Friday, June 27, 2014

Organic agriculture boosts biodiversity on farmlands

Does organic farming foster biodiversity? The answer is yes, however, the number of habitats on the land plays an important role alongside the type and intensity of farming practices. These are the findings of an international study that looked at ten regions in Europe and two in Africa. The results has been published in Nature Communications. The study shows that even organic farms have to actively support biodiversity by, for example, conserving different habitats on their holdings.

An international team, including scientists from Technische Universität München (TUM), investigated the contribution of organic farming to supporting farmland biodiversity between 2010 and 2013. Researchers wanted to explore whether organic farms are home to more species than their conventional neighbors. The team used uniform methods across Europe to capture data and analyze it to establish the impact of farming methods and intensity and of landscape features on biodiversity.

"Organic farming is beneficial to the richness of plant and bee species. However, observed benefits concentrate on arable fields," says TUM's Prof. Kurt-Jürgen Hülsbergen. His Chair for Organic Agriculture and Agronomy analyzed 16 Bavarian dairy farms.

The study investigated farms in twelve regions with different production systems. In each region, farms were selected randomly, half of them certified organic for at least five years. In Switzerland, grassland-based cattle farms were studied and in Austria the study looked at arable farms. In Italy and Spain, researchers focused on farms with permanent crops such as wine and olives, and on small-scale subsistence farms in Uganda.

More species because of field boundaries

More species were found in organic arable fields than in non-organic fields. In contrast, there was little difference in grasslands or vineyards. Organic farming benefited the four taxonomic groups of plants, earthworms, spiders and bees -- which were sampled as surrogates for the multitude of creatures living on farmland -- in different ways. In general, more species of plants and bees were found on organic than on non-organic fields, but not more species of spiders and earthworms.

If types of field boundaries such as grass verges or hedges were included in the comparison, the difference between organic and non-organic decreases. "Obviously, most species found in fields on organic farms tend to be concentrated in boundary areas on non-organic farms. There was little difference in the total number of species on the farms," explains Max Kainz, who headed the sub-project at TUM. The occurrence of rare or threatened species did not increase on organic farms, according to Kainz.

Even organic farms need to increase habitats

To sustain farmland biodiversity, which is currently under grave threat, researchers have identified complement organic farming methods with dedicated efforts to conserve habitats. To increase the number of habitats, the authors of the study recommend adding structural elements, such as woods, grass verges and fallow land, to farms. "Surprisingly, viewed across all regions, we did not find a higher number of natural habitats on organic farms than non-organic farms," reports Kainz.

"However, it was clear that habitat diversity is the key to species diversity," adds Prof. Hülsbergen. He continues: "The results of the study underline the importance of maintaining and expanding natural landscape features -- something that the EU's Greening Program has been trying to accomplish." If these additional habitats are different to the rest of the farm, for example hedges in grassland farms or herbaceous strips in arable farms, they have a huge impact on the biodiversity of a farm.


Packing hundreds of sensors into a single optical fiber for use in harsh environments

By fusing together the concepts of active fiber sensors and high-temperature fiber sensors, a team of researchers at the University of Pittsburgh has created an all-optical high-temperature sensor for gas flow measurements that operates at record-setting temperatures above 800 degrees Celsius.

This technology is expected to find industrial sensing applications in harsh environments ranging from deep geothermal drill cores to the interiors of nuclear reactors to the cold vacuum of space missions, and it may eventually be extended to many others.

The team describes their all-optical approach in a paper published today in The Optical Society's (OSA) journal Optics Letters. They successfully demonstrated simultaneous flow/temperature sensors at 850 C, which is a 200 C improvement on an earlier notable demonstration of MEMS-based sensors by researchers at Oak Ridge National Laboratory.
The basic concept of the new approach involves integrating optical heating elements, optical sensors, an energy delivery cable and a signal cable within a single optical fiber. Optical power delivered by the fiber is used to supply energy to the heating element, while the optical sensor within the same fiber measures the heat transfer from the heating element and transmits it back.

"We call it a 'smart optical fiber sensor powered by in-fiber light'," said Kevin P. Chen, an associate professor and the Paul E. Lego Faculty Fellow in the University of Pittsburg's Department of Electrical and Computer Engineering.

The team's work expands the use of fiber-optic sensors well beyond traditional applications of temperature and strain measurements. "Tapping into the energy carried by the optical fiber enables fiber sensors capable of performing much more sophisticated and multifunctional types of measurements that previously were only achievable using electronic sensors," Chen said.

In microgravity situations, for example, it's difficult to measure the level of liquid hydrogen fuel in tanks because it doesn't settle at the bottom of the tank. It's a challenge that requires the use of many electronic sensors -- a problem Chen initially noticed years ago while visiting NASA, which was the original inspiration to develop a more streamlined and efficient approach.

"For this type of microgravity situation, each sensor requires wires, a.k.a. 'leads,' to deliver a sensing signal, along with a shared ground wire," explained Chen. "So it means that many leads -- often more than 40 -- are necessary to get measurements from the numerous sensors. I couldn't help thinking there must be a better way to do it."

It turned out, there is. The team looked to optical-fiber sensors, which are one of the best sensor technologies for use in harsh environments thanks to their extraordinary multiplexing capabilities and immunity to electromagnetic interference. And they were able to pack many of these sensors into a single fiber to reduce or eliminate the wiring problems associated with having numerous leads involved.


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