Global vegetation variability and its response to elevated CO<sub>2</sub>, global warming, and climate variability – a study using the offline SSiB4/TRIFFID model and satellite data
<p>The climate regime shift during the 1980s had a substantial impact on the terrestrial ecosystems and vegetation at different scales. However, the mechanisms driving vegetation changes, before and after the shift, remain unclear. In this study, we used a biophysical dynamic vegetation model...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-01-01
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| Series: | Earth System Dynamics |
| Online Access: | https://www.earth-syst-dynam.net/10/9/2019/esd-10-9-2019.pdf |
| Summary: | <p>The climate regime shift during the 1980s had a
substantial impact on the terrestrial ecosystems and vegetation at different
scales. However, the mechanisms driving vegetation changes, before and after
the shift, remain unclear. In this study, we used a biophysical dynamic
vegetation model to estimate large-scale trends in terms of carbon fixation,
vegetation growth, and expansion during the period 1958–2007, and to
attribute these changes to environmental drivers including elevated
atmospheric <span class="inline-formula">CO<sub>2</sub></span> concentration (hereafter <span class="inline-formula">eCO<sub>2</sub></span>), global warming,
and climate variability (hereafter CV). Simulated leaf area index (LAI) and
gross primary production (GPP) were evaluated against observation-based data.
Significant spatial correlations are found (correlations <span class="inline-formula">></span> 0.87),
along with regionally varying temporal correlations of 0.34–0.80 for LAI and
0.45–0.83 for GPP. More than 40 % of the global land area shows
significant positive (increase) or negative (decrease) trends in LAI and GPP
during 1958–2007. Regions over the globe show different characteristics in terms
of ecosystem trends before and after the 1980s. While 11.7 % and 19.3 %
of land have had consistently positive LAI and GPP trends, respectively,
since 1958, 17.1 % and 20.1 % of land saw LAI and GPP trends, respectively,
reverse during the 1980s. Vegetation fraction cover (FRAC) trends,
representing vegetation expansion and/or shrinking, are found at the edges of
semi-arid areas and polar areas. Environmental drivers affect the change in
ecosystem trend over different regions. Overall, <span class="inline-formula">eCO<sub>2</sub></span> consistently
contributes to positive LAI and GPP trends in the tropics. Global warming
mostly affects LAI, with positive effects in high latitudes and negative
effects in subtropical semi-arid areas. CV is found to dominate the
variability of FRAC, LAI, and GPP in the semi-humid and semi-arid areas. The
<span class="inline-formula">eCO<sub>2</sub></span> and global warming effects increased after the 1980s, while the CV
effect reversed during the 1980s. In addition, plant competition is shown to
have played an important role in determining which driver dominated the
regional trends. This paper presents new insight into ecosystem
variability and changes in the varying climate since the 1950s.</p> |
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| ISSN: | 2190-4979 2190-4987 |