Shrub expansion at the forest–tundra ecotone: spatial heterogeneity linked to local topography

Ropars, Pascale; Boudreau, Stéphane

doi:10.1088/1748-9326/7/1/015501

Cited by 132 publications

(146 citation statements)

References 38 publications

(27 reference statements)

Supporting

Mentioning

138

Contrasting

Unclassified

Order By: Relevance

“…The monitoring of shrub vegetation is therefore important for the understanding of the ongoing changes in northern environments. Current methods rely either on field sampling or aerial and satellite imagery in the visible and infrared spectrum to assess changes in shrub coverage or growth [6,8,[16][17][18][19][20]. However, these methods have certain limitations as the field sampling methods can be very costly and do not provide a high spatial coverage, while satellite imagery in the visible and infrared spectrum is affected by the presence of clouds, which can be persistent in northern regions [16,21].…”

Section: Introductionmentioning

confidence: 99%

Land Cover Classification in SubArctic Regions Using Fully Polarimetric RADARSAT-2 Data

et al. 2016

View full text Add to dashboard Cite

Abstract:The expansion of shrub vegetation in Arctic and sub-Arctic environments observed in the past decades can have significant effects on northern ecosystems. There is a need for efficient tools to monitor those changes, not only in terms of the spatial coverage of shrubs, but also their vertical growth. The objective of the current paper is to evaluate the performance of polarimetric C-band SAR datasets for land cover classification in sub-Arctic environments. A series of RADARSAT-2 quad-pol images were acquired between October 2011 and April 2012. The Support Vector Machine (SVM) classification scheme was used on three sets of features: the elements of the polarimetric coherency matrix [T], the parameters extracted from a polarimetric decomposition based on the eigenvalues and eigenvectors of [T] and the parameters extracted from a model-based decomposition. Using a single image, the results show that the best classification accuracies (≈ 75%) are obtained using the [T] matrix with the October images. When adding a second image to the feature set, either from two different dates or two incidence angles, the classification accuracy is improved and reaches 90.1% with two images from October 2011 and April 2012 at 27 • incidence. The results show that C-band polarimetric SAR imagery is an adequate tool to map shrub vegetation in sub-Arctic environments.

show abstract

Section: Introductionmentioning

confidence: 99%

Land Cover Classification in SubArctic Regions Using Fully Polarimetric RADARSAT-2 Data

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Vegetation structural attributes, such as height, may influence ground temperatures, active-layer depth, albedo, and atmospheric warming [8][9][10][11][12][13][14]. The TTE is also variable in its response to environmental change, likely a result of interacting environmental factors including substrate, disturbance history, and geographic position [15][16][17]. TTE vegetation height is neither spatially uniform in its current state nor in the manner in which it is changing [18].…”

Section: Introductionmentioning

confidence: 99%

The Uncertainty of Plot-Scale Forest Height Estimates from Complementary Spaceborne Observations in the Taiga-Tundra Ecotone

et al. 2014

View full text Add to dashboard Cite

Satellite-based estimates of vegetation structure capture broad-scale vegetation characteristics as well as differences in vegetation structure at plot-scales. Active remote sensing from laser altimetry and radar systems is regularly used to measure vegetation height and infer vegetation structural attributes, however, the current uncertainty of their spaceborne measurements is likely to mask actual plot-scale differences in vertical structures in sparse forests. In the taiga (boreal forest)-tundra ecotone (TTE) the accumulated effect of subtle plot-scale differences in vegetation height across broad-scales may be significant. This paper examines the uncertainty of plot-scale forest canopy height measurements in northern Siberia Larix stands by combining complementary canopy surface elevations derived from satellite photogrammetry and ground elevations derived from the Geosciences Laser Altimeter System (GLAS) from the ICESat-1 satellite. With a linear model, spaceborne-derived canopy height measurements at the plot-scale predicted TTE stand height ~5 m-~10 m tall (R 2 = 0.55, bootstrapped 95% confidence interval of R 2 = 0.36-0.74) with an uncertainty ranging from ±0.86 m-1.37 m. A larger sample may mitigate the broad uncertainty of the model fit, however, the methodology provides a means for capturing plot-scale canopy height and its uncertainty from spaceborne data at GLAS footprints in

show abstract

“…On the regional to global level, shrub growth is limited by summer air temperatures and the length of the growing season (Myers-Smith, Forbes et al 2011;Myers-Smith et al 2015), while locally other factors such as topography, hydrology and nutrient availability can become limiting (Shaver & Chapin 1980;Walker 2000;Naito & Cairns 2011;Ropars & Boudreau 2012), making the response of vegetation to climatic change more heterogeneous (Lantz et al 2010;.…”

mentioning

confidence: 99%

Vegetation composition and shrub extent on the Yukon coast, Canada, are strongly linked to ice-wedge polygon degradation

et al. 2016

View full text Add to dashboard Cite

Shrub expansion at the forest–tundra ecotone: spatial heterogeneity linked to local topography

Cited by 132 publications

References 38 publications

Land Cover Classification in SubArctic Regions Using Fully Polarimetric RADARSAT-2 Data

Land Cover Classification in SubArctic Regions Using Fully Polarimetric RADARSAT-2 Data

The Uncertainty of Plot-Scale Forest Height Estimates from Complementary Spaceborne Observations in the Taiga-Tundra Ecotone

Vegetation composition and shrub extent on the Yukon coast, Canada, are strongly linked to ice-wedge polygon degradation

Contact Info

Product

Resources

About