scholarly journals MODIS vegetation products as proxies of photosynthetic potential along a gradient of meteorologically and biologically driven ecosystem productivity

2016 ◽  
Vol 13 (19) ◽  
pp. 5587-5608 ◽  
Author(s):  
Natalia Restrepo-Coupe ◽  
Alfredo Huete ◽  
Kevin Davies ◽  
James Cleverly ◽  
Jason Beringer ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Photosynthetic Active Radiation ◽  
Ecosystem Structure ◽  
Ecosystem Productivity ◽  
Area Index ◽  
Active Radiation ◽  
Flux Tower ◽  
Photosynthetic Potential ◽  
Assimilation Capacity

Abstract. A direct relationship between gross ecosystem productivity (GEP) estimated by the eddy covariance (EC) method and Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices (VIs) has been observed in many temperate and tropical ecosystems. However, in Australian evergreen forests, and particularly sclerophyll and temperate woodlands, MODIS VIs do not capture seasonality of GEP. In this study, we re-evaluate the connection between satellite and flux tower data at four contrasting Australian ecosystems, through comparisons of GEP and four measures of photosynthetic potential, derived via parameterization of the light response curve: ecosystem light use efficiency (LUE), photosynthetic capacity (Pc), GEP at saturation (GEPsat), and quantum yield (α), with MODIS vegetation satellite products, including VIs, gross primary productivity (GPPMOD), leaf area index (LAIMOD), and fraction of photosynthetic active radiation (fPARMOD). We found that satellite-derived biophysical products constitute a measurement of ecosystem structure (e.g. leaf area index – quantity of leaves) and function (e.g. leaf level photosynthetic assimilation capacity – quality of leaves), rather than GEP. Our results show that in primarily meteorological-driven (e.g. photosynthetic active radiation, air temperature, and/or precipitation) and relatively aseasonal ecosystems (e.g. evergreen wet sclerophyll forests), there were no statistically significant relationships between GEP and satellite-derived measures of greenness. In contrast, for phenology-driven ecosystems (e.g. tropical savannas), changes in the vegetation status drove GEP, and tower-based measurements of photosynthetic activity were best represented by VIs. We observed the highest correlations between MODIS products and GEP in locations where key meteorological variables and vegetation phenology were synchronous (e.g. semi-arid Acacia woodlands) and low correlation at locations where they were asynchronous (e.g. Mediterranean ecosystems). However, we found a statistical significant relationship between the seasonal measures of photosynthetic potential (Pc and LUE) and VIs, where each ecosystem aligns along a continuum; we emphasize here that knowledge of the conditions in which flux tower measurements and VIs or other remote sensing products converge greatly advances our understanding of the mechanisms driving the carbon cycle (phenology and climate drivers) and provides an ecological basis for interpretation of satellite-derived measures of greenness.

scholarly journals MODIS vegetation products as proxies of photosynthetic potential: a look across meteorological and biologic driven ecosystem productivity

2015 ◽  
Vol 12 (23) ◽  
pp. 19213-19267 ◽  
Author(s):  
N. Restrepo-Coupe ◽  
A. Huete ◽  
K. Davies ◽  
J. Cleverly ◽  
J. Beringer ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Eddy Covariance ◽  
Photosynthetic Activity ◽  
Photosynthetic Active Radiation ◽  
Ecosystem Productivity ◽  
Area Index ◽  
Active Radiation ◽  
Flux Tower ◽  
Photosynthetic Potential

Abstract. A direct relationship between gross ecosystem productivity (GEP) measured by the eddy covariance (EC) method and Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices (VIs) has been observed in many temperate and tropical ecosystems. However, in Australian evergreen forests, and particularly sclerophyll woodlands, MODIS VIs do not capture seasonality of GEP. In this study, we re-evaluate the connection between satellite and flux tower data at four contrasting Australian ecosystems, through comparisons of ecosystem photosynthetic activity (GEP) and potential (e.g. ecosystem light use efficiency and quantum yield) with MODIS vegetation satellite products, including VIs, gross primary productivity (GPPMOD), leaf area index (LAIMOD), and fraction of photosynthetic active radiation (fPARMOD). We found that satellite derived greenness products constitute a measurement of ecosystem structure (e.g. leaf area index – quantity of leaves) and function (e.g. leaf level photosynthetic assimilation capacity – quality of leaves), rather than productivity. Our results show that in primarily meteorological-driven (e.g. photosynthetic active radiation, air temperature and/or precipitation) and relatively aseasonal vegetation photosynthetic potential ecosystems (e.g. evergreen wet sclerophyll forests), there were no statistically significant relationships between GEP and satellite derived measures of greenness. In contrast, for phenology-driven ecosystems (e.g. tropical savannas), changes in the vegetation status drove GEP, and tower-based measurements of photosynthetic activity were best represented by VIs. We observed the highest correlations between MODIS products and GEP in locations where key meteorological variables and vegetation phenology were synchronous (e.g. semi-arid Acacia woodlands) and low correlation at locations where they were asynchronous (e.g. Mediterranean ecosystems). Eddy covariance data offer much more than validation and/or calibration of satellite data and models. Knowledge of the conditions in which flux tower measurements and VIs or other remote sensing products converge greatly advances our understanding of the mechanisms driving the carbon cycle (phenology and climate drivers) and provides an ecological basis for interpretation of satellite derived measures of greenness.

Light interception and canopy radiation balance of staghorn sumac (Rhus typhina)

2008 ◽  
Vol 38 (6) ◽  
pp. 1695-1700
Author(s):  
Peter M. Lafleur ◽  
Andrew G. Farnsworth
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Photosynthetically Active Radiation ◽  
Solar Zenith Angle ◽  
Radiation Balance ◽  
Area Index ◽  
Mean Values ◽  
Active Radiation ◽  
Rhus Typhina ◽  
Flux Incident

We measured interaction of photosynthetically active radiation (PAR) at a staghorn sumac ( Rhus typhina L.) canopy near Peterborough, Ontario, during summer 2006. Measurements included above-canopy and below-canopy incoming and reflected PAR fluxes and leaf area index (LAI). The ratio of down-welling PAR below the canopy to the flux incident at the top of the canopy (τ) and proportion of incident PAR absorbed by the canopy (fPAR), were calculated. While the canopy was leafless, the sumac stems absorb 10%–20% of incident PAR. LAI increased rapidly during the month of June, and correspondingly τ decreased rapidly while fPAR increased rapidly. Mean values of τ and fPAR at maximum LAI were 0.38±0.09 (SD) and 0.60 ±0.04, respectively. Neither variable showed a relationship with solar zenith angle. We present a simple idealized model of PAR interaction with sumac. Although only one stand was studied, we hypothesize that these results may be more widely applicable to other mature sumac stands.

Influence of primed seed and varying seed rate on growth and productivity of soybean (Glycine max L.) under different planting techniques

2018 ◽  
Author(s):  
Rupinder Kaur Jassal ◽  
Harmeet Singh
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Plant Height ◽  
Seed Yield ◽  
Dry Matter ◽  
Seed Priming ◽  
Dry Matter Accumulation ◽  
Area Index ◽  
Active Radiation ◽  
Seed Rate

An experiment was conducted at Punjab Agricultural University, Ludhiana during 2015 and 2016 to study the effect of priming, different seed rate on growth and seed yield of soybean planted under bed and flat method. The study was planned in factorial split plot design, keeping two planting techniques (flat sowing and bed sowing) and two seed priming treatments ( non primed seeds and 100 ppm GA3 primed seeds) in main plot and three seed levels ( 50, 62.5 and 75 kg ha-1) in sub plot. The objective of the study was to evaluate the effect of seed priming on growth and productivity under different planting techniques with the use of varying seed rates. The results revealed that growth attributes viz. emergence count, plant height, dry matter accumulation, leaf area index and photosynthetic active radiation interception (%) was significantly higher under bed planting technique as compared to flat sowing method. The pooled seed yield was increased by 15.6 % in bed planted soybean crop as compared to flat planted crop. Soybean seeds primed with 100 ppm GA3 recorded significant results in all the growth parameters. Primed seed recorded increase in yield 15.3 % than non primed seeds. Seed rate of 62.5 kg ha-1 recorded significantly higher emergence count, plant height, dry matter accumulation, leaf area index and photosynthetic active radiation interception (%) which was statistically similar in results with 75 kg ha-1 seed rate in both the two years. Pooled seed yield of 62.5 kg ha-1seed rate was 4.61 % higher than 75 kg ha-1 and 12.6 % than 50 kg ha-1 seed rate.

scholarly journals Impact of Vermicompost, Poultry Manure and Jeevaamrit on Growth Parameters of Kiwifruit (Actinidia deliciosa) cv. Allison

2020 ◽  
pp. 31-40
Author(s):  
Ashok K. Garg ◽  
Rajesh Kaushal ◽  
Vishal S. Rana
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Photosynthetically Active Radiation ◽  
Poultry Manure ◽  
Growth And Yield ◽  
Recommended Dose ◽  
Inorganic Fertilizers ◽  
Area Index ◽  
Active Radiation ◽  
Chlorophyll Index

The present investigation was conducted on 6 years old kiwifruit vines cultivar ‘Allison’ at a spacing of 4.0 m × 6.0 m for two consecutive years 2018-19 and 2019-20 at experimental block of Department of Fruit Science, Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan (HP). The experiment was laid out in triplicate in Randomized Block Design with 8 treatments under three farming systems viz., Inorganic Fertilizer Based System (IFBS), Organic Farming Based System (OFBS) and Subhash Palekar’s Natural Farming System (SPNFS). The maximum leaf area (158.1 cm2), leaf area index (4.36), chlorophyll index (51.2), comparative photosynthetically active radiation (612 µ mol quanta m-2 s-1) was found in the treatment (T8) receiving 30 liters of jeevaamrit (JM) + 3 kg ghana jeevaamrit and 40 kg FYM per vine under SPNFS. Among OFBS, the treatment T2 (100% recommended dose of nitrogen (RDN) through vermicompost and poultry manure on 50:50 basis) observed maximum leaf area (151.8 cm2), leaf area index (4.35), comparative photosynthetically active radiation (642 µ mol quanta m-2 s-1) but lower significantly lower chlorophyll index (51.2) over T1 (Recommended dose of inorganic fertilizers + FYM) treatment of IFBS. Hence application of 30 litres jeevaamrit and 3 kg ghana jeevaamrit (both in 3 equal splits first in end of January, second in February and third in the month of April) along with 40 kg FYM per vine or alternatively substitution of 100% RDN through vermicompost and poultry manure on 50:50 basis along with 40 kg FYM were found to be best and alternate different option in place of inorganic fertilizers to ‘Allison’ cultivar of kiwifruit under mid-hill conditions of Himachal Pradesh, India. Furthermore, the research emphases mainly on improving soil health without compromising growth and yield of kiwifruits in the region. By using alternative sources of nutrients, farmers can obtain the comparable growth and yield of kiwifruits.

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