Foliar nitrogen in relation to plant traits and reflectance properties of New Hampshire forests

2013 ◽  
Vol 43 (1) ◽  
pp. 18-27 ◽  
Author(s):  
Franklin B. Sullivan ◽  
Scott V. Ollinger ◽  
Mary E. Martin ◽  
Mark J. Ducey ◽  
Lucie C. Lepine ◽  
...  
Keyword(s):  
Near Infrared ◽  
Plant Traits ◽  
Canopy Structure ◽  
Multiple Traits ◽  
Near Infrared Reflectance ◽  
Area Index ◽  
Foliar Nitrogen ◽  
Canopy Volume ◽  
Number Of Leaves ◽  
Structural Traits

Several recent studies have shown that the mass-based concentration of nitrogen in foliage (%N) is positively correlated with canopy near-infrared reflectance (NIRr) and midsummer shortwave albedo across North American forests. Understanding the mechanisms behind this relationship would aid in interpretation of remote sensing imagery and improve our ability to predict changes in reflectance under future environmental conditions. The purpose of this study was to investigate the extent to which foliar nitrogen at leaf and canopy scales covary with leaf- and canopy-scale structural traits that are known to influence NIR scattering and reflectance. To accomplish this, we compared leaf and canopy traits with reflectance spectra at 17 mixed temperate forest stands. We found significant positive associations among %N and NIRr at both the leaf and canopy scale. At the canopy scale, both %N and NIRr were correlated with a number of structural traits as well as with the proportional abundance of deciduous and evergreen foliage. Identifying specific causal factors for observed reflectance patterns was complicated by interrelations among multiple traits across scales. Among simple metrics of canopy structure, we saw no relationship between NIRr and leaf area index, but we observed a strong, inverse relationship with the number of leaves per unit canopy volume.

scholarly journals Monitoring the Impact of Environmental Manipulation on Peatland Surface by Simple Remote Sensing Indices

2018 ◽  
Vol 23 ◽  
pp. 00030 ◽  
Author(s):  
Anshu Rastogi ◽  
Subhajit Bandopadhyay ◽  
Marcin Stróżecki ◽  
Radosław Juszczak
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Vegetation Index ◽  
Near Infrared ◽  
Near Infrared Reflectance ◽  
Area Index ◽  
Environmental Manipulation ◽  
Chlorophyll Index ◽  
The Impact ◽  
Remote Sensing Indices

The behaviour of nature depends on the different components of climates. Among these, temperature and rainfall are two of the most important components which are known to change plant productivity. Peatlands are among the most valuable ecosystems on the Earth, which is due to its high biodiversity, huge soil carbon storage, and its sensitivity to different environmental factors. With the rapid growth in industrialization, the climate change is becoming a big concern. Therefore, this work is focused on the behaviour of Sphagnum peatland in Poland, subjected to environment manipulation. Here it has been shown how a simple reflectance based technique can be used to assess the impact of climate change on peatland. The experimental setup consists of four plots with two kind of manipulations (control, warming, reduced precipitation, and a combination of warming and reduced precipitation). Reflectance data were measured twice in August 2017 under a clear sky. Vegetation indices (VIs) such as Normalized Difference Vegetation Index (NDVI), Photochemical Reflectance Index (PRI), near-infrared reflectance of vegetation (NIRv), MERIS terrestrial chlorophyll index (MTCI), Green chlorophyll index (CIgreen), Simple Ration (SR), and Water Band Index (WBI) were calculated to trace the impact of environmental manipulation on the plant community. Leaf Area Index of vascular plants was also measured for the purpose to correlate it with different VIs. The observation predicts that the global warming of 1°C may cause a significant change in peatland behaviour which can be tracked and monitored by simple remote sensing indices.

scholarly journals Simulation and Verification of Vertical Heterogeneity Spectral Response of Winter Wheat Based on the mSCOPE Model

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4570
Author(s):  
Linsheng Huang ◽  
Yuanyuan Zhang ◽  
Guijun Yang ◽  
Dong Liang ◽  
Heli Li ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Vertical Profile ◽  
Near Infrared ◽  
Spectral Response ◽  
Visible Region ◽  
Operating Efficiency ◽  
Canopy Reflectance ◽  
Near Infrared Reflectance ◽  
Area Index ◽  
Vertical Heterogeneity

Vertical heterogeneity of the biochemical characteristics of crop canopy is important in diagnosing and monitoring nutrition, disease, and crop yield via remote sensing. However, the research on vertical isomerism was not comprehensive. Experiments were carried out from the two levels of simulation and verification to analyze the applicability of this recently development model. Effects of winter wheat on spectrum were studied when input different structure parameters (e.g., leaf area index (LAI)) and physicochemical parameters (e.g., chlorophyll content (Chla+b) and water content (Cw)) to the mSCOPE (Soil Canopy Observation, Photochemistry, and Energy fluxes) model. The maximum operating efficiency was 127.43, when the winter wheat was stratified into three layers. Meanwhile, the simulation results also proved that: the vertical profile of LAI had an influence on canopy reflectance in almost all bands; the vertical profile of Chla+b mainly affected the reflectivity of visible region; the vertical profile of Cw only affected the near-infrared reflectance. The verification results showed that the vegetation indexes (VIs) selected of different bands were strongly correlated with the parameters of the canopy. LAI, Chla+b and Cw affected VIs estimation related to LAI, Chla+b and Cw respectively. The Root Mean Square Error (RMSE) of the new-proposed NDVIgreen was the smallest, which was 0.05. Sensitivity analysis showed that the spectrum was more sensitive to changes in upper layer parameters, which verified the rationality of mSCOPE model in explaining the law that light penetration in vertical nonuniform canopy gradually decreases with the increase of layers.

Himalayan yew: stand structure, canopy damage, regeneration and conservation strategy

1998 ◽  
Vol 25 (4) ◽  
pp. 334-341 ◽  
Author(s):  
H.C. RIKHARI ◽  
L.M.S. PALNI ◽  
S. SHARMA ◽  
S.K. NANDI
Keyword(s):  
Stand Structure ◽  
Canopy Structure ◽  
Conservation Strategy ◽  
Cancer Drug ◽  
Taxus Baccata ◽  
Area Index ◽  
Canopy Volume ◽  
Anti Cancer ◽  
Canopy Removal ◽  
Canopy Damage

Taxus baccata L. subsp. wallichiana (Zucc.) Pilger has come into prominence in recent times due to its uncontrolled harvesting from the Himalayan wilds for the extraction of the anti-cancer drug Taxol. It is a very slow growing tree with poor regeneration, and the extent of canopy damage is likely to have serious consequences on biomass yield, plant survival and natural regeneration by affecting 'seed' output. The present study in the Jageshwar area of the Central Himalaya aimed to determine the stand and canopy structure, microsite characteristics, extent of canopy removal, and regeneration in human-disturbed and undisturbed sites. The number of trees, saplings and seedlings varied amongst plots. Leaf area index and canopy volume increased with increasing circumference at breast height. Of the total canopy volume, 57.4% was found to have been removed from the study area (9.54 ha; representing about 8% of the total T. baccata habitat). Regeneration of the species was found to be better in moist and shady microsites at undisturbed locations than in disturbed sites. Efforts made thus far for its conservation, and future strategies are discussed.

Effects of competition with weeds on the growth, development and yield of sorghum

1993 ◽  
Vol 120 (2) ◽  
pp. 187-196 ◽  
Author(s):  
A. P. Everaarts
Keyword(s):  
Weed Control ◽  
Field Experiments ◽  
Canopy Structure ◽  
Ground Cover ◽  
Stem Length ◽  
Yield Reduction ◽  
Area Index ◽  
Weed Growth ◽  
Competition For Light ◽  
Number Of Leaves

SUMMARYIn two field experiments in Suriname, competition between weeds and sorghum (Sorghum bicolor(L.) Moench) was studied in the rainy seasons of 1982 and 1983. The crop was kept either weed-free or without weed control for each of six different periods of time from planting. Observations made at the end of each period allowed an analysis to be made of the growth and development of a crop with and without weed control.Due to the crop canopy structure and fertilizer placement near the row, weed growth was concentrated in the rows. Starting atc.20–30 days after planting, competition with weeds reduced ground-cover and leaf area index of the crop. Competition reduced growth rates, leading to lower yields. Plant population density was not affected, but competition reduced the number of leaves present. Stem length initially increased with competition in one season, but was retarded in another. Competition for nutrients was strong and was found as early as 15 days after planting. Nitrogen was the element most competed for initially. Competition for water occurred, but competition for light seemed unlikely. About 20 weed-free days after planting were necessary to avoid yield losses and around 30 weed-free days to attain negligible weed growth at harvest. Yield reduction was mainly due to a decrease in number of grains per panicle. Competition during floret establishment (c.30–40 days after planting) should be avoided.

scholarly journals UAV and ground-based imagery analysis detects canopy structure changes after canopy management applications

OENO One ◽  
2020 ◽  
Vol 54 (4) ◽  
pp. 1093-1103
Author(s):  
Jingyun Ouyang ◽  
Roberta De Bei ◽  
Sigfredo Fuentes ◽  
Cassandra Collins
Keyword(s):  
Vegetation Index ◽  
Management Practices ◽  
Canopy Structure ◽  
Area Index ◽  
Structure Changes ◽  
Grape Quality ◽  
Canopy Volume ◽  
Canopy Area ◽  
Plant Area Index ◽  
Canopy Management

Aim: To analyse unmanned aerial vehicle (UAV)-based imagery to assess canopy structural changes after the application of different canopy management practices in the vineyard.Methods and results: Four different canopy management practices: i–ii) leaf removal within the bunch zone (eastern side/both eastern and western sides), iii) bunch thinning and iv) shoot trimming were applied to grapevines at veraison, in a commercial Cabernet-Sauvignon vineyard in McLaren Vale, South Australia. UAV-based imagery captures were taken: i) before the canopy treatments, ii) after the treatments and iii) at harvest to assess the treatment outcomes. Canopy volume, projected canopy area and normalized difference vegetation index (NDVI) were derived from the analysis of RGB and multispectral imagery collected using the UAV. Plant area index (PAI) was calculated using the smartphone app VitiCanopy as a ground-based measurement for comparison with UAV-derived measurements. Results showed that all three types of UAV-based measurements detected changes in the canopy structure after the application of canopy management practices, except for the bunch thinning treatment. As expected, ground-based PAI was the only technique to effectively detect internal canopy structure changes caused by bunch thinning. Canopy volume and PAI were found to better detect variations in canopy structure compared to NDVI and projected canopy area. The latter were negatively affected by the interference of the trimmed shoots left on the ground.Conclusions: UAV-based tools can provide accurate assessments to some canopy management outcomes at the vineyard scale. Among different UAV-based measurements, canopy volume was more sensitive to changes in canopy structure, compared to NDVI and projected canopy area, and demonstrated a greater potential to assess the outcomes of a range of canopy management practices.  Significance and impact of the study: Canopy management practices are widely applied to regulate canopy growth, improve grape quality and reduce disease pressure in the bunch zone. Being able to detect major changes in canopy structure, with some limitations when the practice affects the internal structure (i.e., bunch thinning), UAV-based imagery analysis can be used to measure the outcome of common canopy management practices and it can improve the efficiency of vineyard management.  

Comparing nondestructive measures of forage structure and phytomass

2000 ◽  
Vol 80 (3) ◽  
pp. 565-573 ◽  
Author(s):  
B. E. Olson ◽  
R. T. Wallander ◽  
J. M. Beaver
Keyword(s):  
Radiative Transfer ◽  
Leaf Area ◽  
Canopy Structure ◽  
Plant Canopy ◽  
Native Range ◽  
Area Index ◽  
Crested Wheatgrass ◽  
Canopy Volume ◽  
Peak Standing Crop ◽  
Intercepted Radiation

Nondestructive radiative transfer and canopy volume methods were compared with the destructive hand-clipping method to determine forage structure and phytomass. On a native range site, fifteen 1-m2 circular plots were located at each of five microsites. On a crested wheatgrass site, thirty 1-m2 plots were located in grazed and in ungrazed areas. At peak standing crop, all plots were measured with a LI-COR Plant Canopy Analyzer to determine leaf area index (LAI), diffuse non-intercepted radiation (DNIR), and mean tilt angle (MTA) of leaves. Then, plants within plots were measured with a ruler to determine volume. Finally, all phytomass within plots was harvested. At the native range site, plant volume was related with LAI and DNIR on four of five microsites. Phytomass was related with LAI and DNIR on two microsites. At the crested wheatgrass site, volume and phytomass were related with LAI, DNIR, and MTA on grazed plots. Only phytomass was related with LAI and DNIR on ungrazed plots. The Plant Canopy Analyzer measures canopy structure and phytomass; it is fast, and its data are transferred directly to a computer. Measuring plant volume is inexpensive and requires minimal training. Determining phytomass by clipping is accurate and requires minimal training, but it is time-consuming and destructive. Key words: Leaf area, canopy, volume, phytomass, radiative transfer

scholarly journals Alterations in growth and canopy architecture among dwarf, semidwarf and tall oat lines grown under northern conditions

2008 ◽  
Vol 13 (1-2) ◽  
pp. 170 ◽  
Author(s):  
P. MÄKELÄ ◽  
S. MUURINEN ◽  
P. PELTONEN-SAINIO
Keyword(s):  
Grain Yield ◽  
Leaf Area ◽  
Stem Elongation ◽  
Canopy Structure ◽  
Growth Period ◽  
Growth And Yield ◽  
Canopy Architecture ◽  
Area Index ◽  
Number Of Leaves ◽  
Yield Formation

The Finnish growing season is particularly short, with an intensive growth period, unfavourable rainfall distribution and frequently occurring fluctuations in climate that affect crop growth and yield formation. A three-year study was conducted in the field to determine the contribution of alterations in canopy structure, tillering and stem elongation among dwarf (D), semidwarf (SD) and tall (T) oat (Avena sativa L.) lines to yield formation. Yield components, leaf characteristics and straw traits were measured from six oat lines (D lines Pal and Grane, SD lines Hja 76416 and Salo, and T lines Veli and Jalostettu maatiainen) separately on the main shoot and tillers. Results indicated that long leaf area duration and high leaf area index were associated with increased grain yield probably due to more persistent and active assimilation. Also, higher number of leaves increased the grain yield. Higher peduncle, straw and node weights associating with increased grain yield may result from more abundant assimilate reserves; however, the longer the straw and peduncle, the lower the grain yield, which may result from increased lodging of SD and T lines. The traits contributing most to the grain yield varied greatly from year to year. It is concluded that no single dominant trait determined grain yield, since yield is a product of several different traits. SD lines seemed to be most promising for further breeding programs on the basis of their growth pattern and yielding ability.;

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