Cross-Scale Correlation between In Situ Measurements of Canopy Gap Fraction and Landsat-Derived Vegetation Indices with Implications for Monitoring the Seasonal Phenology in Tropical Forests Using MODIS Data

Abstract The paper deals with the evaluation of mountain meadow vegetation condition using in-situ measurements of the fraction of Accumulated Photosynthetically Active Radiation (fAPAR) and Leaf Area Index (LAI). The study analyses the relationship between these parameters and spectral properties of meadow vegetation and selected invasive species with the goal of finding out vegetation indices for the detection of fAPAR and LAI. The developed vegetation indices were applied on hyperspectral data from an APEX (Airborne Prism Experiment) sensor in the area of interest in the Krkonoše National Park. The results of index development on the level of the field data were quite good. The maximal sensitivity expressed by the coefficient of determination for LAI was R2 = 0.56 and R2 = 0.79 for fAPAR. However, the sensitivity of all the indices developed at the image level was quite low. The output values of in-situ measurements confirmed the condition of invasive species as better than that of the valuable original meadow vegetation, which is a serious problem for national park management.

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Quantification of the terrestrial phytomass and carbon in the mountainous forest ecosystem using remote sensing and in-situ observations

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-7-w3-483-2015 ◽

2015 ◽

Vol XL-7/W3 ◽

pp. 483-487

Author(s):

P. Patil ◽

D. Dutta ◽

C. Biradar ◽

M. Singh

Keyword(s):

Temperate Forest ◽

Vegetation Indices ◽

Carbon Accumulation ◽

Terrestrial Vegetation ◽

Pinus Roxburghii ◽

Modis Data ◽

Infra Red ◽

In Situ Observations ◽

Best Fit

The aim of this research was to develop an understanding of how mountainous forests function in relation to forest phytomass and carbon accumulation in the terrestrial vegetation pools which will help develop options for climate change. In this study, the forest phytomass has been assessed in range of subtropical and temperate forest dominated by tree species of Quercus semicarpifolia Sm. and Pinus roxburghii Sarg in Himalayan region Purola tehsil in Uttarkashi district of Uttarakhand state of India. In-situ measurements of the phytomass were taken with clustered sampling approach on a total of 40 plots (0.1 ha each), i.e. in 10 MODIS pixels with 4 plots laid in an individual pixel. The field measured phytomass was found in the range of 67.76 - 1,108 t ha-1. Weighted-area phytomass was estimated at an individual MODIS (MOD13Q1, 250m) pixel where in-situ measurements varied from 207.93 t ha-1 - 1,042 t ha-1. The best fit equation of pixel phytomass values was regressed on red, infra-red and vegetation indices (NDVI) derived from the MODIS data. The correlation between the measured phytomass and NDVI was found significant and maximum in the month of December (R value -0.71, p < 0.01). However, such a relationship was not persistent throughout the year. The R2 value between observed phytomass and predicted phytomass was 0.53. The predicted phytomass based on 250×250 m MODIS data varied from 216.88 - 1,011 t ha-1. The average phytomass density in study area was 470.42 t ha-1 and carbon density 221.09 t ha-1.

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Evaluating MODIS, MERIS, and VEGETATION vegetation indices using in situ measurements in a semiarid environment

IEEE Transactions on Geoscience and Remote Sensing ◽

10.1109/tgrs.2006.875940 ◽

2006 ◽

Vol 44 (7) ◽

pp. 1774-1786 ◽

Cited By ~ 92

Author(s):

R. Fensholt ◽

I. Sandholt ◽

S. Stisen

Keyword(s):

Vegetation Indices ◽

In Situ Measurements ◽

Semiarid Environment

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Atmospheric CO2 Record from In Situ Measurements at Amsterdam Island

Carbon Dioxide Information Analysis Center (CDIAC) Datasets ◽

10.3334/cdiac/atg.013 ◽

1996 ◽

Author(s):

A. Guadry, ◽

V. Kazan, ◽

P. Monfray,

Keyword(s):

In Situ Measurements ◽

Atmospheric Co2

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The Carbon:²³⁴Thorium ratios of sinking particles in the California Current Ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model

10.26434/chemrxiv.7803698 ◽

2019 ◽

Author(s):

Michael Stukel ◽

Thomas Kelly

Keyword(s):

Organic Carbon ◽

Water Column ◽

Particulate Organic Carbon ◽

Transport Model ◽

California Current ◽

In Situ Measurements ◽

Power Law Distribution ◽

Sinking Particles ◽

Organic Carbon Concentration

Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon:thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U-234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking.

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