Declining Forests of Hawai'i Island
University of California, Los Angeles
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Introduction to Remote Sensing
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Winter 2021
RESEARCH QUESTION
Has there been a significant change in NDVI in Hawaii based upon Landsat imagery from October 1977 to 2020 (dry season) and January 1978 to 2020 (wet season)?
Historically, the native forests of Hawaii have been susceptible to forest loss. Since the onset of human arrival, Hawaii has lost roughly 50% of the native forest cover throughout the state (6). We are interested in understanding where these native forests have been decreasing and whether this decrease is attributed to drought, fire, herbivores, or other factors.
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Prior studies have shown that native vegetation and forests are indeed receding. For example, Ōhiʻa lehua trees, which are native to Hawaii, have been rapidly dying due to a fungal disease, and this disease is more widespread on the Big Island, where it has spread over more than 175,000 acres (5). After analyzing our study area on Google Earth Engine Timelapse, it does appear that forest coverage is declining in the visible light.
1984
2018
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Introduction
The NDVIs for months in the dry and wet seasons in the past (October 1977 and January 1978 respectively) and the present (October & January of 2020) are unknown. The change in NDVIs for the dry and wet seasons (October 1977 to October 2020 and January 1978 to January 2020 respectively) are also unknown. We are interested in seeing whether or not Hawaii vegetation health has been declining over time, and whether or not more changes in vegetation health are observed in a particular season.
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This project is important for understanding the extent of forest cover change over the last 40 years on the island of Hawaii and the potential causes of forest coverage change. Monitoring the health and change of forests is important since Hawaii supports crucial ecosystems and hosts a diversity of flora and fauna.
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Our project seeks to answer the following question; has there been a significant change in NDVI on Hawaii Island-based upon Landsat imagery from 1977 to 2020 (dry season) and 1978 to 2020 (wet season)