and housing a growing human population.