scholarly journals Seasonal Spectral Separation of Western Snowberry and Wolfwillow in Grasslands with Field Spectroradiometer and Simulated Multispectral Bands

Environments ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 60
Author(s):  
Irini Soubry ◽  
Xulin Guo
Keyword(s):  
Cross Validation ◽  
Woody Plant ◽  
Woody Species ◽  
Woody Plant Encroachment ◽  
Canadian Prairies ◽  
Fall Season ◽  
Spectral Separation ◽  
Significant Difference ◽  
Spectral Separability ◽  
Trees And Shrubs

Woody plant encroachment (WPE), the expansion of native and non-native trees and shrubs into grasslands, has led to degradation worldwide. In the Canadian prairies, western snowberry and wolfwillow shrubs are common encroachers, whose cover is currently unknown. As the use of remote sensing in grassland monitoring increases, opportunities to detect and map these woody species are enhanced. Therefore, the purpose of this study is to identify the optimal season for detection of the two shrubs, to determine the sensitive wavelengths and bands that allow for their separation, and to investigate differences in separability potential between a hyperspectral and broadband multispectral approach. We do this by using spring, summer, and fall field-based spectra of both shrubs for the calculation of spectral separability metrics and for the simulation of broadband spectra. Our results show that the summer offers higher discrimination between the two species, especially when using the red and blue spectral regions and to a lesser extent the green region. The fall season fails to provide significant spectral separation along the wavelength spectrum. Moreover, there is no significant difference in the results from the hyperspectral or broadband approach. Nevertheless, cross-validation with satellite imagery is needed to confirm the current results.

scholarly journals Identification of the Optimal Season and Spectral Regions for Shrub Cover Estimation in Grasslands

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3098
Author(s):  
Irini Soubry ◽  
Xulin Guo
Keyword(s):  
Remote Sensing ◽  
Ecosystem Health ◽  
Woody Species ◽  
Shrub Encroachment ◽  
Shrub Cover ◽  
Grassland Ecosystem ◽  
Good Separation ◽  
Spectral Separability ◽  
Late Stages ◽  
Trees And Shrubs

Woody plant encroachment (WPE), the expansion of native and non-native trees and shrubs into grasslands, is a less studied factor that leads to declines in grassland ecosystem health. With the increasing application of remote sensing in grassland monitoring and measuring, it is still difficult to detect WPE at its early stages when its spectral signals are not strong enough. Even at late stages, woody species have strong vegetation characteristics that are commonly categorized as healthy ecosystems. We focus on how shrub encroachment can be detected through remote sensing by looking at the biophysical and spectral properties of the WPE grassland ecosystem, investigating the appropriate season and wavelengths that identify shrub cover, testing the spectral separability of different shrub cover groups and by revealing the lowest shrub cover that can be detected by remote sensing. Biophysical results indicate spring as the best season to distinguish shrubs in our study area. The earliest shrub encroachment can be identified most likely only when the cover reaches between 10% and 25%. A correlation between wavelength spectra and shrub cover indicated four regions that are statistically significant, which differ by season. Furthermore, spectral separability of shrubs increases with their cover; however, good separation is only possible for pure shrub pixels. From the five separability metrics used, Transformed divergence and Jeffries-Matusita distance have better interpretations. The spectral regions for pure shrub pixel separation are slightly different from those derived by correlation and can be explained by the influences from land cover mixtures along our study transect.

Conservation and Restoration of Grasslands

2018 ◽  
Author(s):  
Brian J. Wilsey
Keyword(s):  
Community Assembly ◽  
Woody Plants ◽  
Woody Plant ◽  
Priority Effects ◽  
Woody Plant Encroachment ◽  
Humpty Dumpty ◽  
Alternate States ◽  
Density And Biomass ◽  
Acid Test ◽  
Stocking Rates

Conservation programs alter herbivore stocking rates and find and protect the remaining areas that have not been plowed or converted to crops. Restoration is an ‘Acid Test’ for ecology. If we fully understand how grassland systems function and assemble after disturbance, then it should be easy to restore them after they have been degraded or destroyed. Alternatively, the idea that restorations will not be equivalent to remnants has been termed the ‘Humpty Dumpty’ hypothesis—once lost, it cannot be put back together again. Community assembly may follow rules, and if these rules are uncovered, then we may be able to accurately predict final species composition after assembly. Priority effects are sometimes found depending on species arrival orders, and they can result in alternate states. Woody plant encroachment is the increase in density and biomass of woody plants, and it is strongly affecting grassland C and water cycles.

Differential effects of nutrient addition and woody plant encroachment on grassland soil, litter and plant dynamics across a precipitation gradient

Pedobiologia ◽  
2021 ◽  
Vol 85-86 ◽  
pp. 150726
Author(s):  
Tiffany Pillay ◽  
David Ward ◽  
Admore Mureva ◽  
Michael Cramer
Keyword(s):  
Woody Plant ◽  
Nutrient Addition ◽  
Precipitation Gradient ◽  
Woody Plant Encroachment ◽  
Grassland Soil ◽  
Differential Effects ◽  
Plant Dynamics

Resilience aspects of woody plant species at the passage of fire: case of Quercus coccifera in Tlemcen Mountains (Algeria)

2020 ◽  
Vol 21 (2) ◽  
pp. 119-128
Author(s):  
Asma Rafa ◽  
◽  
Mohamed Berrichi ◽  
Ahmed Haddad ◽  
◽  
...  
Keyword(s):  
Heat Conduction ◽  
Porous Structure ◽  
Root System ◽  
Cross Sections ◽  
Woody Plant ◽  
Secondary Xylem ◽  
Woody Species ◽  
Average Diameter ◽  
Quercus Coccifera ◽  
Pyrolysis Gases

In this study, on the aspects of the resilience of woody species to the passage of fire, we wanted to test the alveolar specificity represented by the size of the pores of the secondary xylem of the root system in Quercus coccifera L., Pore size assessment is based on measuring 100 pores in cross sections, from the roots of 10 shrubs. The aim of this study is to explain how the roots can maintain their vitality after passing a fire and thus guarantee regeneration. In addition to the vigor of the root system of this species, the release of pyrolysis gases and the propagation of heat by conduction are provided by the porosity of the material. The results show that the pores are qualified as “fine” in the initial wood with an average diameter of 83.35 µm. In final wood, they are "very thin" with 42.30 µm in diameter. The absence of oxygen and the less porous structure delay the combustion cycle of the root system, the roots distant from the surface are thus protected from proliferation by heat conduction and thus guarantee regeneration.

scholarly journals Leaf geometric morphometrics among populations of Dalbergia ecastaphyllum (L.) Taub.

2019 ◽  
Vol 35 (6) ◽  
Author(s):  
Daniel Vieira de Morais ◽  
Lorena Andrade Nunes ◽  
Vandira Pereira da Mata ◽  
Maria Angélica Pereira de Carvalho Costa ◽  
Geni da Silva Sodré ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Geometric Morphometrics ◽  
Cross Validation ◽  
Abiotic Factors ◽  
Principal Component ◽  
Canonical Variate ◽  
Validation Test ◽  
Significant Difference ◽  
Variate Analysis ◽  
Geographical Distances

Leaves are plant structures that express important traits of the environment where they live. Leaf description has allowed identification of plant species as well as investigation of abiotic factors effects on their development, such as gases, light, temperature, and herbivory. This study described populations of Dalbergia ecastaphyllum through leaf geometric morphometrics in Brazil. We evaluated 200 leaves from four populations. The principal component analysis (PCA) showed that the first four principal components were responsible for 97.81% of variation. The non-parametric multivariate analysis of variance (NPMANOVA) indicated significant difference between samples (p = 0.0001). The Mentel test showed no correlation between geographical distances and shape. The canonical variate analysis (CVA) indicated that the first two variables were responsible for 96.77 % of total variation, while the cross-validation test showed an average of 83.33%. D. ecastaphyllum leaves are elliptical and ovate.

scholarly journals Alien and native woody plants in scattered vegetation in agricultural landscape

2020 ◽  
Vol 47 (2) ◽  
pp. 109-120
Author(s):  
Ján Supuka ◽  
Attila Tóth ◽  
Mária Bihuňová ◽  
Martina Verešová ◽  
Karol Šinka
Keyword(s):  
Tree Species ◽  
Woody Plants ◽  
Agricultural Landscape ◽  
Woody Plant ◽  
Robinia Pseudoacacia ◽  
Woody Species ◽  
Fruit Trees ◽  
Lycium Barbarum ◽  
Dominance Index ◽  
Acer Campestre

AbstractThe woody plant species composition has been evaluated in three cadastral territories of southwestern Slovakia, together in 77 habitats of non-forest woody vegetation (NFWV). A total of 43 tree species have been identified; 8 of them were alien and 5 species were cultural fruit trees. In total 20 shrub species were identified, out of which 3 were alien. Three woody species are classified as invasive according to the law in Slovakia: Acer negundo L., Ailanthus altissima (Mill.) Swingle, and Lycium barbarum L. They occurred only in 2, maximum in 4 of the evaluated habitats. The most occurring alien tree species Robinia pseudoacacia L. was generally identified in 58 habitats and in 48 habitats, with an incidence over 40% and dominance index of 70.6. The second most occurring alien tree Populus × canadensis had a dominance index of 8.3. The dominant native trees in NFWV were Acer campestre L., Fraxinus excelsior L., Quercus robur L., Salix fragilis L. with the dominance index of 1–5 only.

scholarly journals Post-fire management and recovery of a pine forest in Greece

Web Ecology ◽  
2010 ◽  
Vol 10 (1) ◽  
pp. 27-31 ◽  
Author(s):  
I. Spanos ◽  
Y. Raftoyannis ◽  
P. Platis ◽  
E. Xanthopoulou
Keyword(s):  
Woody Plant ◽  
Pinus Halepensis ◽  
Plant Cover ◽  
Woody Species ◽  
Control Site ◽  
Plant Composition ◽  
Northern Greece ◽  
Pine Regeneration ◽  
Negative Effect ◽  
Treatment Application

Abstract. The effects of management after fire in Pinus halepensis forests were assessed in northern Greece. Seeding, logging and building of log barriers were applied in burned sites and compared to a control site. Two years after treatment application, 70–80% of the ground in all sites was covered with vegetation. Seeding with herbaceous plants did not increase plant cover. Logging and building of log barriers negatively affected herbaceous species but increased woody species. During the first spring after fire, the highest numbers of P. halepensis seedlings were observed in the control site and the lowest number in the logged site. Logging and log barrier building had a negative effect on pine regeneration compared to control and seeding treatments. Woody plant composition was similar in control and seeding sites, with dominance of P. halepensis and Cistus species. A different pattern was observed in the logging and log-barrier sites with a low number of seeders and a high number of resprouter species.

scholarly journals Use of waste material in cultivation substrates

2004 ◽  
Vol 52 (2) ◽  
pp. 43-52
Author(s):  
Petr Salaš
Keyword(s):  
Large Scale ◽  
Woody Species ◽  
Practical Experience ◽  
Biological Properties ◽  
Waste Material ◽  
Research Activities ◽  
Cultivation Technology ◽  
Mutual Relations ◽  
Trees And Shrubs ◽  
Special Soil

Gardeners' practical experience and experimental work prove the affirmation that the used substrate is a very important base for the production of quality nursery products. It is important to emphasis the complexity and synergy of all factors influencing the ecosystem and there mutual relations. Physical, chemical and biological properties do not separately affect the growth and development of plants. In addition, the relations are not statical but differ in relation with other factors changes. This article is dealing with the possibility to use waste material from timber processing in cultivation substrates. The large scale use of such substrates would enable people to reach a relative independence from peat substrates, of which the global reserve is gradually decreasing.Our research activities focus on the use of bark. The basic problems of a bark substrate are easy dehydration and unbalanced nutrition of trees and shrubs. The suggested and experimented cultivation technology solves these problems. It is based on the cultivation of woody species in bark substrates, using modern irrigation systems, slow release fertilisers (Silvamix Forte) and special soil conditioners (TerraCottem). This technology was tested on the following species of trees and shrubs:MalusandBuxus.

scholarly journals Drivers of woody plant encroachment over Africa

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Z. S. Venter ◽  
M. D. Cramer ◽  
H.-J. Hawkins
Keyword(s):  
Woody Plant ◽  
Woody Plant Encroachment
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