In: Wagner W., Sz6kely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010,1 APRS, Vol. XXXVIII, Part 7B
703
EVALUATION OF TIME-SERIES OF MODIS DATA FOR TRANSITIONAL LAND
MAPPING IN SUPPORT OF BIOENERGY POLICY DEVELOPMENT
F. Zhou, A. Zhang, H. Wang, G. Hong
Canada Centre for Remote Sensing, Booth Street, Ottawa, Ontario, K1A 0Y7 Canada -
(Fuqun.Zhou, Aining.Zhang, Huili.Wang, Gang.Hong)@nrcan.gc.ca
KEYWORDS: Land cover, Vegetation, Change Detection, Data mining, Research, Decision Support
ABSTRACT:
Demanding for information on spatial distribution of biomass as feedstock supply and on land resources that could potentially be used for
renewable bioenergy production is rising as a result of increasing government investment for bioenergy and bioeconomy development,
and as a way of adaptation to climate warning. Lands transitioned over the past between the types of forest, grassland, forage land, and
cropland are considered as the most promising for the production of dedicated bioenergy crops as a primary source of biomass feedstock
for the development of the second generation biofuels, without compromising regular agriculture production.
Aimed at the transitional land mapping at a region scale, Earth Observation data with medium spatial resolution are considered as one of
the most effective data sources. Time series of 10 days cloud-free composite MODIS images and its derivation, NDVI and vegetation
phenology in the vegetation-growing season, are then used to derive the required information. With these datasets, three groups of data
combinations are explored for the identification of the best combinations for land cover identification, then for transitional land mapping,
using a data mining tool.
Results showed that longer time series of Earth Observation data could lead to more accurate land cover identification than that of shorter
time series of data; Bands (1-7) only and NDVI or phenology with other bands (3-7) could yield almost the same highest accurate
information. Results also showed that land cover identification accuracy depends on the degree of homogeneity of the landscape of the
region under the study.
1. INTRODUCTION
Demanding for information on spatial distribution of biomass
as feedstock supply is rising as a result of increasing
government investment for bioenergy and bioeconomy
development, and as a way of adaptation to climate warning.
The recent global food crisis has raised an important question
of how to develop a sustainable bioenergy and bioeconomy
without compromising the food production for a growing world
population. A response to this challenge involves information
on land cover, both for lands currently used in crop production
and for transitional lands that could be used for growth of
dedicated energy crops. Such information will have to be
available over large areas, usually at regional, even at national
scale (Zhou et al„ 2009; Gang et al., 2010).
Transitional lands refer to the lands transitioned over the past
between types such as forest, grassland, forage land, and
cropland due to factors such as climate or market fluctuations
or other reasons. This category of lands is considered most
promising for the production of dedicated bioenergy crops as a
primary source of biomass feedstock for the development of the
second generation biofuels, without compromising regular
agriculture production. Identification of these lands for biomass
growth potential is a gap in the Canadian national biomass
inventory, which has been undertaken by Canadian Forest
Service and Agriculture and Agri-food Canada, with funding
from the federal, interdepartmental Program for Energy
Research and Development (PERD) operated by Natural
Resources Canada. The purpose of the transitional land
mapping is to enable the application of earth observation data
to fill this gap and to provide science-based information in
support of bioenergy policy development.
Aimed at the task at a regional scale, Earth Observation data
with medium spatial resolution are considered as the most
effective data sources. Time series of the Moderate Resolution
Imaging Spectroradiometer (MODIS) images and its derived
information, such as Normalized Difference Vegetation Index
(NDVI) and vegetation phenology, are then used to derive the
required information. Time series of data have many
advantages compared to a single time image as the former
captures dynamic spectral information at various vegetation
growth stages. However, it also poses challenge of such as how
to efficiently use the ‘high-dimensional’ and a large volume of
data and extract needed information for the issues at hand
(Zhou et al., 2009). In this regard, a data mining tool is applied
to explore and identify the optimal data combinations from all
the data available in the vegetation growing season for land
cover identification, and then for transitional land mapping.
Results showed that, in general, longer time series of data set
would yield higher accurate land cover classification than that
of a shorter time series of data, and due to the medium spatial
resolution of MODIS data, land cover identification accuracy
also depends on the degree of homogeneity of the landscape
setting of the region under study. The following sections will
describe in some details about the data used, the methodology