Vegetation phenology gradients along the west and east coasts of Greenland from 2001 to 2015

Karami, Mojtaba; Hansen, Birger Ulf; Westergaard‐Nielsen, Andreas; Abermann, Jakob; Lund, Magnus; Schmidt, Niels Martin; Elberling, Bo

doi:10.1007/s13280-016-0866-6

Cited by 17 publications

(12 citation statements)

References 33 publications

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“…Here we consequently use cloud-free data only which are gap-filled based on empirical relationships between estimates of net daily shortwave radiation and LST, as described in ref. 20 . Terra overpasses central Greenland at approx.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, a method to use LST to assess ground temperatures in a larger North Atlantic region was presented, but scarcely validated for sub-regions such as Greenland 13 . Here we use a gap-filled version of MOD11A1 (following 20 ), due to otherwise missing data in cloudy conditions that can cause a significant cold bias 21 . The resulting distribution of LST data across Greenland (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Contrasting temperature trends across the ice-free part of Greenland

Westergaard‐Nielsen

Karami

Hansen

et al. 2018

Sci Rep

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Temperature changes in the Arctic have notable impacts on ecosystem structure and functioning, on soil carbon dynamics, and on the stability of permafrost, thus affecting ecosystem functions and putting man-built infrastructure at risk. Future warming in the Arctic could accelerate important feedbacks in permafrost degradation processes. Therefore it is important to map vulnerable areas most likely to be impacted by temperature changes and at higher risk of degradation, particularly near communities, to assist adaptation to climate change. Currently, these areas are poorly assessed, especially in Greenland. Here we quantify trends in satellite-derived land surface temperatures and modelled air temperatures, validated against observations, across the entire ice-free Greenland. Focus is on the past 30 years, to characterize significant changes and potentially vulnerable regions at a 1 km resolution. We show that recent temperature trends in Greenland vary significantly between seasons and regions and that data with resolutions down to single km2 are critical to map temperature changes for guidance of further local studies and decision-making. Only a fraction of the ice-free Greenland seems vulnerable due to warming when analyzing year 2001–2015, but the most pronounced changes are found in the most populated parts of Greenland. As Greenland represents important gradients of north/south coast/inland/distance to large ice sheets, the conclusions are also relevant in an upscaling to greater Arctic areas.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Contrasting temperature trends across the ice-free part of Greenland

Westergaard‐Nielsen

Karami

Hansen

et al. 2018

Sci Rep

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“…When compared with previous studies that used MODIS datasets after 2000 to analyze vegetation variation [78,79], this study used the GLASS GPP product and revealed the spatiotemporal characteristics of GPP in the GKM from 1982 to 2015. Obviously, an extension of the study period could provide much more information about the dynamic change of vegetation and the carbon cycle.…”

Section: Study Limitationsmentioning

confidence: 99%

Spatiotemporal Dynamics in Vegetation GPP over the Great Khingan Mountains Using GLASS Products from 1982 to 2015

Fan

Ren

et al. 2018

Remote Sensing

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Gross primary productivity (GPP) is an important parameter that represents the productivity of vegetation and responses to various ecological environments. The Greater Khingan Mountain (GKM) is one of the most important state-owned forest bases, and boreal forests, including the largest primeval cold-temperature bright coniferous forest in China, are widely distributed in the GKM. This study aimed to reveal spatiotemporal vegetation variations in the GKM on the basis of GPP products that were generated by the Global LAnd Surface Satellite (GLASS) program from 1982 to 2015. First, we explored the spatiotemporal distribution of vegetation across the GKM. Then we analyzed the relationships between GPP variation and driving factors, including meteorological elements, growing season length (GSL), and Fraction of Photosynthetically Active Radiation (FPAR), to investigate the dominant factor for GPP dynamics. Results demonstrated that (1) the spatial distribution of accumulated GPP (AG) in spring, summer, autumn, and the growing season varied due to three main reasons: understory vegetation, altitude, and land cover; (2) interannual AG in summer, autumn, and the growing season significantly increased at the regional scale during the past 34 years under climate warming and drying; (3) interannual changes of accumulated GPP in the growing season (AGG) at the pixel scale displayed a rapid expansion in areas with a significant increasing trend (p < 0.05) during the period of 1982-2015 and this trend was caused by the natural forest protection project launched in 1998; and finally, (4) an analysis of driving factors showed that daily sunshine duration in summer was the most important factor for GPP in the GKM and this is different from previous studies, which reported that the GSL plays a crucial role in other areas.

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“…Each satellite provides an NDVI dataset with a temporal resolution of 16 days and a spatial resolution of approximately 250 m. The data from the two satellites were combined in order to achieve a more complete time series covering years 2001–2017. The data were processed in agreement with Karami et al (), in order to remove the effects of cloud cover and smooth the time series through temporal interpolation of the NDVI. Some modifications were applied to the original algorithm to improve the cloud detection mechanism and to obtain a more realistic seasonal NDVI curve (see Karami et al, ).…”

Section: Methodsmentioning

confidence: 99%

Immediate and carry‐over effects of insect outbreaks on vegetation growth in West Greenland assessed from cells to satellite

Prendin

Carrer

Karami

et al. 2019

Journal of Biogeography

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Aim Tundra ecosystems are highly vulnerable to climate change, and climate–growth responses of Arctic shrubs are variable and altered by microsite environmental conditions and biotic factors. With warming and drought during the growing season, insect‐driven defoliation is expected to increase in frequency and severity with potential broad‐scale impacts on tundra ecosystem functioning. Here we provide the first broad‐scale reconstruction of spatio‐temporal dynamics of past insect outbreaks by assessing their effects on shrub growth along a typical Greenlandic fjord climate gradient from the inland ice to the sea. Location Nuuk Fjord (64°30′N/51°23′W) and adjacent areas, West Greenland. Taxa Great brocade (Eurois occulta L.) and grey willow (Salix glauca L.). Methods We combined dendro‐anatomical and remote sensing analyses. Time series of ring width (RW) and wood‐anatomical traits were obtained from chronologies of >40 years established from 153 individuals of S. glauca collected at nine sites. We detected anomalies in satellite‐based Normalized Difference Vegetation Index (NDVI) related to defoliation and reconstructed past changes in photosynthetic activity across the region. Results We identified outbreaks as distinctive years with reduced RW, cell‐wall thickness and vessel size, without being directly related to climate but matching with years of parallel reduction in NDVI. The two subsequent years after the defoliation showed a significant increase in RW. The reconstructed spatio‐temporal dynamics of these events indicate substantial regional variation in outbreak intensity linked to the climate variability across the fjord system. Main conclusions Our results highlight the ability of S. glauca to cope with severe insect defoliation by changing carbon investment and xylem conductivity leading to high resilience and rapid recovery after the disturbance. Our multiproxy approach allows us to pinpoint biotic drivers of narrow ring formation and to provide new broad‐scale insight on the C‐budget and vegetation productivity of shrub communities in a widespread arctic ecosystem.

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Vegetation phenology gradients along the west and east coasts of Greenland from 2001 to 2015

Cited by 17 publications

References 33 publications

Contrasting temperature trends across the ice-free part of Greenland

Contrasting temperature trends across the ice-free part of Greenland

Spatiotemporal Dynamics in Vegetation GPP over the Great Khingan Mountains Using GLASS Products from 1982 to 2015

Immediate and carry‐over effects of insect outbreaks on vegetation growth in West Greenland assessed from cells to satellite

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