Evaluating Beech Tree Phenology in a Deciduous Broadleaf Forest in Northern Iran Using Ground Observation and MODIS Images |
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Authors: | Seyed Armin Hashemi Sasan Babaei Kafaki Asadollah Mataji |
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Affiliation: | 1. Department of Forestry, Lahijan Branch , Islamic Azad University , Lahijan, Iran ahashemi_2004@yahoo.com;3. Department of Forestry, Faculty of Agriculture and Natural Resources, Science and Research Branch , Islamic Azad University , Tehran, Iran |
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Abstract: | We selected 15 beech trees (Fagus orientalis) from the study area in a mountainous region from 520 to 1310 m above sea level. Ground observations of the beech tree growth process from January to December 2004 in 7- to 15-day intervals were performed both visually and by measuring leaf chlorophyll concentration (chlorophyll meter SPAD-502). Results for the regression analysis showed that the leaved period positively correlated with the air temperature (r?=?.894). Anthesis and SPAD measurements have a negative relationship with air temperature and as temperature increases they appear earlier in the year. Anthesis and SPAD measurements had correlation coefficients of r?=??.883 and r?=??.855, respectively. The anthesis and bud bursting and leaf tip appearance have a negative relationship with increasing altitude from sea level and as altitude increases they appear later in the year. To make phenological events in deciduous broadleaf forests recognizable, we used a seasonal 8-day composite Moderate Resolution Imaging Spectroradiometer/Normalized Difference Vegetation Index (MODIS/NDVI). Prior to leaf expansion, NDVI increased from the 109th day of the year or earlier. Existence of the evergreen plants (Ruscus hyrcanus) on the ground and snow-melting exert an influence on inconsistency of phenology monitoring of MODIS/NDVI images. Regression analysis showed that there is a positive relationship between NDVI and SPAD measurements (chlorophyll content) in beech trees. |
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Keywords: | leaved period air temperature MODIS/NDVI phenology chlorophyll meter (SPAD) |
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