LiDAR datasets allow us to work with digital facsimiles of the earth surface and its adornments (e.g., vegetation). It’s also possible to transform the digital models back into physical form. I have been trying this with my 3D printer.Continue reading “Plastic LiDAR”
The new LiDAR dataset for Glacier Bay includes not only the “bare earth” digital terrain model but also the point cloud which can represent vegetation and other things the airplane-borne LiDAR bounced off first before it bounced off the ground. This “first returns” cloud can show the shape of the upper vegetation canopy and even distinct understory strata. I have been trying to determine if any useful information can be quantified from the point cloud and to use QGIS to make colorful 3D images of the canopy models.Continue reading “LiDAR canopies”
In 2019 Glacier Bay National Park paid to have LIDAR mapping data collected for about a third of the park. Last summer the processed data were delivered and have now started to appear online for downloading. Most of the data are good quality (6.14 points/meter²) and the area around Park Headquarters and two areas of the outer coast (Pacific coast) are better quality (16.52 points/meter²).Continue reading “Bare Earth surface”
The Fred and Goose Cove study sites at Glacier Bay are only 4.2 km (2.7 miles) apart and the glacier exposed Goose Cove only about a decade earlier than Fred. The vegetation development at Goose Cove during the two decades after I established the plots (ca. 1990-2010) should be comparable to the most recent two decades of development at Fred (ca. 2000-2020). Precise comparisons require that I know how old the two sites are.Continue reading “Have photo – will date”
The second youngest of my 10 study sites at Glacier Bay is called Fred because there is a USGS benchmark there named Fred. Fred is dominated by alder. When the plots were established in 1988, there were no spruce and the average diameter of the cottonwood trees was 7 cm (2.8 inches). There were about five of these little cottonwood trees in each plot and 280 alder stems. There are 10 plots and we measured the diameter of all 2800+ stems.
The primary source I used to date Fred’s emergence from under the glacier was an aerial photo taken in 1948. The McBride remnant, a large extent of shrinking, stagnant ice, was 550 m away from the plots and I guessed that four years earlier the ice had probably covered the plots. I was probably off by a few years.Continue reading “Dating Fred”
Three decades ago I started monitoring vegetation change in Glacier Bay National Park where glaciers have been retreating and exposing new land to colonization by plants. Each of the 10 sites I study was exposed at a different date over the last 250 years and it’s important to know that date for each site. It seems even more important now that I have so much data from the sites.Continue reading “Dating retreat”
More than a year ago I took a hike along the Green Mountain Escarpment (Vermont) in search of an old mine. I had read in an old report that Indiana bats hibernated in a mine in the area, and that was enough of an excuse to go exploring. I watched a bear and two cubs for 15 minutes but never found a mine. It was a pleasant hike along old logging roads through private property. No one lived on the several properties I traversed, none of which was posted.Continue reading “Indiana Bats and the Grotto of Doom”
After 12 nights of recording bat calls near an Indiana bat maternity roosting colony, we deployed the AudioMoths for a week at the vernal pool where we recorded bat calls in August. Instead of putting two AudioMoths at the vernal pool, we put one by the pool and two in the forest surrounding the pool. One of the forest AudioMoths recorded nothing (a battery was inserted backwards), so we got data from only one non-pool AudioMoth.Continue reading “More noise, fewer bats”
Indiana bats live throughout the US Midwest and into New England. In winter they gather in a small number of caves where as many as 50,000 bats may hibernate together. This makes the population vulnerable to vandalism and since 1967 the Indiana bat has been on the US endangered species list. It was listed as Vermont’s first endangered species in 1972. Communal hibernation also makes bats vulnerable to the spread of white-nose syndrome and Indiana bat populations have declined moderately since the disease appeared in 2006.
Vermont is at the northeastern edge of the Indiana bat’s range where it has been observed foraging and raising young throughout the southern Champlain Valley. About 10 maternity roosting colonies where females raise their pups have been documented in Addison County. Female bats select forested sites with large trees and spend the day under loose bark with their single pups and forage at night for flying insects within two or three miles of the roosting trees.Continue reading “Maternal roosting”
Part of the Vermont Center for Ecosystem Studies Vernal Pool Monitoring Project includes audio recordings to document the first calls of frogs at the pools. This year they started using AudioMoths to make the recordings. AudioMoths are open-source data loggers with a low-power sleep mode, real-time clock, microSD card slot, MEMS microphone, and circuitry to support audio capture. AudioMoths can be configured to automatically save audio recordings on a custom schedule. The AudioMoth software and hardware are well thought out and the audio quality is very good (see audio file below). The AudioMoths were deployed at about 50 Vermont vernal pools in weather-tight cases (Figure 1) and recorded for a few short sessions every night for several weeks in the spring.Continue reading “Sound data”
A water depth data logger has been running unattended at a vernal pool (MLS619) at Snake Mountain in Bridport since April 10. The water was a meter deep when I waded out then to change the batteries and swap the microSD card. I have not been in a hurry to do the swap again assuming that the longer I wait the less wet I will get doing it. But I didn’t know how long the batteries would power the logger. The previous record was 11+ weeks, although a similar logger has been running in my office for more than a year on the same batteries. That one only saves data when certain conditions are met but it has been waking up every 30 minutes and sensing its environment for almost 13 months. I decided 16 weeks would make a good record for field deployment at MLS619 and was pleased to find that data had been written to the microSD card once every 30 minutes during those 3.7 months.Continue reading “Unsound data”
Some “then and now” sliders in the last post about Glacier Bay suggested that blueberry and hemlock were spreading in the understory at two of the older study sites we visited last month. Below I am trying out another method of displaying these pairs of old (1990 or 1995) and new (last month) photos. Some new photo pairs from York Creek and Beartrack Cove have been added as well as pairs from a third site.Continue reading “Blueberry and hemlock”