Article

Linking physiological responses, chlorophyll fluorescence and hyperspectral imagery to detect salinity stress using the physiological reflectance index in the coastal shrub, Myrica cerifera

Department of Biology, Virginia Commonwealth University, Richmond, Virginia 23284, USA; US Army ERDC, Fluorescence Spectroscopy Lab, 7701 Telegraph Road, Alexandria, VA 22315, USA
Remote Sensing of Environment (Impact Factor: 4.77). 06/2008; 112(10):3865-3875. DOI: 10.1016/j.rse.2008.06.004

ABSTRACT Measurements of physiology, chlorophyll fluorescence and hyperspectral reflectance were used to detect salinity stress in the evergreen coastal shrub, Myrica cerifera on Hog Island, Virginia. Two experimental sites were used in our study, the oceanside of a M. cerifera thicket, which is exposed to sea spray, and the protected, leeside of the thicket. Using the physiological reflectance index (PRI), we were able to detect stress at both the canopy and landscape level. Monthly variations in stomatal conductance, photosynthesis, and relative water content indicated a strong summer drought response that was not apparent in chlorophyll fluorescence or in the water band index (WBI) derived from canopy and airborne reflectance measurements. In contrast, there were significant differences in both physiological measurements and tissue chlorides between the two sites used in the study, indicating salinity stress. This was reflected in measurements of PRI. There was a positive relationship between PRI measured at the canopy-level and light-adapted fluorescence (ΔF/F′m; r2 = 0.69). PRI was significantly lower on the oceanside of the Myrica cerifera thicket. PRI was not significantly related to NDVI (r2 = 0.01) at the canopy-level and only weakly related (r2 = 0.04) at the landscape-level, suggesting that the indices are independent. The chlorophyll index (CI) did not show any significant changes between the two sites. Frequency histograms of pixels sampled from airborne hyperspectral imagery revealed that the distribution of PRI was shifted to the right on the backside of the thicket relative to the oceanside and there was a significant difference between sites. These results suggest that PRI may be used for early identification of salt-stress and to identify areas across the landscape where community structure may change due to sea-level rise.

0 Bookmarks
 · 
81 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: With the environmental deterioration caused by the advance of climate change, soil salinization is a serious and growing global problem. Currently about 7% of the world’s land surface is threatened by salinization. China is a country whose soils are severely affected by this problem, which, due to its extensive area, and wide distribution poses a serious threat to regional agricultural development. In this review, we summarize the framework for soil salinization research in China over the past 70 years, assess the weaknesses of existing research in both a domestic and international context, highlight the trends and key findings of global research about saline soils over the past 30 years, and propose six major fields and directions for future research on saline soil.
    Journal of Geographical Sciences 10/2014; 24(5). · 1.12 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Remote-sensing techniques can detect and up-scale leaf-level physiological responses to large areas, and provide significant and reliable information on water use and irrigation management. The objectives of this study were to screen leaf-level physiological changes that occur during the cyclic irrigation of pecan orchards to determine which responses best represent changes in moisture status of plants and link plant physiological changes to remotely sensed surface reflectance data derived from the Landsat Thematic Mapper and Enhanced Thematic Mapper Plus ETM+. The study was conducted simultaneously on two southern New Mexico mature pecan orchards. For both orchards, plant physiological responses and remotely sensed surface reflectance data were collected from trees that were either well watered or in water deficit. Remotely sensed variables included reflectance in band 1, the ratio between shortwave infrared SWIR bands B5:B7, the normalized difference vegetation index, and SWIR moisture indices. Midday stem water potential Ψsmd was the best performing leaf-level physiological response variable for detecting moisture status in pecans. The B5:B7 ratio positively and significantly correlated with Ψsmd in five of six irrigation cycles while multiple linear regression weighted with six remotely sensed surface reflectance variables revealed a significant relationship with moisture status in all cycles in both orchards R2 > 0.73. Because changes in the B5:B7 band ratio and multiple regression of spectral variables correlate with the moisture status of pecan orchards, we conclude that remotely sensed data hold promise for detecting the moisture status of pecans.
    International Journal of Remote Sensing 02/2014; 35(3):949-966. · 1.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this investigation was to determine the feasibility of using the chlorophyll content index (cci) from a ccm-200 unit as an estimator of the seasonal variation of leaf pigment [chlorophyll a (chla), chlorophyll b (chlb), and total chlorophyll (tchl = chla + chlb)] content for a range of mangrove species within a degraded environment of the mexican pacific. two seasons (dry and rainy) of measurements were made on six mangrove classes: healthy and dwarf Avicennia germinans (linnaeus) linnaeus, healthy and poor condition Rhizophora mangle linnaeus, and healthy and poor condition Laguncularia racemosa (linnaeus) c.f. gaertn. tests of leaf pigment contents from 360 cci readings (30 per class) indicated that each equation was a valid predictor of chla and tchl for all six mangrove classes during both seasons. however, there was a poorer fit (lower R2) for the three species in poor/dwarf condition during the rainy season. chla and tchl were statistically well correlated with all of the cci data; however, the correlating chlb were lower (R2 < 0.68) for all classes except dwarf condition A. germinans (R2 = 0.80). The strong relationship observed between the readings from the portable ccm-200 and the pigment content suggest that the handheld ccm-200 can be a portable cost-effective tool for quickly predicting chla and tchl content for a range of mangrove forests.
    Bulletin of Marine Science -Miami- 04/2013; 89(2):621-633. · 1.33 Impact Factor

Full-text

Download
14 Downloads
Available from
May 22, 2014