Temperature and vegetation seasonality diminishment over northern lands

Xu, Liang; Myneni, Ranga B.; Chapin, F. Stuart; Callaghan, Terry V.; Pinzón, Jorge Enrique Dí­az; Tucker, Compton J.; Zhu, Zhiliang; Bi, Jian; Ciais, Philippe; Tømmervik, Hans; Euskirchen, Eugénie; Forbes, Bruce C.; Piao, Shilong; Anderson, Bruce T.; Ganguly, Sangram; Nemani, R. R.; Goetz, Scott J.; Beck, Pieter S. A.; Bunn, A. G.; Cao, Chunxiang; Stroeve, Julienne

doi:10.1038/nclimate1836

Cited by 540 publications

(457 citation statements)

References 29 publications

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“…Most of the Eurasian boreal forests and Arctic regions have greened, whereas in North America only the Arctic region underlain by continuous permafrost north of the treeline has greened and most of the boreal forests have undergone browning trends. Although these contrasting continental and biome trends have been documented in earlier analyses of the GIMMS NDVI record [9,[15][16][17]19,22], our empirical results highlight the significant role of factors other than temperature and moisture on these vegetation patterns. A similar regional heterogeneity in the drivers of the greening trends in northern ecosystems has been found in attribution studies based on ecosystem models [85].…”

Section: Drivers Of Vegetation Greening and Browning Trendsmentioning

confidence: 38%

“…The boreal forest region was defined as all evergreen needleleaf, deciduous needleleaf and mixed forests north of 45 • N with woody fraction greater than 30% [19]. Natural grasslands, crops and relatively small areas of temperate forests north of 45 • N and south of the boreal forests were considered as the northern temperate grassland and cropland region.…”

Section: Northern Biomesmentioning

confidence: 99%

“…The analysis of the global satellite record of Normalized Difference Vegetation Index (NDVI) imagery since 1981 (e.g., [14]) has shown that increases in vegetation photosynthetic activity have been stronger in Eurasia than in North America and more sustained in the colder tundra biome than over the boreal forests [15][16][17][18][19]. The most recent studies have found that after the initial increasing trend in NDVI (i.e., greening) observed in the first decade of the record [5,20], longer and hotter growing seasons appear to have resulted in reductions of summer NDVI (i.e., browning) in the drier and more continental regions of the boreal forest since the 1990s [15][16][17]21].…”

Section: Introductionmentioning

confidence: 99%

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Temperature and Snow-Mediated Moisture Controls of Summer Photosynthetic Activity in Northern Terrestrial Ecosystems between 1982 and 2011

et al. 2014

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Recent warming has stimulated the productivity of boreal and Arctic vegetation by reducing temperature limitations. However, several studies have hypothesized that warming may have also increased moisture limitations because of intensified summer drought severity. Establishing the connections between warming and drought stress has been difficult because soil moisture observations are scarce. Here we use recently developed gridded datasets of moisture variability to investigate the links between warming and changes in available soil moisture and summer vegetation photosynthetic activity at northern latitudes (>45 • N) based on the Normalized Difference Vegetation Index (NDVI) since 1982. Moisture and temperature exert a significant influence on the interannual variability of Remote Sens. 2014, 6 1391 summer NDVI over about 29% (mean r 2 = 0.29 ± 0.16) and 43% (mean r 2 = 0.25 ± 0.12) of the northern vegetated land, respectively. Rapid summer warming since the late 1980s (∼0.7 • C) has increased evapotranspiration demand and consequently summer drought severity, but contrary to earlier suggestions it has not changed the dominant climate controls of NDVI over time. Furthermore, changes in snow dynamics (accumulation and melting) appear to be more important than increased evaporative demand in controlling changes in summer soil moisture availability and NDVI in moisture-sensitive regions of the boreal forest. In boreal North America, forest NDVI declines are more consistent with reduced snowpack rather than with temperature-induced increases in evaporative demand as suggested in earlier studies. Moreover, summer NDVI variability over about 28% of the northern vegetated land is not significantly associated with moisture or temperature variability, yet most of this land shows increasing NDVI trends. These results suggest that changes in snow accumulation and melt, together with other possibly non-climatic factors are likely to play a significant role in modulating regional ecosystem responses to the projected warming and increase in evapotranspiration demand during the coming decades.

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Section: Drivers Of Vegetation Greening and Browning Trendsmentioning

confidence: 38%

Section: Northern Biomesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temperature and Snow-Mediated Moisture Controls of Summer Photosynthetic Activity in Northern Terrestrial Ecosystems between 1982 and 2011

et al. 2014

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“…In addition, climate warming is expected to influence the vegetation abundance and composition in arctic and subarctic areas Larsen et al 2014), but to what extent temporal changes in cryogenic disturbance have contributed to temporal changes in vegetation is not well known. Recent vegetation change in the Arctic includes increased primary productivity recorded as increased Normalized Difference Vegetation Index in a large part of the Arctic (Xu et al 2013). This increased greenness is often attributed to increased abundance of shrubs, a phenomenon observed using modern and historical aerial photographs (Sturm et al 2001;Tape et al 2006;Lantz et al 2012;Becher et al 2013;Fraser et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Decreased cryogenic disturbance: one of the potential mechanisms behind the vegetation change in the Arctic

et al. 2017

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During the last few decades, the Arctic has experienced large-scale vegetation changes. Understanding the mechanisms behind this vegetation change is crucial for our ability to predict future changes. This study tested the hypothesis that decreased cryogenic disturbances cause vegetation change in patterned ground study fields (nonsorted circles) in Abisko, Sweden during the last few decades. The hypothesis was tested by surveying the composition of plant communities across a gradient in cryogenic disturbance and by reinvestigating plant communities previously surveyed in the 1980s to scrutinise how these communities changed in response to reduced cryogenic disturbance. Whereas the historical changes in species occurrence associated with decreased cryogenic disturbances were relatively consistent with the changes along the contemporary gradient of cryogenic disturbances, the species abundance revealed important transient changes highly dependent on the initial plant community composition. Our results suggest that altered cryogenic disturbances cause temporal changes in vegetation dynamics, but the net effects on vegetation communities depend on the composition of initial plant species.

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“…For Arctic marine biota, the rapid reduction of summer ice cover causes a tipping element that is now severely Permafrost degradation has contributed to widespread hydrological changes including lake formation or disappearance within a few years' time (high confidence; Prowse and Brown, 2010;Callaghan et al, 2013; Table 18-6), while increasing winter rains have had consequences for the tundra food webs (medium confidence; Post et al, 2009;Callaghan et al, 2013;Hansen et al, 2013). Indigenous people throughout the Arctic are impacted by these changes (Eira, 2012;Crate, 2013; see also Section 18.4.6).…”

Section: Impacts and Impact Eventsmentioning

confidence: 99%