Phytomass and photosynthetically active radiation distribution in the brown alga Cystoseira crinita (Desf.) Bory canopy (the Black Sea) at different time of day

2020 ◽  
Author(s):  
Alexandr V. Prazukin ◽  
Yury K. Firsov ◽  
Alexandr A. Latushkin ◽  
Anna A. Chepyzhenko
Keyword(s):  
Black Sea ◽  
Photosynthetically Active Radiation ◽  
Brown Alga ◽  
Time Of Day ◽  
The Black Sea ◽  
Active Radiation ◽  
Radiation Distribution

Temperature stratification and photosynthetically active radiation distribution in the Zostera noltii Hornemann canopy under shallow water conditions at different solar elevation angles (the Black sea)

2020 ◽  
pp. 160-178
Author(s):  
Александр Васильевич Празукин ◽  
Юрий Константинович Фирсов ◽  
Александр Александрович Латушкин ◽  
Анна Алексеевна Чепыженко
Keyword(s):  
Black Sea ◽  
Photosynthetically Active Radiation ◽  
Light Availability ◽  
Temperature Stratification ◽  
The Black Sea ◽  
Shallow Waters ◽  
Zostera Noltii ◽  
Active Radiation ◽  
Solar Elevation ◽  
Radiation Distribution

Морские травы экологически важны, но чрезвычайно уязвимы перед антропогенными изменениями в прибрежных зонах, которые влияют на доступность света в этих экосистемах. При разной высоте Солнца над горизонтом в зондирующем режиме проводилось одновременное измерение значений температуры воды и интенсивности фотосинтетически активной радиации (IPAR) по профилю полога Zostera noltii Hornemann (высота полога 32 см.) в мелководной части Казачьей бухты (г. Севастополь, Черное море, 44°57′26″ с.ш., 33°40′33″ в.д.). Для полога Z. noltii характерен одномодальный тип вертикального распределения биомассы с максимумом (65,7 г (сухой массы) / м2) в его нижней части. Рассматривается изменение температурной стратификации и распределения IPAR по профилю растительного полога Z. noltii в течение светового дня. Seagrass is environmentally significant but extremely vulnerable in coastal areas to anthropogenic changes, which affect light availability. Simultaneous measurements of water temperature and photosynthetically active radiation (PAR) intensity in the sounding mode were taken at different solar elevation angles for the Zostera noltii Hornemann canopy (canopy height 32 cm) in shallow waters of the Cossack Bay (Sevastopol, the Black Sea, 44°57′26″ с.ш., 33°40′33″ в.д.). Z. noltii canopy is characterized by a unimodal type of biomass vertical distribution with its maximum (65,7 g (dry matter)/m2) in the lower part. Temperature stratification and IPAR distribution changes within the Z. noltii vegetation canopy profile during daylight hours are considered.

Penetration of Photosynthetically Active Radiation Into Tobacco Crops

1980 ◽  
Vol 7 (4) ◽  
pp. 449 ◽  
Author(s):  
DM Whitfield ◽  
DJ Connor
Keyword(s):  
Mathematical Model ◽  
Spatial Distribution ◽  
Photosynthetically Active Radiation ◽  
Time Of Day ◽  
Frequency Distributions ◽  
Active Radiation ◽  
Crop Size ◽  
Leaf Surfaces ◽  
Physical Representation ◽  
Beam Component

The spatial distribution of photosynthetically active radiation (PAR) was measured on several occasions during the growth of a tobacco crop. The data describe the penetration of PAR into the crop. Penetration was influenced by crop size, row structure, time of day and conditions of incident irradiance. At solar elevations greater than 15° on clear days, there were few regions in the crop with flux densities between 0.1I0 and 0.9I0, where I0 is the flux density of PAR above the canopy. Frequency distributions of flux densities were therefore bimodal. At lower elevations, the direct- beam component was attentuated and frequency distributions were unimodal with few flux densities above 0.6I0. Under diffuse irradiance, the bimodal response was attentuated to give a relatively uniform distribution of flux densities on the transects. These data were used to appraise two estimates of the penetration of PAR into the canopy. The first was based on a physical representation of the display of leaf surfaces in the canopy. Alternative estimates were derived from a mathematical model of the display of foliage of single plants which was extended here to account for the effect of neighbouring plants on the penetration of PAR into the crop.

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