Unmanned Aerial Vehicles

Natural Resources


Natural Resources

UAV Benefits

  • Establish a conservation plan
  • Identify problem areas in a particular ecosystem
  • Locate and quantify damage from invasive species
  • Identify disease in canopy coverage
  • Geotag trees for timber removal or to save neighboring trees
  • Faster, safe determination of canopy structure than with human climbers
  • Assess existing conservation areas for biodiversity
  • Monitor and modify soil conservation practices with reduced environmental impact
  • Check surface water for potential contaminants

UAV Challenges

Forests: Flying a UAV near timber stands is inherently risky. Signal strength also weakens within a forested area.

  • Tip: Fly above the canopy when possible and choose low-density areas.

Water: Most UAVs are not waterproof and a crash could destroy the aircraft.

  • Tip: Fly around water – not over it – when possible.

Examples

Detecting tree stress after invasive plant herbicide application

Flown by Phill Woolery, Agriculture & Natural Resource Educator, Purdue Extension – Starke County

A demonstration trial of methods to control the invasive winged burning bush was conducted in the forest at the Pinney Purdue Ag Center. The treatments consisted of four different herbicides and two different timings of application. The herbicide treatments were glyphosate, glyphosate and metsulfuron-methyl, triclopyr, and triclopyr and metsulfuron-methyl. Metsulfuron-methyl has some soil activity, so there was concern about damage to desirable trees in the forest. The drone was used to monitor damage to the overstory trees.

The forest was flown with both an RGB camera and an infrared camera in August. At the time, some of the plots had had two herbicide treatments.

Map of Pinney Purdue Ag Center.
Using the VARI algorithm, several spots showed up as dead and stressed.
Using the VARI algorithm, several spots showed up as dead and stressed.
Looking at the NDVI image, things look different.
Looking at the NDVI image, things look different.
Manual flight shows the trees located in red as dead.
Manual flight shows the trees located in red as dead.

There were a few trees that showed up as stressed in both sets of imagery. So the pilot checked the area from the ground and through manual, drone flights. On the ground, the pilot found a group of small hackberries that had died. It was from the spring triclopyr and metsulfuron-methyl treatment.

There were burning bush at the base of the trees that had been treated. There was also another dead hackberry in the treatment area. There is not a lot of hackberry on the site, so it was hard to determine whether the tree had a greater dose of the chemicals or if it was just more sensitive to the treatment.

The other stressed trees shown in the VARI imagery were black cherry trees. These did not show up as being stressed in the NDVI image. Using the manual drone flights, the pilot took some closer images of the crowns as well as photos from the ground.

Hackberry tree
Hackberry tree
Burning bush
Burning bush
Drone image from the top of the canopy
Drone image from the top of the canopy
Image from the ground foot of the tree
Image from the ground foot of the tree

Native seeding with a drone

Flown by John Scott, Purdue Extension Digital Agriculture Coordinator

This project was completed at Ivy Tech in Lafayette, Indiana and in collaboration with Ivy Tech agriculture faculty, the Tippecanoe Soil and Water Conservation District, Natural Resources Conservation Service (NRCS), and Purdue’s wildlife extension specialist Jarred Brook.

The pilot frost seeded native-type grasses and forbes, mimicking a natural dispersion on a large mound created from the excavation of a retention pond. The mound is approximately four acres and 2-feet tall from base to peak. We used the DJI Agras MG-1P and spread a mixture of native seeds with pelletized lime as a carrier at approximately 50 pounds per acre. This was conducted on January 27 with temperatures in the 20s (Fahrenheit) and a morning snow. After application, the spread was checked by walking across the mound and observing the dispersal pattern in the snow. Extension was pleased to see that the spread pattern was similar to that of seed dispersal observed for fall cover crops.

FS1

Weed survey in Bass Lake

Flown by Phill Woolery, Agriculture & Natural Resource Educator, Purdue Extension – Starke County

Bass Lake is a 1,345-acre lake in Starke County, Indiana and has problems with invasive Eurasian milfoil (an aquatic weed). Extension conducted a survey of the weeds in a shallow area.

Weed beds were visible in shallow areas, but the pilot encountered significant limitations due to the specific weather conditions needed for data collection -- low winds and an overcast to prevent glare on the water.

Aerial RBG image of a shallow section of Bass Lake.
Aerial RBG image of a shallow section of Bass Lake.
Zoom view of the RBG image of a shallow section of Bass Lake.
Zoom view of the RBG image of a shallow section of Bass Lake.
VARI heath image of Bass Lake.
VARI heath image of Bass Lake.

State Parks Virtual Field Trip program

Ashley Adair, Extension Organic Agriculture Specialist

This project was initiated to create a State Parks Virtual Field Trip program, geared for use in fourth, fifth and sixth grade classrooms. The goal is to give students an opportunity to learn about state parks (and address grade-level science standards) when they are unable to leave the classroom. The parks featured are Shades State Park and Turkey Run State Park. Science standards addressed are glaciation, ecological relationships and Indiana history. The tour content will vary depending on which state park is visited as each park has different attributes.

To avoid repetitive content, teachers are encouraged to use all Indiana state parks in their teaching. Aerial imagery can only be collected from Indiana State Parks with a permit, so the drone perspectives have rarely been seen by visitors. They add an aspect of wonderment and provide context to the state parks. For example, some of the aerial imagery collected at Shades State Park shows a stark contrast between nearby farm ground and the park itself. If this pilot program works well, Purdue Extension plans to expand to other state parks around Indiana.

Invasive weed: common reed

Flown by Bryan Overstreet, Agriculture & Natural Resource Educator, Purdue Extension – Jasper County

Common reed (Phragmites australis) is an Indiana native, but invasive, weed. It’s especially problematic in natural areas and wetlands where it spreads rapidly, pushing out other native plants. Here we map a wetland to identify and eradicate areas of common reed. A stitched image of the wetland allows conservationists to target the weed, quantify areas of most concern and remove the species.

The map on the far right shows the entire 193-acre wetland with the greatest areas of common reed outlined in blue. The invasive weed totals 39.4 acres, which doesn’t include the entire population but helps concentrate on initial removal efforts.

Lighter colored vegetation = Phragmites australis

wline
0445
acreage
July -- a year following herbicide applications
September -- a year following herbicide application

Invasive species: honeysuckle

Flown by Dave Osborne, Agriculture & Natural Resource Educator, Purdue Extension – Ripley County

UAV use in wooded areas can identify invasive plant species for removal along as well as track the effectiveness of control measures. Here we locate honeysuckle from fall 2018 to winter/spring 2019. The green in both of the natural, RGB orthomosaic and VARI plant health maps identify the invasive species growth before and after invasive control.

Before control

RGB Before

After Control

RGB After
VARI Before
VARI After

Supporting data for NRCS Environmental Quality Incentives Program (EQIP)

Flown by Dave Osborne, Agriculture & Natural Resource Educator, Purdue Extension – Ripley County

Invasive species control flights provided wood rating for EQIP application in partnership Ripley County SWCD and NRCS. Heavy invasive areas are outlined in blue.

DO_RGB_NRCS
DO_VARI_NRCS

Oak Wilt

Flown by Dave Osborne, Agriculture & Natural Resource Educator, Purdue Extension – Ripley County

UAVs were used to locate known trees at Southeast Purdue Agricultural Center (SEPAC) affected by oak wilt, a fatal disease in red and black oak trees. As we flew the woods, we identified several more infected areas. There is no cure for oak wilt, so trees will be harvested in the winter to save their value and eliminate spread of the disease. The value of the trees harvested is more than what it cost for the drone technology used. Imagery was also presented during the 2019 forestry field day at SEPAC.

DO_RGB_OakWilt
DO_VARI_OakWilt

Tree loss from invasive species

Flown by John Scott, Digital Agriculture Extension Coordinator, Purdue Extension

The Emerald Ash Borer killed all dead trees in this orthomosaic image. This woodlot is approximately eight acres, with approximately 144 trees have been damaged or destroyed. An exact number requires human inspection, but an aerial view offers a general idea of the total number while identifying areas of greatest concentration. We can also mark accessibility points for tree removal.

Dead Ash

Comprehensive forest report

Flown by Phil Woolery, Agriculture & Natural Resource Educator, Purdue Extension – Starke and Pulaski Counties

To explore UAV uses in forestry applications, several forests were flown over the course of 2019. One forest had documented history of planting and harvests and flown in two missions in August using a Phantom 4 Pro V2.0 with standard RGB and Sentera Double 4K cameras.

This stitched map was produced of the forest and subsequently analyzed. As you scroll down, you'll see RGB images allow identification of specific tree species upon color and texture.

Total Forest
Tree identification
Tree ID
Tree mortality
PW_RGB_TreeMortality
Tree stand and growing conditions

By using mapping tools such as the elevation tool in Drone Deply, we get values for total tree heights and location of young and short trees. We can also locate the best growing conditions.

Started
Harvest

The canopy gaps show up by elevation, and in this instance, are due to a recent timber harvest and sale. This can be useful to compare pre- and post-harvest to evaluate goals.

Harvest Closeup

Closeup and map of canopy gap along with square feet.

Plant health features

Differences can be seen when comparing plant health maps, such as VARI, NDVI and NDRE.

VARI
NDVI
NDRE

In comparing the three models, we can see similar patterns. The NDVI and NDRE show a few more differences than VARI. All three do a nice job in highlighting trees.

NDVI Tree Mortality
RGB Tree Mortality
Disease and stress pressure

NDVI indicated unhealthy trees in a few instances, while the RGB did not indicate any obvious sign of stress or disease.

NDVI Stress
RGB Stress

Ground truthing:

Several of the trees were checked by ground in September. Overall, it appears the NDVI is doing a good job pinpointing stress. Further investigation will evaluate potential disease spotting and susceptibility in tree breeding.

A black walnut was planted 33 years ago with a diameter of 14 inches – a growth rate of about a half inch per year. The crown looked large and healthy. This particular tree showed signs of stress in the NDVI map, but may be a result of growth pattern. Vigorous growing black walnut trees will continue growth late into the summer, and the new growth may be a result of the NDVI data.

Walnut Bark
Walnut Canopy
White Pine

The eastern white pine in this photo showed signs of stress in the NDVI. It’s likely suffering from allelopathy from the black walnut.

White Pine

The third tree identified is a hackberry. It appeared healthy but was in a suppressed canopy position. It could be the leaf color that indicated stress in the NDVI.