Avian habitat suitability in Newfoundland
Species extinctions are happening at a rate greater than the natural background extinction rate (Pimm and Raven, 2000), as a result of this, it is important to know what aspects of a habitat each species requires to survive. High diversity of birds in an ecosystem can indicate a healthy ecosystem (Browder et al., 2002; Gregory and Strien, 2010; Robledano et al., 2010). Since bird abundance is dependent on forest structure (Beedy, 1981; Engstrom et al., 1984), structural metrics can be used to predict bird diversity in areas devoid of bird population data. About 20% of the island of Newfoundland is forested (fig 1). As such, predicting bird diversity in Newfoundland’s forests is important to the management and conservation of the island’s wild lands.
Traditionally, data on forest structure have been collected by on the ground field surveyors. This method comes with several drawbacks: data collection is time consuming, limited by accessibility, expensive, and is reserved to small samples of a forested area. There is also an element of surveyor bias which must be overcome with training and practice (Ott, 2017). More recently, an active remote sensing technology known as airborne laser scanning (ALS) has grown in popularity in the forestry industry. ALS is capable of capturing a census of the structural aspects of a forest quickly, however the technology creates large files which must be processed and collecting the data can be very expensive (Tattoni et al., 2012). Due to the high monetary expense of ALS, researchers are often forced to use ageing data for analysis (Vierling et al., 2014).
A link between structural vegetation indices and bird species diversity has long been known from traditional field surveys (Erdelen, 1984; Karr and Roth, 1971; MacArthur and MacArthur, 1961; Mills et al., 1991; Willson, 1974), and many studies have used ALS data to study these relationships (Bradbury et al., 2005; Clawges et al., 2008; Seavy et al., 2009), however, to model these relationships on a wall to wall scale over large tracts of land, traditional forest cruising and ALS data are inadequate due to their high cost. Passively collected remote sensing data such as multispectral images are available on a wall to wall scale at little or no cost making them ideal for wall to wall modelling, however there is no established link between the structural characteristics of forest structural indices and multispectral data. It is therefore essential to establish relationships between these different scales and data types to model bird habitat suitability over large areas. This study focuses on using remote sensing data at multiple scales to address this issue.
This project aims to link forest structure data to bird presence data at two spatial scales over Newfoundland – a focal area, known as Harry’s River Watershed (fig 2), and the entirety of the island (fig 3). The procedure will be congruent at both scales: build relationships between avian occurrence and forest structure, measured in permanent sample plots, then extract these relationships with ALS data and subsequently extrapolate over the whole of Newfoundland using contiguous spatial layers.
This study will ultimately address the following questions:
- Which structural characteristics of Newfoundland forests have the greatest influence on the presence of birds?
- Can structural characteristics be used to infer bird habitat over Newfoundland with remote sensing?
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