Phenological Changes In Chlorophyll Content And Fluorescence Values In Forest Species
Karolina Orłowska1,2, Adrian Ochtyra1,2, Zbigniew Bochenek3, Bogdan Zagajewski1, Marlena Kycko1
[email protected]
Department of Geoinformatics, Cartography and Remote Sensing, Faculty of Geography and
Regional Studies, University of Warsaw, Poland
2
College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of
Warsaw, Poland
3
Remote Sensing Department, Institute of Geodesy and Cartography, Warsaw, Poland
1
Keywords: Bialowieza National Park, Poland, chlorophyll, fluorescence, forest
Abstract:
Variations in plant's abiotic conditions, such as accessibility to light, water or nutrients,
frequently results from seasonal changes. Non-contact identification of plant stressors and condition
is possible through remote sensing techniques. While plant's physiological processes are highly
dependent on external factors, their alterations can be observed through variations in plant's
spectral characteristics, thus enabling to observe, using remote sensing, growth and senescence.
During photosynthesis vegetation uses chlorophyll to absorb blue and red ranges of visible
light and create chemical energy (Adenosine triphosphate - ATP). Two types of chlorophyll
participate in this process - chlorophyll a, which is the main factor in this mechanism and chlorophyll
b, which plays supporting role. High amount of chlorophyll is associated with healthy vegetation.
Excess light absorbed by vegetation can be re-emitted as chlorophyll fluorescence.
The study used hyperspectral remote sensing to assess variations of the amount of
photosynthetic pigments and efficiency of fluorescence photosystems in plants at the beginning,
during and at the end of a phenological period. Six tree species underwent analysis: arborescent
species - deciduous: hornbeam (Carpinus betulus), oak (Quercus robur), alder (Alnus glutinosa), birch
(Betula pubescens) and coniferous: spruce (Picea abies) and pine (Pinus sylvestris). The study was
conducted in May, July and September of 2015 in protected forest areas of north-eastern Poland Bialowieza National Park, Borecka Wilderness and Knyszynska Wilderness. Following data were
collected: spectral signatures (ASD FieldSpec 4 spectroradiometer), chlorophyll content (Dualex
Scientific+ Polyphenol & Chlorophyll-Meter) and chlorophyll fluorescence in non-adapted and darkadapted states (OS1p Chlorophyll Fluorometer).
Spectral signatures allowed calculating amount of chlorophyll a and b (RARS, REP, MTCI and
others). The data were compared to chlorophyll content measured with hand-held chlorophyll-meter
and fluorescence values in both states. The highest amount of chlorophyll was found in plants in July
and September while the smallest at the beginning of the phenological period. The highest
performance of the photosystem was observed at the end of the period (September) and the lowest
at the beginning (May). All data were characteristic for healthy vegetation. The data showed
significant differences between species in amount of photosynthetically active pigments. Correlation
between amount of chlorophyll and efficiency of photosystems was observed as well as between
field-acquired chlorophyll amounts and those calculated from spectral signatures.
The research was conducted as a part of the WICLAP Project - “Ecosystem stress from the
combined effects of winter climate change and air pollution - how do the impacts differ between
biomes?”, funded from Polish-Norwegian Research Programme.