. "7 Land-Use Change, Ecosystem Dynamics, and Biodiversity." Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond. Washington, DC: The National Academies Press, 2007.
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data—especially global, high-resolution satellite data—have proved their value and are now fundamental to studies of ecosystem change in academe, government, and the private sector. Improved sensors will increase the information content of ecosystem remote sensing from empirical measurements of type (more or less the current state of the art) to measurements of function, such as nutrient cycling and carbon sequestration (achievable with current exploratory technologies). If those measurements of function are coupled with sufficiently-precise and globally extensive measurements of atmospheric CO2, the interactions between water, carbon, and other element cycles will be better understood.
Changes in Disturbance Cycles
Drought, wildfire, severe weather (tornados, hurricanes, windstorms, and ice storms), and insect out-breaks are major disturbances of ecosystems and disrupt to ecosystem services. Altered disturbance regimes occur in response to intensification of land-use and climate change (Figure 7.3). For example, dramatic increases in the growth rate of CO2 in the atmosphere during 1997 were traced to wildfires in drought-affected areas of Indonesia (Page et al., 2002). The wildfires, although possible because of the drought, were initiated by human activity and occurred mainly in regions where soil moisture was reduced because of land-use change. Disturbance regimes affect the marine and coastal realms as well: coral reef, estuarine, and coastal ecosystems were reshaped for decades to come by the 2005 hurricanes and tsunami. Even the crude prognostic models of disturbance and mortality tested in the early 2000s suggest that climate change could have its largest effects through ecosystem dieback and vegetation change, even without the interactive effects of disturbance and land-use, as suggested in Indonesia. Observing disturbance cycles requires precise observations of ecosystems (i.e., effects of insects could be evident in hyperspectral data before many ground measurements would detect a problem), of disturbance (e.g., fire area and severity) and of local consequences (such as smoke plumes, sediment-loaded waters, and habitats for disease vectors) and global consequences (such as CO2 trends).
Summary of Data Needs
The challenges posed by changing climate, changing land use, changing air quality, invasive species, harmful algal blooms, and a host of other factors call for the capability to maintain and enhance a continuous observational record of ecosystem properties; observe episodic and extreme events, such as fire, pest, and disease outbreaks when and where they occur; and begin records of critical ecosystem functions through measurements of carbon cycling, soil water, and vegetation structure. To perform these functions, observation systems must provide data on an array of terrestrial, coastal, and open-ocean properties, as listed in Box 7.3.
PRIORITY SATELLITE DATA RECORDS AND MISSIONS
In this section, the panel identifies priority satellite missions to address the critical issues of climate-driven and resource-use-driven changes in ecosystems and the consequences for ecosystem functions. The suite includes missions for obtaining ongoing, long-term data records, as well as future missions with new technologies (Table 7.1). This suite is designed to detect and understand ecosystem change and to expand the information available for predicting, managing, and enhancing the provision of ecosystem services. The missions focus on quantitative observations of changing ecosystem processes, including ecosystem biogeochemistry, vegetation and landscape structure, water relations, and disturbance patterns, which are the key diagnostics for the wide array of key questions shown in Box 7.2. Although the missions are