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

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.

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

OENO One ◽

10.20870/oeno-one.2020.54.4.3647 ◽

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.

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Comparing nondestructive measures of forage structure and phytomass

Canadian Journal of Plant Science ◽

10.4141/p99-073 ◽

2000 ◽

Vol 80 (3) ◽

pp. 565-573 ◽

Cited By ~ 6

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

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Forest structure estimation and pattern exploration from discrete-return lidar in subalpine forests of the central Rockies

Canadian Journal of Forest Research ◽

10.1139/x08-059 ◽

2008 ◽

Vol 38 (8) ◽

pp. 2081-2096 ◽

Cited By ~ 24

Author(s):

K. R. Sherrill ◽

M. A. Lefsky ◽

J. B. Bradford ◽

M. G. Ryan

Keyword(s):

Leaf Area ◽

Forest Structure ◽

Stand Structure ◽

Forest Biomass ◽

Canopy Structure ◽

Primary Source ◽

Subalpine Forest ◽

Stand Age ◽

Area Index ◽

The North

This study evaluates the relative ability of simple light detection and ranging (lidar) indices (i.e., mean and maximum heights) and statistically derived canonical correlation analysis (CCA) variables attained from discrete-return lidar to estimate forest structure and forest biomass variables for three temperate subalpine forest sites. Both lidar and CCA explanatory variables performed well with lidar models having slightly higher explained variance and lower root mean square error. Adjusted R2 values were 0.93 and 0.93 for mean height, 0.74 and 0.73 for leaf area index, and 0.93 and 0.85 for all carbon in live biomass for the lidar and CCA explanatory regression models, respectively. The CCA results indicate that the primary source of variability in canopy structure is related to forest height, biomass, and total leaf area, and the second most important source of variability is related to the amount of midstory foliage and tree density. When stand age is graphed as a function of individual plot scores for canonicals one and two, there is a clear relationship with stand age and the development of stand structure. Lidar-derived biomass and related estimates developed in this work will be used to parameterize decision-support tools for analysis of carbon cycle impacts as part of the North American Carbon Program.

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

Canadian Journal of Forest Research ◽

10.1139/cjfr-2012-0324 ◽

2013 ◽

Vol 43 (1) ◽

pp. 18-27 ◽

Cited By ~ 9

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.

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