It's not enough to simply classify a large swath of habitat as protected. Conservation requires regularly monitoring, researchers at the Vienna University of Technology say.

In a recent study, scientists at the Austrian school explain how nature preserves can be effectively monitored from the air, using aircraft and laser technology.

Nature preserves make up some 20 percent of European Union surface area. Keeping tabs on the ecological health of so much acreage isn't possible by foot, but advanced airborne imaging offers a solution, researchers say.

Plane-based infrared instrumentation, when flown above wilderness preserves at an altitude of roughly 1,500 to 6,500 feet, can offer ecologists a detailed image of the terrain below.

"Our team has developed special classification software which can use this data to distinguish different types of vegetation," lead researcher Norbert Pfeifer explained in a press release.

The data collected by infrared beams bounced off the Earth's surface allow scientists to build a picture detailed enough to even reveal specifics like weed growth and vehicle tracks. Researchers say the many layers of vegetation that make up healthy forests and fields can be deduced and detailed using the mathematical data returned by the reflected light signals -- from the top-layer canopies of various tree and shrub layers, down to lower layers of herbs and grasses.

Research recently compared their aerial monitoring techniques to foot-based observations, using a nature preserve in Hungary as the test subject.

"We achieved an agreement of 80 to 90 percent between our data and on-site observations," Pfeifer confirmed. "This is a huge success. It is about the same level of agreement that would be expected if two different people assess the same region."

"This study is a major step forward in closing the gap between the remote sensing and conservation ecology communities," remarked Andras Zlinszky, a researcher at the Center for Ecological Research in Hungary. "We have shown that it is possible to monitor Natura 2000 conservation status by remote sensing, exactly following the rules laid out by the local ecology experts."

The new research was published in the journal Remote Sensing.