Geography

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Impact of recent forest management and disturbances on carbon dynamics in the Greater Yellowstone Ecosystem
(2015) Zhao, Feng; Huang, Chengquan; Dubayah, Ralph; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Protected areas are recognized worldwide as being important components of climate change mitigation and adaptation strategies. With increasing interests in quantifying greenhouse gas emissions and potentially managing forests to increase the rate of carbon sequestration, there are urgent needs to quantify impact of forest management and disturbances on carbon dynamics. The overall goal of this study is to quantify the impact of recent forest management and disturbances on forest carbon dynamics in GYE, by integrating forest inventory, remote sensing data and carbon modeling approach. Four specific goals for this study include: (1) Develop a method to compare historical and current fire regimes using time series remote sensing data and a landscape succession model; (2) Assess post-fire and post-harvest forest recovery in GYE using time series remote sensing data; (3) Characterize recent forest management and disturbance history (1984-2011) in GYE using local management record and time series remote sensing data; (4) Quantify the impact of recent forest management and disturbances on carbon dynamics in GYE by linking forest inventory, time series remote sensing and carbon modeling. This dissertation is a synthesized analysis of the impact of recent forest management and disturbance on carbon dynamics in GYE, by integrating forest inventory, remote sensing and C modeling approach. The results of this study could contribute to a better understanding of management-disturbance-carbon interactions over ecosystems with complex management regimes and environmental gradients, such as GYE. This study provides a comprehensive and consistent annualized record of forest disturbances, post-disturbance forest recovery, carbon stocks, and relative impact of forest management and disturbance on carbon dynamics in GYE. Such a record would be useful for informed forest management and policy making, ecosystem conservation and restoration, biodiversity protection and carbon assessment in this region. With the availability of input data nationwide, this approach can be applied to the rest of U.S. for many research and management purposes.
Long-Term Post-Disturbance Forest Recovery in the Greater Yellowstone Ecosystem Analyzed Using Landsat Time Series Stack
(MDPI, 2016-10-29) Zhao, Feng R.; Meng, Ran; Huang, Chengquan; Zhao, Maosheng; Zhao, Feng A.; Gong, Peng; Yu, Le; Zhu, Zhiliang
Forest recovery from past disturbance is an integral process of ecosystem carbon cycles, and remote sensing provides an effective tool for tracking forest disturbance and recovery over large areas. Although the disturbance products (tracking the conversion from forest to non-forest type) derived using the Landsat Time Series Stack-Vegetation Change Tracker (LTSS-VCT) algorithm have been validated extensively for mapping forest disturbances across the United States, the ability of this approach to characterize long-term post-disturbance recovery (the conversion from non-forest to forest) has yet to be assessed. In this study, the LTSS-VCT approach was applied to examine long-term (up to 24 years) post-disturbance forest spectral recovery following stand-clearing disturbances (fire and harvests) in the Greater Yellowstone Ecosystem (GYE). Using high spatial resolution images from Google Earth, we validated the detectable forest recovery status mapped by VCT by year 2011. Validation results show that the VCT was able to map long-term post-disturbance forest recovery with overall accuracy of ~80% for different disturbance types and forest types in the GYE. Harvested areas in the GYE have higher percentages of forest recovery than burned areas by year 2011, and National Forests land generally has higher recovery rates compared with National Parks. The results also indicate that forest recovery is highly related with forest type, elevation and environmental variables such as soil type. Findings from this study can provide valuable insights for ecosystem modeling that aim to predict future carbon dynamics by integrating fine scale forest recovery conditions in GYE, in the face of climate change. With the availability of the VCT product nationwide, this approach can also be applied to examine long-term post-disturbance forest recovery in other study regions across the U.S.