Rosenqvist, A. 
  
and polarizations, and very good results can be achieved when optical and microwave data are combined. While multi- 
band/polarimetric and interferometric radar systems are not yet available in a space-borne mode, they are available on 
aircraft platforms and could be used for local to regional scale applications. 
A major limitation of radar systems, with respect to vegetation mapping, is their sensitivity to surface topography 
which limits their application to flat or gently undulating terrain. Radar data are also subject to speckle, which on one hand 
enables techniques such as radar interferometry, but reduces the effective ground resolution. The advantage of radar 
systems is their all-weather capability, which assures image acquisitions independent of cloud cover and daylight, thereby 
enabling timely and reliable acquisitions at local, regional and global scales. 
Active Optical Systems (LIDAR) 
LIDAR systems are only just recently being explored for vegetation mapping. At the time of this writing, NASA's 
Vegetation Canopy LIDAR (VCL) is the only LIDAR system planned for orbit in the near future. VCL is an active infrared 
laser altimeter which will make soundings of the vegetation canopy, providing unprecedented information on the structure 
of the Earth's forests and land surfaces by directly observing vegetation canopy height, forest vertical and spatial 
distribution, and ground topography at high resolution (Dubayah et al. 1997). VCL is however not an imaging instrument. It 
will collect data in a series of samples, along the flight path. However, using VCL data in combination with other spatially 
extensive data, such as optical/multispectral or SAR, holds a significant potential. j 
2.1.2 Support to the establishment of a 1990 carbon stock baseline 
According to Art. 3:4 of the Kyoto Protocol, each Annex I country shall "provide data to establish its level of carbon 
stocks in 1990 and to enable an estimate to be made of its changes in carbon stocks in subsequent years". However, Art. 3:5 
of the Protocol also states that Annex I countries "undergoing the process of transition to a market economy" may, under 
certain circumstances, "use a historical base year or period other than 1990 for the implementation of its commitments" 
under Art. 3. Hence, baselines formulated after 1990 may, for certain countries, be considered. Nevertheless, as it can be 
expected that the year 1990 will be the by far predominant base year, the selection of potential sensors to be used to support 
the establishment of this base line will to the largest extent be limited to those in operation during this specific year. 
Multi-spectral Sensors. 
Among the high resolution optical sensors, only Landsat TM and SPOT HRV were in operation in 1990. The use of 
high resolution data for compiling a regional-global 1990 land cover map to support the establishment of the carbon stock 
baseline is possible - albeit expensive. It is feasible at a national level, especially for smaller countries or regions. Archives 
of Landsat TM and MSS, and SPOT HRV exist and could be used for this purpose. 
The use of coarse resolution data is also feasible, although spatial resolution issues for many areas would limit its 
utility. A Global Land Cover map from 1992 has been generated from NOAA AVHRR data within IGBP DIS and archives 
of NOAA AVHRR data exist for the required time period (Belward et al. 1999, Townshend et al. 1994,). In order to be 
useful, however, the land cover classes used need to be re-defined and adapted to classes relevant to the Kyoto Protocol. 
Active Microwave Systems. : 
No orbital active microwave systems were in operation in 1990 and the use of SAR data to support a 1990 baseline is 
thus not feasible. For non-1990 baseline countries in the tropical and boreal zones of the Earth, continental scale (100 m 
resolution) JERS-1 L-band SAR mosaics from 1995-96, generated within the GRFM/GBFM projects (Rosenqvist et al. 
2000), can be used to support the establishment of a mid-1990's carbon baseline. 
LIDAR. 
Not feasible. No data available. 
2.1.3 Detection and quantification of change in forest area 
This application concerns the detection and spatial quantification of afforestation, reforestation and deforestation 
(ARD) activities, and changes resulting from fire events. Article 3:3 of the treaty states that "The net changes in greenhouse 
gas emissions by sources and removals by sinks resulting from direct human-induced land-use change and forestry 
activities, limited to afforestation, reforestation and deforestation since 1990, measured as verifiable changes in carbon 
stocks in each commitment period, shall be used to meet the commitments under this Article...". Article 12 furthermore 
defines a "clean development mechanism", which in principle stipulates the conditions for "carbon trading" between | 
countries. This, in turn, requires verifiable measurements of ARD. 
While the articles above concern measurements of carbon stocks and changes therein, a first important step is the 
identification and quantification of the areas subject to ARD. In combination with up-to-date in situ data and relevant 
allometric models, changes in biomass (carbon) stocks may be estimated. In order to detect ARD activities, image 
acquisitions at a repetitive basis will be required, preferably annually and performed during a specific season, in order to 
  
  
1280 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.