Evaluation of drought and UV radiation impacts on above-ground biomass of mountain grassland by spectral reflectance and thermal imaging techniques

Abstract

Novotná K., Klem K., Holub P., Rapantová B., Urban O. 2016: Evaluation of drought and UV radiation impacts on above-ground biomass of mountain grassland by spectral reflectance and thermal imaging techniques. -Beskydy, 9 (1-2): 21-30Drought represents one of the major factors limiting productivity of managed and natural ecosystems. Under natural field conditions drought is often associated with other stress factors such as high temperature and UV radiation, which may result in enhancement or vice versa alleviation of drought impact. Remote sensing methods have a large potential to evaluate impacts of drought on plant production at regional scale. The main objective of this study was to analyse the potential of ground-based measurement of spectral reflectance and thermal imaging for monitoring the impacts of drought and UV radiation on above-ground biomass production of mountain grassland ecosystem. Experimental rain-out shelters were used to manipulate incident precipitation and UV radiation for 7 weeks (May-July). A canopy spectral reflectance, thermal images, and total aboveground biomass were determined at the end of drought and UV treatment. Results show that drought led to a significant reduction of above-ground biomass, particularly under ambient UV radiation. In contrary, UV had only negligible effect on biomass production. Canopy temperature as well as selected spectral reflectance indices showed significant response to drought stress and also significant relationships to above-ground biomass. However, the relationship between canopy temperature and above-ground biomass is modified by UV radiation. Best prediction of changes in biomass caused by drought stress was provided by vegetation index NDVI.

Ultraviolet radiation causes leaf warming due to partial stomatal closure

“…For example, although our polytunnels were designed to allow greater air movement than in a fully enclosed structure ( Figure S1 ), less air movement is likely than in an open field, so a given reduction in conductance should increase T leaf to a lesser extent than in a field crop. Nonetheless, our data, and other reports [ 21 , 37 ], suggest that UV-mediated increases in leaf temperature of up to 2°C might commonly occur in crops growing in the field or well-ventilated protected environments.…”

“…This need to increase the signal:noise ratio led us to use different approaches to measuring leaf warming under our different experimental regimes. Of course, the same issue of low signal to noise ratio may occur in long-term datasets of mean leaf temperature in the field [ 37 ]. Possibly other researchers have observed leaf warming due to UV exposure, but not reported it due to lack of formal statistical significance.…”

Natural Holobiome Engineering by Using Native Extreme Microbiome to Counteract the Climate Change Effects

“…However, both acted synergistically in order to induce protective mechanisms to reduce the stress in wheat and pea plants. In contrast, Novotná et al (2016), shown that drought led to a significant reduction of above-ground biomass, particularly under ambient UV radiation. Thus, the combined effect of drought and UV radiation which may result in an enhance or vice-versa alleviation of drought impact.…”

Linkages between stratospheric ozone, UV radiation and climate change and their implications for terrestrial ecosystems

“…164 Osmotic stress-induced upregulation of the UVR8 transcript and protein levels might also contribute to interactive effects of drought and UV-B radiation. 165 This complexity can also be observed in a study where, only in the presence of ambient UV radiation did drought increase canopy temperature and result in decreased accumulation of above-ground biomass in a grassland ecosystem.. 166 Thus, interactive effects of drought and UV-B radiation need to be considered in the context of prevailing and future conditions, particularly warming temperatures. UV radiation and temperature.…”