Earth Science and Applications from Space National Imperatives for the Next Decade and Beyond (2007) / Chapter Skim
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7 Land-Use Change, Ecosystem Dynamics, and Biodiversity
7 Land-Use Change, Ecosystem Dynamics, and Biodiversity
Pages 190-216
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From page 190... ...
The Panel on Land-Use Change, Ecosystem Dynamics, and Biodiversity accords its highest priority to maintaining and improving the long-term records of the productivity of terrestrial and marine ecosystems and to measuring land-cover change at high spatial resolution. Daily observations from space since the early 1980s have provided critical time series of ocean color and terrestrial productivity, and repeated high-resolution images from the Landsat series have been the foundation for identifying changes in land cover, habitat fragmentation, human infrastructure, and other surface features since the 1970s.
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From page 191... ...
Vector winds are key for analyzing ocean and coastal ecosystem dynamics. Temperature, precipitation, cloud cover, aerosols, sea-surface temperature, and ocean topographic characteristics are also vital observations.
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From page 192... ...
Optical, multispectral sensors have been the mainstay of remote sensing for ecosystems over the last two decades. Scientific advances in applications of hyperspectral and active radar and lidar sensors hold promise for considerably enhancing the capabilities to observe and understand ecosystems, including invasive species, air quality, harmful algal blooms, and a host of other issues (e.g., Asner et al., 2004; Treuhaft et al., 2004)
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From page 193... ...
Models suggest that changes in terrestrial and marine ecosystems accelerate the rate of CO2 increase in the atmosphere and hence global warming. But models disagree about the response of primary productivity to the competing or synergistic effects of temperature and moisture (e.g., Cox et al., 2000; Fung et al., 2005; Friedlingstein et al., 2006)
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From page 194... ...
Although many ecosystem issues develop slowly, there is also a need for remote sensing to provide decision support during and in the wake of episodic events, including abrupt events such as tropical storms and wildfires, and "slower" events, such as insect outbreaks, harmful algal blooms, and droughts. These strategic needs are encapsulated in the overarching questions (listed in Box 7.1)
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From page 195... ...
. There is growing evidence that excess nitrogen deposition in terrestrial systems from fertilizers and other sources can affect the carbon cycle and other ecosystem services through changes in crop yield and biodiversity (which is reduced by excess nitrogen)
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From page 196... ...
For example, the occurrence of harmful algal blooms appears to be increasing in U.S. coastal waters, and these blooms may be stimulated by increased nutrient availability (Figure 7.2)
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From page 197... ...
The increasing intensity and extent of human land-use are as global as is changing climate. Harvesting of fisheries from the ocean and water quality impacts from coastal development are also leading to massive alteration of ocean ecosystems.
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From page 198... ...
. 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.
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From page 199... ...
Courtesy of the National Center for Infectious Diseases, Centers for Disease Control and Prevention. designed to be comprehensive in the sense that they measure various quantities for detecting changes in ecosystem structure and dynamics, they focus on rigorous detection of effects related to the carbon cycle, the water cycle, the productivity and management of ecological communities, and habitat characteristics.
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From page 200... ...
. Operational satellite records to enhance and Maintain the Long-term record on ecosystem dynamics The currently available long-term record of ecosystem dynamics from a variety of sensors is critical for understanding and managing ecosystems in the coming decades.
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From page 201... ...
This measurement has been continually improved since the launch of CZCS in 1978. Further improvements are possible on the basis of developments in scientific understanding, technology development, and atmospheric correction (see the panel's mission recommendation below to enhance capabilities to monitor productivity in the open ocean)
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From page 202... ...
The Integrated Program Office for NPOESS has ruled out similar lunar observations for their platforms; thus, new approaches must be found for a global-scale, multiyear, consistent time series of ocean color (see the section below titled "Global Ocean Productivity")
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From page 203... ...
. Hyperion data have been provisionally used in a mainstream ecosystem dynamics model to simulate carbon sources and sinks in the northeast United States and have shown substantial increases in accuracy over previous methods.
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From page 204... ...
ecosystem structure and Biomass Mission summary -- ecosystem structure and Biomass Variables: Standing biomass; vegetation height and canopy structure; habitat structure Sensor(s) : Lidar and InSAR Orbit/coverage: LEO/global Panel synergies: Climate, Health, Solid Earth New science: Global biomass distribution, canopy structure, ecosystem extent, disturbance, recovery Applications: Ecosystem carbon and interactions with climate, human activity, disturbance (including deforestation, invasive species, wildfires)
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From page 205... ...
The ideal ecosystem structure and biomass mission would combine the two approaches, taking advantage of the precision and directness of lidar to calibrate and validate InSAR, especially in ecosystem types for which field campaigns have not been undertaken. The two sensors could fly on different platforms, but the need for coincident observations separated by not more than a few weeks is critical for using the lidar measurements to calibrate the radar measurements.
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From page 206... ...
Global measurements of column-integrated atmospheric CO2 with sufficient precision and sample density for accurately recovering surface fluxes are feasible only from satellite platforms. The first step in inferring terrestrial ecosystem processes from atmospheric data is to separate photosynthesis and respiration; for this, diurnal sampling is required to observe nighttime concentrations resulting from respiration.
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From page 207... ...
The coupling of this high-precision, high-volume data stream combining in situ and satellite observations with atmospheric inversion, data assimilation, and coupled atmospheric, terrestrial, and ocean carbon modeling will permit quantification of the sources and sinks at unprecedented space and time resolution. The final scientific outcomes will be greatly advanced understanding of the global carbon cycle and the scientific foundation essential for making reasoned projections of atmospheric concentrations of CO 2.
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From page 208... ...
Recent work highlights the progress in estimating ocean primary productivity from satellite-derived measurements of chlorophyll, phytoplankton growth rates, natural and harmful algal blooms, and carbon uptake (Behrenfeld et al., 2005)
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From page 209... ...
In coastal waters, the presence of absorbing aerosols and high in-water particle loads, which can invalidate the black-ocean assumption for short near-IR bands used in current atmospheric correction algorithms, complicate standard atmospheric corrections applied for current ocean-color satellite observations. Negative water-leaving radiances for the 412-nm band (and at times for the 443-nm band)
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From page 210... ...
has identified new processes based on continuous evolution in the technical capabilities of the sensors. As with the coastal-ecosystem mission, the global ocean-productivity mission will focus on the quantification of upper-ocean biomass and primary productivity and on important aspects of ecosystem structure as they are related to changes in climate and their effects on biogeochemical cycling (Behrenfeld et al., 2005)
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From page 211... ...
The mission would provide the necessary next-generation global ocean-color measurements to advance understanding of the interplay between climate, biogeochemical cycling, and ecosystem structure in the upper ocean. With projected changes in atmospheric forcing and increasing acidity, it is essential to develop more sophisticated prognostic models in order so that the future role of ocean uptake in carbon cycling and ecosystem services can be understood.
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From page 212... ...
That interval is also critical for monitoring the development of plant-water limitations and wet intervals associated with rapid and important soil activity. The spatial resolution required must correspond to scales of variability in terrestrial ecosystems and in the soil moisture anomalies that affect them.
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From page 213... ...
In a survey of the community for research needs, it became clear that various science applications can be met efficiently and cost-effectively with aircraft-based instruments. Especially where there is a demand for data with a high spatial resolution but not global coverage, aircraft allow an attractive balance of low development cost, simple maintenance, and ready deployment in response to specific conditions or events.
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From page 214... ...
, atmospheric measurements (such as CO2, N2O, NOx, CO, CH4) , or statistical databases (such as fisheries landings, harmful algal blooms, agricultural yield, timber harvests, fertilizer application, or
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From page 215... ...
2005. Carbon-based ocean productivity and phytoplankton physiology from space.
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From page 216... ...
2006. Multi-dimensional forested ecosystem structure: Requirements for remote sensing observations.
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