Very High Resolution Plant Community Mapping
at High Moor, Kushiro Wetland
Kunihiko Yoshino, Sayuri Kawaguchi, Fusayuki Kanda, Keiji Kushida, and Fuan Tsai
Abstract
Frequent monitoring of the state of wetlands is important in
order to sustain these valuable ecosystems. Reliable refer-
ence maps make this monitoring more effective. A very high
resolution and reliable vegetation map with a nominal spatial
resolution of 2 cm by 2 cm was created for a study area in the
high moor in the Kushiro wetland, Japan. The reference map
was created using aerial photography recorded in the sum-
mer of 1998 with a 35 mm, non-metric camera mounted on a
balloon. The study site contains 40 wetland plant community
types covering about 10 ha of the high moor. The resulting
map shows that belt-like spatial patterns of typical wetland
plant community groups can be clearly distinguished and
confirmed through visual interpretation and spatial pattern
analysis. The optimal spatial resolution for monitoring vege-
tation in this area using remote sensing is 0.3 m or smaller.
Introduction
Wetland ecosystems play various roles in regional natural
environments. For example, they function as important
entities in regional carbon and nutrient cycles, as hotspots of
biodiversity and as tourism landscapes (Dugan, 1993). Wet-
lands throughout the world are thought to contain precious
natural environments and landscapes that should be pre-
served (Mitsch and Gosselink, 2007). Recently, these valuable
wetland landscapes have been reduced by many types of
human activities (Williams, 1990). In order to sustain these
valuable wetland ecosystems in the long term, it is important
to continuously monitor the state of wetland ecosystems, to
carefully watch the environment and to provide warnings of
any environmental changes (Lyon and McCartby, 1995). A
reliable reference map is essential for identifying environ-
mental changes. Using detailed and reliable reference maps,
quantitative information on wetland ecosystems, such as the
spatial distribution of plant communities and their spatial
relationships, will effectively help in monitoring and char-
acterizing the target wetland, and will increase awareness of
environmental changes (Johnston, 1989; Roush, 2007).
In addition to information related to environmental
change, detailed and reliable reference maps provide other
types of information, such as spatial patterns of plant com-
munities and average patch sizes of plant communities.
Reference maps also assist in establishing appropriate remote
sensing techniques. For example, maps can assist in determin-
ing the ranges of semi-variograms, which help to determine
the optimal ground instantaneous field of view (
GIFOV
) of re-
mote sensors. The average numbers of plant communities per
unit area, i.e., the spatial diversity of classes within a specific
search window (Robinove, 1986), is useful in determining the
effectiveness of spectral mixture analysis (Somers
et al
., 2011)
when using hyperspectral remote sensing data.
Recently, the Kushiro wetland in Japan has been in the
spotlight due to a large-scale national conservation project
called the “Natural Restoration Project in the Kushiro Shitsu-
gen Wetland.” This project by the Japanese government has
been underway since 2002 in several parts of the Kushiro wet-
land to restore the wetland environment. However, the Kushi-
ro wetland requires more intensive monitoring, especially in
the high moor area near Akanuma, since some local ecologists
have claimed there have been environmental changes even in
the core area of the wetland. A detailed and reliable reference
map of the plant communities in the wetland is necessary to
quantitatively determine environmental changes.
The present study has created a very detailed map of the
wetland plant communities at the high moor in the Kushiro
wetland. The map has a nominal spatial resolution of 2 cm by
2 cm and was derived from very high resolution color aerial
photography. The map was used to analyze the spatial pat-
terns of wetland plant communities. The specific objectives
of the present study are: (a) to rectify aerial photos using a
sufficient number of ground control points and to mosaic the
rectified photos using digital photogrammetry, (b) to interpret
plant communities and to delineate a wetland plant commu-
nity map using an object-based segmentation method, and
(c) to analyze the spatial pattern of plant communities using
GIS
-based spatial analysis techniques. The term “very high
spatial resolution” is used to indicate that the pixel size of the
imagery is in the order of several centimeters.
Study Area and Methods
High Moor Study Area near Akanuma in the Kushiro Wetland
The Kushiro wetland is the largest wetland in Japan and is
located in the eastern part of Hokkaido Island, northern Japan
(43°5'N, 144°25'E and 5 m in elevation). Figure 1 shows a map
Kunihiko Yoshino is with the Faculty of Engineering, Informa-
tion and Systems, University of Tsukuba, Japan, 1-1-1 Tennou-
dai, Tsukuba, Ibaraki 305-8573, Japan (
).
Sayuri Kawaguchi is with the Kushiro Parks and Greenery
Association, 9-34 Ichikawa-Kawakitacho, Kushiro, Hokkaido,
085-0003, Japan.
Fusayuki Kanda is with Hokkaido University of Education
Kushiro Campus, 1-15-55 Shiroyama, Kushiro, Hokkaido 085-
8580, Japan.
Keiji Kushida is with the Department of Bioenvironmental
and Agricultural Engineering, College of Bioresource Sciences,
Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-
0880, Japan.
Fuan Tsai is with the National Central University, Taiwan,
No.300, Jhongda Rd., Jhongli City, Taoyuan County 32001,
Taiwan (R.O.C.).
Photogrammetric Engineering & Remote Sensing
Vol. 80, No. 9, September 2014, pp. 895–905.
0099-1112/14/8009–895
© 2014 American Society for Photogrammetry
and Remote Sensing
doi: 10.14358/PERS.80.9.895
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
September 2014
895
