An Effective Method for Detecting Potential Woodland Vernal Pools Using High-Resolution LiDAR Data and Aerial Imagery

Qiusheng Wu,Hongxing Liu,Charles Lane

doi:10.3390/rs61111444

Qiusheng Wu, Hongxing Liu + Show 1 more

Open Access

https://doi.org/10.3390/rs61111444

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Abstract

Effective conservation of woodland vernal pools—important components of regional amphibian diversity and ecosystem services—depends on locating and mapping these pools accurately. Current methods for identifying potential vernal pools are primarily based on visual interpretation and digitization of aerial photographs, with variable accuracy and low repeatability. In this paper, we present an effective and efficient method for detecting and mapping potential vernal pools using stochastic depression analysis with additional geospatial analysis. Our method was designed to take advantage of high-resolution light detection and ranging (LiDAR) data, which are becoming increasingly available, though not yet frequently employed in vernal pool studies. We successfully detected more than 2000 potential vernal pools in a ~150 km2 study area in eastern Massachusetts. The accuracy assessment in our study indicated that the commission rates ranged from 2.5% to 6.0%, while the proxy omission rate was 8.2%, rates that are much lower than reported errors of previous vernal pool studies conducted in the northeastern United States. One significant advantage of our semi-automated approach for vernal pool identification is that it may reduce inconsistencies and alleviate repeatability concerns associated with manual photointerpretation methods. Another strength of our strategy is that, in addition to detecting the point-based vernal pool locations for the inventory, the boundaries of vernal pools can be extracted as polygon features to characterize their geometric properties, which are not available in the current statewide vernal pool databases in Massachusetts.

Highlights

Vernal pools are frequently considered a type of so-called “geographically isolated wetland”, temporary or semi-permanent pools typically defined as occurring in a confined basin depression without a permanently flowing outlet [1,2,3]
The potential vernal pools mapped by Burne [10] for the study area were not field-verified, the Potential Vernal Pools (PVPs) database can still serve as a source of information for validating our methods for vernal pool identification
The points representing potential vernal pools have a precision of ≤ 5 m or so from the center of an interpreted pool, while the locations of certified vernal pools have a precision of approximately 15 m in any direction

Summary

Introduction

Vernal pools are frequently considered a type of so-called “geographically isolated wetland”, temporary or semi-permanent pools typically defined as occurring in a confined basin depression without a permanently flowing outlet [1,2,3]. These systems can become inundated pools in the fall, winter, or spring, and frequently dry completely in the summer [3,4]. Due in part to their small size and short hydroperiods, as well as the relative lack of resilience to hydrologic alterations to the surrounding landscape, vernal pool wetlands are at risk of destruction across the northeastern United States [2,5,6,7]. Some geopolitical entities of the United States have developed guidance and regulations for vernal pool protection, including New Jersey [4], Maine [8], and Massachusetts [9,10], as well as smaller municipalities such as towns of Farmington, Simsbury, and Suffield in Connecticut [11,12]

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