Biotope Types of the Treeline of the Central Greater Caucasus

Nakhutsrishvili, George; Abdaladze, Otar; Akhalkatsi, Maia

doi:10.1007/978-3-540-47229-2_22

Cited by 16 publications

(21 citation statements)

References 7 publications

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“…B. litwinowii in particular invaded sites in which R. caucasicum and H. rhamnoides formed dominant stands. These results are consistent with other studies conducted in the Kazbegi region that found R. caucasicum facilitates the growth of B. litwinowii seedlings by enhancing the microclimate and nutrient availability of the habitat (Akhalkatsi et al 2006). A similar process can be assumed for the H. rhamnoides stands.…”

Section: Spectral Separation Of Target Speciessupporting

confidence: 92%

“…However, some studies report that B. litwinowii and tall herb communities with V. lobelianum grow in close proximity (Walter ; Nakhutsrishvili et al. ; Togonidze & Akhalkatsi ). The separation of the reflectance signal extracted from the vegetation relevés was thus considerably lower than the separation achieved with the simulated data.…”

Section: Discussionmentioning

confidence: 99%

“…In this study region forests are limited to steep, north-facing and inaccessible slopes, and the landscape is mainly characterized by grassland communities (Ketskhoveli et al 1975). Up to the 1990s, very strong grazing pressure and illegal cutting of firewood hampered any establishment of woody species (Akhalkatsi et al 2006). However, a visual comparison of aerial images of the region from 1975, 1980 and 2005 based on expert knowledge and field visits already revealed a trend towards re-forestation and initial succession of birch (Betula litwinowii) in the Kazbegi district (Waldhardt et al 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Individual trees form the tree line at about 2500 m a.s.l. (Akhalkatsi et al 2006). In contrast, the thorny H. rhamnoides with its silvery lanceolate leaves forms dense shrubs (up to 350-cm high), which occur mainly on disturbed sites, such as areas of landslide or fluvial deposits of the small streams and rivers in the valley (Tephnadze et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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Separating reflectance signatures of shrub species – a case study in the Central Greater Caucasus

Magiera

Feilhauer

Tephnadze

et al. 2015

Applied Vegetation Science

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Questions Shrub encroachment has been observed in many alpine and arctic environments and is expected to significantly alter these ecosystems. Mapping these processes with remote sensing is a powerful tool for monitoring purposes. Thus, we test the distinctiveness of the reflectance signature of target species relative to their co‐occurring shrub species using uni‐ and multivariate analyses for an alpine ecosystem. We ask: (i) is it possible to differentiate shrub species with a unique growth form by their reflectance signature; (ii) which of the tested multispectral sensors produces the best separation; and (iii) how are the results affected by the timing of data acquisition in the vegetation period? Location Kazbegi district, Central Greater Caucasus, Georgia. Method We analysed three shrub (Betula litwinowii, Rhododendron caucasicum, Hippophae rhamnoides) and one tall forb (Veratrum lobelianum) species occurring in the sub‐alpine to alpine belt The vegetation of 52 relevés was analysed using non‐metric multidimensional scaling and indicator species analysis. From field spectrometric data we simulated multispectral sensor bands (IKONOS, Quickbird 2, RapidEye, WorldView‐2) directly taken from the target species. We analysed the reflectance signature in RapidEye data from June and September. For all data sets we calculated the Jeffries‐Matusita distance (JMD) as a separation measure and tested the reflectance signature of the single bands for differences. Results Betula litwinowii and V. lobelianum always co‐occurred in our data. A high abundance of B. litwinowii could also be found in the Rhododendron cluster and vice versa, whereas the Hippophae cluster was more homogeneous. Simulated bands showed good overall separation (JMD 1.58–2.00) of the target species. The separation increased with the increase of number of bands and inclusion of the red edge band. There was a general trend in which the reflectance from satellite images produced a lower separation (JMD 1.20–1.55) than the simulations, with the best separation in the late vegetation period. Conclusion Our results showed the possibility to spectrally separate encroaching shrub species with a unique growth form in a high‐mountain environment using simulated multispectral data and satellite imagery.

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Section: Spectral Separation Of Target Speciessupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Separating reflectance signatures of shrub species – a case study in the Central Greater Caucasus

Magiera

Feilhauer

Tephnadze

et al. 2015

Applied Vegetation Science

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“…Cattle tracks and erosion can be observed on the steep slopes of the grassland (Figure 2A). Due to anthropogenic impact and topographic features, no clear demarcation line can be drawn between the high-montane and subalpine zones of the Greater Caucasus (Lichtenegger et al 2006;Nakhutsrishvili et al 2006). We defined the high-montane zone border at about 1900 masl, where scattered rhododendron shrubs (Rhododendron luteum) indicate a transition to the subalpine zone.…”

Section: Study Areamentioning

confidence: 99%

Remote Sensing for Grassland Management in the Arid Southwest

Marsett¹,

Heilman

et al. 2006

REM

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We surveyed a group of rangeland managers in the Southwest about vegetation monitoring needs on grassland. Based on their responses, the objective of the RANGES (Rangeland Analysis Utilizing Geospatial Information Science) project was defined to be the accurate conversion of remotely sensed data (satellite imagery) to quantitative estimates of total (green and senescent) standing cover and biomass on grasslands and semidesert grasslands. Although remote sensing has been used to estimate green vegetation cover, in arid grasslands herbaceous vegetation is senescent much of the year and is not detected by current remote sensing techniques. We developed a ground truth protocol compatible with both range management requirements and Landsat’s 30 m resolution imagery. The resulting ground-truth data were then used to develop image processing algorithms that quantified total herbaceous vegetation cover, height, and biomass. Cover was calculated based on a newly developed Soil Adjusted Total Vegetation Index (SATVI), and height and biomass were estimated based on reflectance in the near infrared (NIR) band. Comparison of the remotely sensed estimates with independent ground measurements produced r2 values of 0.80, 0.85, and 0.77 and Nash Sutcliffe values of 0.78, 0.70, and 0.77 for the cover, plant height, and biomass, respectively. The approach for estimating plant height and biomass did not work for sites where forbs comprised more than 30% of total vegetative cover. The ground reconnaissance protocol and image processing techniques together offer land managers accurate and timely methods for monitoring extensive grasslands. The time-consuming requirement to collect concurrent data in the field for each image implies a need to share the high fixed costs of processing an image across multiple users to reduce the costs for individual rangeland managers.

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Vegetation of the Central Great Caucasus Along W-E and N-S Transects

Nakhutsrishvili

Abdaladze

2017

Geobotany Studies

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Biotope Types of the Treeline of the Central Greater Caucasus

Cited by 16 publications

References 7 publications

Separating reflectance signatures of shrub species – a case study in the Central Greater Caucasus

Separating reflectance signatures of shrub species – a case study in the Central Greater Caucasus

Remote Sensing for Grassland Management in the Arid Southwest

Vegetation of the Central Great Caucasus Along W-E and N-S Transects

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