In the past decades, deforestation and forest degradation accounted for about 20% of greenhouse gas emissions showing that the mitigation of global warming cannot be achieved without the implication of forest contributions in international agreements. The Global Forest Resources Assessment noted that the overall rate ofdeforestation remained alarmingly high, although the rate was slowing. Therefore, measuring and modeling biomass from forest ecosystems has become a main challenge for governments and forest managers to make sure that forests contribute to climate change mitigation and continue to play all his roles including providing healthing environment, goods and biodiversity to sustain live of people around the world. Forest inventory and biomass estimation require a combination of different techniques. This book explains in simple words the various techniques used for measuring and modeling biomass from forest ecosystems.