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

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

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.

Grassed waterway management

Flown by Jon Charlesworth, Agriculture & Natural Resources Educator, 4-H Youth Development, Purdue Extension - Benton County 

Stitching software can measure the depth of a grassed waterway to determine both water capacity and compliance within a Conservation Reserve Program (CRP). The graph on the left shows a shift in the elevation profile. The spike in elevation could have been caused by ground cover or inaccuracy of initial GPS points. We later determined weeds were the cause, which we validated from the ground. The use of a UAV for this type of management practice does not replace traditional boots-on-the-ground methods; however, it greatly reduces time and labor.

Grassed waterway

Here are views of three water and sediment control basin (WASCOB) structures, each containing two to three basins. A WASCOB is designed to control water runoff after a rain. Each structure has a subsurface drainage system at the lowest point of the basin where the water pools. Once the water reaches the top of the drainage system, it is discharged through the main tile system. Any sediment in the water settles to the bottom of the basin, which prevents permanent erosion and reduces pollution in other water bodies.

The elevation profile on the left of the image above makes it possible to see overall hillslope as well as each individual berm.

WASCOB
Down Upright

The image below shows a subsurface drainage structure knocked over, most likely due to flooding. It was not functioning and needed repair.

Flooded grass waterway

Water standing in this newly installed grassed waterway (below) indicates a problem. While several issues could be at fault, an exact determination requires someone to closely examine the tile However, the UAV is a good tool to offer a snapshot of performance to conservationists.