Historical mapping and monitoring of the mangrove forests of Ambergris Caye (Belize) using multi-date Landsat imagery: a twenty-six year history

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Date
2013
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University of Alabama Libraries
Abstract

Ambergris Caye of Belize has in the last three decades become a hotspot for tourism and attracts snorkelers, divers, sight seers, beachcombers, and vacationers from all over the world. This growth in the tourism economy of Ambergris Caye has led to an increased pressure on the mangrove ecosystems due to the direct removal of mangrove habitat and replacing it with sewage ponds and infilling for roads, housing units and hotels. Decisions on environmental policies are hard to make and are compounded when there is a lack of knowledge on the amount and distribution of resources. Knowing how the quantity and quality of mangrove forests have changed through time will help facilitate decisions about how environmental policy needs to adapt to community concerns on the sustainability of their natural resource based tourism economy. In this study, I analyzed historical Landsat TM and ETM+ imagery of Ambergris Caye to examine how mangrove forest cover has changed from 1986 to 2012. Four classes were used based on spectral similarities: mangrove, water, non-mangrove vegetation, and residential/urban/barren land. Once mangrove areas were delineated a Normalized Difference Vegetation Index (NDVI) was performed to assess the health of the mangrove vegetation through time. Specifically, I mapped the historical spatial distribution and health of mangrove forests, examined the land use/land cover changes to mangrove forest distribution and health and assessed the rate of change throughout the study area over a 26 year period. Ambergris Caye lost 766 ha of mangrove forests through out the study time period. In total mangrove coverage went from 8535 ha in 1986 to 7769 ha in 2012 for a total decrease of 9%. Non-mangrove forest cover also decreased from 4408 to 3917 ha, an 11.1% decline. Mean while urban/barren growth increased 264% during the 26 year study. It is also important to note that Ambergris also lost 5% of its total land area to water. Mangrove quality on Ambergris decreased during the 26 year study period. In 1986, 3898 ha of mangrove forest was considered densely growing good quality mangrove habitat. By 1990 good quality mangrove forest coverage had decreased by 3% to 3777 ha. In 1995, mangrove quality dropped by 1% to 3731 ha. From 1995 to 2000 mangrove quality dropped by 9% with 3391 ha being considered good quality. From the year 2000 on mangrove quality dropped drastically going from 3391 ha to 2177 ha in the 2003/4 image. From 2003/4 to 2010/1 the good quality mangrove held relatively steady. However by 2012 only 1663 ha of quality mangrove habitat remains a 57% decrease in overall health from 1986 to 2012.

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Electronic Thesis or Dissertation
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Geography
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