Assessing the Evidence for Changes in Vegetation Phenology in High-Altitude Wetlands of Ladakh (2002–2015)

Spatial patterns of long‐term vegetation greening and browning are consistent across multiple scales: Implications for monitoring land degradation

“…We addressed intraannual and interannual trends by examining the linear trend (Figure 1) for each pixel, for each of the dates (Julian Day) in their respective time series (Bagchi, Gupta, et al, 2017;Verbyla, 2008).…”

“…We addressed intraannual and interannual trends by examining the linear trend (Figure ) for each pixel, for each of the dates (Julian Day) in their respective time series (Bagchi, Gupta, et al, ; Verbyla, ). For this, we used Theil–Sen estimate for slope of regression (i.e., Sen's slope; Fernandes & Leblanc, ), as it is a more robust estimator of trend than ordinary least squares regression in the presence of outliers in the data.…”

“…Trees are rare ( Salix , Populus , and Juniperus ) and are often restricted to river valleys where people plant them for timber and fuelwood. Vegetation growth period is short, between May and August (Bagchi, Gupta, et al, ). Grazing, by livestock and wild herbivores, is the primary land use across the Trans‐Himalaya, alongside subsistence‐based agriculture in human settlements near river valleys.…”

“…Degradation and desertification across the larger Trans-Himalayan landscape are serious concerns that are often linked with livestock overgrazing (Shaohong et al, 2007) but remain to be adequately addressed (Bagchi, Gupta, Murthy, & Singh, 2017). Loss of ecosystem function and services, declining wildlife populations, negative impacts on human livelihoods with increase in ecological refugees, intensified soil erosion, and severe dust-storms, as well as devastating locust outbreaks, are some consequences linked to altered vegetation and climate in this ecoregion (Feng, Guo, Luo, & Qin, 2012;Neumann et al, 2015;Piao, Friedlingstein, Ciais, Viovy, & Demarty, 2007;Wang, Dong, Zhang, & Liu, 2004;Wang et al, 2017).…”

“…In a second step, we screened areas that were vegetated (grasslands and shrubsteppes), because large regions of the study area are under permanent snow or ice, or are barren scree, and otherwise lack natural vegetation cover. Through previous ground surveys in Ladakh and Spiti regions, we found that annual peak NDVI of typical vegetated patches ranges between 0.18 and 0.55 (Bagchi, Gupta, et al, 2017). We applied this as a selection criterion; pixels with annual peak NDVI value >0.18 for at least 70% of the time series were included in further analysis.…”