Intercepted photosynthetically active radiation (IPAR) is an important variable in vegetation processes such as photosynthesis, and water and energy exchange. Measurement of this quantity and the related fractional interception efficiency (f PAR )) can be time consuming because of the need to sample for spatial and temporal variability. A method is presented for estimation of IPAR and f PAR using a commercially available hemispherical radiation sensor (Li-Coy LAI-2000) originally designed for the estimation of canopy leaf area index. This instrument provides sufficient information on the structure of the canopy and the angular dependence of light interception for single measurements to be interpreted for all solar zenith angles. These data can be used to infer instantaneous direct and diffuse interception as well as the daily integrated values. The method was tested in a millet crop and a shrub fallow area in semi-arid West Africa. LAI-2000 estimates were compared with a more traditional method using PAR sensor arrays. The errors in estimation of instantaneous IPAR were small at most times of day, rising to a maximum of 15–30 W m −2 at solar noon, when incident PAR was more than 400 W m −2 . Instantaneous f PAR estimates exhibited some bias towards underestimation at small solar zenith angles, and overestimation at larger angles, particularly on the shrub fallow site. These errors were generally small (much less than 0.l unit of f PAR ). Daily IPAR was estimated to within 7% of the direct PAR sensor measurements.
Agricultural and Forest Meteorology – Elsevier
Published: May 1, 1995
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera