The Alaska Division of Forestry is in the process of using state-of-the-art Geographic Information System (GIS) technology to update geographic data of the region.
GIS involves the use of computers to overlay datasets and images of an area to better understand its composition. For the Division of Forestry, the composition of a forest influences the types of activities that can occur there, such as timber harvest and road construction.
Last year, the division contracted with the Alaska Division of Geographical and Geophysical Surveys to collect detailed topographic information to create a 3-D model of an area between Mosquito Lake and town, bounded by the Takhin and Takshanuk ridges. The project involved use of Light Detection and Ranging (LiDAR) technology, which uses lasers to measure distances.
The area was selected because it includes forest lands with proposed management activities in the current Haines State Forest five-year management plan,” forester Greg Palmieri said.
This year, the Division of Forestry has contracted Quantum Spatial, a company that collects and analyzes geospatial data for use in resource management, to take high-resolution, low-altitude images of the same area.
In recent weeks, an employee of DOWL, the company hired by Quantum Spatial to collect the aerial images, has been reaching out to residents in the area to place “ground control points,” markers to improve the accuracy of the final data by serving as reference points when the images are stitched together.
The high-resolution images will allow the division to “get to know the ground within a foot of accuracy,” Palmieri said. And they are multispectral, meaning they capture a broader range of light than is visible to the naked eye. The Division of Forestry can use the near-infrared light captured to distinguish between live and dead trees.
The LiDAR data and aerial images can be analyzed separately or in conjunction using GIS.
“We put those two things together—very detailed images and 3-D modeling—to do different types of resource analysis from steepness of slope to hydrology analysis,” Palmieri said. “This data has become the standard for resource management work.”
Together, the LiDAR 3-D modeling and the multispectral images will allow division employees to understand the composition of large areas of forest to a degree of precision that was previously only possible on a small scale, after hours of field data collection.
“I could determine a particular tree height if I wanted to,” Palmieri said. “It allows one individual to do pertinent analysis on their own to develop things that would have taken eight to twelve people before.”
New applications for GIS in relation to resource management are still being discovered, Palmieri said, but at present, it hasn’t replaced fieldwork. “Some people are arguing that it will, but we’re not there yet,” he said.
Before GIS, aerial photos were the prevailing technology for large-scale forest analysis. The most recent division of forestry images of the area were taken in 1998 using analog cameras.
Palmieri said the division didn’t have funding available to image the entire forest this time, so they selected the smaller area running between Mosquito Lake and town.
In total, the multispectral imagery taken this year will cost the state roughly $136,000. The funding comes from capital project dollars set aside for this purpose some time ago, according to Palmieri. He said he expects the project will be completed by the end of September.