Mass scans from a proton transfer mass spectrometry analysis of air over Mediterranean shrubland browsed by horses.

The research sought to understand the effects of large herbivores, specifically horses, on the emission of volatile compounds from plants using a sensitive analytical technique known as proton transfer reaction-mass spectrometry.

Proton Transfer Reaction-Mass Spectrometry (PTR-MS)

• The researchers used Proton Transfer Reaction-Mass Spectrometry (PTR-MS) as their analytical tool. This is an innovative and powerful technique capable of detecting volatile organic compounds in low concentrations, meaning it can capture those generated by leaf damage.
• PTR-MS is able to monitor a wider range of volatile compounds compared to other methods due to its highly sensitive detection capability.
• The use of PTR-MS in this study provided an enhanced understanding of the overall composition of biogenic volatile organic compounds in air over browsed shrubland.

Herbivory Influence on Plant Emission

• The researchers found that plant-emitted volatiles increased significantly from areas where horses had browsed. This proves that large herbivores, such as horses, impact the concentration of volatile organic compounds in the atmosphere.
• It was identified that the masses 57, 43, and 41 (representing mostly hexenals, acetone, and acetic acid) showed higher concentrations in the air over browsed shrubland than the air over non-browsed shrubland.
• This study improves the understanding of herbivore-elicited plant volatile emission and analyzes the effects of large mammals, an area not as explored previously.

Implications of Findings

• These compounds can influence various processes and organisms in the environment. They are biogeochemically active, making them significant components of volatile organic carbon in the atmosphere.
• These compounds can also affect the physical and chemical processes in the Earth’s atmosphere, implying that herbivory activities by larger mammals could impact local and possibly global environments.
• The pivotal role of these large herbivores in impacting environmental chemistry may have implications for various ecological and atmospheric studies, hence requiring further exploration in future studies.