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| Titel |
Dynamics in mangroves assessed by high-resolution and multi-temporal satellite data: a case study in Zhanjiang Mangrove National Nature Reserve (ZMNNR), P. R. China |
| VerfasserIn |
K. Leempoel, B. Satyaranayana, C. Bourgeois, J. Zhang, M. Chen, J. Wang, J. Bogaert, F. Dahdouh-Guebas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 8 ; Nr. 10, no. 8 (2013-08-27), S.5681-5689 |
| Datensatznummer |
250085312
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| Publikation (Nr.) |
 copernicus.org/bg-10-5681-2013.pdf |
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| Zusammenfassung |
| Mangrove forests are declining across the globe, mainly because of human
intervention, and therefore require an evaluation of their past and present
status (e.g. areal extent, species-level distribution, etc.) to implement
better conservation and management strategies. In this paper, mangrove cover
dynamics at Gaoqiao (P. R. China) were assessed through time using 1967, 2000
and 2009 satellite imagery (sensors Corona KH-4B, Landsat ETM+, GeoEye-1
respectively). Firstly, multi-temporal analysis of satellite data was
undertaken, and secondly biotic and abiotic differences were analysed between
the different mangrove stands, assessed through a supervised classification
of a high-resolution satellite image. A major decline in mangrove cover
(−36%) was observed between 1967 and 2009 due to rice cultivation and
aquaculture practices. Moreover, dike construction has prevented mangroves
from expanding landward. Although a small increase of mangrove area was
observed between 2000 and 2009 (+24%), the ratio
mangrove / aquaculture kept decreasing due to increased aquaculture at the
expense of rice cultivation in the vicinity. From the land-use/cover map
based on ground-truth data (5 × 5 m plot-based tree measurements)
(August–September, 2009) as well as spectral reflectance values (obtained
from pansharpened GeoEye-1), both Bruguiera gymnorrhiza and small
Aegiceras corniculatum are distinguishable at 73–100%
accuracy, whereas tall A. corniculatum was correctly classified at
only 53% due to its mixed vegetation stands with B. gymnorrhiza
(overall classification accuracy: 85%). In the case of sediments, sand
proportion was significantly different between the three mangrove classes.
Overall, the advantage of very high resolution satellite images like GeoEye-1
(0.5 m) for mangrove spatial heterogeneity assessment and/or species-level
discrimination was well demonstrated, along with the complexity to provide a
precise classification for non-dominant species (e.g. Kandelia
obovata) at Gaoqiao. Despite limitations such as geometric distortion and
single panchromatic band, the 42 yr old Corona declassified images are
invaluable for land-use/cover change detections when compared to recent
satellite data sets. |
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